Order Now Product Folder Support & Community Tools & Software Technical Documents LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 LMK04906 Ultralow Noise Clock Jitter Cleaner and Multiplier With 6 Programmable Outputs 1 Features 2 Applications * * * 1 * * * * * * * * * * * * * * Ultralow RMS Jitter Performance - 100-fs RMS Jitter (12 kHz to 20 MHz) - 123-fs RMS Jitter (100 Hz to 20 MHz) Dual Loop PLLatinumTM PLL Architecture - PLL1 - Integrated Low-Noise Crystal Oscillator Circuit - Holdover Mode when Input Clocks are Lost - Automatic or Manual Triggering/Recovery - PLL2 - Normalized [1 Hz] PLL Noise Floor of -227 dBc/Hz - Phase Detector Rate up to 155 MHz - OSCin Frequency-doubler - Integrated Low-Noise VCO 3 Redundant Input Clocks with LOS - Automatic and Manual Switch-Over Modes 50% Duty Cycle Output Divides, 1 to 1045 (Even and Odd) LVPECL, LVDS, or LVCMOS Programmable Outputs Precision Digital Delay, Fixed or Dynamically Adjustable 25-ps Step Analog Delay Control. 6 Differential Outputs. Up to 12 Single Ended. - Up to 5 VCXO/Crystal Buffered Outputs Clock Rates of up to 2600 MHz 0-Delay Mode Three Default Clock Outputs at Power Up Multi-mode: Dual PLL, Single PLL, and Clock Distribution Industrial Temperature Range: -40 to 85 C 3.15-V to 3.45-V Operation Package: 64-Pin WQFN (9 mm x 9 mm x 0.8 mm) System Application Diagram Backplane * * * * * * * * * * 10G, 40G, and 100G OTN Line Cards SONET/SDH OC-48/STM-16 and OC-192/STM64 Line Cards GbE/10GbE, 1/2/4/8/10GFC Line Cards ITU G.709 and Custom FEC Line Cards Synchronous Ethernet Optical Modules DSLAM/MSANs Test and Measurement Broadcast Video Wireless Basestations Data Converter Clocking Microwave ODU and IDUs for Wireless Backhaul 3 Description The LMK04906 is the industry's highest performance clock jitter attenuator with superior clock jitter cleaning, generation, and distribution with advanced features to meet high performance timing application needs. The LMK04906 accepts 3 clock inputs ranging from 1 kHz to 500 MHz and generates 6 unique clock output frequencies ranging from 284 kHz to 2.6 GHz. The LMK04906 can also buffer a crystal or VCXO to generate a 7th unique clock frequency. The device provides virtually all frequency translation combinations required for SONET, Ethernet, Fibre Channel and multi-mode Wireless Base Stations. The LMK04906 input clock frequency and clock multiplication ratio are programmable through a SPI interface. Device Information(1) PART NUMBER LMK04906 VCO FREQUENCY REFERENCE INPUTS 2370 to 2600 MHz 3 (1) For all available packages, see the orderable addendum at the end of the data sheet. Simplified LMK04906 Block Diagram Crystal or VCXO Hitless Switching, Jitter Cleaning, Frequency Multiplication, and Programmable Clock Distribution LMK04906 156.25 MHz LVPECL 10 GbE PHY 10 GbE PHY 100 MHz LVDS 33.33 MHz LVCMOS FPGA NPU LMX2541 OSCout0 0XOWLSOH FOHDQ clocks at different frequencies PLL+VCO LMK04906 CLKin0 Recovered GLUW\ FORFNV or clean clocks SONET CLKout2 CLKout3 CLKin2 Backup Reference Clock SONET CLKout1 Precision Clock Conditioner 622.08, 155.52, 77.76, 19.44 MHz Copyright (c) 2016, Texas Instruments Incorporated Serializer/ Deserializer CLKout0 LMK04906 CLKin1 ADC CLKout4 FPGA DAC CPLD Copyright (c) 2016, Texas Instruments Incorporated 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table of Contents 1 2 3 4 5 6 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 6.1 6.2 6.3 6.4 6.5 6.6 6.7 7 1 1 1 2 3 5 Absolute Maximum Ratings ..................................... 5 ESD Ratings.............................................................. 5 Recommended Operating Conditions ...................... 5 Thermal Information .................................................. 5 Electrical Characteristics........................................... 6 Timing Requirements .............................................. 12 Typical Characteristics ............................................ 13 Parameter Measurement Information ................ 14 7.1 Charge Pump Current Specification Definitions...... 14 7.2 Differential Voltage Measurement Terminology...... 15 8 Detailed Description ............................................ 17 8.1 8.2 8.3 8.4 8.5 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ Programming........................................................... 17 21 21 42 45 8.6 Register Maps ......................................................... 48 9 Application and Implementation ........................ 85 9.1 9.2 9.3 9.4 Application Information............................................ 85 Typical Application ............................................... 101 System Examples ................................................. 108 Do's and Don'ts ..................................................... 111 10 Power Supply Recommendations ................... 112 10.1 Pin Connection Recommendations..................... 112 10.2 Current Consumption and Power Dissipation Calculations............................................................ 113 11 Layout................................................................. 115 11.1 Layout Guidelines ............................................... 115 11.2 Layout Example .................................................. 117 12 Device and Documentation Support ............... 118 12.1 Device Support.................................................... 12.2 Receiving Notification of Documentation Updates.................................................................. 12.3 Community Resource.......................................... 12.4 Trademarks ......................................................... 12.5 Electrostatic Discharge Caution .......................... 12.6 Glossary .............................................................. 118 118 118 118 118 118 13 Mechanical, Packaging, and Orderable Information ......................................................... 118 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision E (August 2016) to Revision F Page * Changed From: CLKout3_PD = 0 To: CLKout2_PD = 0 in Table 7..................................................................................... 37 * Changed From: CLKout3_PD = 0 To: CLKout2_PD = 0 in Table 9..................................................................................... 40 Changes from Revision D (May 2013) to Revision E Page * Changed 750 to 500 ............................................................................................................................................................... 1 * Changed 2.26 MHz to 284 kHz .............................................................................................................................................. 1 * Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section ................................................................................................. 1 * Changed Clock Switch Event With Holdover section. .......................................................................................................... 26 * Deleted Clock Switch Event without Holdover section. ........................................................................................................ 26 * Changed 5 cycles to 5.5 cycles............................................................................................................................................ 38 * Changed 5 cycles to 5.5 cycles............................................................................................................................................ 41 * Added (Auto modes only). .................................................................................................................................................... 70 * Changed equation ................................................................................................................................................................ 94 Changes from Revision C (May 2013) to Revision D * 2 Page Changed layout of National Semiconductor Data Sheet to TI format. ............................................................................... 115 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 5 Pin Configuration and Functions NC Status_CLKin1 Status_CLKin0 NC NC CLKout5* CLKout5 Vcc12 NC NC CLKout4* CLKout4 Vcc11 NC CLKout3* CLKout3 NKD Package 64-Pin WQFN With Exposed Pad Top View 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 Vcc13 1 48 Vcc10 NC 2 47 NC CLKout0* 3 46 DATAuWire CLKout0 4 45 CLKuWire NC 5 44 LEuWire SYNC/ Status_CLKin2 6 43 Vcc9 NC 7 42 CPout2 NC 8 41 Vcc8 NC 9 40 OSCout0* Vcc1 10 39 OSCout0 LDObyp1 11 38 Vcc7 LDObyp2 12 37 OSCin* CLKout1 13 36 OSCin CLKout1* 14 35 Vcc6 NC 15 34 CPout1 Vcc2 16 33 Status_LD NC 27 28 29 30 31 32 CLKin2* CLKout2 26 CLKin2 CLKout2* 25 Vcc5 NC 24 CLKin0* NC 23 CLKin0 22 Status_Holdover 21 FBCLKin*/Fin*/CLKin1* 20 FBCLKin/Fin/CLKin1 19 GND 18 Vcc4 17 Vcc3 DAP Pin Functions PIN I/O TYPE 1 -- PWR 2, 5, 7, 8, 9, 15, 17, 19 22, 47, 51, 55, 56, 60, 61, 64 -- No Connect NAME NO. Vcc13 NC CLKout0*, CLKout0 DESCRIPTION (1) Power Supply for CLKou0 These pins must be left floating. 3, 4 O Programmable Clock output 0. SYNC / Status_CLKin2 6 I/O Programmable CLKout Synchronization input or CLKin2 Status output. Vcc1 10 -- PWR Power supply for VCO LDO. LDObyp1 11 -- ANLG LDO Bypass, bypassed to ground with 10 F capacitor. (1) See Application and Implementation section for recommended connections. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 3 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Pin Functions (continued) PIN NAME NO. LDObyp2 CLKout1, CLKout1* Vcc2 Vcc3 I/O 12 -- 13, 14 O 16 -- DESCRIPTION (1) TYPE ANLG LDO Bypass, bypassed to ground with a 0.1 F capacitor. Programmable Clock output 1. PWR Power supply for CLKout1. PWR Power supply for CLKout2 18 -- 20, 21 O GND 23 -- PWR Ground Vcc4 24 -- PWR Power supply for digital. CLKout2*, CLKout2 Programmable Clock output 2 CLKin1, CLKin1* FBCLKin, FBCLKin* Reference Clock Input Port 1 for PLL1. AC or DC Coupled. 25, 26 I ANLG Fin/Fin* Feedback input for external clock feedback input (0-delay mode). AC or DC Coupled. External VCO input (External VCO mode). AC or DC Coupled. Programmable status pin, default readback output. Programmable Programmable to holdover mode indicator. Other options available by programming. Status_Holdover 27 I/O CLKin0, CLKin0* 28, 29 I ANLG Reference Clock Input Port 0 for PLL1. AC or DC Coupled. 30 -- PWR Power supply for clock inputs. 31, 32 I ANLG Reference Clock Input Port 2 for PLL1, AC or DC Coupled. Status_LD 33 I/O Programmable CPout1 34 O ANLG Charge pump 1 output. Vcc6 35 -- PWR Power supply for PLL1, charge pump 1. 36, 37 I ANLG Feedback to PLL1, Reference input to PLL2. AC Coupled. PWR Power supply for OSCin port. Vcc5 CLKin2, CLKin2* OSCin, OSCin* Vcc7 Programmable status pin, default lock detect for PLL1 and PLL2. Other options available by programming. 38 -- 39, 40 O Vcc8 41 -- PWR Power supply for PLL2, charge pump 2. CPout2 42 O ANLG Charge pump 2 output. Vcc9 43 -- PWR Power supply for PLL2. LEuWire 44 I CMOS MICROWIRE Latch Enable Input. CLKuWire 45 I CMOS MICROWIRE Clock Input. DATAuWire 46 I CMOS MICROWIRE Data Input. Vcc10 48 -- PWR OSCout0, OSCout0* CLKout3, CLKout3* Vcc11 CLKout4, CLKout4* Vcc12 49, 50 O 52 -- 53, 54 O Programmable Buffered output 0 of OSCin port. Power supply for CLKout3. Programmable Clock output 3. PWR Power supply for CLKout4. Programmable Clock output 4. 57 -- 58, 59 O Programmable Clock output 5. Status_CLKin0 62 I/O Programmable status pin. Default is input for pin control of PLL1 Programmable reference clock selection. CLKin0 LOS status and other options available by programming. Status_CLKin1 63 I/O Programmable status pin. Default is input for pin control of PLL1 Programmable reference clock selection. CLKin1 LOS status and other options available by programming. DAP -- CLKout5, CLKout5* DAP 4 PWR GND Power supply for CLKout5. DIE ATTACH PAD, connect to GND. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2) (3) VCC Supply voltage VIN Input voltage IIN Differential input current (CLKinX/X*, OSCin/OSCin*, FBCLKin/FBCLKin*, Fin/Fin*) MSL Moisture sensitivity level TJ Junction temperature Tstg Storage temperature (1) (2) (3) MIN MAX UNIT -0.3 3.6 V -0.3 (VCC + 0.3) V 5 mA 3 -65 150 C 150 C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications. Never to exceed 3.6 V. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) 2000 Charged-device model (CDM), per JEDEC specification JESD22C101 (2) 750 Machine model (MM) 150 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions TJ Junction temperature TA Ambient temperature VCC Supply voltage VCC = 3.3 V MIN NOM -40 25 3.15 3.3 MAX UNIT 125 C 85 C 3.45 V 6.4 Thermal Information LMK04906 THERMAL METRIC (1) NKD (WQFN) UNIT 64 PINS RJA Junction-to-ambient thermal resistance 25.2 C/W RJC(top) Junction-to-case (top) thermal resistance 6.9 C/W RJB Junction-to-board thermal resistance JT Junction-to-top characterization parameter JB RJC(bot) (1) 4 C/W 0.1 C/W Junction-to-board characterization parameter 4 C/W Junction-to-case (bottom) thermal resistance 0.8 C/W For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 5 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 6.5 Electrical Characteristics (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 1 3 mA 410 470 mA 500 MHz CURRENT CONSUMPTION ICC_PD Power Down Supply Current ICC_CLKS Supply Current with all clocks enabled (1) All clock delays disabled, CLKoutX_DIV = 1045, CLKoutX_TYPE = 1 (LVDS), PLL1 and PLL2 locked. CLKin0/0*, CLKin1/1*, and CLKin2/2* INPUT CLOCK SPECIFICATIONS Clock Input Frequency fCLKin 0.001 (2) SLEWCLKin VIDCLKin VSSCLKin VIDCLKin VSSCLKin Clock Input Slew Rate (3) Clock Input Differential Input Voltage 0.15 AC coupled CLKinX_BUF_TYPE = 0 (Bipolar) 0.25 AC coupled CLKinX_BUF_TYPE = 1 (MOS) Figure 4 (3) VCLKin0-offset DC offset voltage between CLKin0/CLKin0* CLKin0* - CLKin0 VCLKin1-offset DC offset voltage between CLKin1/CLKin1* CLKin1* - CLKin1 VCLKin2-offset DC offset voltage between CLKin2/CLKin2* CLKin2* - CLKin2 VCLKinX-offset DC offset voltage between CLKinX/CLKinX* CLKinX* - CLKinX VCLKin- VIH High input voltage VCLKin- VIL Low input voltage 0.5 V/ns 1.55 |V| 0.5 3.1 Vpp 0.25 1.55 |V| 0.5 3.1 Vpp AC coupled to CLKinX; CLKinX* AC coupled to Ground CLKinX_BUF_TYPE = 0 (Bipolar) 0.25 2.4 Vpp AC coupled to CLKinX; CLKinX* AC coupled to Ground CLKinX_BUF_TYPE = 1 (MOS) 0.25 2.4 Vpp (4) Clock Input Single-ended Input Voltage VCLKin 20% to 80% Each pin AC coupled CLKin0_BUF_TYPE = 0 (Bipolar) Each pin AC coupled CLKinX_BUF_TYPE = 1 (MOS) DC coupled to CLKinX; CLKinX* AC coupled to Ground CLKinX_BUF_TYPE = 1 (MOS) 20 mV 0 mV 20 mV 55 mV 2 VCC V 0 0.4 V AC coupled (CLKinX_BUF_TYPE = 0) MODE = 2 or 8; FEEDBACK_MUX = 6 0.001 1000 MHz AC coupled (CLKinX_BUF_TYPE = 0) MODE = 3 or 11 0.001 3100 MHz AC coupled; (CLKinX_BUF_TYPE = 0) 0.25 2 Vpp AC coupled; 20% to 80%; (CLKinX_BUF_TYPE = 0) 0.15 FBCLKin/FBCLKin* and Fin/Fin* INPUT SPECIFICATIONS Clock Input Frequency fFBCLKin (3) Clock Input Frequency fFin (3) VFBCLKin/Fin SLEWFBCLKin/Fin (1) (2) (3) (4) 6 Single Ended Clock Input Voltage (3) Slew Rate on CLKin (3) 0.5 V/ns Load conditions for output clocks: LVDS: 100 differential. See Current Consumption and Power Dissipation Calculations for ICC for specific part configuration and how to calculate ICC for a specific design. CLKin0, CLKin1, and CLKin2 maximum is specified by characterization, production tested at 200 MHz. Specified by characterization. See Differential Voltage Measurement Terminology for definition of VID and VOD voltages. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Electrical Characteristics (continued) (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 40 MHz PLL1 SPECIFICATIONS fPD1 PLL1 Phase Detector Frequency ICPout1SOURCE PLL1 Charge Pump Source Current (5) VCPout1 = VCC/2, PLL1_CP_GAIN = 0 100 VCPout1 = VCC/2, PLL1_CP_GAIN = 1 200 VCPout1 = VCC/2, PLL1_CP_GAIN = 2 400 VCPout1 = VCC/2, PLL1_CP_GAIN = 3 1600 VCPout1=VCC/2, PLL1_CP_GAIN = 0 -100 VCPout1=VCC/2, PLL1_CP_GAIN = 1 -200 VCPout1=VCC/2, PLL1_CP_GAIN = 2 -400 VCPout1=VCC/2, PLL1_CP_GAIN = 3 -1600 ICPout1SINK PLL1 Charge Pump Sink Current ICPout1%MIS Charge Pump Sink / Source Mismatch VCPout1 = VCC/2, T = 25 C 3% ICPout1VTUNE Magnitude of Charge Pump Current Variation vs. Charge Pump Voltage 0.5 V < VCPout1 < VCC - 0.5 V TA = 25 C 4% ICPout1%TEMP Charge Pump Current vs. Temperature Variation ICPout1 TRI Charge Pump TRI-STATELeakage Current PN10kHz PLL 1/f Noise at 10-kHz offset. Normalized to 1-GHz Output Frequency PN1Hz Normalized Phase Noise Contribution (5) A A 10 4% 0.5 V < VCPout < VCC - 0.5 V 5 PLL1_CP_GAIN = 400 A -117 PLL1_CP_GAIN = 1600 A -118 PLL1_CP_GAIN = 400 A dBc/Hz -221.5 PLL1_CP_GAIN = 1600 A nA dBc/Hz -223 PLL2 REFERENCE INPUT (OSCin) SPECIFICATIONS fOSCin SLEWOSCin PLL2 Reference Input 500 (6) PLL2 Reference Clock minimum slew rate on OSCin (3) 0.15 (3) AC coupled; Single-ended (Unused pin AC coupled to GND) Differential voltage swing Figure 4 AC coupled VOSCin-offset DC offset voltage between OSCin/OSCin* OSCinX* - OSCinX Each pin AC coupled fdoubler_max Doubler input frequency VOSCin VIDOSCin VSSOSCin Input Voltage for OSCin or OSCin* 20% to 80% 0.5 V/ns 0.2 2.4 0.2 1.55 |V| 0.4 3.1 Vpp 20 EN_PLL2_REF_2X = 1; OSCin Duty Cycle 40% to 60% (3) MHz Vpp mV 155 MHz 20.5 MHz CRYSTAL OSCILLATOR MODE SPECIFICATIONS fXTAL Crystal frequency range RESR < 40 (3) Vectron VXB1 crystal, 20.48 MHz, RESR < 40 XTAL_LVL = 0 (7) PXTAL Crystal power dissipation CIN Input capacitance of LMK04906 OSCin port (5) (6) (7) -40 to +85 C 6 100 W 6 pF This parameter is programmable FOSCin maximum frequency specified by characterization. Production tested at 200 MHz. See Optional Crystal Oscillator Implementation (OSCin/OSCin*) Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 7 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Electrical Characteristics (continued) (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 155 MHz PLL2 PHASE DETECTOR AND CHARGE PUMP SPECIFICATIONS fPD2 Phase detector frequency ICPoutSOURCE PLL2 charge pump source current (5) (5) VCPout2=VCC/2, PLL2_CP_GAIN = 0 100 VCPout2=VCC/2, PLL2_CP_GAIN = 1 400 VCPout2=VCC/2, PLL2_CP_GAIN = 2 1600 VCPout2=VCC/2, PLL2_CP_GAIN = 3 3200 VCPout2=VCC/2, PLL2_CP_GAIN = 0 -100 VCPout2=VCC/2, PLL2_CP_GAIN = 1 -400 VCPout2=VCC/2, PLL2_CP_GAIN = 2 -1600 VCPout2=VCC/2, PLL2_CP_GAIN = 3 -3200 ICPoutSINK PLL2 charge pump sink current ICPout2%MIS Charge pump sink/source mismatch VCPout2=VCC/2, TA = 25 C 3% ICPout2VTUNE Magnitude of charge pump current vs charge pump voltage variation 0.5 V < VCPout2 < VCC - 0.5 V TA = 25 C 4% ICPout2%TEMP Charge pump current vs temperature variation ICPout2TRI Charge pump leakage 0.5 V < VCPout2 < VCC - 0.5 V PLL2_CP_GAIN = 400 A -118 PN10kHz PLL 1/f noise at 10-kHz offset (8) . Normalized to 1-GHz output frequency PLL2_CP_GAIN = 3200 A -121 PN1Hz Normalized phase noise contribution A A 10% 4% (9) 10 PLL2_CP_GAIN = 400 A dBc/Hz -222.5 PLL2_CP_GAIN = 3200 A nA dBc/Hz -227 INTERNAL VCO SPECIFICATIONS fVCO VCO tuning range KVCO Fine tuning sensitivity (The range displayed in the typical column indicates the lower sensitivity is typical at the lower end of the tuning LMK04906 range, and the higher tuning sensitivity is typical at the higher end of the tuning range). |TCL| Allowable temperature drift for continuous lock (10) (3) LMK04906 2370 2600 16 to 21 After programming R30 for lock, no changes to output configuration are permitted to guarantee continuous lock MHz MHz/V 125 C (8) A specification in modeling PLL in-band phase noise is the 1/f flicker noise, LPLL_flicker(f), which is dominant close to the carrier. Flicker noise has a 10 dB/decade slope. PN10kHz is normalized to a 10 kHz offset and a 1 GHz carrier frequency. PN10kHz = LPLL_flicker(10 kHz) - 20log(Fout / 1 GHz), where LPLL_flicker(f) is the single side band phase noise of only the flicker noise's contribution to total noise, L(f). To measure LPLL_flicker(f) it is important to be on the 10 dB/decade slope close to the carrier. A high compare frequency and a clean crystal are important to isolating this noise source from the total phase noise, L(f). LPLL_flicker(f) can be masked by the reference oscillator performance if a low power or noisy source is used. The total PLL in-band phase noise performance is the sum of LPLL_flicker(f) and LPLL_flat(f). (9) A specification modeling PLL in-band phase noise. The normalized phase noise contribution of the PLL, LPLL_flat(f), is defined as: PN1HZ=LPLL_flat(f) - 20log(N) - 10log(fPDX). LPLL_flat(f) is the single side band phase noise measured at an offset frequency, f, in a 1 Hz bandwidth and fPDX is the phase detector frequency of the synthesizer. LPLL_flat(f) contributes to the total noise, L(f). (10) Maximum Allowable Temperature Drift for Continuous Lock is how far the temperature can drift in either direction from the value it was at the time that the R30 register was last programmed, and still have the part stay in lock. The action of programming the R30 register, even to the same value, activates a frequency calibration routine. This implies the part will work over the entire frequency range, but if the temperature drifts more than the maximum allowable drift for continuous lock, then it will be necessary to reload the R30 register to ensure it stays in lock. Regardless of what temperature the part was initially programmed at, the temperature can never drift outside the frequency range of -40 C to 85 C without violating specifications. 8 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Electrical Characteristics (continued) (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS CLKout CLOSED LOOP JITTER SPECIFICATIONS USING A COMMERCIAL QUALITY VCXO L(f)CLKout LMK04906 fCLKout = 245.76 MHz SSB phase noise Measured at clock outputs Value is average for all output types MIN TYP MAX UNIT (11) Offset = 1 kHz -122.5 Offset = 10 kHz -132.9 Offset = 100 kHz -135.2 Offset = 800 kHz -143.9 Offset = 10 MHz; LVDS dBc/Hz -156 (12) JCLKout LVDS/LVPECL/ LVCMOS LMK04906 (12) fCLKout = 245.76 MHz Integrated RMS jitter Offset = 10 MHz; LVPECL 1600 mVpp -157.5 Offset = 10 MHz; LVCMOS -157.1 BW = 12 kHz to 20 MHz 115 BW = 100 Hz to 20 MHz 123 fs rms CLKout CLOSED LOOP JITTER SPECIFICATIONS USING THE INTEGRATED LOW NOISE CRYSTAL OSCILLATOR CIRCUIT LMK04906 fCLKout = 245.76 MHz Integrated RMS jitter BW = 12 kHz to 20 MHz XTAL_LVL = 3 192 BW = 100 Hz to 20 MHz XTAL_LVL = 3 450 (13) DEFAULT POWER ON RESET CLOCK OUTPUT FREQUENCY fCLKout-startup Default output clock frequency at device power on CLKout4, LVDS, LMK04906 (14) 90 98 110 MHz CLOCK SKEW AND DELAY LVDS-to-LVDS, T = 25 C, FCLK = 800 MHz, RL= 100 AC coupled 30 LVPECL-to-LVPECL, T = 25 C, FCLK = 800 MHz, RL= 100 emitter resistors = 240 to GND AC coupled 30 Maximum skew between any two LVCMOS outputs, same CLKout or different CLKout (15) (3) RL = 50 , CL = 5 pF, T = 25 C, FCLK = 100 MHz. 100 LVDS or LVPECL to LVCMOS Same device, T = 25 C, 250 MHz 750 Maximum CLKoutX to CLKoutY (15) (3) |TSKEW| MixedTSKEW td0-DELAY CLKin to CLKoutX delay (15) (15) MODE = 2 PLL1_R_DLY = 0; PLL1_N_DLY = 0 1850 MODE = 2 PLL1_R_DLY = 0; PLL1_N_DLY = 0; VCO Frequency = 2949.12 MHz Analog delay select = 0; Feedback clock digital delay = 11; Feedback clock half step = 1; Output clock digital delay = 5; Output clock half step = 0; 0 ps ps ps (11) VCXO used is a 122.88 MHz Crystek CVHD-950-122.880. (12) fVCO = 2457.6 MHz, PLL1 parameters: EN_PLL2_REF_2X = 1, PLL2_R = 2, FPD1 = 1.024 MHz, ICP1 = 100 A, loop bandwidth = 10 Hz. A 122.88 MHz Crystek CVHD-950-122.880. PLL2 parameters: PLL2_R = 1, FPD2 = 122.88 MHz, ICP2 = 3200 A, C1 = 47 pF, C2 = 3.9 nF, R2 = 620 , PLL2_C3_LF = 0, PLL2_R3_LF = 0, PLL2_C4_LF = 0, PLL2_R4_LF = 0, CLKoutX_DIV = 10, and CLKoutX_ADLY_SEL = 0. (13) Crystal used is a 20.48 MHz Vectron VXB1-1150-20M480 and Skyworks varactor diode, SMV-1249-074LF. (14) CLKout3 and OSCout0 also oscillate at start-up at the frequency of the VCXO attached to OSCin port. (15) Equal loading and identical clock output configuration on each clock output is required for specification to be valid. Specification not valid for delay mode. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 9 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Electrical Characteristics (continued) (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT LVDS CLOCK OUTPUTS (CLKoutX), CLKoutX_TYPE = 1 fCLKout VOD Maximum frequency RL = 100 (3) (16) VSS Differential output voltage Figure 5 VOD Change in Magnitude of VOD for complementary output states VOS Output offset voltage VOS Change in VOS for complementary output states 1536 T = 25 C, DC measurement AC coupled to receiver input R = 100 differential termination MHz 250 400 450 |mV| 500 800 900 mVpp 50 mV -50 1.125 1.25 1.375 35 V |mV| Output rise time 20% to 80%, RL = 100 Output fall time 80% to 20%, RL = 100 ISA ISB Output short-circuit current: single ended Single-ended output shorted to GND, T = 25 C -24 24 mA ISAB Output short-circuit current: differential Complimentary outputs tied together -12 12 mA TR / TF 200 ps LVPECL CLOCK OUTPUTS (CLKoutX) fCLKout Maximum frequency 20% to 80% output rise TR / TF 1536 (3) (16) 80% to 20% output fall time RL = 100 , emitter resistors = 240 to GND CLKoutX_TYPE = 4 or 5 (1600 or 2000 mVpp) MHz 150 ps VCC - 1.03 V VCC - 1.41 V 700-mVpp LVPECL CLOCK OUTPUTS (CLKoutX), CLKoutX_TYPE = 2 VOH Output high voltage VOL Output low voltage VOD Output voltage Figure 5 VSS T = 25 C, DC measurement Termination = 50 to VCC - 1.4 V 305 380 440 |mV| 610 760 880 mVpp 1200-mVpp LVPECL CLOCK OUTPUTS (CLKoutX), CLKoutX_TYPE = 3 VOH Output high voltage VOL Output low voltage VOD Output voltage Figure 5 VSS T = 25 C, DC measurement Termination = 50 to VCC - 1.7 V VCC - 1.07 V VCC - 1.69 V 545 625 705 |mV| 1090 1250 1410 mVpp 1600-mVpp LVPECL CLOCK OUTPUTS (CLKoutX), CLKoutX_TYPE = 4 VOH Output high voltage VOL Output low voltage VOD Output voltage Figure 5 VSS T = 25 C, DC Measurement Termination = 50 to VCC - 2 V VCC - 1.10 V VCC - 1.97 V 660 870 965 |mV| 1320 1740 1930 mVpp (16) See Typical Characteristics for output operation performance at higher frequencies than the minimum maximum output frequency. 10 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Electrical Characteristics (continued) (3.15 V VCC 3.45 V, -40 C TA 85 C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 C, at the Recommended Operating Conditions at the time of product characterization and are not ensured.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 2000-mVpp LVPECL (2VPECL) CLOCK OUTPUTS (CLKoutX), CLKoutX_TYPE = 5 VOH Output high voltage VOL Output low voltage VOD Output voltage Figure 5 VSS T = 25 C, DC Measurement Termination = 50 to VCC - 2.3 V VCC - 1.13 V VCC - 2.20 V 800 1070 1200 |mV| 1600 2140 2400 mVpp LVCMOS CLOCK OUTPUTS (CLKoutX) fCLKout Maximum frequency (3) (16) 5-pF Load VOH Output high voltage 1-mA Load VOL Output low voltage 1-mA Load IOH Output high current (source) VCC = 3.3 V, VO = 1.65 V 28 mA IOL Output low current (sink) VCC = 3.3 V, VO = 1.65 V 28 mA Output duty cycle (3) VCC/2 to VCC/2, FCLK = 100 MHz, T = 25 C TR Output rise time 20% to 80%, RL = 50 , CL = 5 pF 400 ps TF Output fall time 80% to 20%, RL = 50 , CL = 5 pF 400 ps DUTYCLK 250 MHz VCC - 0.1 V 0.1 45% 50% V 55% DIGITAL OUTPUTS (Status_CLKinX, Status_LD, Status_Holdover, SYNC) VOH High-level output voltage IOH = -500 A VOL Low-level output voltage IOL = 500 A VCC - 0.4 V 0.4 V VCC V 0.4 V DIGITAL INPUTS (Status_CLKinX, SYNC) VIH High-level input voltage VIL Low-level input voltage IIH IIL 1.6 High-level input current VIH = VCC Low-level input current VIL = 0 V Status_CLKinX_TYPE = 0 (High Impedance) -5 5 Status_CLKinX_TYPE = 1 (Pull-up) -5 5 Status_CLKinX_TYPE = 2 (Pull-down) 10 80 Status_CLKinX_TYPE = 0 (High Impedance) -5 5 Status_CLKinX_TYPE = 1 (Pull-up) -40 -5 Status_CLKinX_TYPE = 2 (Pulldown) -5 5 1.6 VCC V 0.4 V 5 25 A -5 5 A A A DIGITAL INPUTS (CLKuWire, DATAuWire, LEuWire) VIH High-level input voltage VIL Low-level input voltage IIH High-level input current VIH = VCC IIL Low-level input current VIL = 0 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 11 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 6.6 Timing Requirements MIN NOM MAX UNIT TECS LE to Clock Set Up Time See Figure 6 25 ns TDCS Data to Clock Set Up Time See Figure 6 25 ns TCDH Clock to Data Hold Time See Figure 6 8 ns TCWH Clock Pulse Width High See Figure 6 25 ns TCWL Clock Pulse Width Low See Figure 6 25 ns TCES Clock to LE Set Up Time See Figure 6 25 ns TEWH LE Pulse Width See Figure 6 25 ns TCR Falling Clock to Readback Time See Figure 9 25 ns 12 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 6.7 Typical Characteristics 1200 500 2000 mVpp 1600 mVpp 1200 mVpp 700 mVpp 450 1000 400 VOD(mV) VOD(mV) 350 300 250 200 800 600 400 150 100 200 50 0 0 0 500 1000 1500 2000 2500 3000 FREQUENCY (MHz) 0 Figure 1. LVDS VOD vs Frequency 500 1000 1500 2000 2500 3000 FREQUENCY (MHz) Figure 2. LVPECL With 240- Emitter Resistors VOD vs Frequency 1200 VOD(mV) 1000 2000 mVpp 800 600 1600 mVpp 400 200 0 0 500 1000 1500 2000 2500 3000 FREQUENCY (MHz) Figure 3. LVPECL With 120- Emitter Resistors VOD vs Frequency Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 13 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 7 Parameter Measurement Information 7.1 Charge Pump Current Specification Definitions I1 = Charge Pump Sink Current at VCPout = VCC - V I2 = Charge Pump Sink Current at VCPout = VCC/2 I3 = Charge Pump Sink Current at VCPout = V I4 = Charge Pump Source Current at VCPout = VCC - V I5 = Charge Pump Source Current at VCPout = VCC/2 I6 = Charge Pump Source Current at VCPout = V V = Voltage offset from the positive and negative supply rails. Defined to be 0.5 V for this device. 7.1.1 Charge Pump Output Current Magnitude Variation Vs. Charge Pump Output Voltage ICPout Vs VCPout = = I1 - I3 100% I1 + I3 I4 - I6 I4 + I6 100% 7.1.2 Charge Pump Sink Current Vs. Charge Pump Output Source Current Mismatch ICPout Sink Vs ICPout Source = 14 I2 - I5 I2 + I5 Submit Documentation Feedback 100% Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Charge Pump Current Specification Definitions (continued) 7.1.3 Charge Pump Output Current Magnitude Variation vs Temperature I2 ICPout Vs TA = TA - I2 I2 I5 = 100% TA = 25C TA - I5 I5 TA = 25C TA = 25C 100% TA = 25C 7.2 Differential Voltage Measurement Terminology The differential voltage of a differential signal can be described by two different definitions causing confusion when reading datasheets or communicating with other engineers. This section will address the measurement and description of a differential signal so that the reader will be able to understand and discern between the two different definitions when used. The first definition used to describe a differential signal is the absolute value of the voltage potential between the inverting and non-inverting signal. The symbol for this first measurement is typically VID or VOD depending on if an input or output voltage is being described. The second definition used to describe a differential signal is to measure the potential of the non-inverting signal with respect to the inverting signal. The symbol for this second measurement is VSS and is a calculated parameter. Nowhere in the IC does this signal exist with respect to ground, it only exists in reference to its differential pair. VSS can be measured directly by oscilloscopes with floating references, otherwise this value can be calculated as twice the value of VOD as described in the first description. Figure 4 illustrates the two different definitions side-by-side for inputs and Figure 5 illustrates the two different definitions side-by-side for outputs. The VID and VOD definitions show VA and VB DC levels that the non-inverting and inverting signals toggle between with respect to ground. VSS input and output definitions show that if the inverting signal is considered the voltage potential reference, the non-inverting signal voltage potential is now increasing and decreasing above and below the non-inverting reference. Thus the peak-to-peak voltage of the differential signal can be measured. VID and VOD are often defined as volts (V) and VSS is often defined as volts peak-to-peak (VPP). VID Definition VSS Definition for Input Non-Inverting Clock VA 2* VID VID VB Inverting Clock VID = | VA - VB | VSS = 2* VID GND Figure 4. Two Different Definitions for Differential Input Signals Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 15 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Differential Voltage Measurement Terminology (continued) VOD Definition VSS Definition for Output Non-Inverting Clock VA 2* VOD VOD VB Inverting Clock VOD = | VA - VB | VSS = 2* VOD GND See the AN-912 Common Data Transmission Parameters and Their Definitions (SNLA036) application note for more information. Figure 5. Two Different Definitions for Differential Output Signals 16 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8 Detailed Description 8.1 Overview In default mode of operation, dual PLL mode with internal VCO, the Phase Frequency Detector in PLL1 compares the active CLKinX reference divided by CLKinX_PreR_DIV and PLL1 R divider with the external VCXO or crystal attached to the PLL2 OSCin port divided by PLL1 N divider. The external loop filter for PLL1 should be narrow to provide an ultra clean reference clock from the external VCXO or crystal to the OSCin/OSCin* pins for PLL2. The Phase Frequency Detector in PLL2 compares the external VCXO or crystal attached to the OCSin port divided by the PLL2 R divider with the output of the internal VCO divided by the PLL2 N divider and N2 prescaler and optionally the VCO divider. The bandwidth of the external loop filter for PLL2 should be designed to be wide enough to take advantage of the low in-band phase noise of PLL2 and the low high offset phase noise of the internal VCO. The VCO output is also placed on the distribution path for the clock distribution section. The clock distribution consists of 6 dividers and delays which drive 6 outputs. Each clock output allows the user to select a divide value, a digital delay value, and an analog delay. The 6 dividers drive programmable output buffers. Two outputs allow their input signal to be from the OSCin port directly. When a 0-delay mode is used, a clock output will be passed through the feedback mux to the PLL1 N Divider for synchronization and 0-delay. When an external VCO mode is used, the Fin port will be used to input an external VCO signal. PLL2 Phase comparison will now be with this signal divided by the PLL2 N divider and N2 pre-scaler. The VCO divider may not be used. One less clock input is available when using an external VCO mode. When a single PLL mode is used, PLL1 is powered down. OSCin is used as a reference to PLL2. 8.1.1 System Architecture The dual loop PLL architecture of the LMK04906 provides the lowest jitter performance over the widest range of output frequencies and phase noise integration bandwidths. The first stage PLL (PLL1) is driven by an external reference clock and uses an external VCXO or tunable crystal to provide a frequency accurate, low phase noise reference clock for the second stage frequency multiplication PLL (PLL2). PLL1 typically uses a narrow loop bandwidth (10 Hz to 200 Hz) to retain the frequency accuracy of the reference clock input signal while at the same time suppressing the higher offset frequency phase noise that the reference clock may have accumulated along its path or from other circuits. This "cleaned" reference clock provides the reference input to PLL2. The low phase noise reference provided to PLL2 allows PLL2 to operate with a wide loop bandwidth (50 kHz to 200 kHz). The loop bandwidth for PLL2 is chosen to take advantage of the superior high offset frequency phase noise profile of the internal VCO and the good low offset frequency phase noise of the reference VCXO or tunable crystal. Ultra low jitter is achieved by allowing the external VCXO or Crystal's phase noise to dominate the final output phase noise at low offset frequencies and the internal VCO's phase noise to dominate the final output phase noise at high offset frequencies. This results in best overall phase noise and jitter performance. The LMK04906 allows subsets of the device to be used to increase the flexibility of device. These different modes are selected using MODE: Device Mode. For instance: * Dual Loop Mode - Typical use case of LMK04906. CLKinX used as reference input to PLL1, OSCin port is connected to VCXO or tunable crystal. * Single Loop Mode - Powers down PLL1. OSCin port is used as reference input. * Clock Distribution Mode - Allows input of CLKin1 to be distributed to output with division, digital delay, and analog delay. See Device Functional Modes for more information on these modes. 8.1.2 PLL1 Redundant Reference Inputs (CLKin0/CLKin0*, CLKin1/CLKin1*, and CLKin2/CLKin2*) The LMK04906 has three reference clock inputs for PLL1, CLKin0, CLKin1, and CLKin2. Ref Mux selects CLKin0, CLKin1, or CLKin2. Automatic or manual switching occurs between the inputs. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 17 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Overview (continued) CLKin0, CLKin1, and CLKin2 each have input dividers. The input divider allows different clock input frequencies to be normalized so that the frequency input to the PLL1 R divider remains constant during automatic switching. By programming these dividers such that the frequency presented to the input of the PLL1_R divider is the same prevents the user from needing to reprogram the PLL1 R divider when the input reference is changed to another CLKin port with a different frequency. CLKin1 is shared for use as an external 0-delay feedback (FBCLKin), or for use with an external VCO (Fin). Fast manual switching between reference clocks is possible with a external pins Status_CLKin0, Status_CLKin1, Status_CLKin2. If Status_CLKinx pins are used to select the reference clock, a minimum pulse width of 500ns must be met. 8.1.3 PLL1 Tunable Crystal Support The LMK04906 integrates a crystal oscillator on PLL1 for use with an external crystal and varactor diode to perform jitter cleaning. The LMK04906 must be programmed to enable Crystal mode. 8.1.4 VCXO/Crystal Buffered Outputs The LMK04906 provides a dedicated output which is a buffered copy of the PLL2 reference input. This reference input is typically a low noise VCXO or Crystal. When using a VCXO, this output can be used to clock external devices such as microcontrollers, FPGAs, CPLDs, etc. before the LMK04906 is programmed. The OSCout0 buffer output type is programmable to LVDS, LVPECL, or LVCMOS. The dedicated output buffer OSCout0 can output frequency lower than the VCXO or Crystal frequency by programming the OSC Divider. The OSC Divider value range is 1 to 8. Each OSCoutX can individually choose to use the OSC Divider output or to bypass the OSC Divider. Two clock outputs can also be programmed to be driven by OSCin. This allows a total of 2 additional differential outputs to be buffered outputs of OSCin. When programmed in this way, a total of 3 differential outputs can be driven by a buffered copy of OSCin. VCXO/Crystal buffered outputs cannot be synchronized to the VCO clock distribution outputs. The assertion of SYNC will still cause these outputs to become low. Since these outputs will turn off and on asynchronously with respect to the VCO sourced clock outputs during a SYNC, it is possible for glitches to occur on the buffered clock outputs when SYNC is asserted and unasserted. If the NO_SYNC_CLKoutX bits are set these outputs will not be affected by the SYNC event except that the phase relationship will change with the other synchronized clocks unless a buffered clock output is used as a qualification clock during SYNC. 8.1.5 Frequency Holdover The LMK04906 supports holdover operation to keep the clock outputs on frequency with minimum drift when the reference is lost until a valid reference clock signal is re-established. 8.1.6 Integrated Loop Filter Poles The LMK04906 features programmable 3rd and 4th order loop filter poles for PLL2. These internal resistors and capacitor values may be selected from a fixed range of values to achieve either a 3rd or 4th order loop filter response. The integrated programmable resistors and capacitors compliment external components mounted near the chip. These integrated components can be effectively disabled by programming the integrated resistors and capacitors to their minimum values. 8.1.7 Internal VCO The output of the internal VCO is routed to a mux which allows the user to select either the direct VCO output or a divided version of the VCO for the Clock Distribution Path. This same selection is also fed back to the PLL2 phase detector through a prescaler and N-divider. 18 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Overview (continued) The mux selectable VCO divider has a divide range of 2 to 8 with 50% output duty cycle for both even and odd divide values. The primary use of the VCO divider is to achieve divides greater than the clock output divider supports alone. 8.1.8 External VCO Mode The Fin/Fin* input allows an external VCO to be used with PLL2 of the LMK04906. Using an external VCO reduces the number of available clock inputs by one. 8.1.9 Clock Distribution The LMK04906 features a total of 6 outputs driven from the internal or external VCO. All VCO driven outputs have programmable output types. They can be programmed to LVPECL, LVDS, or LVCMOS. When all distribution outputs are configured for LVCMOS or single ended LVPECL a total of 24 outputs are available. If the buffered OSCin output OSCout0 is included in the total number of clock outputs the LMK04906 is able to distribute, then up to 6 differential clocks or up to 12 single ended clocks may be generated with the LMK04906. The following sections discuss specific features of the clock distribution channels that allow the user to control various aspects of the output clocks. 8.1.9.1 CLKout DIVIDER Each clock output has a single clock output divider. The divider supports a divide range of 1 to 1045 (even and odd) with 50% output duty cycle. When divides of 26 or greater are used, the divider/delay block uses extended mode. The VCO Divider may be used to reduce the divide needed by the clock output divider so that it may operate in normal mode instead of extended mode. This can result in a small current saving if enabling the VCO Divider allows 3 or more clock output divides to change from extended to normal mode. 8.1.9.2 CLKout Delay The clock distribution section includes both a fine (analog) and coarse (digital) delay for phase adjustment of the clock outputs. The fine (analog) delay allows a nominal 25 ps step size and range from 0 to 475 ps of total delay. Enabling the analog delay adds a nominal 500 ps of delay in addition to the programmed value. When adjusting analog delay, glitches may occur on the clock outputs being adjusted. Analog delay may not operate at frequencies above the minimum-specified maximum output frequency of 1536 MHz. The coarse (digital) delay allows a group of outputs to be delayed by 4.5 to 12 clock distribution path cycles in normal mode, or from 12.5 to 522 VCO cycles in extended mode. The delay step can be as small as half the period of the clock distribution path by using the CLKoutX_HS bit provided the output divide value is greater than 1. For example 2 GHz VCO frequency without using the VCO divider results in 250 ps coarse tuning steps. The coarse (digital) delay value takes effect on the clock outputs after a SYNC event. There are 3 different ways to use the digital (coarse) delay. 1. Fixed Digital Delay 2. Absolute Dynamic Digital Delay 3. Relative Dynamic Digital Delay 8.1.9.3 Programmable Output Type For increased flexibility all LMK04906 clock outputs (CLKoutX) and OSCout0 can be programmed to an LVDS, LVPECL, or LVCMOS output type. Any LVPECL output type can be programmed to 700, 1200, 1600, or 2000 mVpp amplitude levels. The 2000 mVpp LVPECL output type is a Texas Instruments proprietary configuration that produces a 2000 mVpp differential swing for compatibility with many data converters and is also known as 2VPECL. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 19 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Overview (continued) 8.1.9.4 Clock Output Synchronization Using the SYNC input causes all active clock outputs to share a rising edge. See Clock Output Synchronization (SYNC) for more information. The SYNC event also causes the digital delay values to take effect. 8.1.10 0-Delay The 0-delay mode synchronizes the input clock phase to the output clock phase. The 0-delay feedback may performed with an internal feedback loop from some of the clock outputs or with an external feedback loop into the FBCLKin port as selected by the FEEDBACK_MUX. Without using 0-delay mode there will be n possible fixed phase relationships from clock input to clock output depending on the clock output divide value. Using an external 0-delay feedback reduces the number of available clock inputs by one. 8.1.11 Default Start-Up Clocks Before the LMK04906 is programmed, CLKout4 is enabled and operating at a nominal frequency and CLKout3 and OSCout0 are enabled and operating at the OSCin frequency. These clocks can be used to clock external devices such as microcontrollers, FPGAs, CPLDs, etc. before the LMK04906 is programmed. For CLKout3 and OSCout0 to work before the LMK04906 is programmed the device must not be using Crystal mode. 8.1.12 Status Pins The LMK04906 provides status pins which can be monitored for feedback or in some cases used for input depending upon device programming. For example: * The Status_Holdover pin may indicate if the device is in hold-over mode. * The Status_CLKin0 pin may indicate the LOS (loss-of-signal) for CLKin0. * The Status_CLKin0 pin may be an input for selecting the active clock input. * The Status_LD pin may indicate if the device is locked. The status pins can be programmed to a variety of other outputs including analog lock detect, PLL divider outputs, combined PLL lock detect signals, PLL1 Vtune railing, readback, and so forth. See Status PINS of this data sheet for more information. Default pin programming is captured in Table 17. 8.1.13 Register Readback Programmed registers may be read back using the MICROWIRE interface. For readback one of the status pins must be programmed for readback mode. At no time may registers be programed to values other than the valid states defined in the data sheet. 20 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 CLKin2* CLKin2 CLKin2 Divider (1, 2, 4, or 8) CLKin0* CLKin0 CLKin0 Divider (1, 2, 4, or 8) CLKin1*/Fin* FBCLKin* CLKin1/ Fin/FBCLKin Ref Mux R Delay CLKin1 Divider (1, 2, 4, or 8) Fin/Fin* R1 Divider (1 to 16,383) Phase Detector PLL1 N1 Divider (1 to 16,383) N Delay CPout1 8.2 Functional Block Diagram Status_LD SYNC/ Status_CLKin2 PWire Port Holdover OSCout0 _MUX Control Registers LEuWire CPout2 Mode Mux2 2X OSCout0 OSCout0* Status_CLKin0 CLKuWire FBMux FB Mux Status_Holdover Status_CLKin1 DATAuWire CLKout1 CLKout3 CLKout4 CLKout5 Device Control 2X Mux OSC Divider (2 to 8) N2 Divider (1 to 262,143) Mode Mux3 FBMux R2 Divider (1 to 4,095) N2 Prescaler (2 to 8) OSCin* OSCin Phase Detector PLL2 Clock Distribution Path Mode Mux1 Partially Integrated Loop Filter VCO Mux Internal VCO VCO Divider (2 to 8) Fin/Fin* CLKout0 CLKout0* Mux Delay Divider (1 to 1045) Digital Delay Osc Mux1 Digital Delay Divider (1 to 1045) Delay Digital Delay Divider (1 to 1045) Delay Divider (1 to 1045) Delay Mux CLKout3 CLKout3* Mux CLKout4 CLKout4* Mux CLKout5 CLKout5* Clock Buffer 1 CLKout1 CLKout1* Mux Delay Divider (1 to 1045) Digital Delay Osc Mux2 Clock Buffer 3 CLKout2 CLKout2* Mux Delay Divider (1 to 1045) Digital Delay Clock Buffer 2 Digital Delay Clock Buffer 1 Copyright (c) 2016, Texas Instruments Incorporated 8.3 Feature Description 8.3.1 Serial MICROWIRE Timing Diagram Register programming information on the DATAuWire pin is clocked into a shift register on each rising edge of the CLKuWire signal. On the rising edge of the LEuWire signal, the register is sent from the shift register to the register addressed. A slew rate of at least 30 V/s is recommended for these signals. After programming is complete the CLKuWire, DATAuWire, and LEuWire signals should be returned to a low state. If the CLKuWire or DATAuWire lines are toggled while the VCO is in lock, as is sometimes the case when these lines are shared with other parts, the phase noise may be degraded during this programming. See Figure 6 for timing diagram. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 21 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Feature Description (continued) MSB DATAuWire D26 LSB D25 D24 D23 D22 D0 A4 A1 A0 CLKuWire tCES tDCS tCDH tCWH tECS tCWL LEuWire tEWH Figure 6. MICROWIRE Timing Diagram 8.3.2 Advanced MICROWIRE Timing Diagrams 8.3.2.1 Three Extra Clocks or Double Program Figure 7 shows the timing for the programming sequence for loading CLKoutX_DIV > 25 or CLKoutX_DDLY > 12 as described in Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY. DATAuWire MSB LSB D26 A0 CLKuWire tCES tECS tCWL LEuWire tCWH tEWH Figure 7. MICROWIRE Timing Diagram: Extra CLKuWire Pulses for R0 to R5 8.3.2.2 Three Extra Clocks With LEuWire High Figure 8 shows the timing for the programming sequence which allows SYNC_EN_AUTO = 1 when loading CLKoutX_DIV > 25 or CLKoutX_DDLY > 12. When SYNC_EN_AUTO = 1, a SYNC event is automatically generated on the falling edge of LEuWire. See Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY. DATAuWire MSB LSB D26 A0 CLKuWire tECS tCES tCES LEuWire Figure 8. MICROWIRE Timing Diagram: Extra CLKuWire Pulses for R0 to R5 With LEuWire Asserted 22 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Feature Description (continued) 8.3.2.3 Readback For timing specifications, see Timing Requirements. See Readback for more information on performing a readback operation. Figure 9 shows timing for LEuWire for both READBACK_LE = 1 and 0. The rising edges of CLKuWire during MICROWIRE readback continue to clock data on DATAuWire into the device during readback. If after the readback, LEuWire transitions from low to high, this data will be latched to the decoded register. The decoded register address consists of the last 5 bits clocked on DATAuWire as shown in the MICROWIRE Timing Diagrams. DATAuWire MSB LSB D26 A0 CLKuWire tCR tECS tCWH tCR tCWL LEuWire READBACK_LE = 0 tCES tEWH tECS LEuWire READBACK_LE = 1 Readback Pin RD26 Register Write RD25 RD24 RD23 RD0 Register Read Figure 9. MICROWIRE Readback Timing Diagram 8.3.3 Inputs / Outputs 8.3.3.1 PLL1 Reference Inputs (CLKin0, CLKin1, and CLKin2) The reference clock inputs for PLL1 may be selected from either CLKin0, CLKin1, or CLKin2. The user has the capability to manually select one of the inputs or to configure an automatic switching mode of operation. See Input Clock Switching for more info. CLKin0, CLKin1, and CLKin2 have dividers which allow the device to switch between reference inputs of different frequencies automatically without needing to reprogram the PLL1 R divider. The CLKin pre-divider values are 1, 2, 4, and 8. CLKin1 input can alternatively be used for external feedback in 0-delay mode (FBCLKin) or for an external VCO input port (Fin). 8.3.3.2 PLL2 OSCin / OSCin* Port The feedback from the external oscillator being locked with PLL1 drives the OSCin/OSCin* pins. Internally this signal is routed to the PLL1 N Divider and to the reference input for PLL2. This input may be driven with either a single-ended or differential signal and must be AC coupled. If operated in single ended mode, the unused input must be connected to GND with a 0.1-F capacitor. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 23 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Feature Description (continued) 8.3.3.3 Crystal Oscillator The internal circuitry of the OSCin port also supports the optional implementation of a crystal based oscillator circuit. A crystal, a varactor diode, and a small number of other external components may be used to implement the oscillator. The internal oscillator circuit is enabled by setting the EN_PLL2_XTAL bit. See EN_PLL2_XTAL. 8.3.4 Input Clock Switching Manual, pin select, and automatic are three different kinds clock input switching modes can be set with the CLKin_SELECT_MODE register. Below is information about how the active input clock is selected and what causes a switching event in the various clock input selection modes. 8.3.4.1 Input Clock Switching - Manual Mode When CLKin_SELECT_MODE is 0, 1, or 2 then CLKin0, CLKin1, or CLKin2 respectively is always selected as the active input clock. Manual mode will also override the EN_CLKinX bits such that the CLKinX buffer will operate even if CLKinX is is disabled with EN_CLKinX = 0. Entering Holdover If holdover mode is enabled then holdover mode is entered if: Digital lock detect of PLL1 goes low and DISABLE_DLD1_DET = 0. Exiting Holdover The active clock for automatic exit of holdover mode is the manually selected clock input. 8.3.4.2 Input Clock Switching - Pin Select Mode When CLKin_SELECT_MODE is 3, the pins Status_CLKin0 and Status_CLKin1 select which clock input is active. Clock Switch Event: Pins Changing the state of Status_CLKin0 or Status_CLKin1 pins causes an input clock switch event. Clock Switch Event: PLL1 DLD To prevent PLL1 DLD high to low transition from causing a input clock switch event and causing the device to enter holdover mode, disable the PLL1 DLD detect by setting DISABLE_DLD1_DET = 1. This is the preferred behavior for Pin Select Mode. Configuring Pin Select Mode The Status_CLKin0_TYPE must be programmed to an input value for the Status_CLKin0 pin to function as an input for pin select mode. The Status_CLKin1_TYPE must be programmed to an input value for the Status_CLKin1 pin to function as an input for pin select mode. If the Status_CLKinX_TYPE is set as output, the input value is considered "0." Table 1 defines which input clock is active depending on Status_CLKin0 and Status_CLKin1 state. Table 1. Active Clock Input - Pin Select Mode 24 Status_CLKin1 Status_CLKin0 ACTIVE CLOCK 0 0 CLKin0 0 1 CLKin1 1 0 CLKin2 1 1 Holdover Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 The pin select mode will override the EN_CLKinX bits such that the CLKinX buffer will operate even if CLKinX is is disabled with EN_CLKinX = 0. To switch as fast as possible, keep the clock input buffers enabled (EN_CLKinX = 1) that could be switched to. 8.3.4.2.1 Pin Select Mode and Host When in the pin select mode, the host can monitor conditions of the clocking system which could cause the host to switch the active clock input. The LMK04906 device can also provide indicators on the Status_LD and Status_HOLDOVER like "DAC Rail," "PLL1 DLD", "PLL1 & PLL2 DLD" which the host can use in determining which clock input to use as active clock input. 8.3.4.2.2 Switch Event Without Holdover When an input clock switch event is triggered and holdover mode is disabled, the active clock input immediately switches to the selected clock. When PLL1 is designed with a narrow loop bandwidth, the switching transient is minimized. 8.3.4.2.3 Switch Event With Holdover When an input clock switch event is triggered and holdover mode is enabled, the device will enter holdover mode and remain in holdover until a holdover exit condition is met as described in Holdover Mode. Then the device will complete the reference switch to the pin selected clock input. 8.3.4.3 Input Clock Switching - Automatic Mode When CLKin_SELECT_MODE is 4, the active clock is selected in priority order of enabled clock inputs starting upon an input clock switch event. The priority order of the clocks is CLKin0 CLKin1 CLKin2, etc. For a clock input to be eligible to be switched through, it must be enabled using EN_CLKinX. 8.3.4.3.1 Starting Active Clock Upon programming this mode, the currently active clock remains active if PLL1 lock detect is high. To ensure a particular clock input is the active clock when starting this mode, program CLKin_SELECT_MODE to the manual mode which selects the desired clock input (CLKin0, 1, or 2). Wait for PLL1 to lock PLL1_DLD = 1, then select this mode with CLKin_SELECT_MODE = 4. 8.3.4.3.2 Clock Switch Event: PLL1 DLD A loss of lock as indicated by PLL1's DLD signal (PLL1_DLD = 0) will cause an input clock switch event if DISABLE_DLD1_DET = 0. PLL1 DLD must go high (PLL1_DLD = 1) in between input clock switching events. 8.3.4.3.3 Clock Switch Event: PLL1 Vtune Rail If Vtune_RAIL_DET_EN is set and the PLL1 Vtune voltage crosses the DAC high or low threshold, holdover mode will be entered. Since PLL1_DLD = 0 in holdover a clock input switching event will occur. 8.3.4.3.4 Clock Switch Event With Holdover Holdover mode is entered and the active clock is set to the next enabled clock input in priority order. When the new active clock meets the holdover exit conditions, holdover is exited and the active clock will continue to be used as a reference until another PLL1 loss of lock event. PLL1 DLD must go high in between input clock switching events. 8.3.4.3.5 Clock Switch Event Without Holdover If holdover is not enabled and an input clock switch event occurs, the active clock is set to the next enabled clock in priority order. The LMK04906 will keep this new input clock as the active clock until another input clock switching event. PLL1 DLD must go high in between input clock switching events. 8.3.4.4 Input Clock Switching - Automatic Mode With Pin Select When CLKin_SELECT_MODE is 6, the active clock is selected using the Status_CLKinX pins upon an input clock switch event according to Table 2. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 25 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.3.4.4.1 Starting Active Clock Upon programming this mode, the currently active clock remains active if PLL1 lock detect is high. To ensure a particular clock input is the active clock when starting this mode, program CLKin_SELECT_MODE to the manual mode which selects the desired clock input (CLKin0 or 1). Wait for PLL1 to lock PLL1_DLD = 1, then select this mode with CLKin_SELECT_MODE = 6. 8.3.4.4.2 Clock Switch Event: PLL1 DLD An input clock switch event is generated by a loss of lock as indicated by PLL1's DLD signal (PLL1 DLD = 0). 8.3.4.4.3 Clock Switch Event: PLL1 Vtune Rail If Vtune_RAIL_DET_EN is set and the PLL1 Vtune voltage crosses the DAC threshold, holdover mode will be entered. Since PLL1_DLD = 0 in holdover, a clock input switching event will occur. 8.3.4.4.4 Clock Switch Event With Holdover Clock switch event with holdover enabled is recommended in this input clock switching mode. When an input clock switch event occurs, holdover mode is entered and the active clock is set to the clock input defined by the Status_CLKinX pins. When the new active clock meets the holdover exit conditions, holdover is exited and the active clock will continue to be used as a reference until another input clock switch event. PLL1 DLD must go high in between input clock switching events. Table 2. Active Clock Input - Auto Pin Mode Status_CLKin1 Status_CLKin0 ACTIVE CLOCK X 1 CLKin0 1 0 CLKin1 0 0 CLKin2 The polarity of Status_CLKin1 and Status_CLKin0 input pins can be inverted with the CLKin_SEL_INV bit. 8.3.5 Holdover Mode Holdover mode causes PLL2 to stay locked on frequency with minimal frequency drift when an input clock reference to PLL1 becomes invalid. While in holdover mode, the PLL1 charge pump is TRI-STATED and a fixed tuning voltage is set on CPout1 to operate PLL1 in open loop. 8.3.5.1 Enable Holdover Program HOLDOVER_MODE to enable holdover mode. Holdover mode can be manually enabled by programming the FORCE_HOLDOVER bit. The holdover mode can be set to operate in 2 different sub-modes. * Fixed CPout1 (EN_TRACK = 0 or 1, EN_MAN_DAC = 1). * Tracked CPout1 (EN_TRACK = 1, EN_MAN_DAC = 0). - Not valid when EN_VTUNE_RAIL_DET = 1. Updates to the DAC value for the Tracked CPout1 sub-mode occurs at the rate of the PLL1 phase detector frequency divided by DAC_CLK_DIV. These updates occur any time EN_TRACK = 1. The DAC update rate should be programmed for <= 100 kHz to ensure DAC holdover accuracy. When tracking is enabled the current voltage of DAC can be readback, see DAC_CNT. 8.3.5.2 Entering Holdover The holdover mode is entered as described in Input Clock Switching. Typically this is because: * FORCE_HOLDOVER bit is set. * PLL1 loses lock according to PLL1_DLD, and - HOLDOVER_MODE = 2 - DISABLE_DLD1_DET = 0 26 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com * SNAS589F - JUNE 2012 - REVISED AUGUST 2017 CPout1 voltage crosses DAC high or low threshold, and - HOLDOVER_MODE = 2 - EN_VTUNE_RAIL_DET = 1 - EN_TRACK = 1 - DAC_HIGH_TRIP = User Value - DAC_LOW_TRIP = User Value - EN_MAN_DAC = 1 - MAN_DAC = User Value 8.3.5.3 During Holdover PLL1 is run in open loop mode. * PLL1 charge pump is set to TRI-STATE. * PLL1 DLD will be unasserted. * The HOLDOVER status is asserted * During holdover If PLL2 was locked prior to entry of holdover mode, PLL2 DLD will continue to be asserted. * CPout1 voltage will be set to: - a voltage set in the MAN_DAC register (fixed CPout1). - a voltage determined to be the last valid CPout1 voltage (tracked CPout1). * PLL1 DLD will attempt to lock with the active clock input. The HOLDOVER status signal can be monitored on the Status_HOLDOVER or Status_LD pin by programming the HOLDOVER_MUX or LD_MUX register to "Holdover Status." 8.3.5.4 Exiting Holdover Holdover mode can be exited in one of two ways. * Manually, by programming the device from the host. * Automatically, By a clock operating within a specified ppm of the current PLL1 frequency on the active clock input. See Input Clock Switching for more detail on which clock input is active. To exit holdover by programming, set HOLDOVER_MODE = Disabled. HOLDOVER_MODE can then be reenabled by programming HOLDOVER_MODE = Enabled. Care should be taken to ensure that the active clock upon exiting holdover is as expected, otherwise the CLKin_SELECT_MODE register may need to be reprogrammed. 8.3.5.5 Holdover Frequency Accuracy and DAC Performance When in holdover mode PLL1 will run in open loop and the DAC will set the CPout1 voltage. If Fixed CPout1 mode is used, then the output of the DAC will be a voltage dependant upon the MAN_DAC register. If Tracked CPout1 mode is used, then the output of the DAC will be the voltage at the CPout1 pin before holdover mode was entered. When using Tracked mode and EN_MAN_DAC = 1, during holdover the DAC value is loaded with the programmed value in MAN_DAC, not the tracked value. When in Tracked CPout1 mode the DAC has a worst case tracking error of 2 LSBs once PLL1 tuning voltage is acquired. The step size is approximately 3.2 mV; therefore, the VCXO frequency error during holdover mode caused by the DAC tracking accuracy is 6.4 mV x Kv. Where Kv is the tuning sensitivity of the VCXO in use. Therefore the accuracy of the system when in holdover mode in ppm is: 6.4 mV x Kv x 1e6 Holdover accuracy (ppm) = VCXO Frequency (1) Example: consider a system with a 19.2 MHz clock input, a 153.6 MHz VCXO with a Kv of 17 kHz/V. The accuracy of the system in holdover in ppm is: 0.71 ppm = 6.4 mV x 17 kHz/V x 1e6 / 153.6 MHz It is important to account for this frequency error when determining the allowable frequency error window to cause holdover mode to exit. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 27 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.3.5.6 Holdover Mode - Automatic Exit of Holdover The LMK04906 device can be programmed to automatically exit holdover mode when the accuracy of the frequency on the active clock input achieves a specified accuracy. The programmable variables include PLL1_WND_SIZE and DLD_HOLD_CNT. See Digital Lock Detect Frequency Accuracy to calculate the register values to cause holdover to automatically exit upon reference signal recovery to within a user specified ppm error of the holdover frequency. It is possible for the time to exit holdover to vary because the condition for automatic holdover exit is for the reference and feedback signals to have a time/phase error less than a programmable value. Because it is possible for two clock signals to be very close in frequency but not close in phase, it may take a long time for the phases of the clocks to align themselves within the allowable time/phase error before holdover exits. 8.3.6 PLLs 8.3.6.1 PLL1 PLL1's maximum phase detector frequency (fPD1) is 40 MHz. Since a narrow loop bandwidth should be used for PLL1, the need to operate at high phase detector rate to lower the in-band phase noise becomes unnecessary. The maximum values for the PLL1 R and N dividers is 16,383. Charge pump current ranges from 100 to 1600 A. PLL1 N divider may be driven by OSCin port at the OSCout0_MUX output (default) or by internal or external feedback as selected by Feedback Mux in 0-delay mode. Low charge pump currents and phase detector frequencies aid design of low loop bandwidth loop filters with reasonably sized components to allow the VCXO or PLL2 to dominate phase noise inside of PLL2 loop bandwidth. High charge pump currents may be used by PLL1 when using VCXOs with leaky tuning voltage inputs to improve system performance. 8.3.6.2 PLL2 PLL2's maximum phase detector frequency (fPD2) is 155 MHz. Operating at highest possible phase detector rate will ensure low in-band phase noise for PLL2 which in turn produces lower total jitter. The in-band phase noise from the reference input and PLL is proportional to N2. The maximum value for the PLL2 R divider is 4,095. The maximum value for the PLL2 N divider is 262,143. The N2 Prescaler in the total N feedback path can be programmed for values 2 to 8 (all divides even and odd). Charge pump current ranges from 100 to 3200 A. High charge pump currents help to widen the PLL2 loop bandwidth to optimize PLL2 performance. 8.3.6.2.1 PLL2 Frequency Doubler The PLL2 reference input at the OSCin port may be routed through a frequency doubler before the PLL2 R Divider. The frequency doubler feature allows the phase comparison frequency to be increased when a relatively low frequency oscillator is driving the OSCin port. By doubling the PLL2 phase detector frequency, the in-band PLL2 noise is reduced by about 3 dB. For applications in which the OSCin frequency and PLL2 phase detector frequency are equal, the best PLL2 inband noise can be achieved when the doubler is enabled (EN_PLL2_REF_2X = 1) and the PLL2 R divide value is 2. Do not use doubler disabled (EN_PLL2_REF_2X = 0) and PLL2 R divide value of 1. When using the doubler take care to use the PLL2 R Divider to reduce the phase detector frequency to the limit of the PLL2 maximum phase detector frequency. 8.3.6.3 Digital Lock Detect Both PLL1 and PLL2 support digital lock detect. Digital lock detect compares the phase between the reference path (R) and the feedback path (N) of the PLL. When the time error, which is phase error, between the two signals is less than a specified window size () a lock detect count increments. When the lock detect count reaches a user specified value lock detect is asserted true. Once digital lock detect is true, a single phase comparison outside the specified window will cause digital lock detect to be asserted false. This is illustrated in Figure 10. The incremental lock detect count feature functions as a digital filter to ensure that lock detect isn't asserted for only a brief time when the phases of R and N are within the specified tolerance for only a brief time during initial phase lock. 28 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 The digital lock detect signal can be monitored on the Status_LD or Status_Holdover pin. The pin may be programmed to output the status of lock detect for PLL1, PLL2, or both PLL1 and PLL2. See Digital Lock Detect Frequency Accuracy for more detailed information on programming the registers to achieve a specified frequency accuracy in ppm with lock detect. The digital lock detect feature can also be used with holdover to automatically exit holdover mode. See Holdover Mode for more info. START PLLX Lock Detected = False Lock Count = 0 Phase Error < a NO YES Increment PLLX Lock Count YES NO PLLX Lock Count = PLLX_DLD_CNT YES PLLX Lock Detected = True NO Phase Error > a YES Figure 10. Digital Lock Detect Flowchart 8.3.7 Status PINS The Status_LD, Status_HOLDOVER, Status_CLKin0, Status_CLKin1, and SYNC/Status_CLKin2 pins can be programmed to output a variety of signals for indicating various statuses like digital lock detect, holdover, several DAC indicators, and several PLL divider outputs. 8.3.7.1 Logic Low This is a vary simple output. In combination with the output _MUX register, this output can be toggled between high and low. Useful to confirm MICROWIRE programming or as a general purpose IO. 8.3.7.2 Digital Lock Detect PLL1 DLD, PLL2 DLD, and PLL1 + PLL2 are selectable on certain output pins. See Digital Lock Detect for more information. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 29 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.3.7.3 Holdover Status Indicates if the device is in Holdover mode. See Holdover Mode for more information. 8.3.7.4 DAC Various flags for the DAC can be monitored including DAC Locked, DAC Rail, DAC Low, and DAC High. When the PLL1 tuning voltage crosses the low threshold, DAC Low is asserted. When PLL1 tuning voltage crosses the high threshold, DAC High is asserted. When either DAC Low or DAC High is asserted, DAC Rail will also be asserted. DAC Locked is asserted when EN_Track = 1 and DAC is closely tracking the PLL1 tuning voltage. 8.3.7.5 PLL Divider Outputs The PLL divider outputs are useful for debugging failure to lock issues. It allows the user to measure the frequency the PLL inputs are receiving. The settings of PLL1_R, PLL1_N, PLL2_R, and PLL2_N output pulses at the phase detector rate. The settings of PLL1_R / 2, PLL1_N / 2, PLL2_R / 2, and PLL2_N / 2 output a 50% duty cycle waveform at half the phase detector rate. 8.3.7.6 CLKinX_LOS The clock input loss of signal indicator is asserted when LOS is enabled (EN_LOS) and the clock no longer detects an input as defined by the time-out threshold, LOS_TIMEOUT. The loss of signal indicator detects a loss of signal on CLKinX only when CLKinX_BUF_TYPE is configured as Bipolar. 8.3.7.7 CLKinX Selected If this clock is the currently selected/active clock, this pin will be asserted. 8.3.7.8 MICROWIRE Readback The readback data can be output on any pin programmable to readback mode. For more information on readback see Readback. 8.3.8 VCO The integrated VCO uses a frequency calibration routine when register R30 is programmed to lock VCO to target frequency. Register R30 contains the PLL2_N register. During the frequency calibration the PLL2_N_CAL value is used instead of PLL2_N, this allows 0-delay modes to have a separate PLL2 N value for VCO frequency calibration and regular operation. 8.3.9 Clock Distribution 8.3.9.1 Fixed Digital Delay This section discussing Fixed Digital delay and associated registers is fundamental to understanding digital delay and dynamic digital delay. Clock outputs may be delayed or advanced from one another by up to 517.5 clock distribution path periods. By programming a digital delay value from 4.5 to 522 clock distribution path periods, a relative clock output delay from 0 to 517.5 periods is achieved. The CLKoutX_DDLY (5 to 522) and CLKoutX_HS (-0.5 or 0) registers set the digital delay as shown in Table 3. Table 3. Possible Digital Delay Values 30 CLKoutX_DDLY CLKoutX_HS Digital Delay 5 1 4.5 5 0 5 6 1 5.5 6 0 6 7 1 6.5 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 3. Possible Digital Delay Values (continued) CLKoutX_DDLY CLKoutX_HS Digital Delay 7 0 7 ... ... ... 520 0 520 521 1 520.5 521 0 521 522 1 521.5 522 0 522 NOTE Digital delay values only take effect during a SYNC event and if the NO_SYNC_CLKoutX bit is cleared for this clock output. See Clock Output Synchronization (SYNC) for more information. The resolution of digital delay is determined by the frequency of the clock distribution path. The clock distribution path is the output of Mode Mux1 (Functional Block Diagram). The best resolution of digital delay is achieved by bypassing the VCO divider. VCO_DIV Digital Delay Resolution = (with VCO Divider) 2 x VCO Frequency (2) Digital Delay Resolution 1 (VCO Divider bypassed or external VCO) = 2 x VCO Frequency (3) The digital delay between clock outputs can be dynamically adjusted with no or minimum disruption of the output clocks. See Dynamically Programming Digital Delay for more information. 8.3.9.2 Fixed Digital Delay - Example Given a VCO frequency of 2457.6 MHz and no VCO divider, by using digital delay the outputs can be adjusted in 1 / (2 x 2457.6 MHz) = approximately 203.5-ps steps. To achieve quadrature (90 degree shift) between the 122.88-MHz outputs on CLKout4 and CLKout3 from a VCO frequency of 2457.6 MHz and bypassing the VCO divider, consider the following: 1. The frequency of 122.88 MHz has a period of ~8.14 ns. 2. To delay 90 degrees of a 122.88 MHz clock period requires an approximately 2.03-ns delay. 3. Given a digital delay step of ~203.5 ps, this requires a digital delay value of 12 steps (2.03 ns / 20.35 ps = 10). 4. Since the 10 steps are half period steps, CLKout3_DDLY is programmed 5 full periods beyond 5 for a total of 10. This result in the following programming: * Clock output dividers to 20. CLKout2_DIV = 20 and CLKout3_DIV = 20. * Set first clock digital delay value. CLKout2_DDLY = 5, CLKout2_HS = 0. * Set second 90 degree shifted clock digital delay value. CLKout3_DDLY = 10, CLKout3_HS = 0. Table 4 shows some of the possible phase delays in degrees achievable in the above example. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 31 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 4. Relative Phase Shift from CLKout2 to CLKout3 CLKout3_DDLY = 5 and CLKout3_HS = 0 CLKout3_DDLY CLKout_HS RELATIVE DIGITAL DELAY DEGREES of 122.88 MHz 5 1 -0.5 -9 5 0 0 0 6 1 0.5 9 6 0 1 18 7 1 1.5 27 7 0 2 36 8 1 2.5 45 8 0 3 54 9 1 3.5 63 9 0 4 72 10 1 4.5 81 10 0 5 90 11 1 5.5 99 11 0 6 108 12 1 6.5 117 12 0 7 126 13 1 7.5 135 13 0 8 144 14 1 8.5 153 -- -- -- -- Figure 12 illustrates clock outputs programmed with different digital delay values during a SYNC event. See Dynamically Programming Digital Delay for more information on dynamically adjusting digital delay. 8.3.9.3 Clock Output Synchronization (SYNC) The purpose of the SYNC function is to synchronize the clock outputs with a fixed and known phase relationship between each clock output selected for SYNC. SYNC can also be used to hold the outputs in a low or 0 state. The NO_SYNC_CLKoutX bits can be set to disable synchronization for a clock output. To enable SYNC, EN_SYNC must be set. See EN_SYNC, Enable Synchronization. The digital delay value set by CLKoutX_DDLY takes effect only upon a SYNC event. The digital delay due to CLKoutX_HS takes effect immediately upon programming. See Dynamically Programming Digital Delay for more information on dynamically changing digital delay. During a SYNC event, clock outputs driven by the VCO are not synchronized to clock outputs driven by OSCin. OSCout0 is always driven by OSCin. CLKout3 or 4 may be driven by OSCin depending on the CLKoutX_OSCin_Sel bit value. While SYNC is asserted, NO_SYNC_CLKoutX operates normally for CLKout3 and 4 under all circumstances. SYNC operates normally for CLKout3 and 4 when driven by VCO. 8.3.9.3.1 Effect of SYNC When SYNC is asserted, the outputs to be synchronized are held in a logic low state. When SYNC is unasserted, the clock outputs to be synchronized are activated and will transition to a high state simultaneously with one another except where different digital delay values have been programmed. See Dynamically Programming Digital Delay for SYNC functionality when SYNC_QUAL = 1. 32 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 5. Steady State Clock Output Condition Given Specified Inputs SYNC_TYPE SYNC_POL _INV SYNC PIN CLOCK OUTPUT STATE 0,1,2 (Input) 0 0 Active 0,1,2 (Input) 0 1 Low 0,1,2 (Input) 1 0 Low 0,1,2 (Input) 1 1 Active 3, 4, 5, 6 (Output) 0 0 or 1 Active 3, 4, 5, 6 (Output) 1 0 or 1 Low 8.3.9.3.2 Methods of Generating SYNC There are five methods to generate a SYNC event: * Manual: - Asserting the SYNC pin according to the polarity set by SYNC_POL_INV. - Toggling the SYNC_POL_INV bit though MICROWIRE will cause a SYNC to be asserted. * Automatic: - If PLL1_SYNC_DLD or PLL2_SYNC_DLD is set, the SYNC pin will be asserted while DLD (digital lock detect) is false for PLL1 or PLL2 respectively. - Programming Register R30, which contains PLL2_N will generate a SYNC event when using the internal VCO. - Programming Register R0 through R5 when SYNC_EN_AUTO = 1. NOTE Due to the speed of the clock distribution path (as fast as approximately 325-ps period) and the slow slew rate of the SYNC, the exact VCO cycle at which the SYNC is asserted or unasserted by the SYNC is undefined. The timing diagrams show a sharp transition of the SYNC to clarify functionality. 8.3.9.3.3 Avoiding Clock Output Interruption Due to SYNC Any CLKout outputs that have their NO_SYNC_CLKoutX bits set will be unaffected by the SYNC event. It is possible to perform a SYNC operation with the NO_SYNC_CLKoutX bits cleared, then set the NO_SYNC_CLKoutX bits so that the selected clocks will not be affected by a future SYNC. Future SYNC events will not effect these clocks but will still cause the newly synchronized clocks to be re-synchronized using the currently programmed digital delay values. When this happens, the phase relationship between the first group of synchronized clocks and the second group of synchronized clocks will be undefined unless the SYNC pulse is qualified by an output clock. See Dynamically Programming Digital Delay. 8.3.9.3.4 SYNC Timing When discussing the timing of the SYNC function, one cycle refers to one period of the clock distribution path. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 33 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 6 cycles 6 cycles CLKoutX_DDLY & CLKoutX_HS Distribution Path SYNC (SYNC_POL _INV=1) CLKout0 CLKout2 CLKout4 A B C D CLKout0_DIV = 0(valid only for external VCO mode) CLKout2_DIV = 2 CLKout4_DIV = 4 The digital delay for all clock outputs is 5 The digital delay half step for all clock outputs is 0 SYNC_QUAL = 0 (No qualification) Figure 11. Clock Output Synchronization Using the SYNC Pin (Active Low) See Figure 11 during this discussion on the timing of SYNC. SYNC must be asserted for greater than one clock cycle of the clock distribution path to latch the SYNC event. After SYNC is asserted, the SYNC event is latched on the rising edge of the distribution path clock, at time A. After this event has been latched, the outputs will not reflect the low state for 6 cycles, at time B. Due to the asynchronous nature of SYNC with respect to the output clocks, it is possible that a glitch pulse could be created when the clock output goes low from the SYNC event. This is shown by CLKout4 in Figure 11 and CLKout2 in Figure 12. See Relative Dynamic Digital Delay for more information on synchronizing relative to an output clock to eliminate or minimize this glitch pulse. After SYNC becomes unasserted the event is latched on the following rising edge of the distribution path clock, time C. The clock outputs will rise at time D, coincident with a rising distribution clock edge that occurs after 6 cycles plus as many more cycles as programmed by the digital delay for that clock output. Therefore, the soonest a clock output will become high is 11 cycles after the SYNC unassertion event registration, time C, when the smallest digital delay value of 5 is set. If CLKoutX_HS = 1 and CLKoutX_DDLY = 5, then the clock output will rise 10.5 cycles after SYNC is unassertion event registration. 34 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 6 cycles CLKoutX_DDLY & CLKoutX_HS Distribution Path 4.5 cycles 6 cycles 2.5 cycles 1 cycle SYNC (SYNC_POL _INV=1) CLKout0 CLKout2 CLKout4 CLKout5 A B C D E F CLKout0_DIV = 2, CLKout0_DDLY = 5 CLKout2_DIV = 4, CLKout2_DDLY = 7 CLKout4_DIV = 4, CLKout4_DDLY = 8 CLKout5_DIV = 4, CLKour4_DDLY = 8 CLKout0_HS = 1 CLKout2_HS = 0 CLKout4_HS = 0 CLKout5_HS = 0 SYNC_QUAL = 0 (No qualification) Figure 12. Clock Output Synchronization Using the SYNC Pin (Active Low) Figure 12 illustrates the timing with different digital delays programmed. * Time A) SYNC assertion event is latched. * Time B) SYNC unassertion latched. * Time C) All outputs toggle and remain low. A glitch pulse can occur at this time as shown by CLKout2. * Time D) After 6 + 4.5 = 10.5 cycles CLKout0 rises. This is the shortest time from SYNC unassertion registration to clock rising edge possible. * Time E) After 6 + 7 = 13 cycles CLKout2 rises. CLKout2 and CLKout4, 5 are programmed for quadrature operation. * Time F) After 6 + 8 = 14 cycles CLKout4 and 5 rise. 8.3.9.4 Dynamically Programming Digital Delay To use dynamic digital delay synchronization qualification set SYNC_QUAL = 1. This causes the SYNC pulse to be qualified by a clock output so that the SYNC event occurs after a specified time from a clock output transition. This allows the relative adjustment of clock output phase in real-time with no or minimum interruption of clock outputs. Hence the term dynamic digital delay. Note that changing the phase of a clock output requires momentarily altering in the rate of change of the clock output phase and therefore by definition results in a frequency distortion of the signal. Without qualifying the SYNC with an output clock, the newly synchronized clocks would have a random and unknown digital delay (or phase) with respect to clock outputs not currently being synchronized. 8.3.9.4.1 Absolute vs Relative Dynamic Digital Delay The clock used for qualification of SYNC is selected with the feedback mux (FEEDBACK_MUX). Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 35 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com If the clock selected by the feedback mux has its NO_SYNC_CLKoutX = 1, then an absolute dynamic digital delay adjustment will be performed during a SYNC event and the digital delay of the feedback clock will not be adjusted. If the clock selected by the feedback mux has its NO_SYNC_CLKoutX = 0, then a self-referenced or relative dynamic digital delay adjustment will be performed during a SYNC event and the digital delay of the feedback clock will be adjusted. Clocks with NO_SYNC_CLKoutX = 1 always operate without interruption. 8.3.9.4.2 Dynamic Digital Delay and 0-Delay Mode When using a 0-delay mode absolute dynamic digital delay is recommended. Using relative dynamic digital delay with a 0-delay mode may result in a momentary clock loss on the adjusted clock also being used for 0delay feedback that may result in PLL1 DLD becoming low. This may result in HOLDOVER mode being activated depending upon device configuration. 8.3.9.4.3 SYNC and Minimum Step Size The minimum step size adjustment for digital delay is half a clock distribution path cycle. This is achieved by using the CLKoutX_HS bit. The CLKoutX_HS bit change effect is immediate without the need for SYNC. To shift digital delay using CLKoutX_DDLY a SYNC signal must be generated for the change to take effect. 8.3.9.4.4 Programming Overview To dynamically adjust the digital delay with respect to an existing clock output the device should be programmed as follows: * Set SYNC_QUAL = 1 for clock output qualification. * Set CLKout2_PD = 0. Required for proper operation of SYNC_QUAL = 1. * Set EN_FEEDBACK_MUX = 1 to enable the feedback buffer. * Set FEEDBACK_MUX to the clock output that the newly synchronized clocks will be qualified by. * Set NO_SYNC_CLKoutX = 1 for the output clocks that will continue to operate during the SYNC event. There is no interruption of output on these clocks. - If FEEDBACK_MUX selects a clock output with NO_SYNC_CLKoutX = 1, then absolute dynamic digital delay is performed. - If FEEDBACK_MUX selects a clock output with NO_SYNC_CLKoutX = 0, then self-referenced or relative dynamic digital delay is performed. * The SYNC_EN_AUTO bit may be set to cause a SYNC event to begin when register R0 to R5 is programmed. The auto SYNC feature is a convenience since does not require the application to manually assert SYNC by toggling the SYNC_POL_INV bit or the SYNC pin when changing digital delay. However, under the following condition a special programming sequence is required if SYNC_EN_AUTO = 1: - The CLKoutX_DDLY value being set in the programmed register is 13 or more. * Under the following condition a SYNC_EN_AUTO must = 0: - If the application requires a digital delay resolution of half a clock distribution path cycle in relative dynamic digital delay mode because the HS bit must be fixed per Table 6 for a qualifying clock. 8.3.9.4.5 Internal Dynamic Digital Delay Timing To dynamically adjust digital delay a SYNC must occur. Once the SYNC is qualified by an output clock, 3 cycles later an internal one shot pulse will occur. The width of the one shot pulse is 3 cycles. This internal one shot pulse will cause the outputs to turn off and then back on with a fixed delay with respect to the falling edge of the qualification clock. This allows for dynamic adjustments of digital delay with respect to an output clock. The qualified SYNC timing is shown in Figure 13 for absolute dynamic digital delay and Figure 14 for relative dynamic digital delay. 8.3.9.4.6 Other Timing Requirements When adjusting digital delay dynamically, the falling edge of the qualifying clock selected by the FEEDBACK_MUX must coincide with the falling edge of the clock distribution path. For this requirement to be met, program the CLKoutX_HS value of the qualifying clock output according to Table 6. 36 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 6. Half Step Programming Requirement of Qualifying Clock During SYNC Event DISTRIBUTION PATH FREQUENCY CLKoutX_DIV value CLKoutX_HS Even Must = 1 during SYNC event. 1.8 GHz < 1.8 GHz Odd Must = 0 during SYNC event. Even Must = 0 during SYNC event. Odd Must = 1 during SYNC event. 8.3.9.5 Absolute Dynamic Digital Delay Absolute dynamic digital delay can be used to program a clock output to a specific phase offset from another clock output. Pros: * Simple direct phase adjustment with respect to another clock output. * CLKoutX_HS will remain constant for qualifying clock. - Can easily use auto sync feature (SYNC_EN_AUTO = 1) when digital delay adjustment requires half step digital delay requirements. * Can be used with 0-delay mode. Cons: * For some phase adjustments there may be a glitch pulse due to SYNC assertion. - For example see CLKout4 in Figure 11 and CLKout2 in Figure 12. 8.3.9.5.1 Absolute Dynamic Digital Delay - Example To illustrate the absolute dynamic digital delay adjust procedure, consider the following example. System Requirements: * VCO Frequency = 2457.6 MHz * CLKout0 = 819.2 MHz (CLKout0_DIV = 3) * CLKout2 = 307.2 MHz (CLKout2_DIV = 8) * CLKout4 = 245.76 MHz (CLKout4_DIV = 10) * For all clock outputs during initial programming: - CLKoutX_DDLY = 5 - CLKoutX_HS = 1 - NO_SYNC_CLKoutX = 0 The application requires the 307.2 MHz clock to be stepped in 22.5 degree steps (approximately 203.4 ps), which is the minimum step resolution allowable by the clock distribution path requiring use of the half step bit (CLKoutX_HS). That is 1 / 2457.6 MHz / 2 = ~203.4 ps. During the stepping of the 307.2 MHz clock the 819.2 MHz and 245.76 MHz clock must not be interrupted. 1. The device is programmed from register R0 to R30 with values that result in the device being locked and operating as desired, see the system requirements above. The phase of all the output clocks are aligned because all the digital delay and half step values were the same when the SYNC was generated by programming register R30. The timing of this is as shown in Figure 11. 2. Now the registers will be programmed to prepare for changing digital delay (or phase) dynamically. Table 7. Register Setup for Absolute Dynamic Digital Delay Example REGISTER PURPOSE SYNC_QUAL = 1 Use a clock output for qualifying the SYNC pulse for dynamically adjusting digital delay. EN_SYNC = 1 (default) Required for SYNC functionality. CLKout2_PD = 0 Required when SYNC_QUAL = 1. CLKout2 outputs may be powered down or in use. EN_FEEDBACK_MUX = 1 Enable the feedback mux for SYNC operation for dynamically adjusting digital delay. FEEDBACK_MUX = 2 (CLKout4) Use the fixed 245.76 MHz clock as the SYNC qualification clock. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 37 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 7. Register Setup for Absolute Dynamic Digital Delay Example (continued) REGISTER PURPOSE NO_SYNC_CLKout0 = 1 This clock output (819.2 MHz) won't be affected by SYNC. It will always operate without interruption. NO_SYNC_CLKout4 = 1 This clock output (245.76 MHz) won't be affected by SYNC. It will always operate without interruption. This clock will also be the qualifying clock in this example. CLKout4_HS = 1 Since CLKout4 is the qualifying clock and CLKoutX_DIV is even, the half step bit must be set to 1. See Table 6. SYNC_EN_AUTO = 1 Automatic generation of SYNC is allowed for this case. After the registers in Table 7 have been programmed, the application may now dynamically adjust the digital delay of CLKout2 (307.2 MHz). 3. Adjust digital delay of CLKout2. See Table 8 for the programming values to set a specified phase offset from the absolute reference clock. Table 8 is dependant upon the qualifying clock divide value of 12, see Calculating Dynamic Digital Delay Values For Any Divide for information on creating tables for any divide value. Table 8. Programming for Absolute Digital Delay Adjustment DEGREES OF ADJUSTMENT FROM INITIAL 307.2-MHZ PHASE 0 or 360 degrees PROGRAMMING CLKout2_DDLY = 14; CLKout2_HS = 1 22.5 -337.5 CLKout2_DDLY = 14; CLKout2_HS = 0 45 -315 CLKout2_DDLY = 15; CLKout2_HS = 1 67.5 -292.54 CLKout2_DDLY = 5; CLKout2_HS = 0 90 -270 CLKout2_DDLY = 6; CLKout2_HS = 1 112.5 -247.5 CLKout2_DDLY = 6; CLKout2_HS = 0 135 -25 CLKout2_DDLY = 7; CLKout2_HS = 1 157.5 -202.5 CLKout2_DDLY = 7; CLKout2_HS = 0 180 -180 CLKout2_DDLY = 8; CLKout2_HS = 1 247.5 -112.5 CLKout2_DDLY = 8; CLKout2_HS = 0 270 -90 CLKout2_DDLY = 9; CLKout2_HS = 1 292.5 -67.5 CLKout2_DDLY = 9; CLKout2_HS = 0 315 -45 CLKout2_DDLY = 10; CLKout2_HS = 1 337.5 -22.5 CLKout2_DDLY = 10; CLKout2_HS = 0 After setting the new digital delay values, the act of programming R1 will start a SYNC automatically because SYNC_EN_AUTO = 1. If the user elects to reduce the number of SYNCs because they are not required when only CLKout2_HS is set, then SYNC_EN_AUTO is = 0 and the SYNC may now be generated by toggling the SYNC pin or by toggling the SYNC_POL_INV bit. Because of the internal one shot pulse, no strict timing of the SYNC pin or SYNC_POL_INV bit is required. After the SYNC event, the clock output will adjust according to Table 8. See Figure 13 for a detailed view of the timing diagram. The timing diagram critical points are: * Time A) SYNC assertion event is latched. * Time B) First qualifying falling clock output edge. * Time C) Second qualifying falling clock output edge. * Time D) Internal one shot pulse begins. 5 cycles later clock outputs will be forced low * Time E) Internal one shot pulse ends. 5.5 cycles + digital delay cycles later the synced clock outputs rise. * Time F) Clock outputs are forced low. (CLKout2 is already low). * Time G) Beginning of digital delay cycles. * Time H) For CLKout2_DDLY = 14; the clock output rises now. 38 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 5 cycles CLKoutX_DDLY and CLKoutX_HS Distribution Path 5.5 cycles 3 cycles 3 cycles 13.5 cycles SYNC Internal One Shot Pulse CLKout0 /3 HS = 1 CLKout2 /8 HS = 1 CLKout4 /10 HS = 1 1 2 AB C D E F G H (SYNC_QUAL = 1, Qualify with clock output) Figure 13. Absolute Dynamic Digital Delay Programming Example 8.3.9.6 Relative Dynamic Digital Delay Relative dynamic digital delay can be used to program a clock output to a specific phase offset from another clock output. Pros: * Simple direct phase adjustment with respect to same clock output. * The clock output will always behave the same during digital delay adjustment transient. For some divide values there will be no glitch pulse. Cons: * For some clock divide values there may be a glitch pulse due to SYNC assertion. * Adjustments of digital delay requiring the half step bit (CLKoutX_HS) for finer digital delay adjust is complicated. * Use with 0-delay mode may result in PLL1 DLD becoming low and HOLDOVER mode becoming activated. - DISABLE_DLD1_DET can be set to prevent HOLDOVER from becoming activated due to PLL1 DLD becoming low. 8.3.9.6.1 Relative Dynamic Digital Delay - Example To illustrate the relative dynamic digital delay adjust procedure, consider the following example. System Requirements: * VCO Frequency = 2457.6 MHz * CLKout0 = 819.2 MHz (CLKout0_DIV = 3) * CLKout2 = 491.52 MHz (CLKout2_DIV = 5) * CLKout4 = 491.52 MHz (CLKout4_DIV = 5) * For all clock outputs during initial programming: - CLKoutX_DDLY = 5 - CLKoutX_HS = 0 - NO_SYNC_CLKoutX = 0 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 39 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com The application requires the 491.52 MHz clock to be stepped in 22.5degree steps (~203.4 ps), which is the minimum step resolution allowable by the clock distribution path. That is 1 / 2457.62 MHz / 2 = ~203.4 ps. During the stepping of the 491.52 MHz clocks the 819.2 MHz clock must not be interrupted. 1. The device is programmed from register R0 to R30 with values that result in the device being locked and operating as desired, see the system requirements above. The phase of all the output clocks are aligned because all the digital delay and half step values were the same when the SYNC was generated by programming register R30. The timing of this is as shown in Figure 11. 2. Now the registers will be programmed to prepare for changing digital delay (or phase) dynamically. Table 9. Register Setup for Relative Dynamic Digital Delay Adjustment REGISTER PURPOSE SYNC_QUAL = 1 Use clock output for qualifying the SYNC pulse for dynamically adjusting digital delay. EN_SYNC = 1 (default) Required for SYNC functionality. CLKout2_PD = 0 Required when SYNC_QUAL = 1. CLKout2 outputs may be powered down or in use. EN_FEEDBACK_MUX = 1 Enable the feedback mux for SYNC operation for dynamically adjusting digital delay. FEEDBACK_MUX = 1 (CLKout2) Use the clock itself as the SYNC qualification clock. NO_SYNC_CLKout0 = 1 This clock output (819.2 MHz) won't be affected by SYNC. It will always operate without interruption. NO_SYNC_CLKout4 = 1 CLKout4's phase is not to change with respect to CLKout0. SYNC_EN_AUTO = 0 (default) Automatic generation of SYNC is not allowed because of the half step requirement in relative dynamic digital delay mode. SYNC must be generated manually by toggling the SYNC_POL_INV bit or the SYNC pin. After the above registers have been programmed, the application may now dynamically adjust the digital delay of the 491.52 MHz clocks. 3. Adjust digital delay of CLKout2 by one step which is 22.5 degrees or approximately 203.4 ps. See Table 10 for the programming sequence to step one half clock distribution period forward or backwards. Refer to Calculating Dynamic Digital Delay Values For Any Divide for more information on how to calculate digital delay and half step values for other cases. To fulfill the qualifying clock output half step requirement in Table 6 when dynamically adjusting digital delay, the CLKoutX_HS bit must be cleared for clocks with even divides. So before any dynamic digital delay adjustment, CLKoutX_HS must be clear because the clock divide value is even. To achieve the final required digital delay adjustment, the CLKoutX_HS bit may set after SYNC. Table 10. Programming Sequence for One Step Adjust STEP DIRECTION AND CURRENT HS STATE PROGRAMMING SEQUENCE Adjust clock output one step forward. CLKout2_HS is 0. 1. CLKout2_HS = 1. Adjust clock output one step forward. CLKout2_HS is 1. 1. CLKout2_DDLY = 11. 2. Perform SYNC event. 3. CLKout2_HS = 0. Adjust clock output one step backward. CLKout2_HS is 0. 1. CLKout2_HS = 1. 2. CLKout2_DDLY =11. 3. Perform SYNC event. Adjust clock output one step backward. CLKout2_HS is 1. 1. CLKout2_HS = 0. After programing the updated CLKout2_DDLY and CLKout2_HS values, perform a SYNC event. The SYNC may be generated by toggling the SYNC pin or by toggling the SYNC_POL_INV bit. Because of the internal one shot pulse, no strict timing of the SYNC pin or SYNC_POL_INV bit is required. After the SYNC event, the clock output will be at the specified phase. See Figure 14 for a detailed view of the timing diagram. The timing diagram critical points are: * Time A) SYNC assertion event is latched. 40 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com * * * * * * * Time Time Time Time Time Time Time SNAS589F - JUNE 2012 - REVISED AUGUST 2017 B) First qualifying falling clock output edge. C) Second qualifying falling clock output edge. D) Internal one shot pulse begins. 5 cycles later clock outputs will be forced low. E) Internal one shot pulse ends. 5.5 cycles + digital delay cycles later the synced clock outputs rise. F) Clock outputs are forced low. (CLKouts are already low). G) Beginning of digital delay cycles. H) For CLKout2_DDLY = 11; the clock output rises now. CLKoutX_DDLY and CLKoutX_HS 5 cycles Distribution Path 5.5 cycles 3 cycles 3 cycles 10.5 cycles SYNC Internal One Shot Pulse CLKout0 /3 HS = 1 CLKout2 /5 HS = 1 1 2 CLKout4 /5 HS = 1 AB C D E F G H (SYNC_QUAL = 1, Qualify with clock output) Starting condition is after half step is removed (CLKout2_HS = 0). Figure 14. Relative Dynamic Digital Delay Programming Example--2nd Adjust 8.3.10 0-Delay Mode When 0-delay mode is enabled the clock output selected by the Feedback Mux is connected to the PLL1 N counter to ensure a fixed phase relationship between the selected CLKin and the fed back CLKout. When all the clock outputs are synced together, all the clock outputs will share the same fixed phase relationship between the selected CLKin and the fed back CLKout. The feedback can be internal or external using FBCLKin port. When 0-delay mode is enabled the lowest frequency clock output is fed back to the Feedback Mux to ensure a repeatable fixed CLKin to CLKout phase relationship between all clock outputs. If a clock output that is not the lowest frequency output is selected for feedback, then clocks with lower frequencies will have an unknown phase relationship with respect the other clocks and clock input. There will be a number of possible phase relationships equal to Feedback_Clock_Frequency / Lower_Clock_Frequency that may occur. The Feedback Mux can select a clock output of some of the clocks for internal feedback or the FBCLKin port for external 0-delay feedback. To use 0-delay mode, the bit EN_FEEDBACK_MUX must be set (=1) to power up the feedback mux. See PLL Programming for more information on programming PLL1_N for 0-delay mode. When using an external VCO mode, internal 0-delay feedback must be used since the FBCLKin port is shared with the Fin input. Table 11 outlines several registers to program for 0-delay mode. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 41 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 11. Programming 0-Delay Mode REGISTER PURPOSE MODE = 2 or 5 Select one of the 0-delay modes for device. EN_FEEDBACK_MUX = 1 Enable feedback mux. FEEDBACK_MUX = Application Specific Select CLKout or FBCLKin for 0-delay feedback. CLKoutX_DIV The divide value of the clock selected by FEEDBACK_MUX is important for PLL2 N value calculation PLL1_N PLL1_N value used with CLKoutX_DIV in loop. 8.3.11 Hitless Switching The LMK04906 supports hitless switching. 8.4 Device Functional Modes 8.4.1 Mode Selection The LMK04906 family is capable of operating in several different modes as programmed by MODE: Device Mode. Table 12. Device Mode Selection MODE R11[31:27] PLL1 PLL2 PLL2 VCO 0 X X Internal 2 X X Internal 3 X X External 5 X X External 6 X Internal 8 X Internal 11 X External 0-DELAY CLOCK DIST X X X X X X X X X X 16 X In addition to selecting the device's mode of operation above, some modes require additional configuration. Also there are other features including holdover and dynamic digital delay that can also be enabled. Table 13. Registers to Further Configure Device Mode of Operation 42 REGISTER HOLDOVER 0-DELAY DYNAMIC DIGITAL DELAY HOLDOVER_MODE 2 -- -- EN_TRACK User -- -- DAC_CLK_DIV User -- -- EN_MAN_DAC User -- -- DISABLE_DLD1_DET User -- -- EN_VTUNE_RAIL_ DET User -- -- DAC_HIGH_TRIP User -- -- -- DAC_LOW_TRIP User -- FORCE_HOLDOVER 0 -- -- SYNC_EN_AUTO -- -- User SYNC_QUAL -- -- 1 EN_SYNC -- -- 1 CLKout2_PD -- -- 0 EN_ FEEDBACK_MUX -- 1 1 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 13. Registers to Further Configure Device Mode of Operation (continued) REGISTER HOLDOVER 0-DELAY DYNAMIC DIGITAL DELAY FEEDBACK_MUX -- Feedback Clock Qualifying Clock NO_SYNC_ CLKoutX -- -- User 8.4.2 Operating Modes The LMK04906 is a flexible device that can be configured for many different use cases. The following simplified block diagrams help show the user the different use cases of the device. 8.4.2.1 Dual PLL Figure 15 illustrates the typical use case of the LMK04906 in dual loop mode. In dual loop mode the reference to PLL1 is either CLKin0, CLKin1, or CLKin2. An external VCXO or tunable crystal will be used to provide feedback for the first PLL and a reference to the second PLL. This first PLL cleans the jitter with the VCXO or low cost tunable crystal by using a narrow loop bandwidth. The VCXO or tunable crystal output may be buffered through the OSCout0 port and optionally on up to 2 of the CLKouts. The VCXO or tunable crystal is used as the reference to PLL2 and may be doubled using the frequency doubler. The internal VCO drives up to six divide/delay blocks which drive 6 clock outputs. Holdover functionality is optionally available when the input reference clock is lost. Holdover works by fixing the tuning voltage of PLL1 to the VCXO or tunable crystal. It is also possible to use an external VCO in place of PLL2's internal VCO. R N Phase Detector PLL1 PLL2 External VCXO or Tunable Crystal External Loop Filter OSCout0 OSCout0* 1 output OSCin CLKinX CLKinX* 3 inputs CPout1 PLL1 External Loop Filter CPout2 R Input Buffer N Phase Detector PLL2 Divider Digital Delay Analog Delay Partially Integrated Loop Filter Internal VCO CLKoutX CLKoutX* 6 outputs 6 blocks LMK04906 Copyright (c) 2016, Texas Instruments Incorporated Figure 15. Simplified Functional Block Diagram for Dual Loop Mode 8.4.2.2 0-Delay Dual PLL Figure 16 illustrates the use case of 0-delay dual loop mode. This configuration is very similar to Dual PLL except that the feedback to the first PLL is driven by a clock output. This causes the clock outputs to have deterministic phase with the clock input. Since all the clock outputs can be synchronized together, all the clock outputs can be in phase with the clock input signal. The feedback to PLL1 can be connected internally as shown, or externally using FBCLKin (CLKin1) as an input port. It is also possible to use an external VCO in place of PLL2's internal VCO. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 43 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com R Phase Detector PLL1 3 inputs N PLL2 External VCXO or Tunable Crystal External Loop Filter OSCout0 OSCout0* 1 output OSCin CLKinX CLKinX* CPout1 PLL1 External Loop Filter CPout2 R Input Buffer N Phase Detector PLL2 Divider Digital Delay Analog Delay Partially Integrated Loop Filter CLKoutX CLKoutX* 6 outputs Internal VCO 6 blocks Internal or external loopback, user programmable LMK04906 Figure 16. Simplified Functional Block Diagram for 0-delay Dual Loop Mode 8.4.2.3 Single PLL Figure 17 illustrates the use case of single PLL mode. In single PLL mode only PLL2 is used and PLL1 is powered down. OSCin is used as the reference input. The internal VCO drives up to 6 divide/delay blocks which drive 6 clock outputs. The reference at OSCin can be used to drive the OSCout0 port. OSCin can also optionally drive up to 2 of the clock outputs. It is also possible to use an external VCO in place of PLL2's internal VCO. PLL2 OSCout0 OSCout0* 1 outputs External Loop Filter CPout2 OSCin OSCin* R N Phase Detector PLL2 Divider Digital Delay Analog Delay Partially Integrated Loop Filter CLKoutX CLKoutX* 6 outputs Internal VCO 6 blocks LMK04906 Figure 17. Simplified Functional Block Diagram for Single Loop Mode 8.4.2.4 0-delay Single PLL Figure 18 illustrates the use case of 0-delay single PLL mode. This configuration is very similar to Single PLL except that the feedback to PLL2 comes from a clock output. This causes the clock outputs to be in phase with the reference input. Since all the clock outputs can be synchronized together, all the clock outputs can be in phase with the clock input signal. The feedback to PLL2 can be performed internally as shown, or externally using FBCLKin (CLKin1) as an input port. It is also possible to use an external VCO in place of PLL2's internal VCO. 44 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 PLL2 OSCout0 OSCout0* 1 output External Loop Filter CPout2 OSCin OSCin* R N Phase Detector PLL2 Divider Digital Delay Analog Delay Partially Integrated Loop Filter CLKoutX CLKoutX* 6 outputs Internal VCO 6 blocks Internal or external loopback, user programmable LMK04906 Figure 18. Simplified Functional Block Diagram for 0-delay Single Loop Mode 8.4.2.5 Clock Distribution Figure 19 illustrates the LMK04906 used for clock distribution. CLKin1 is used to drive up to 6 divide/delay blocks which drive 6 outputs. OSCin can be used to drive the OSCout port. OSCin can also optionally drive up to 2 of the clock outputs. CLKin1 CLKin1* Divider Digital Delay Analog Delay CLKoutX CLKoutX* 6 outputs 6 blocks OSCout0 OSCout0* 1 output OSCin OSCin* LMK04906 Figure 19. Simplified Functional Block Diagram for Mode Clock Distribution 8.5 Programming LMK04906 devices are programmed using 32-bit registers. Each register consists of a 5-bit address field and 27bit data field. The address field is formed by bits 0 through 4 (LSBs) and the data field is formed by bits 5 through 31 (MSBs). The contents of each register is clocked in MSB first (bit 31), and the LSB (bit 0) last. During programming, the LEuWire signal should be held low. The serial data is clocked in on the rising edge of the CLKuWire signal. After the LSB (bit 0) is clocked in the LEuWire signal should be toggled low-to-high-to-low to latch the contents into the register selected in the address field. It is recommended to program registers in numeric order, for example R0 to R16, and R24 to R31 to achieve proper device operation. Figure 6 illustrates the serial data timing sequence. To achieve proper frequency calibration, the OSCin port must be driven with a valid signal before programming register R30. Changes to PLL2 R divider or the OSCin port frequency require register R30 to be reloaded in order to activate the frequency calibration process. 8.5.1 Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY In some cases when programming register R0 to R5 to change the CLKoutX_DIV divide value or CLKoutX_DDLY delay value, 3 additional CLKuWire cycles must occur after loading the register for the newly programmed divide or delay value to take effect. These special cases include: * When CLKoutX_DIV is > 25. * When CLKoutX_DDLY is > 12. Note, loading the digital delay value only prepares for a future SYNC event. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 45 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Programming (continued) Also, since SYNC_EN_AUTO bit = 1 automatically generates a SYNC on the falling edge of LE when R0 to R5 is programmed, further programming considerations must be made when SYNC_EN_AUTO = 1. These special programming cases requiring the additional three clock cycles may be properly programmed by one of the following methods shown in Table 14. Table 14. R0 to R5 Special Case CLKoutX_DIV & CLKoutX_DDLY SYNC _EN_ AUTO PROGRAMMING METHOD CLKoutX_DIV 25 and CLKoutX_DDLY 12 0 or 1 No Additional Clocks Required (Normal) CLKoutX_DIV > 25 or CLKoutX_DDLY > 12 0 Three Extra CLKuWire Clocks (Or program another register) CLKoutX_DIV > 25 or CLKoutX_DDLY > 12 1 Three Extra CLKuWire Clocks while LEuWire is High Method: No Additional Clocks Required (Normal) No special consideration to CLKuWire is required when changing divide value to 25, digital delay value to 12, or when the digital delay and divide value do not change. See MICROWIRE timing Figure 6. Method: Three Extra CLKuWire Clocks Three extra clocks must be provided before CLKoutX_DIV > 25 or CLKoutX_DDLY > 12 take effect. See MICROWIRE timing Figure 7. Also, by programming another register the three clock requirement can be satisfied. Method: Three Extra CLKuWire Clocks with LEuWire Asserted When SYNC_EN_AUTO = 1 the falling edge of LEuWire will generate a SYNC event. CLKoutX_DIV and CLKoutX_DDLY values must be updated before the SYNC event occurs. So 3 CLKuWire rising edges must occur before LEuWire goes low. See MICROWIRE timing Figure 8. Initial Programming Sequence During the recommended programming sequence the device is programmed in order from R0 to R31, so it is expected at least one additional register will be programmed after programming the last CLKoutX_DIV or CLKoutX_DDLY value in R0 to R5. This will result in the extra needed CLKuWire rising edges, so this special note is of little concern. If programming R0 to R5 to change CLKout frequency or digital delay or dynamic digital delay at a later time in the application, care must be taken to provide these extra CLKuWire cycles to properly load the new divide and/or delay values. 8.5.1.1 Example In this example, all registers have been programmed, the PLLs are locked. An LMK04906 has been generating a clock output frequency of 61.44 MHz on CLKout4 using a VCO frequency of 2457.6 MHz and a divide value of 40. SYNC_EN_AUTO = 0. At a later time the application requires a 30.72 MHz output on CLKout4. By reprogramming register R4 with CLKout4_DIV = 80 twice, the divide value of 80 is set for clock output 4 which results in an output frequency of 30.72 MHz (2457.6 MHz / 80 = 30.72 MHz) on CLKout4. In this example the required 3 CLKuWire cycles were achieved by reprogramming the R4 register with the same value twice. 8.5.2 Recommended Programming Sequence Registers are programmed in numeric order with R0 being the first and R31 being the last register programmed. The recommended programming sequence involves programming R0 with the reset bit (b17) set to 1 to ensure the device is in a default state. If R0 is programmed again, the reset bit must be cleared to 0 during the programming of R0. 46 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.5.2.1 Overview * Program R0 with RESET bit = 1. This ensures that the device is configured with default settings. When RESET = 1, all other R0 bits are ignored. - If R0 is programmed again during the initial configuration of the device, the RESET bit must be cleared. * R0 through R5: CLKouts. - Program as necessary to configure the clock outputs, CLKout0 to CLKout5 as desired. These registers configure clock output controls such as powerdown, digital delay and divider value, analog delay select, and clock source select. * R6 through R8: CLKouts. - Program as necessary to configure the clock outputs, CLKout0 to CLKout5 as desired. These registers configure the output format for each clock outputs and the analog delay for the clock outputs. * R9: Required programming - Program this register as shown in the register map for proper operation. * R10: OSCouts, VCO divider, and 0-delay. - Enable and configure clock outputs OSCout0/1. - Set and select VCO divider (VCO bypass is recommended). - Set 0-delay feedback source if used. * R11: Part mode, SYNC, and XTAL. - Program to configure the mode of the part, to configure SYNC functionality and pin, and to enable crystal mode. * R12: Pins, SYNC, and holdover mode. - Status_LD pin, more SYNC options to generate a SYNC upon PLL1 and/or PLL2 lock detect. - Enable clock features such as holdover. * R13: Pins, holdover mode, and CLKins. - Status_HOLDOVER, Status_CLKin0, and Status_CLKin1 pin controls. - Enable clock inputs for use in specific part modes. * R14: Pins, LOS, CLKins, and DAC. - Status_CLKin1 pin control. - Loss of signal detection, CLKin type, DAC rail detect enable and high and low trip points. * R15: DAC and holdover mode. - Program to enable and set the manual DAC value. - HOLDOVER mode options. * R16: Crystal amplitude. - Increasing XTAL_LVL can improve tunable crystal phase noise performance. * R24: PLL1 and PLL2. - PLL1 N and R delay and PLL1 digital lock delay value. - PLL2 integrated loop filter. * R25: DAC and PLL1. - Program to configure DAC update clock divider and PLL1 digital lock detect count. * R26: PLL2. - Program to configure PLL2 options. * R27: CLKins and PLL1. - Clock input pre-dividers. - Program to configure PLL1 options. * R28: PLL1 and PLL2. - Program to configure PLL2 R and PLL1 N. * R29: OSCin and PLL2. - Program to configure oscillator input frequency, PLL2 fast phase detector frequency mode, and PLL2 N calibration value. * R30: PLL2. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 47 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 * www.ti.com - Program to configure PLL2 prescaler and PLL2 N value. R31: uWire lock. - Program to set the uWire_LOCK bit. 8.5.3 Readback At no time should the MICROWIRE registers be programmed to any value other than what is specified in the datasheet. For debug of the MICROWIRE interface, it is recommended to simply program an output pin mux to active low and then toggle the output type register between output and inverting output while observing the output pin for a low to high transition. For example, to verify MICROWIRE programming, set the LD_MUX = 0 (Low) and then toggle the LD_TYPE register between 3 (Output, push-pull) and 4 (Output inverted, push-pull). The result will be that the Status_LD pin will toggle from low to high. Readback from the MICROWIRE programming registers is available. The MICROWIRE readback function can be enabled on the Status_LD, Status_HOLDOVER, Status_CLKin0, Status_CLKin1, or SYNC pin by programming the corresponding MUX register to "uWire Readback" and the corresponding TYPE register to "Output (push-pull)." Power on reset defaults the Status_HOLDOVER pin to "uWire Readback." Figure 9 illustrates the serial data timing sequence for a readback operation for both cases of READBACK_LE = 0 (POR default) and READBACK_LE = 1. To perform a readback operation first set the register to be read back by programming the READBACK_ADDR register. Then after any MICROWIRE write operation, with the LEuWire pin held low continue to clock the CLKuWire pin. On every rising edge of the CLKuWire pin a new data bit is clocked onto the any pins programmed for uWire Readback. If the READBACK_LE bit is set, the LEuWire pin should be left high after LEuWire rising edge while continuing to clock the CLKuWire pin. It is allowable to perform a register read back in the same MICROWIRE operation which set the READBACK_ADDR register value. Data is clocked out MSB first. After 27 clocks all the data values will have been read and the read operation is complete. If READBACK_LE = 1, the LEuWire line may now be lowered. It is allowable for the CLKuWire pin to be clocked additional cycles, but the data on the readback pin will be invalid. CLKuWire must be low before the falling edge of LEuWire. 8.5.3.1 Readback - Example To readback register R3 perform the following steps: * Write R31 with READBACK_ADDR = 3; READBACK_LE = 0. DATAuWire and CLKuWire are toggled as shown in Figure 6 with new data being clocked in on rising edges of CLKuWire * Toggle LEuWire high and then low as shown in Figure 6 and Figure 9. LEuWire is returned low because READBACK_LE = 0. * Toggle CLKuWire high and then low 27 times to read back all 27 bits of register R3. Data is read MSB first. Data is valid on falling edge of CLKuWire. * Read operation is complete. 8.6 Register Maps 8.6.1 Register Map and Readback Register Map Table 15 provides the register map for device programming. Normally any register can be read from the same data address it is written to. However, READBACK_LE has a different readback address. Also, the DAC_CNT register is a read only register. Table 16 shows the address for READBACK_LE and DAC_CNT. Bits marked as reserved are undefined upon readback. Observe that only the DATA bits are readback during a readback which can result in an offset of 5 bits between the two register tables. 48 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 15. Register Map Description Register 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 POWERDOWN CLKout 2_PD 0 CLKout2_ ADLY_SEL 0 CLKout2_DDLY [27:18] 0 CLKout 3_PD CLKout3_ OSCin_Sel 0 CLKout3_ ADLY_SEL CLKout3_DDLY [27:18] 0 C0LKout4_ OSCin_Sel 0 CLKout4_ ADLY_SEL CLKout4_DDLY [27:18] 0 0 0 CLKout5 ADLY_SEL CLKout5_DDLY [27:18] 0 R4 R5 CLKout 0_HS CLKout1_ ADLY_SEL CLKout1_DDLY [27:18] 0 0 0 0 0 CLKout 1_HS 0 CLKout0_DIV [15:5] CLKout1_DIV [15:5] 0 0 0 0 1 CLKout 2_HS CLKout 1_PD 0 R3 0 CLKout2_DIV [15:5] 0 0 0 1 0 CLKout 3_HS RESET R2 1 CLKout3_DiV [15:5] 0 0 0 1 1 CLKout 4_HS CLKout0_ ADLY_SEL CLKout0_DDLY [27:18] R1 2 CLKout4_DIV [15:5] 0 0 1 0 0 CLKout 5_HS CLKout 0_PD 0 CLKout 5_PD 0 R0 3 Address [4:0] CLKout 4_PD Data [26:0] CLKout5_DIV [15:5] 0 0 1 0 1 R6 0 CLKout1_TYPE [27:24] CLKout0_TYPE [23:20] 0 CLKout1_ADLY [15:11] 0 CLKout0_ADLY [9:5] 0 0 1 1 0 R7 0 CLKout3_TYPE [27:24] CLKout2_TYPE [23:20] 0 CLKout3_ADLY [15:11] 0 CLKout2_ADLY [9:5] 0 0 1 1 1 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 49 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 15. Register Map Description (continued) Register 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 Data [26:0] 50 LD_TYPE [26:24] (1) R13 HOLDOVER_MUX [31:27] HOLDOVER _TYPE [26:24] 0 Status_ CLKin1 _TYPE [26:24] 0 1 0 CLKin0_BUF_TYPE CLKin1_BUF_TYPE 0 0 Status_ CLKin1 _MUX [22:20] CLKin2_BUF_TYPE EN_LOS 0 0 OSCout_DIV [18:16] 1 0 0 0 1 0 0 0 0 Status_ CLKin0 _TYPE [18:16] DAC_HIGH_TRIP [19:14] SYNC _TYPE [14:12] 0 0 0 Status_ CLKin0 _MUX [14:12] 0 1 0 0 VCO_DIV [10:8] 1 1 0 0 0 0 1 0 0 1 0 1 0 1 0 0 1 0 1 1 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 0 0 FEEDBACK _MUX [7:5] 0 0 0 0 0 0 0 CLKin _Select _MODE [11:8] 0 1 0 EN_PLL2_XTAL LD_MUX [31:27] 1 EN_CLKin0 PD_OSCin R12 NO_SYNC_CLKout5 MODE [31:27] EN_SYNC R11 LOS_ TIMEOUT [31:30] 0 2 EN_VTUNE_ RAIL_DET 0 1 0 0 HOLDOVER _MODE [7:6] OSCout0_TYPE [27:24] 0 EN_CLKin1 1 1 EN_CLKin2 0 0 EN_TRACK 0 1 CLKin_Sel_INV 0 0 EN_ FEEDBACK_MUX R10 1 CLKout4_ADLY [9:5] 0 VCO_MUX 0 SYNC_EN_AUTO 1 DISABLE_ DLD1_DET 0 SYNC_POL_INV 1 SYNC_QUAL 0 SYNC _CLKin2_ MUX [19:18] 1 NO_SYNC_CLKout1 0 EN_OSCout0 1 NO_SYNC_CLKout2 0 SYNC_PLL1 _DLD 1 NO_SYNC_CLKout3 0 SYNC_PLL2 _DLD 0 CLKout5_ADLY [15:11] CLKout4_TYPE [19:16] NO_SYNC_CLKout4 1 0 OSCout0_MUX CLKout5_TYPE [27:24] R9 R14 (1) 0 NO_SYNC_CLKout0 R8 3 Address [4:0] DAC_LOW_TRIP [11:6] Although the value of 0 is written here, during readback the value of READBACK_LE will be read at this location. See Register Map and Readback Register Map. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 15. Register Map Description (continued) Register 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 0 PLL2_C4_LF [31:28] R24 0 1 PLL2_C3_LF [27:24] 0 1 PLL2_CP _GAIN [27:26] 0 0 PLL1_CP_POL PLL1_CP_GAIN 0 1 0 0 0 1 0 1 PLL2_R3_LF [18:16] 0 0 0 0 PLL1_ WND_ SIZE PLL1_R_DLY [10:8] 0 0 1 0 1 0 0 0 0 0 1 1 0 0 0 1 1 0 0 1 1 0 PLL2_DLD_CNT [19:6] 1 1 0 1 0 PLL1_R [19:6] 1 1 0 1 1 PLL1_N [19:6] 0 1 1 1 0 0 1 1 1 0 1 1 1 1 1 0 1 1 1 1 1 0 0 OSCin_FREQ [26:24] PLL2_N_CAL [22:5] R30 0 0 0 0 0 PLL2_P 0 PLL2_N [22:5] R31 0 0 0 0 0 READBACK _LE 0 0 0 1 0 0 0 0 1 PLL1_DLD_CNT [19:6] 0 0 1 1 0 R29 0 0 0 0 PLL2_R 0 0 PLL1_N_DLY [14:12] 0 PLL2_ FAST_PDF R28 1 HOLDOVER_DLD_CNT [19:6] CLKin0_ PreR_DIV PLL2_ CP_POL R27 1 1 CLKin1_ PreR_DIV PLL2_ WND_SIZE [31:30] CLKin2_ PreR_DIV R26 0 PLL2_R4_LF [22:20] 0 DAC_CLK_DIV [31:22] EN_PLL2_ REF_2X R25 0 0 FORCE_ HOLDOVER 0 1 PLL2_CP_TRI 0 2 PLL1_CP_TRI XTAL_ LVL R16 0 3 Address [4:0] READBACK_ADDR [20:16] 0 0 0 0 0 0 0 0 0 0 uWire_LOCK MAN_DAC [31:22] R15 EN_MAN_DAC Data [26:0] Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 51 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Register RD 26 RD 25 RD 24 RD 23 RD 22 RD 21 RD 20 RD 19 RD 18 RD 17 RD 16 RD 15 RD 14 RD 13 RD 12 RD 11 RD 10 RD 9 RD 8 RD 7 RD 6 RD 5 RD 4 RD 3 0 0 0 0 0 0 0 0 0 EN_TRACK Table 16. Readback Register Map RD 2 RD 1 RD 0 RESERVED [26:24] RD R31 52 0 1 1 DAC_CNT [23:14] HOLDOVER_MODE [2:1] READBACK_LE LD_TYPE [21:19] 1 RESERVED [13:0] RESERVED [26:10] Submit Documentation Feedback uWire_LOCK RD R23 LD_MUX [26:22] SYNC_PLL1_DLD RD R12 SYNC_PLL2_DLD Data [26:0] Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.2 Default Device Register Settings After Power On Reset Table 17 illustrates the default register settings programmed in silicon for the LMK04906 after power on or asserting the reset bit. Capital X and Y represent numeric values. Table 17. Default Device Register Settings After Power On Reset GROUP FIELD NAME DEFAULT VALUE (DECIMAL) DEFAULT STATE CLKout0_PD 1 PD R0 CLKout1_PD 1 PD R1 CLKout2_PD 1 PD CLKout3_PD 0 Normal CLKout4_PD 0 Normal R4 CLKout5_PD 1 PD R5 CLKout3_OSCin_Sel 1 OSCin CLKout4_OSCin_Sel 0 VCO Selects the clock source for a clock output from internal VCO or external OSCin CLKoutX_ADLY_SEL 0 None CLKoutX_DDLY 0 5 RESET 0 Not in reset 0 Disabled (device is active) POWERDOWN Clock Output Control FIELD DESCRIPTION Powerdown control for analog and digital delay, divider, and both output buffers REGISTER R2 31 R3 R3 30 R4 30 Add analog delay for clock output R0 to R5 28, 29 Digital delay value R0 to R5 27:18 [10] Performs power on reset for device R0 17 Device power down control R1 17 R0 to R5 16 CLKoutX_HS 0 No shift CLKout0_DIV 25 Divide-by-25 R0 CLKout1_DIV 25 Divide-by-25 R1 CLKout2_DIV 25 Divide-by-25 CLKout3_DIV 1 Divide-by-1 Half shift for digital delay R3 CLKout4_DIV 25 Divide-by-25 R4 CLKout5_DIV 25 Divide-by-25 R5 CLKout1_TYPE 0 Powerdown R6 8 LVCMOS (Norm/Norm) R2 Divide for clock outputs CLKout3_TYPE BIT LOCATION (MSB:LSB) 15:5 [11] R7 Individual clock output format. Select from LVDS/LVPECL/LVCMOS. CLKout5_TYPE 0 Powerdown CLKout0_TYPE 0 Powerdown R6 CLKout2_TYPE 0 Powerdown R7 CLKout4_TYPE 1 LVDS CLKoutX_ADLY 0 No delay OSCout0_TYPE 1 LVDS EN_OSCout0 1 Enabled OSCout0_MUX 0 27:24 [4] R8 23:20 [4] Mode R8 19:16 [4] R6 to R8 15:11, 9:5 [5] OSCout0 default clock output R10 27:24 [4] Enable OSCout0 output buffer R10 22 Bypass Divider Select OSCout divider for OSCout0 or bypass R10 20 Allows OSCin to be powered down. For use in clock distribution mode. R10 19 Analog delay setting for clock output PD_OSCin 0 OSCin powered OSCout_DIV 0 Divide-by-8 OSCout divider value R10 18:16 [3] VCO_MUX 0 VCO Select VCO or VCO Divider output R10 12 EN_FEEDBACK_MUX 0 Disabled Feedback MUX is powered down. R10 11 VCO_DIV 2 Divide-by-2 VCO Divide value R10 10:8 [3] FEEDBACK_MUX 0 CLKout0 Selects CLKout to feedback into the PLL1 N divider R10 7:5 [3] MODE 0 Internal VCO Device mode R11 31:27 [5] Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 53 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 17. Default Device Register Settings After Power On Reset (continued) GROUP FIELD NAME Clock Synchronization CLKin Control DAC Control FIELD DESCRIPTION Enables synchronization circuitry. REGISTER BIT LOCATION (MSB:LSB) 1 Enabled R11 26 NO_SYNC_CLKout5 0 Will sync R11 25 NO_SYNC_CLKout4 1 Will not sync R11 24 NO_SYNC_CLKout3 1 Will not sync R11 23 NO_SYNC_CLKout2 0 Will sync R11 22 NO_SYNC_CLKout1 0 Will sync R11 21 NO_SYNC_CLKout0 0 Will sync R11 20 SYNC_CLKin2_MUX 0 Logic Low Mux controlling SYNC pin when set to output R11 19:18 [2] SYNC_QUAL 0 Not qualified Allows SYNC operations to be qualified by a clock output. R11 17 SYNC_POL_INV 1 Logic Low Sets the polarity of the SYNC pin when input R11 16 R11 15 14:12 [3] Disable individual clock output from becoming synchronized. 0 Manual SYNC is not started by programming a register R0 to R5. SYNC_TYPE 1 Input /w Pull-up SYNC IO pin type R11 EN_PLL2_XTAL 0 Disabled Enable Crystal oscillator for OSCin R11 5 LD_MUX 3 PLL1 & 2 DLD Lock detect mux selection when output R12 31:27 [5] LD_TYPE 3 Output (Push-Pull) LD IO pin type R12 26:24 [3] SYNC_PLL2_DLD 0 Normal Force synchronization mode until PLL2 locks R12 23 SYNC_PLL1_DLD 0 Normal Force synchronization mode until PLL1 locks R12 22 EN_TRACK 1 Enable Tracking DAC tracking of the PLL1 tuning voltage R12 8 HOLDOVER_MODE 2 Enable Holdover Causes holdover to activate when lock is lost R12 7:6 [2] HOLDOVER_MUX 7 uWire Readback Holdover mux selection R13 31:27 [5] HOLDOVER_TYPE 3 Output (Push-Pull) HOLDOVER IO pin type R13 26:24 [3] Status_CLKin1_MUX 0 Logic Low Status_CLKin1 pin MUX selection R13 22:20 [3] Status_CLKin0_TYPE 2 Input /w Pull-down Status_CLKin0 IO pin type R13 18:16 [3] Disables PLL1 DLD falling edge from causing HOLDOVER mode to be entered R13 15 Status_CLKin0 pin MUX selection R13 14:12 [3] Mode to use in determining reference CLKin for PLL1 R13 11:9 [3] Invert Status 0 and 1 pin polarity for input R13 8 DISABLE_DLD1_DET 0 Status_CLKin0_MUX 0 Logic Low CLKin_SELECT_MODE 3 Manual Select CLKin_Sel_INV 0 Active High EN_CLKin2 1 Usable Set CLKin2 to be usable R13 7 EN_CLKin1 1 Usable Set CLKin1 to be usable R13 6 EN_CLKin0 1 Usable Set CLKin0 to be usable R13 5 LOS_TIMEOUT 0 1200 ns, 420 kHz Time until no activity on CLKin asserts LOS R14 31:30 [2] EN_LOS 1 Enabled Loss of Signal Detect at CLKin R14 28 Status_CLKin1_TYPE 2 Input /w Pull-down Status_CLKin1 pin IO pin type R14 26:24 [3] CLKin2_BUF_TYPE 0 Bipolar CLKin2 Buffer Type R14 22 CLKin1_BUF_TYPE 0 Bipolar CLKin1 Buffer Type R14 21 CLKin0_BUF_TYPE 0 Bipolar CLKin0 Buffer Type R14 Not Disabled 20 R14 19:14 [6] DAC_HIGH_TRIP 0 ~50 mV from Vcc Voltage from Vcc at which holdover mode is entered if EN_VTUNE_RAIL_DAC is enabled. DAC_LOW_TRIP 0 ~50 mV from GND Voltage from GND at which holdover mode is entered if EN_VTUNE_RAIL_DAC is enabled. R14 11:6 [6] Enable PLL1 unlock state when DAC trip points are achieved R14 5 Writing to this register will set the value for DAC when in manual override. Readback from this register is DAC value. R15 31:22 [10] Set manual DAC override R15 20 Lock must be valid n many clocks of PLL1 PDF before holdover mode is exited. R15 19:6 [14] Forces holdover mode. R15 5 Sets drive power level of Crystal R16 31:30 [2] EN_VTUNE_RAIL_DET MAN_DAC EN_MAN_DAC HOLDOVER_DLD_CNT 54 DEFAULT STATE EN_SYNC SYNC_EN_AUTO Other Mode Control DEFAULT VALUE (DECIMAL) 0 Disabled 512 3V/2 0 Disabled 512 512 counts FORCE_HOLDOVER 0 Holdover not forced XTAL_LVL 0 1.65 Vpp Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 17. Default Device Register Settings After Power On Reset (continued) GROUP FIELD NAME DEFAULT VALUE (DECIMAL) DEFAULT STATE PLL2_C4_LF 0 10 pF PLL2_C3_LF 0 10 pF PLL2_R4_LF 0 PLL2_R3_LF 0 (1) BIT LOCATION (MSB:LSB) PLL2 integrated capacitor C4 value R24 31:28 [4] PLL2 integrated capacitor C3 value R24 27:24 [4] 200 PLL2 integrated resistor R4 value R24 22:20 [3] 200 PLL2 integrated resistor R3 value R24 18:16 [3] R24 14:12 [3] PLL1_N_DLY 0 No delay Delay in PLL1 feedback path to decrease lag from input to output PLL1_R_DLY 0 No delay Delay in PLL1 reference path to increase lag from input to output R24 10:8 [3] PLL1_WND_SIZE 3 40 ns Window size used for digital lock detect for PLL1 R24 7:6 [2] R25 31:22 [10] 4 Divide-by-4 DAC update clock divisor. Divides PLL1 phase detector frequency. PLL1_DLD_CNT 1024 1024 cycles Lock must be valid n many cycles before LD is asserted R25 19:6 [14] PLL2_WND_SIZE 0 Window size used for digital lock detect for PLL2 R26 31:30 [2] EN_PLL2_REF_2X 0 Disabled, 1x Doubles reference frequency of PLL2. R26 29 PLL2_CP_POL 0 Negative Polarity of PLL2 Charge Pump R26 28 PLL2_CP_GAIN 3 3.2 mA PLL2 Charge Pump Gain R26 27:26 [2] PLL2_DLD_CNT 8192 8192 Counts Number of PDF cycles which phase error must be within DLD window before LD state is asserted. R26 19:6 [14] DAC_CLK_DIV PLL Control REGISTER FIELD DESCRIPTION Reserved (1) PLL2_CP_TRI 0 Active PLL2 Charge Pump Active R26 5 PLL1_CP_POL 1 Positive Polarity of PLL1 Charge Pump R27 28 PLL1_CP_GAIN 0 100 uA PLL1 Charge Pump Gain R27 27:26 [2] CLKin2_PreR_DIV 0 Divide-by-1 CLKin2 Pre-R divide value (1, 2, 4, or 8) R27 25:24 [2] CLKin1_PreR_DIV 0 Divide-by-1 CLKin1 Pre-R divide value (1, 2, 4, or 8) R27 23:22 [2] CLKin0_PreR_DIV 0 Divide-by-1 CLKin0 Pre-R divide value (1, 2, 4, or 8) R27 21:20 [2] PLL1_R 96 Divide-by-96 PLL1 R Divider (1 to 16383) R27 19:6 [14] PLL1_CP_TRI 0 Active PLL1 Charge Pump Active R27 5 PLL2_R 4 Divide-by-4 PLL2 R Divider (1 to 4095) R28 31:20 [12] PLL1_N PLL1 N Divider (1 to 16383) R28 19:6 [14] OSCin frequency range R29 26:24 [3] When set, PLL2 PDF of greater than 100 MHz may be used R29 23 192 Divide-by-192 OSCin_FREQ 7 448 to 511 MHz PLL2_FAST_PDF 1 PLL2 PDF > 100 MHz PLL2_N_CAL 48 Divide-by-48 Must be programmed to PLL2_N value. R29 22:5 [18] PLL2_P 2 Divide-by-2 PLL2 N Divider Prescaler (2 to 8) R30 26:24 [3] PLL2_N 48 Divide-by-48 PLL2 N Divider (1 to 262143) R30 22:5 [18] READBACK_LE 0 LEuWire Low for Readback State LEuWire pin must be in for readback R31 21 READBACK_ADDR 31 Register 31 Register to read back R31 20:16 [5] uWire_LOCK 0 Writable The values of registers R0 to R30 are lockable R31 5 This register must be reprogrammed to a value of 2 (3.7 ns) during user programming. 8.6.3 Register Descriptions 8.6.3.1 Register R0 to R5 Registers R0 through R5 control the 6 clock outputs CLKout0 to CLKout5. Register R0 controls CLKout0, Register R1 controls CLKout1, and so on. All functions of the bits in these six registers are identical except the different registers control different clock outputs. The X in CLKoutX_PD, CLKoutX_ADLY_SEL, CLKoutX_DDLY, CLKoutX_HS, CLKoutX_DIV denote the actual clock output which may be from 0 to 5. The RESET bit is only in register R0. The POWERDOWN bit is only in register R1. The CLKoutX_OSCin_Sel bit is only in registers R3 and R4. 8.6.3.1.1 CLKoutX_PD, Powerdown CLKoutX Output Path This bit powers down the clock output as specified by CLKoutX. This includes the divider, digital delay, analog delay, and output buffers. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 55 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 18. CLKoutX_PD R0-R5[31] 0 1 STATE Power up clock output Power down clock output 8.6.3.1.2 CLKoutX_OSCin_Sel, Clock Output Source This bit sets the source for the clock CLKoutX. The selected source will be either from a VCO via Mode Mux1 or from the OSCin buffer. This bit is valid only for registers R3 and R4, clock outputs CLKout3 and CLKout4 respectively. All other clock outputs are driven by a VCO via Mode Mux1. Table 19. CLKoutX_OSCin_Sel R3-R4[30] 0 1 CLOCK OUTPUT SOURCE VCO OSCin 8.6.3.1.3 CLKoutX_ADLX_SEL[29], CLKoutX_ADLX_SEL[28], Select Analog Delay These bits individually select the analog delay block (CLKoutX_ADLY) for use with CLKoutX. If a clock output does not use analog delay, the analog delay block is powered down. Table 20. CLKoutX_ADLX_SEL[29], CLKoutX_ADLX_SEL[28] R0-R5[28],[29] 0 1 STATE Analog delay powered down Analog delay on CLKoutX 8.6.3.1.4 CLKoutX_DDLY, Clock Channel Digital Delay CLKoutX_DDLY and CLKoutX_HS sets the digital delay used for CLKoutX. This value only takes effect during a SYNC event and if the NO_SYNC_CLKoutX bit is cleared for this clock output. See Clock Output Synchronization (SYNC). Programming CLKoutX_DDLY can require special attention. See section Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY for more details. Using a CLKoutX_DDLY value of 13 or greater will cause the clock output to operate in extended mode regardless of the clock ouptut's divide value or the half step value. One clock cycle is equal to the period of the clock distribution path. The period of the clock distribution path is equal to VCO Divider value divided by the frequency of the VCO. If the VCO divider is disabled or an external VCO is used, the VCO divide value is treated as 1. tclock distribution path = VCO divide value / fVCO 56 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 21. CLKoutX_DDLY, 10 Bits R0-R5[27:18] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) ... 12 (0x0C) 13 (0x0D) ... 520 (0x208) 521 (0x209) DELAY clock cycles clock cycles clock cycles clock cycles clock cycles clock cycles clock cycles clock cycles ... 12 clock cycles 13 clock cycles ... 520 clock cycles 521 clock cycles 522 (0x20A) 522 clock cycles POWER MODE 5 5 5 5 5 5 6 7 Normal Mode Extended Mode 8.6.3.1.5 Reset The RESET bit is located in register R0 only. Setting this bit will cause the silicon default values to be loaded. When programming register R0 with the RESET bit set, all other programmed values are ignored. After resetting the device, the register R0 must be programmed again (with RESET = 0) to set non-default values in register R0. The reset occurs on the falling edge of the LEuWire pin which loaded R0 with RESET = 1. The RESET bit is automatically cleared upon writing any other register. For instance, when R0 is written to again with default values. Table 22. RESET R0[17] 0 1 STATE Normal operation Reset (automatically cleared) 8.6.3.1.6 POWERDOWN The POWERDOWN bit is located in register R1 only. Setting the bit causes the device to enter powerdown mode. Normal operation is resumed by clearing this bit with MICROWIRE. Table 23. POWERDOWN R1[17] 0 1 STATE Normal operation Powerdown 8.6.3.1.7 CLKoutX_HS, Digital Delay Half Shift This bit subtracts a half clock cycle of the clock distribution path period to the digital delay of CLKoutX. CLKoutX_HS is used together with CLKoutX_DDLY to set the digital delay value. When changing CLKoutX_HS, the digital delay immediately takes effect without a SYNC event. Table 24. CLKoutX_HS R0-R5[16] 0 1 STATE Normal Subtract half of a clock distribution path period from the total digital delay Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 57 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.1.8 CLKoutX_DIV, Clock Output Divide CLKoutX_DIV sets the divide value for the clock output. The divide may be even or odd. Both even and odd divides output a 50% duty cycle clock. Using a divide value of 26 or greater will cause the clock output to operate in extended mode regardless of the clock output's digital delay value. Programming CLKoutX_DIV can require special attention. See section Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY for more details. Table 25. CLKoutX_DIV, 11 Bits R0-R5[15:5] DIVIDE VALUE 0 (0x00) Reserved 1 (0x01) 1 (1) 2 (0x02) 2 (2) 3 (0x03) (1) (2) POWER MODE 3 4 (0x04) 4 (2) 5 (0x05) 5 (2) 6 (0x06) 6 ... ... 24 (0x18) 24 25 (0x19) 25 26 (0x1A) 26 27 (0x1B) 27 ... ... 1044 (0x414) 1044 1045 (0x415) 1045 Normal Mode Extended Mode CLKoutX_HS must = 0 for divide by 1. After programming PLL2_N value, a SYNC must occur on channels using this divide value. Programming PLL2_N does generate a SYNC event automatically which satisfies this requirement, but NO_SYNC_CLKoutX must be set to 0 for these clock outputs. 8.6.3.2 Registers R6 to R8 Registers R6 to R8 set the clock output types and analog delays. 8.6.3.2.1 CLKoutX_TYPE The clock output types of the LMK04906 are individually programmable. The CLKoutX_TYPE registers set the output type of an individual clock output to LVDS, LVPECL, LVCMOS, or powers down the output buffer. Note that LVPECL supports four different amplitude levels and LVCMOS supports single LVCMOS outputs, inverted, and normal polarity of each output pin for maximum flexibility. For lowest spurious levels, configure the LVCMOS outputs as LVCMOS (Inv/Norm) or LVCMOS (Norm/Inv). LVCMOS (Inv/Inv) and LVCMOS (Norm/Norm) are the worst for spurious levels. The programming addresses table shows at what register and address the specified clock output CLKoutX_TYPE register is located. The CLKoutX_TYPE table shows the programming definition for these registers. 58 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 26. CLKoutX_TYPE Programming Addresses CLKoutX PROGRAMMING ADDRESS CLKout0 R6[23:20] CLKout1 R6[27:24] CLKout2 R723:20] CLKout3 R7[27:24] CLKout4 R8[19:16] CLKout5 R8[27:24] Table 27. CLKoutX_TYPE, 4 Bits R6-R8[31:28, 27:24, 23:20] DEFINITION 0 (0x00) Power down 1 (0x01) LVDS 2 (0x02) LVPECL (700 mVpp) 3 (0x03) LVPECL (1200 mVpp) 4 (0x04) LVPECL (1600 mVpp) 5 (0x05) LVPECL (2000 mVpp) 6 (0x06) LVCMOS (Norm/Inv) 7 (0x07) LVCMOS (Inv/Norm) 8 (0x08) LVCMOS (Norm/Norm) 9 (0x09) LVCMOS (Inv/Inv) 10 (0x0A) LVCMOS (Low/Norm) 11 (0x0A) LVCMOS (Low/Inv) 12 (0x0C) LVCMOS (Norm/Low) 13 (0x0D) LVCMOS (Inv/Low) 14 (0x0E) LVCMOS (Low/Low) 8.6.3.2.2 CLKoutX_ADLY These registers control the analog delay of the clock output CLKoutX. Adding analog delay to the output will increase the noise floor of the output. For this analog delay to be active for a clock output, it must be selected with CLKoutX_ADL_SEL. If neither clock output in a clock output selects the analog delay, then the analog delay block is powered down. In addition to the programmed delay, a fixed 500 ps of delay will be added by engaging the delay block. The programming addresses table shows at what register and address the specified clock output CLKoutX_ADLY register is located. The CLKoutX_ADLY table shows the programming definition for these registers. Table 28. CLKoutX_ADLY Programming Addresses CLKoutX_ADLY CLKout0_ADLY CLKout1_ADLY CLKout2_ADLY CLKout3_ADLY CLKout4_ADLY CLKout5_ADLY PROGRAMMING ADDRESS R6[9:5] R6[15:11] R7[9:5] R7[15:11] R8[9:5] R8[15:11] Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 59 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 29. CLKoutX_ADLY, 5 Bits R6-R8[15:11, 9:5] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0x0E) 15 (0x0F) 16 (0x10) 17 (0x11) 18 (0x12) 19 (0x13) 20 (0x14) 21 (0x15) 22 (0x16) 23 (0x17) DEFINITION 500 ps + No delay 500 ps + 25 ps 500 ps + 50 ps 500 ps + 75 ps 500 ps + 100 ps 500 ps + 125 ps 500 ps + 150 ps 500 ps + 175 ps 500 ps + 200 ps 500 ps + 225 ps 500 ps + 250 ps 500 ps + 275 ps 500 ps + 300 ps 500 ps + 325 ps 500 ps + 350 ps 500 ps + 375 ps 500 ps + 400 ps 500 ps + 425 ps 500 ps + 450 ps 500 ps + 475 ps 500 ps + 500 ps 500 ps + 525 ps 500 ps + 550 ps 500 ps + 575 ps 8.6.3.3 Register R10 8.6.3.3.1 OSCout0_TYPE The OSCout0 clock output has a programmable output type. The OSCout0_TYPE register sets the output type to LVDS, LVPECL, LVCMOS, or powers down the output buffer. Note that LVPECL supports four different amplitude levels and LVCMOS supports dual and single LVCMOS outputs with inverted, and normal polarity of each output pin for maximum flexibility. To turn on the output, the OSCout0_TYPE must be set to a non-power down setting and enabled with EN_OSCout0, OSCout0 Output Enable. 60 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 30. OSCout0_TYPE, 4 Bits R10[27:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) DEFINITION Powerdown LVDS LVPECL (700 mVpp) LVPECL (1200 mVpp) LVPECL (1600 mVpp) LVPECL (2000 mVpp) LVCMOS (Norm/Inv) LVCMOS (Inv/Norm) LVCMOS (Norm/Norm) LVCMOS (Inv/Inv) LVCMOS (Low/Norm) LVCMOS (Low/Inv) LVCMOS (Norm/Low) LVCMOS (Inv/Low) 14 (0x0E) LVCMOS (Low/Low) 8.6.3.3.2 EN_OSCout0, OSCout0 Output Enable EN_OSCout0 is used to enable an oscillator buffered output. Table 31. EN_OSCout0 R10[22] 0 1 OUTPUT STATE OSCout0 Disabled OSCout0 Enabled OSCout0 note: In addition to enabling the output with EN_OSCout0. The OSCout0_TYPE must be programmed to a non-power down value for the output buffer to power up. 8.6.3.3.3 OSCout0_MUX, Clock Output Mux Sets OSCout0 buffer to output a divided or bypassed OSCin signal. The divisor is set by OSCout_DIV, Oscillator Output Divide. Table 32. OSCout0_MUX R10[20] 0 1 MUX OUTPUT Bypass divider Divided 8.6.3.3.4 PD_OSCin, OSCin Powerdown Control Except in clock distribution mode, the OSCin buffer must always be powered up. In clock distribution mode, the OSCin buffer must be powered down if not used. Table 33. PD_OSCin R10[19] 0 1 OSCin BUFFER Normal Operation Powerdown 8.6.3.3.5 OSCout_DIV, Oscillator Output Divide The OSCout divider can be programmed from 2 to 8. Divide by 1 is achieved by bypassing the divider with OSCout0_MUX, Clock Output Mux. Note that OSCout_DIV will be in the PLL1 N feedback path if OSCout0_MUX selects divided as an output. When OSCout_DIV is in the PLL1 N feedback path, the OSCout_DIV divide value must be accounted for when programming PLL1 N. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 61 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com See PLL Programming for more information on programming PLL1 to lock. Table 34. OSCout_DIV, 3 Bits R10[18:16] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) DIVIDE 8 2 2 3 4 5 6 7 8.6.3.3.6 VCO_MUX When the internal VCO is used, the VCO divider can be selected to divide the VCO output frequency to reduce the frequency on the clock distribution path. It is recommended to use the VCO directly unless: * Very low output frequencies are required. * If using the VCO divider results in three or more clock output divider/delays changing from extended to normal power mode, a small power savings may be achieved by using the VCO divider. A consequence of using the VCO divider is a small degradation in phase noise. Table 35. VCO_MUX R10[12] 0 1 DIVIDE VCO selected VCO divider selected 8.6.3.3.7 EN_FEEDBACK_MUX When using 0-delay or dynamic digital delay (SYNC_QUAL = 1), EN_FEEDBACK_MUX must be set to 1 to power up the feedback mux. Table 36. EN_FEEDBACK_MUX R10[11] 0 1 DIVIDE Feedback mux powered down Feedback mux enabled 8.6.3.3.8 VCO_DIV, VCO Divider Divide value of the VCO Divider. See PLL Programming for more information on programming PLL2 to lock. Table 37. VCO_DIV, 3 Bits R10[10:8] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 62 DIVIDE 8 2 2 3 4 5 6 7 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.3.9 FEEDBACK_MUX When in 0-delay mode, the feedback mux selects the clock output to be fed back into the PLL1 N Divider. Table 38. FEEDBACK_MUX, 3 Bits R10[7:5] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) DIVIDE Reserved CLKout1 Reserved CLKout3 CLKout4 CLKout5 FBCLKin/FBCLKin* 8.6.3.4 REGISTER R11 8.6.3.4.1 MODE: Device Mode MODE determines how the LMK04906 operates from a high level. Different blocks of the device can be powered up and down for specific application requirements from a dual loop architecture to clock distribution. The LMK04906 can operate in: * Dual PLL mode with the internal VCO or an external VCO. * Single PLL mode uses PLL2 and powers down PLL1. OSCin is used for PLL reference input. * Clock Distribution mode allows use of CLKin1 to distribute to clock outputs CLKout0 through CLKout11, and OSCin to distribute to OSCout0, and optionally CLKout3 through CLKout9. For the PLL modes, 0-delay can be used have deterministic phase with the input clock. For the PLL modes it is also possible to use an external VCO. Table 39. MODE, 5 Bits R11[31:27] 0 (0x00) 1 (0x01) VALUE Dual PLL, Internal VCO Reserved Dual PLL, Internal VCO, 0-Delay Dual PLL, External VCO (Fin) Reserved Dual PLL, External VCO (Fin), 0-Delay PLL2, Internal VCO Reserved PLL2, Internal VCO, 0-Delay Reserved Reserved PLL2, External VCO (Fin) Reserved Reserved Reserved Reserved Clock Distribution 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0x0E) 15 (0x0F) 16 (0x10) Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 63 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.4.2 EN_SYNC, Enable Synchronization The EN_SYNC bit (default on) must be enabled for synchronization to work. Synchronization is required for dynamic digital delay. The synchronization enable may be turned off once the clocks are operating to save current. If EN_SYNC is set after it has been cleared (a transition from 0 to 1), a SYNC is generated that can disrupt the active clock outputs. Setting the NO_SYNC_CLKoutX bits will prevent this SYNC pulse from affecting the output clocks. Setting the EN_SYNC bit is not a valid method for synchronizing the clock outputs. See the Clock Output Synchronization (SYNC) for more information on synchronization. Table 40. EN_SYNC R11[26] 0 1 DEFINITION Synchronization disabled Synchronization enabled 8.6.3.4.3 NO_SYNC_CLKoutX The NO_SYNC_CLKoutX bits prevent individual clock outputs from becoming synchronized during a SYNC event. A reason to prevent individual clock output from becoming synchronized is that during synchronization, the clock output is in a fixed low state or can have a glitch pulse. By disabling SYNC on a clock output, it will continue to operate normally during a SYNC event. Digital delay requires a SYNC operation to take effect. If NO_SYNC_CLKoutX is set before a SYNC event, the digital delay value will be unused. Setting the NO_SYNC_CLKoutX bit has no effect on clocks already synchronized together. Table 41. NO_SYNC_CLKoutX Programming Addresses NO_SYNC_CLKoutX CLKout0 CLKout1 CLKout2 CLKout3 CLKout4 CLKout5 PROGRAMMING ADDRESS R11:20 R11:21 R11:22 R11:23 R11:24 R11:25 Table 42. NO_SYNC_CLKoutX R11[25, 24, 23, 22, 21, 20] 0 1 DEFINITION CLKoutX will synchronize CLKoutX will not synchronize 8.6.3.4.4 SYNC_CLKin2_MUX Mux controlling SYNC/Status_CLKin2 pin. All the outputs logic is active high when SYNC_TYPE = 3 (Output). All the outputs logic is active low when SYNC_TYPE = 4 (Output Inverted). For example, when SYNC_MUX = 0 (Logic Low) and SYNC_TYPE = 3 (Output) then SYNC outputs a logic low. When SYNC_MUX = 0 (Logic Low) and SYNC_TYPE = 4 (Output Inverted) then SYNC outputs a logic high. Table 43. SYNC_MUX, 2 Bits R11[19:18] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 64 SYNC PIN OUTPUT Logic Low CLKin2 LOS CLKin2 Selected uWire Readback Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.4.5 SYNC_QUAL When SYNC_QUAL is set, clock outputs will be synchronized to an existing clock output selected by FEEDBACK_MUX. By using the NO_SYNC_CLKoutX bits, selected clock outputs will not be interrupted during the SYNC event. Qualifying the SYNC by an output clock means that the pulse which turns the clock outputs off and on will have a fixed time relationship to the qualifying output clock. SYNC_QUAL = 1 requires CLKout2_PD = 0 for proper operation. CLKout2_TYPE may be set to Powerdown mode. See Clock Output Synchronization (SYNC) for more information. Table 44. SYNC_QUAL R11[17] 0 MODE No qualification Qualification by clock output from feedback mux (Must set CLKout2_PD = 0) 1 8.6.3.4.6 SYNC_POL_INV Sets the polarity of the SYNC pin when input. When SYNC is asserted the clock outputs will transition to a low state. See Clock Output Synchronization (SYNC) for more information on SYNC. A SYNC event can be generated by toggling this bit through the MICROWIRE interface. Table 45. SYNC_POL_INV R11[16] 0 1 POLARITY SYNC is active high SYNC is active low 8.6.3.4.7 SYNC_EN_AUTO When set, causes a SYNC event to occur when programming register R0 to R5 to adjust digital delay values. The SYNC event will coincide with the LEuWire pin falling edge. See Special Programming Case for R0 to R5 for CLKoutX_DIV and CLKoutX_DDLY for more information on possible special programming considerations when SYNC_EN_AUTO = 1. Table 46. SYNC_EN_AUTO R11[15] 0 1 MODE Manual SYNC SYNC Internally Generated 8.6.3.4.8 SYNC_TYPE Sets the IO type of the SYNC pin. Table 47. SYNC_TYPE, 3 Bits R11[14:12] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) POLARITY Input Input /w pull-up resistor Input /w pull-down resistor Output (push-pull) Output inverted (push-pull) Output (open source) Output (open drain) Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 65 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com When in output mode the SYNC input is forced to 0 regardless of the SYNC_MUX setting. A synchronization can then be activated by uWire by programming the SYNC_POL_INV register to active low to assert SYNC. SYNC can then be released by programming SYNC_POL_INV to active high. Using this uWire programming method to create a SYNC event saves the need for an IO pin from another device. 8.6.3.4.9 EN_PLL2_XTAL If an external crystal is being used to implement a discrete VCXO, the internal feedback amplifier must be enabled with this bit in order to complete the oscillator circuit. Table 48. EN_PLL2_XTAL R11[5] 0 1 OSCILLATOR AMPLIFIER STATE Disabled Enabled 8.6.3.5 Register R12 8.6.3.5.1 LD_MUX LD_MUX sets the output value of the LD pin. All the outputs logic is active high when LD_TYPE = 3 (Output). All the outputs logic is active low when LD_TYPE = 4 (Output Inverted). For example, when LD_MUX = 0 (Logic Low) and LD_TYPE = 3 (Output) then Status_LD outputs a logic low. When LD_MUX = 0 (Logic Low) and LD_TYPE = 4 (Output Inverted) then Status_LD outputs a logic high. Table 49. LD_MUX, 5 Bits R12[31:27] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0x0E) 15 (0x0F) 16 (0x10) 17 (0x11) 18 (0x12) (1) 66 DIVIDE Logic Low PLL1 DLD PLL2 DLD PLL1 & PLL2 DLD Holdover Status DAC Locked Reserved uWire Readback DAC Rail DAC Low DAC High PLL1_N PLL1_N/2 PLL2 N PLL2 N/2 PLL1_R PLL1_R/2 PLL2 R (1) PLL2 R/2 (1) Only valid when HOLDOVER_MUX is not set to 2 (PLL2_DLD) or 3 (PLL1 & PLL2 DLD). Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.5.2 LD_TYPE Sets the IO type of the LD pin. Table 50. LD_TYPE, 3 Bits R12[26:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) POLARITY Reserved Reserved Reserved Output (push-pull) Output inverted (push-pull) Output (open source) Output (open drain) 8.6.3.5.3 SYNC_PLLX_DLD By setting SYNC_PLLX_DLD a SYNC mode will be engaged (asserted SYNC) until PLL1 and/or PLL2 locks. SYNC_QUAL must be 0 to use this functionality. Table 51. SYNC_PLL2_DLD R12[23] 0 1 SYNC MODE FORCED No Yes Table 52. SYNC_PLL1_DLD R12[22] 0 1 SYNC MODE FORCED No Yes 8.6.3.5.4 EN_TRACK Enable the DAC to track the PLL1 tuning voltage. For optional use in in holdover mode. Tracking can be used to monitor PLL1 voltage by readback of DAC_CNT register in any mode. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 67 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 53. EN_TRACK R12[8] 0 1 DAC TRACKING Disabled Enabled 8.6.3.5.5 HOLDOVER_MODE Enable the holdover mode. Table 54. HOLDOVER_MODE, 2 Bits R12[7:6] 0 1 2 3 HOLDOVER MODE Reserved Disabled Enabled Reserved 8.6.3.6 Register R13 8.6.3.6.1 HOLDOVER_MUX HOLDOVER_MUX sets the output value of the Status_Holdover pin. The outputs are active high when HOLDOVER_TYPE = 3 (Output). The outputs are active low when HOLDOVER_TYPE = 4 (Output Inverted). Table 55. HOLDOVER_MUX, 5 Bits R13[31:27] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0x0E) 15 (0x0F) 16 (0x10) 17 (0x11) 18 (0x12) (1) 68 DIVIDE Logic Low PLL1 DLD PLL2 DLD PLL1 & PLL2 DLD Holdover Status DAC Locked Reserved uWire Readback DAC Rail DAC Low DAC High PLL1 N PLL1 N/2 PLL2 N PLL2 N/2 PLL1 R PLL1 R/2 PLL2 R (1) PLL2 R/2 (1) Only valid when LD_MUX is not set to 2 (PLL2_DLD) or 3 (PLL1 & PLL2 DLD). Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.6.2 HOLDOVER_TYPE Sets the IO mode of the Status_Holdover pin. Table 56. HOLDOVER_TYPE, 3 Bits R13[26:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) POLARITY Reserved Reserved Reserved Output (push-pull) Output inverted (push-pull) Output (open source) Output (open drain) 8.6.3.6.3 Status_CLKin1_MUX Status_CLKin1_MUX sets the output value of the Status_CLKin1 pin. If Status_CLKin1_TYPE is set to an input type, this register has no effect. This MUX register only sets the output signal. The outputs are active high when Status_CLKin1_TYPE = 3 (Output). The outputs are active low when Status_CLKin1_TYPE = 4 (Output Inverted). Table 57. Status_CLKin1_MUX, 3 Bits R13[22:20] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) DIVIDE Logic Low CLKin1 LOS CLKin1 Selected DAC Locked DAC Low DAC High uWire Readback 8.6.3.6.4 Status_CLKin0_TYPE Status_CLKin0_TYPE sets the IO type of the Status_CLKin0 pin. Table 58. Status_CLKin0_TYPE, 3 Bits R13[18:16] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) POLARITY Input Input /w pull-up resistor Input /w pull-down resistor Output (push-pull) Output inverted (push-pull) Output (open source) Output (open drain) 8.6.3.6.5 DISABLE_DLD1_DET DISABLE_DLD1_DET disables the HOLDOVER mode from being activated when PLL1 lock detect signal transitions from high to low. When using Pin Select Mode as the input clock switch mode, this bit should normally be set. Table 59. DISABLE_DLD1_DET R13[15] 0 1 HOLDOVER DLD1 DETECT PLL1 DLD causes clock switch event PLL1 DLD does not cause clock switch event Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 69 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.6.6 Status_CLKin0_MUX CLKin0_MUX sets the output value of the Status_CLKin0 pin. If Status_CLKin0_TYPE is set to an input type, this register has no effect. This MUX register only sets the output signal. The outputs logic is active high when Status_CLKin0_TYPE = 3 (Output). The outputs logic is active low when Status_CLKin0_TYPE = 4 (Output Inverted). Table 60. Status_CLKin0_MUX, 3 Bits R13[14:12] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) DIVIDE Logic Low CLKin0 LOS CLKin0 Selected DAC Locked DAC Low DAC High uWire Readback 8.6.3.6.7 CLKin_SELECT_MODE CLKin_SELECT_MODE sets the mode used in determining reference CLKin for PLL1. Table 61. CLKin_SELECT_MODE, 3 Bits R13[11:9] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) MODE CLKin0 Manual CLKin1 Manual CLKin2 Manual Pin Select Mode Auto Mode Reserved Auto mode & next clock pin select Reserved 8.6.3.6.8 CLKin_Sel_INV CLKin_Sel_INV sets the input polarity of Status_CLKin0 and Status_CLKin1 pins (Auto modes only). Table 62. CLKin_Sel_INV R13[8] 0 1 INPUT Active High Active Low 8.6.3.6.9 EN_CLKinX Each clock input can individually be enabled to be used during auto-switching CLKin_SELECT_MODE. Clock input switching priority is always CLKin0 CLKin1 CLKin2 CLKin0. 70 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 63. EN_CLKin2 R13[7] 0 1 INPUT No Yes Table 64. EN_CLKin1 R13[6] 0 1 VALID No Yes Table 65. EN_CLKin0 R13[5] 0 1 VALID No Yes 8.6.3.7 Register 14 8.6.3.7.1 LOS_TIMEOUT This bit controls the amount of time in which no activity on a CLKin causes LOS (Loss-of-Signal) to be asserted. Table 66. LOS_TIMEOUT, 2 Bits R14[31:30] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) TIMEOUT 1200 ns, 420 kHz 206 ns, 2.5 MHz 52.9 ns, 10 MHz 23.7 ns, 22 MHz 8.6.3.7.2 EN_LOS Enables the LOS (Loss-of-Signal) timeout control. Table 67. EN_LOS R14[28] 0 1 LOS Disabled Enabled 8.6.3.7.3 Status_CLKin1_TYPE Sets the IO type of the Status_CLKin1 pin. Table 68. Status_CLKin1_TYPE, 3 Bits R14[26:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) POLARITY Input Input /w pull-up resistor Input /w pull-down resistor Output (push-pull) Output inverted (push-pull) Output (open source) Output (open drain) 8.6.3.7.4 CLKinX_BUF_TYPE, PLL1 CLKinX/CLKinX* Buffer Type There are two input buffer types for the PLL1 reference clock inputs: either bipolar or CMOS. Bipolar is recommended for differential inputs such as LVDS and LVPECL. CMOS is recommended for DC coupled single ended inputs. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 71 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com When using bipolar, CLKinX and CLKinX* input pins must be AC coupled when using a differential or single ended input. When using CMOS, CLKinX and CLKinX* input pins may be AC or DC coupled with a differential input. When using CMOS in single ended mode, the unused clock input pin (CLKinX or CLKinX*) must be AC grounded. The used clock input pin (CLKinX* or CLKinX) may be AC or DC coupled to the signal source. The programming addresses table shows at what register and address the specified CLKinX_BUF_TYPE bit is located. The CLKinX_BUF_TYPE table shows the programming definition for these registers. Table 69. CLKinX_BUF_TYPE Programming Addresses CLKinX_BUF_TYPE CLKin2_BUF_TYPE CLKin1_BUF_TYPE CLKin0_BUF_TYPE PROGRAMMING ADDRESS R14[22] R14[21] R14[20] Table 70. CLKinX_BUF_TYPE R14[22, 21, 20] 0 1 CLKinX BUFFER TYPE Bipolar CMOS 8.6.3.7.5 DAC_HIGH_TRIP Voltage from Vcc at which holdover mode is entered if EN_VTUNE_RAIL_DAC is enabled. Will also set flags which can be monitored out Status_LD/Status_Holdover pins. Step size is ~51 mV Table 71. DAC_HIGH_TRIP, 6 Bits R14[19:14] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) ... 61 (0x3D) 62 (0x3E) 63 (0x3F) TRIP VOLTAGE FROM VCC (V) 1 x Vcc / 64 2 x Vcc / 64 3 x Vcc / 64 4 x Vcc / 64 5 x Vcc / 64 ... 62 x Vcc / 64 63 x Vcc / 64 64 x Vcc / 64 8.6.3.7.6 DAC_LOW_TRIP Voltage from GND at which holdover mode is entered if EN_VTUNE_RAIL_DAC is enabled. Will also set flags which can be monitored out Status_LD/Status_Holdover pins. Step size is ~51 mV 72 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 72. DAC_LOW_TRIP, 6 Bits R14[11:6] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) ... 61 (0x3D) 62 (0x3E) 63 (0x3F) TRIP VOLTAGE FROM GND (V) 1 x Vcc / 64 2 x Vcc / 64 3 x Vcc / 64 4 x Vcc / 64 5 x Vcc / 64 ... 62 x Vcc / 64 63 x Vcc / 64 64 x Vcc / 64 8.6.3.7.7 EN_VTUNE_RAIL_DET Enables the DAC Vtune rail detection. When the DAC achieves a specified Vtune, if this bit is enabled, the current clock input is considered invalid and an input clock switch event is generated. Table 73. EN_VTUNE_RAIL_DET R14[5] 0 1 STATE Disabled Enabled 8.6.3.8 Register 15 8.6.3.8.1 MAN_DAC Sets the DAC value when in manual DAC mode in approximately 3.2-mV steps. Table 74. MAN_DAC, 10 Bits R15[31:22] 0 (0x00) 1 (0x01) 2 (0x02) ... 1023 (0x3FF) DAC VOLTAGE 0 x Vcc / 1023 1 x Vcc / 1023 2 x Vcc / 1023 ... 1023 x Vcc / 1023 8.6.3.8.2 EN_MAN_DAC This bit enables the manual DAC mode. Table 75. EN_MAN_DAC R15[20] 0 1 DAC MODE Automatic Manual 8.6.3.8.3 HOLDOVER_DLD_CNT Lock must be valid for this many clocks of PLL1 PDF before holdover mode is exited. Table 76. HOLDOVER_DLD_CNT, 14 Bits R15[19:6] 0 (0x00) 1 (0x01) 2 (0x02) ... 16,383 (0x3FFF) EXIT COUNTS Reserved 1 2 ... 16,383 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 73 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.8.4 FORCE_HOLDOVER This bit forces the holdover mode. When holdover is forced, if in fixed CPout1 mode, then the DAC will set the programmed MAN_DAC value. If in tracked CPout1 mode, then the DAC will set the current tracked DAC value. Setting FORCE_HOLDOVER does not constitute a clock input switch event unless DISABLE_DLD1_DET = 0, since in holdover mode, PLL1_DLD = 0 this will trigger the clock input switch event. Table 77. FORCE_HOLDOVER R15[5] 0 1 HOLDOVER Disabled Enabled 8.6.3.9 Register 16 8.6.3.9.1 XTAL_LVL Sets the peak amplitude on the tunable crystal. Increasing this value can improve the crystal oscillator phase noise performance at the cost of increased current and higher crystal power dissipation levels. Table 78. XTAL_LVL, 2 Bits PEAK AMPLITUDE (1) 1.65 Vpp 1.75 Vpp 1.90 Vpp 2.05 Vpp R15[31:22] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) (1) At crystal frequency of 20.48 MHz 8.6.3.10 Register 23 This register must not be programmed, it is a readback only register. 8.6.3.10.1 DAC_CNT The DAC_CNT register is 10 bits in size and located at readback bit position [23:14]. When using tracking mode for holdover, the DAC value can be readback at this address. 8.6.3.11 Register 24 8.6.3.11.1 PLL2_C4_LF, PLL2 Integrated Loop Filter Component Internal loop filter components are available for PLL2, enabling either 3rd or 4th order loop filters without requiring external components. Internal loop filter capacitor C4 can be set according to the following table. 74 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 79. PLL2_C4_LF, 4 Bits R24[31:28] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) LOOP FILTER CAPACITANCE (pF) 10 pF 15 pF 29 pF 34 pF 47 pF 52 pF 66 pF 71 pF 103 pF 108 pF 122 pF 126 pF 141 pF 146 pF 14 (0x0E) 15 (0x0F) Reserved Reserved 8.6.3.11.2 PLL2_C3_LF, PLL2 Integrated Loop Filter Component Internal loop filter components are available for PLL2, enabling either 3rd or 4th order loop filters without requiring external components. Internal loop filter capacitor C3 can be set according to the following table. Table 80. PLL2_C3_LF, 4 Bits R24[27:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0x0E) 15 (0x0F) LOOP FILTER CAPACITANCE (pF) 10 pF 11 pF 15 pF 16 pF 19 pF 20 pF 24 pF 25 pF 29 pF 30 pF 33 pF 34 pF 38 pF 39 pF Reserved Reserved 8.6.3.11.3 PLL2_R4_LF, PLL2 Integrated Loop Filter Component Internal loop filter components are available for PLL2, enabling either 3rd or 4th order loop filters without requiring external components. Internal loop filter resistor R4 can be set according to the following table. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 75 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 81. PLL2_R4_LF, 3 Bits R24[22:20] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) RESISTANCE 200 1 k 2 k 4 k 16 k Reserved Reserved Reserved 8.6.3.11.4 PLL2_R3_LF, PLL2 Integrated Loop Filter Component Internal loop filter components are available for PLL2, enabling either 3rd or 4th order loop filters without requiring external components. Internal loop filter resistor R3 can be set according to Table 82. Table 82. PLL2_R3_LF, 3 Bits R24[18:16] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) RESISTANCE 200 1 k 2 k 4 k 16 k Reserved Reserved Reserved 8.6.3.11.5 PLL1_N_DLY Increasing delay of PLL1_N_DLY will cause the outputs to lead from CLKinX. For use in 0-delay mode. Table 83. PLL1_N_DLY, 3 Bits R24[14:12] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 76 DEFINITION 0 ps 205 ps 410 ps 615 ps 820 ps 1025 ps 1230 ps 1435 ps Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.11.6 PLL1_R_DLY Increasing delay of PLL1_R_DLY will cause the outputs to lag from CLKinX. For use in 0-delay mode. Table 84. PLL1_R_DLY, 3 Bits R24[10:8] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) DEFINITION 0 ps 205 ps 410 ps 615 ps 820 ps 1025 ps 1230 ps 1435 ps 8.6.3.11.7 PLL1_WND_SIZE PLL1_WND_SIZE sets the window size used for digital lock detect for PLL1. If the phase error between the reference and feedback of PLL1 is less than specified time, then the PLL1 lock counter increments. See Digital Lock Detect Frequency Accuracy for more information. Table 85. PLL1_WND_SIZE, 2 Bits R24[7:6] 0 1 2 3 DEFINITION 5.5 ns 10 ns 18.6 ns 40 ns 8.6.3.12 Register 25 8.6.3.12.1 DAC_CLK_DIV The DAC update clock frequency is the PLL1 phase detector frequency divided by this divisor. Table 86. DAC_CLK_DIV, 10 Bits R25[31:22] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) ... 1,022 (0x3FE) 1,023 (0x3FF) DIVIDE Reserved 1 2 3 ... 1022 1023 8.6.3.12.2 PLL1_DLD_CNT The reference and feedback of PLL1 must be within the window of phase error as specified by PLL1_WND_SIZE for this many phase detector cycles before PLL1 digital lock detect is asserted. See Digital Lock Detect Frequency Accuracy for more information. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 77 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 87. PLL1_DLD_CNT, 14 Bits R25[19:6] 0 1 2 3 ... 16,382 (0x3FFE) 16,383 (0x3FFF) DIVIDE Reserved 1 2 3 ... 16,382 16,383 8.6.3.13 Register 26 8.6.3.13.1 PLL2_WND_SIZE PLL2_WND_SIZE sets the window size used for digital lock detect for PLL2. If the phase error between the reference and feedback of PLL2 is less than specified time, then the PLL2 lock counter increments. This value must be programmed to 2 (3.7 ns). See Digital Lock Detect Frequency Accuracy for more information. Table 88. PLL2_WND_SIZE, 2 Bits R26[31:30] 0 1 2 3 DEFINITION Reserved Reserved 3.7 ns Reserved 8.6.3.13.2 EN_PLL2_REF_2X, PLL2 Reference Frequency Doubler Enabling the PLL2 reference frequency doubler allows for higher phase detector frequencies on PLL2 than would normally be allowed with the given VCXO or Crystal frequency. Higher phase detector frequencies reduces the PLL N values which makes the design of wider loop bandwidth filters possible. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 89. EN_PLL2_REF_2X R26[29] DESCRIPTION Reference frequency normal 0 (1) 1 (1) Reference frequency doubled (2x) When the doubler is not enabled, PLL2_R should not be programmed to 1. 8.6.3.13.3 PLL2_CP_POL, PLL2 Charge Pump Polarity PLL2_CP_POL sets the charge pump polarity for PLL2. The internal VCO requires the negative charge pump polarity to be selected. Many VCOs use positive slope. A positive slope VCO increases output frequency with increasing voltage. A negative slope VCO decreases output frequency with increasing voltage. Table 90. PLL2_CP_POL R26[28] 0 1 78 DESCRIPTION Negative Slope VCO/VCXO Positive Slope VCO/VCXO Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.13.4 PLL2_CP_GAIN, PLL2 Charge Pump Current This bit programs the PLL2 charge pump output current level. The table below also illustrates the impact of the PLL2 TRI-STATE bit in conjunction with PLL2_CP_GAIN. Table 91. PLL2_CP_GAIN, 2 Bits PLL2_CP_TRI R27[5] 1 0 0 0 0 R26[27:26] 0 1 2 3 X (0x00) (0x01) (0x02) (0x03) CHARGE PUMP CURRENT (A) Hi-Z 100 400 1600 3200 8.6.3.13.5 PLL2_DLD_CNT The reference and feedback of PLL2 must be within the window of phase error as specified by PLL2_WND_SIZE for PLL2_DLD_CNT cycles before PLL2 digital lock detect is asserted. See Digital Lock Detect Frequency Accuracy for more information Table 92. PLL2_DLD_CNT, 14 Bits R26[19:6] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) ... 16,382 (0x3FFE) 16,383 (0x3FFF) DIVIDE Reserved 1 2 3 ... 16,382 16,383 8.6.3.13.6 PLL2_CP_TRI, PLL2 Charge Pump TRI-STATE This bit allows for the PLL2 charge pump output pin, CPout2, to be placed into TRI-STATE. Table 93. PLL2_CP_TRI R26[5] 0 1 DESCRIPTION PLL2 CPout2 is active PLL2 CPout2 is at TRI-STATE 8.6.3.14 Register 27 8.6.3.14.1 PLL1_CP_POL, PLL1 Charge Pump Polarity PLL1_CP_POL sets the charge pump polarity for PLL1. Many VCXOs use positive slope. A positive slope VCXO increases output frequency with increasing voltage. A negative slope VCXO decreases output frequency with increasing voltage. Table 94. PLL1_CP_POL R27[28] 0 1 DESCRIPTION Negative Slope VCO/VCXO Positive Slope VCO/VCXO Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 79 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.14.2 PLL1_CP_GAIN, PLL1 Charge Pump Current This bit programs the PLL1 charge pump output current level. The table below also illustrates the impact of the PLL1 TRI-STATE bit in conjunction with PLL1_CP_GAIN. Table 95. PLL1_CP_GAIN, 2 Bits PLL1_CP_TRI R27[5] 1 0 0 0 0 R26[27:26] 0 1 2 3 X (0x00) (0x01) (0x02) (0x03) CHARGE PUMP CURRENT (A) Hi-Z 100 200 400 1600 8.6.3.14.3 CLKinX_PreR_DIV The pre-R dividers before the PLL1 R divider can be programmed such that when the active clock input is switched, the frequency at the input of the PLL1 R divider will be the same. This allows PLL1 to stay in lock without needing to re-program the PLL1 R register when different clock input frequencies are used. This is especially useful in the auto CLKin switching modes. Table 96. CLKinX_PreR_DIV Programming Addresses CLKinX_PreR_DIV CLKin2_PreR_DIV CLKin1_PreR_DIV CLKin0_PreR_DIV PROGRAMMING ADDRESS R27[25:24] R27[23:22] R27[21:20] Table 97. CLKinX_PreR_DIV, 2 Bits R27[25:24, 23:22, 21:20] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) DIVIDE 1 2 4 8 8.6.3.14.4 PLL1_R, PLL1 R Divider The reference path into the PLL1 phase detector includes the PLL1 R divider. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. The valid values for PLL1_R are shown in the table below. Table 98. PLL1_R, 14 Bits R27[19:6] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) ... 16,382 (0x3FFE) 16,383 (0x3FFF) DIVIDE Reserved 1 2 3 ... 16,382 16,383 8.6.3.14.5 PLL1_CP_TRI, PLL1 Charge Pump TRI-STATE This bit allows for the PLL1 charge pump output pin, CPout1, to be placed into TRI-STATE. Table 99. PLL1_CP_TRI R27[5] 0 1 80 DESCRIPTION PLL1 CPout1 is active PLL1 CPout1 is at TRI-STATE Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 8.6.3.15 Register 28 8.6.3.15.1 PLL2_R, PLL2 R Divider The reference path into the PLL2 phase detector includes the PLL2 R divider. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 100 shows the valid values for PLL2_R . Table 100. PLL2_R, 12 Bits R28[31:20] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) ... 4,094 (0xFFE) 4,095 (0xFFF) (1) DIVIDE Not Valid 1 (1) 2 3 ... 4,094 4,095 When using PLL2_R divide value of 1, the PLL2 reference doubler should be used (EN_PLL2_REF_2X = 1). 8.6.3.15.2 PLL1_N, PLL1 N Divider The feedback path into the PLL1 phase detector includes the PLL1 N divider. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 101 shows the valid values for PLL1_N. Table 101. PLL1_N, 14 Bits R28[19:6] 0 (0x00) 1 (0x01) 2 (0x02) ... 4,095 (0xFFF) DIVIDE Not Valid 1 2 ... 4,095 8.6.3.16 REGISTER 29 8.6.3.16.1 OSCin_FREQ, PLL2 Oscillator Input Frequency Register The frequency of the PLL2 reference input to the PLL2 Phase Detector (OSCin/OSCin* port) must be programmed to support proper operation of the frequency calibration routine which locks the internal VCO to the target frequency. Table 102. OSCin_FREQ, 3 Bits R29[26:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) OSCin FREQUENCY 0 to 63 MHz >63 MHz to 127 MHz >127 MHz to 255 MHz Reserved >255 MHz to 400 MHz Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 81 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 8.6.3.16.2 PLL2_FAST_PDF, High PLL2 Phase Detector Frequency When PLL2 phase detector frequency is greater than 100 MHz, set the PLL2_FAST_PDF to ensure proper operation of device. Table 103. PLL2_FAST_PDF R29[23] PLL2 PDF Less than or equal to 100 MHz Greater than 100 MHz 0 1 8.6.3.16.3 PLL2_N_CAL, PLL2 N Calibration Divider During the frequency calibration routine, the PLL uses the divide value of the PLL2_N_CAL register instead of the divide value of the PLL2_N register to lock the VCO to the target frequency. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 104. PLL2_N_CAL, 18 Bits R30[22:5] DIVIDE 0 (0x00) 1 (0x01) 2 (0x02) ... 262,143 (0x3FFFF) Not Valid 1 2 ... 262,143 8.6.3.17 Register 30 If an internal VCO mode is used, programming Register 30 triggers the frequency calibration routine. This calibration routine will also generate a SYNC event. See Clock Output Synchronization (SYNC) for more details on a SYNC. 8.6.3.17.1 PLL2_P, PLL2 N Prescaler Divider The PLL2 N Prescaler divides the output of the VCO as selected by Mode_MUX1 and is connected to the PLL2 N divider. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 105. PLL2_P, 3 Bits R30[26:24] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) DIVIDE VALUE 8 2 2 3 4 5 6 7 8.6.3.17.2 PLL2_N, PLL2 N Divider The feeback path into the PLL2 phase detector includes the PLL2 N divider. Each time register 30 is updated via the MICROWIRE interface, a frequency calibration routine runs to lock the VCO to the target frequency. During this calibration PLL2_N is substituted with PLL2_N_CAL. See PLL Programming for more information on how to program the PLL dividers to lock the PLL. Table 106 shows the valid values for PLL2_N. 82 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 106. PLL2_N, 18 Bits R30[22:5] 0 (0x00) 1 (0x01) 2 (0x02) ... 262,143 (0x3FFFF) DIVIDE Not Valid 1 2 ... 262,143 8.6.3.18 Register 31 8.6.3.18.1 READBACK_LE Sets the required state of the LEuWire pin when performing register readback. See Readback. Table 107. READBACK_LE R31[21] 0 (0x00) 1 (0x01) REGISTER LE must be low for readback LE must be high for readback 8.6.3.18.2 READBACK_ADDR Sets the address of the register to read back when performing readback. When reading register 12, the READBACK_ADDR will be read back at R12[20:16]. When reading back from R31 bits 6 to 31 should be ignored. Only uWire_LOCK is valid. See Register Readback for more information on readback. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 83 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 108. READBACK_ADDR, 5 Bits R31[20:16] 0 (0x00) 1 (0x01) 2 (0x02) 3 (0x03) 4 (0x04) 5 (0x05) 6 (0x06) 7 (0x07) 8 (0x08) 9 (0x09) 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) REGISTER R0 R1 R2 R3 R4 R5 R6 R7 R8 Reserved R10 R11 R12 R13 14 (0x0E) 15 (0x0F) 16 (0x10) 17 (0x11) ... 22 (0x16) 23 (0x17) 24 (0x18) 25 (0x19) 26 (0x1A) 27 (0x1B) 28 (0x1C) 29 (0x1D) 30 (0x1E) 31 (0x1F) R14 R15 Reserved Reserved ... Reserved Reserved R24 R25 R26 R27 R28 R29 R30 R31 8.6.3.18.3 uWire_LOCK Setting uWire_LOCK will prevent any changes to uWire registers R0 to R30. Only by clearing the uWire_LOCK bit in R31 can the uWire registers be unlocked and written to once more. It is not necessary to lock the registers to perform a readback operation. Table 109. uWire_LOCK R31[5] 0 1 84 STATE Registers unlocked Registers locked, Write-protect Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 9 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI's customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 9.1 Application Information To assist customers in frequency planning and design of loop filters, Texas Instruments provides the Clock Design Tool and Clock Architect. 9.1.1 Loop Filter Each PLL of the LMK04906 requires a dedicated loop filter. 9.1.1.1 PLL1 The loop filter for PLL1 must be connected to the CPout1 pin. Figure 20 shows a simple 2-pole loop filter. The output of the filter drives an external VCXO module or discrete implementation of a VCXO using a crystal resonator and external varactor diode. Higher order loop filters may be implemented using additional external R and C components. It is recommended the loop filter for PLL1 result in a total closed loop bandwidth in the range of 10 Hz to 200 Hz. The design of the loop filter is application specific and highly dependent on parameters such as the phase noise of the reference clock, VCXO phase noise, and phase detector frequency for PLL1. TI's Clock Conditioner Owner's Manual covers this topic in detail and TI's Clock Design Tool can be used to simulate loop filter designs for both PLLs. These resources may be found: Clock and Timing landing page. 9.1.1.2 PLL2 As shown in Figure 20, the charge pump for PLL2 is directly connected to the optional internal loop filter components, which are normally used only if either a third or fourth pole is needed. The first and second poles are implemented with external components. The loop must be designed to be stable over the entire applicationspecific tuning range of the VCO. The designer should note the range of KVCO listed in Electrical Characteristics and how this value can change over the expected range of VCO tuning frequencies. Because loop bandwidth is directly proportional to KVCO, the designer should model and simulate the loop at the expected extremes of the desired tuning range, using the appropriate values for KVCO. When designing with the integrated loop filter of the LMK04906 family, considerations for minimum resistor thermal noise often lead one to the decision to design for the minimum value for integrated resistors, R3 and R4. Both the integrated loop filter resistors (R3 and R4) and capacitors (C3 and C4) also restrict the maximum loop bandwidth. However, these integrated components do have the advantage that they are closer to the VCO and can therefore filter out some noise and spurs better than external components. For this reason, a common strategy is to minimize the internal loop filter resistors and then design for the largest internal capacitor values that permit a wide enough loop bandwidth. In situations where spur requirements are very stringent and there is margin on phase noise, a feasible strategy would be to design a loop filter with integrated resistor values larger than their minimum value. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 85 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Application Information (continued) LMK04906 PLL1 LMK04906 PLL2 PLL2 Internal Loop Filter R3 PLL2 Phase Detector PLL1 Phase Detector Internal VCO R4 C3 C4 CPout2 CPout1 External VCXO PLL1 External Loop Filter LF1_C2 LF1_C1 LF2_C2 LF2_C1 LF1_R2 PLL2 External Loop Filter LF2_R2 Figure 20. PLL1 and PLL2 Loop Filters 9.1.2 Driving CLKin and OSCin Inputs 9.1.2.1 Driving CLKin Pins With a Differential Source Both CLKin ports can be driven by differential signals. It is recommended that the input mode be set to bipolar (CLKinX_BUF_TYPE = 0) when using differential reference clocks. The LMK04906 family internally biases the input pins so the differential interface should be AC coupled. The recommended circuits for driving the CLKin pins with either LVDS or LVPECL are shown in Figure 21 and Figure 22. 100: Trace (Differential) LVDS 100: CLKinX 0.1 PF LMK04906 Input 0.1 PF CLKinX* 240: Figure 21. CLKinX/X* Termination for an LVDS Reference Clock Source LVPECL Ref Clk 0.1 PF 0.1 PF 100: Trace (Differential) 100: CLKinX 0.1 PF 0.1 PF LMK04906 Input 240: CLKinX* Figure 22. CLKinX/X* Termination for an LVPECL Reference Clock Source 86 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Application Information (continued) Finally, a reference clock source that produces a differential sine wave output can drive the CLKin pins using the following circuit. Note: the signal level must conform to the requirements for the CLKin pins listed in Electrical Characteristics. CLKinX 0.1 PF 100: 100: Trace (Differential) 0.1 PF Differential Sinewave Clock Source LMK04906 Input CLKinX* Figure 23. CLKinX/X* Termination for a Differential Sinewave Reference Clock Source 9.1.2.2 Driving CLKin Pins With a Single-Ended Source The CLKin pins of the LMK04906 family can be driven using a single-ended reference clock source, for example, either a sine wave source or an LVCMOS/LVTTL source. Either AC coupling or DC coupling may be used. In the case of the sine wave source that is expecting a 50- load, it is recommended that AC coupling be used as shown in the circuit below with a 50- termination. NOTE The signal level must conform to the requirements for the CLKin pins listed in the Electrical Characteristics table. CLKinX_BUF_TYPE in Register 11 is recommended to be set to bipolar mode (CLKinX_BUF_TYPE = 0). 0.1 PF 50: Trace Clock Source CLKinX 50: 0.1 PF LMK04906 CLKinX* Figure 24. CLKinX/X* Single-Ended Termination If the CLKin pins are being driven with a single-ended LVCMOS/LVTTL source, either DC coupling or AC coupling may be used. If DC coupling is used, the CLKinX_BUF_TYPE should be set to MOS buffer mode (CLKinX_BUF_TYPE = 1) and the voltage swing of the source must meet the specifications for DC coupled, MOS-mode clock inputs given in the table of Electrical Characteristics. If AC coupling is used, the CLKinX_BUF_TYPE should be set to the bipolar buffer mode (CLKinX_BUF_TYPE = 0). The voltage swing at the input pins must meet the specifications for AC coupled, bipolar mode clock inputs given in the table of Electrical Characteristics. In this case, some attenuation of the clock input level may be required. A simple resistive divider circuit before the AC coupling capacitor is sufficient. Figure 25. DC Coupled LVCMOS/LVTTL Reference Clock Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 87 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Application Information (continued) 9.1.3 Termination and Use of Clock Output (Drivers) When terminating clock drivers keep in mind these guidelines for optimum phase noise and jitter performance: * Transmission line theory should be followed for good impedance matching to prevent reflections. * Clock drivers should be presented with the proper loads. For example: - LVDS drivers are current drivers and require a closed current loop. - LVPECL drivers are open emitters and require a DC path to ground. * Receivers should be presented with a signal biased to their specified DC bias level (common mode voltage) for proper operation. Some receivers have self-biasing inputs that automatically bias to the proper voltage level. In this case, the signal should normally be AC coupled. It is possible to drive a non-LVPECL or non-LVDS receiver with an LVDS or LVPECL driver as long as the above guidelines are followed. Check the datasheet of the receiver or input being driven to determine the best termination and coupling method to be sure that the receiver is biased at its optimum DC voltage (common mode voltage). For example, when driving the OSCin/OSCin* input of the LMK04906 family, OSCin/OSCin* should be AC coupled because OSCin/OSCin* biases the signal to the proper DC level (See Figure 39) This is only slightly different from the AC coupled cases described in Driving CLKin Pins With a Single-Ended Source because the DC blocking capacitors are placed between the termination and the OSCin/OSCin* pins, but the concept remains the same. The receiver (OSCin/OSCin*) sets the input to the optimum DC bias voltage (common mode voltage), not the driver. 9.1.3.1 Termination for DC Coupled Differential Operation For DC coupled operation of an LVDS driver, terminate with 100 as close as possible to the LVDS receiver as shown in Figure 26. 100: Trace (Differential) LVDS Driver 100: CLKoutX LVDS Receiver CLKoutX* Figure 26. Differential LVDS Operation, DC Coupling, No Biasing of the Receiver For DC coupled operation of an LVPECL driver, terminate with 50 to VCC - 2 V as shown in Figure 27. Alternatively terminate with a Thevenin equivalent circuit (120- resistor connected to VCC and an 82- resistor connected to ground with the driver connected to the junction of the 120- and 82- resistors) as shown in Figure 28 for VCC = 3.3 V. 50: Vcc - 2 V CLKoutX 100: Trace (Differential) LVPECL Driver LVPECL Receiver 50: CLKoutX* Vcc - 2 V Figure 27. Differential LVPECL Operation, DC Coupling 88 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Application Information (continued) 82: 120: Vcc CLKoutX 100: Trace (Differential) LVPECL Driver LVPECL Receiver 82: 120: CLKoutX* Vcc Figure 28. Differential LVPECL Operation, DC Coupling, Thevenin Equivalent 9.1.3.2 Termination for AC Coupled Differential Operation AC coupling allows for shifting the DC bias level (common mode voltage) when driving different receiver standards. Since AC coupling prevents the driver from providing a DC bias voltage at the receiver it is important to ensure the receiver is biased to its ideal DC level. When driving non-biased LVDS receivers with an LVDS driver, the signal may be AC coupled by adding DC blocking capacitors; however, the proper DC bias point needs to be established at the receiver. One way to do this is with the termination circuitry in Figure 29. 0.1 PF LVDS Driver 100: Trace (Differential) 50: CLKoutX LVDS Receiver CLKoutX* 50: Vbias 0.1 PF Figure 29. Differential LVDS Operation, AC Coupling, External Biasing at the Receiver Some LVDS receivers may have internal biasing on the inputs. In this case, the circuit shown in Figure 29 is modified by replacing the 50- terminations to Vbias with a single 100- resistor across the input pins of the receiver, as shown in Figure 30. When using AC coupling with LVDS outputs, there may be a start-up delay observed in the clock output due to capacitor charging. The previous figures employ a 0.1-F capacitor. This value may need to be adjusted to meet the start-up requirements for a particular application. LVDS Driver 100: Trace (Differential) 100: 0.1 PF LVDS Receiver 0.1 PF Figure 30. LVDS Termination for a Self-Biased Receiver Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 89 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Application Information (continued) LVPECL drivers require a DC path to ground. When AC coupling an LVPECL signal use 120- emitter resistors close to the LVPECL driver to provide a DC path to ground as shown in Figure 31. For proper receiver operation, the signal should be biased to the DC bias level (common mode voltage) specified by the receiver. The typical DC bias voltage for LVPECL receivers is 2 V. A Thevenin equivalent circuit (82- resistor connected to VCC and a 120- resistor connected to ground with the driver connected to the junction of the 82- and 120- resistors) is a valid termination as shown in Figure 31 for VCC = 3.3 V. Note this Thevenin circuit is different from the DC coupled example in Figure 28. 82: 120: 0.1 PF LVPECL Driver 0.1 PF LVPECL Receiver 82: 120: CLKoutX* 100: Trace (Differential) 120: CLKoutX 120: Vcc Vcc Figure 31. Differential LVPECL Operation, AC Coupling, Thevenin Equivalent, External Biasing at the Receiver 9.1.3.3 Termination for Single-Ended Operation A balun can be used with either LVDS or LVPECL drivers to convert the balanced, differential signal into an unbalanced, single-ended signal. It is possible to use an LVPECL driver as one or two separate 800 mVpp signals. When using only one LVPECL driver of a CLKoutX/CLKoutX* pair, be sure to properly terminated the unused driver. When DC coupling one of the LMK04906 family clock LVPECL drivers, the termination should be 50 to VCC - 2 V as shown in Figure 32. The Thevenin equivalent circuit is also a valid termination as shown in Figure 33 for Vcc = 3.3 V. 50: Vcc - 2V CLKoutX 50: Trace LVPECL Driver Vcc - 2V CLKoutX* Load 50: Figure 32. Single-Ended LVPECL Operation, DC Coupling 90 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Application Information (continued) CLKoutX Vcc 50: Trace 120: LVPECL Driver Load 82 : CLKoutX* 82: 120: Vcc Figure 33. Single-Ended LVPECL Operation, DC Coupling, Thevenin Equivalent 0.1 PF LVPECL Driver 50: Trace 50: CLKoutX* 120: 0.1 PF 50: CLKoutX 120: When AC coupling an LVPECL driver use a 120 emitter resistor to provide a DC path to ground and ensure a 50- termination with the proper DC bias level for the receiver. The typical DC bias voltage for LVPECL receivers is 2 V (See Driving CLKin Pins With a Single-Ended Source). If the companion driver is not used it should be terminated with either a proper AC or DC termination. This latter example of AC coupling a singleended LVPECL signal can be used to measure single-ended LVPECL performance using a spectrum analyzer or phase noise analyzer. When using most RF test equipment no DC bias point (0 VDC) is required for safe and proper operation. The internal 50 termination of the test equipment correctly terminates the LVPECL driver being measured as shown in Figure 34. Load Figure 34. Single-Ended LVPECL Operation, AC-Coupling 9.1.4 Frequency Planning With the LMK04906 Family Calculating the value of the output dividers for use with the LMK04906 family is simple due to the architecture of the LMK04906. That is, the VCO divider may be bypassed and the clock output dividers allow for even and odd output divide values from 2 to 1045. For most applications it is recommended to bypass the VCO divider. The procedure for determining the needed LMK04906 device and clock output divider values for a set of clock output frequencies is straightforward. 1. Calculate the least common multiple (LCM) of the clock output frequencies. 2. Determine which VCO ranges will support the target clock output frequencies given the LCM. 3. Determine the clock output divide values based on VCO frequency. 4. Determine the PLL2 reference frequency doubler mode and PLL2_P, PLL2_N, and PLL2_R divider values given the OSCin VCXO or crystal frequency and VCO frequency. For example, given the following target output frequencies: 200 MHz, 120 MHz, and 25 MHz with a VCXO frequency of 40 MHz: Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 91 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Application Information (continued) First determine the LCM of the three frequencies. LCM(200 MHz, 120 MHz, 25 MHz) = 600 MHz. The LCM frequency is the lowest frequency for which all of the target output frequencies are integer divisors of the LCM. Note, if there is one frequency which causes the LCM to be very large, greater than 3 GHz for example, determine if there is a single frequency requirement which causes this. It may be possible to select the VCXO/crystal frequency to satisfy this frequency requirement through OSCout or CLKout3/4 driven by OSCin. In this way it is possible to get non-integer related frequencies at the outputs. Second, since the LCM is not in a VCO frequency range supported by the LMK04906, multiply the LCM frequency by an integer which causes it to fall into a valid VCO frequency range of an LMK04906 device. In this case 600 MHz * 4 = 2400 MHz which is valid for the LMK04906. Third, continuing the example by using a VCO frequency of 2400 MHz and the LMK04906, the CLKout dividers can be calculated by simply dividing the VCO frequency by the output frequency. To output 200 MHz, 120 MHz, and 25 MHz the output dividers will be 12, 20, and 96 respectively. * 2400 MHz / 200 MHz = 12 * 2400 MHz / 120 MHz = 20 * 2400 MHz / 25 MHz = 96 Fourth, PLL2 must be locked to its input reference. See PLL Programming for more information on this topic. By programming the clock output dividers and the PLL2 dividers the VCO can lock to the frequency of 2400 MHz and the clock outputs dividers will each divide the VCO frequency down to the target output frequencies of 200 MHz, 120 MHz, and 25 MHz. NOTE Refer to application note AN-1865 Frequency Synthesis and Planning for PLL Architectures for more information on this topic and LCM calculations. 9.1.5 PLL Programming To lock a PLL the divided reference and divided feedback from VCO or VCXO must result in the same phase detector frequency. The tables below illustrate how the divides are structured for the reference path (R) and feedback path (N) depending on the MODE of the device. Table 110. PLL1 Phase Detector Frequency -- Reference Path (R) MODE (R) PLL1 PDF = All CLKinX Frequency / CLKinX_PreR_DIV / PLL1_R Table 111. PLL1 Phase Detector Frequency -- Feedback Path (N) MODE Internal VCO Dual PLL Internal VCO /w 0-delay (1) VCO_MUX OSCout0 -- Bypass PLL1 PDF (N) = VCXO Frequency / PLL1_N -- Divided VCXO Frequency / OSCin_DIV / PLL1_N Bypass -- VCO Frequency / CLKoutX_DIV / PLL1_N Divided -- VCO Frequency / VCO_DIV / CLKoutX_DIV / PLL1_N (1) (1) The actual CLKoutX_DIV used is selected by FEEDBACK_MUX. Table 112. PLL2 Phase Detector Frequency -- Reference Path (R) EN_PLL2_REF_2X (1) 92 PLL2 PDF (R) = (1) Disabled OSCin Frequency / PLL2_R Enabled OSCin Frequency * 2 / PLL2_R (1) For applications in which the OSCin frequency and PLL2 phase detector frequency are equal, the best PLL2 in-band noise can be achieved when the doubler is enabled (EN_PLL2_REF_2X = 1) and the PLL2 R divide value is 2. Do not use doubler disabled (EN_PLL2_REF_2X = 0) and PLL2 R divide value of 1. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 113. PLL2 Phase Detector Frequency -- Feedback Path (N) MODE VCO_MUX PLL2 PDF (N) = Dual PLL Dual PLL /w 0-delay VCO VCO Frequency / PLL2_P / PLL2_N Single PLL Dual PLL Dual PLL /w 0-delay VCO Divider VCO Frequency / VCO_DIV / PLL2_P / PLL2_N -- VCO Frequency / VCO_DIV / PLL2_P / PLL2_N Single PLL Dual PLL External VCO Dual PLL External VCO /w 0-delay VCO Single PLL /w 0-delay VCO Divider VCO Frequency / CLKoutX_DIV / PLL2_N VCO Frequency / VCO_DIV / CLKoutX_DIV / PLL2_N Table 114. PLL2 Phase Detector Frequency -- Feedback Path (N) during VCO Frequency Calibration MODE VCO_MUX VCO All Internal VCO Modes VCO Divider PLL2 PDF (N_CAL) = VCO Frequency / PLL2_P / PLL2_N_CAL VCO Frequency / VCO_DIV / PLL2_P / PLL2_N_CAL 9.1.5.1 Example PLL2 N Divider Programming To program PLL2 to lock an LMK04906 using Dual PLL mode to a VCO frequency of 2400 MHz using a 40 MHz VCXO reference, first determine the total PLL2 N divide value. This is VCO Frequency / PLL2 phase detector frequency. This example assumes the PLL2 reference frequency doubler is enabled and a PLL2 R divider value of 2 (1) which results in PLL2 R divide value of 1 which results in PLL2 phase detector frequency the same as PLL2 reference frequency (40 MHz). 2400 MHz / 40 MHz = 60, so the total PLL2 N divide value is 60. The dividers in the PLL2 N feedback path for Dual PLL mode include PLL2_P and PLL2_N. PLL2_P can be programmed from 2 to 8 even and odd. PLL2_N can be programmed from 1 to 263,143 even and odd. Since the total PLL2 N divide value of 60 contains the factors 2, 2, 3, and 5, it would be allowable to program PLL2_P to 2, 3 or 5. It is simplest to use the smallest divide, so PLL2_P = 2, and PLL2_N = 30 which results in a Total PLL2 N = 60. For this example and in most cases, PLL2_N_CAL will have the same value as PLL2_N. However when using Single PLL mode with 0-delay, the values will differ. When using an external VCO, PLL2_N_CAL value is unused. 9.1.6 Digital Lock Detect Frequency Accuracy The digital lock detect circuit is used to determine PLL1 locked, PLL2 locked, and holdover exit events. A window size and lock count register are programmed to set a ppm frequency accuracy of reference to feedback signals of the PLL for each event to occur. When a PLL digital lock event occurs the PLL's digital lock detect is asserted true. When the holdover exit event occurs, the device will exit holdover mode. EVENT PLL WINDOW SIZE LOCK COUNT PLL1 Locked PLL1 PLL1_WND_SIZE PLL1_DLD_CNT PLL2 Locked PLL2 PLL2_WND_SIZE PLL2_DLD_CNT Holdover exit PLL1 PLL1_WND_SIZE HOLDOVER_DLD_CNT (1) For applications in which the OSCin frequency and PLL2 phase detector frequency are equal, the best PLL2 in-band noise can be achieved when the doubler is enabled (EN_PLL2_REF_2X = 1) and the PLL2 R divide value is 2. Do not use doubler disabled (EN_PLL2_REF_2X = 0) and PLL2 R divide value of 1. For a digital lock detect event to occur there must be a "lock count" number of phase detector cycles of PLLX during which the time/phase error of the PLLX_R reference and PLLX_N feedback signal edges are within the user programmable "window size." Since there must be at least "lock count" phase detector events before a lock event occurs, a minimum digital lock event time can be calculated as "lock count" / fPDX where X = 1 for PLL1 or 2 for PLL2. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 93 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com By using Equation 4, values for a lock count and window size can be chosen to set the frequency accuracy required by the system in ppm before the digital lock detect event occurs: ppm = 1e6 x PLLX_WND_SIZE x fPDX PLLX_DLD_CNT (4) The effect of the lock count value is that it shortens the effective lock window size by dividing the window size by lock count. If at any time the PLLX_R reference and PLLX_N feedback signals are outside the time window set by window size, then the lock count value is reset to 0. 9.1.6.1 Minimum Lock Time Calculation Example To calculate the minimum PLL2 digital lock time given a PLL2 phase detector frequency of 40 MHz and PLL2_DLD_CNT = 10,000. Then the minimum lock time of PLL2 will be 10,000 / 40 MHz = 250 s. 9.1.7 Calculating Dynamic Digital Delay Values For Any Divide This section explains how to calculate the dynamic digital delay for any divide value. Dynamic digital delay allows the time offset between two or more clock outputs to be adjusted with no or minimal interruption of clock outputs. Since the clock outputs are operating at a known frequency, the time offset can also be expressed as a phase shift. When dynamically adjusting the digital delay of clock outputs with different frequencies the phase shift should be expressed in terms of the higher frequency clock. The step size of the smallest time adjustment possible is equal to half the period of the Clock Distribution Path, which is the VCO frequency (Equation 2) or the VCO frequency divided by the VCO divider (Equation 3) if not bypassed. The smallest degree phase adjustment with respect to a clock frequency will be 360 * the smallest time adjustment * the clock frequency. The total number of phase offsets that the LMK04906 family is able to achieve using dynamic digital delay is equal 1 / (higher clock frequency * the smallest phase adjustment). Equation 5 calculates the digital delay value that must be programmed for a synchronizing clock to achieve a 0 time/phase offset from the qualifying clock. Once this digital delay value is known, it is possible to calculate the digital delay value for any phase offset. The qualifying clock for dynamic digital delay is selected by the FEEDBACK_MUX. When dynamic digital delay is engaged with same clock output used for the qualifying clock and the new synchronized clock, it is termed relative dynamic digital delay since causing another SYNC event with the same digital delay value will offset the clock by the same phase once again. The important part of relative dynamic digital delay is that the CLKoutX_HS must be programmed correctly when the SYNC event occurs (Table 6). This can result in needing to program the device twice. Once to set the new CLKoutX_DDLY with CLKoutX_HS as required for the SYNC event, and again to set the CLKoutX_HS to its desired value. Digital delay values are programmed using the CLKoutX_DDLY and CLKoutX_HS registers as shown in Equation 6. For example, to achieve a digital delay of 13.5, program CLKoutX_DDLY = 14 and CLKoutX_HS = 1. 16 CLKoutX_DIV (c)(c) 0 digital delay = * * + 0.5 x CLKoutX_DIV - 11.5 (5) Equation 5 uses the ceiling operator. To find the ceiling of a fractional number round up. An integer remains the same value. Digital delay = CLKoutX_DDLY - (0.5 * CLKoutX_HS) (6) Note: since the digital delay value for 0 time/phase offset is a function of the qualifying clock's divide value, the resulting digital delay value can be used for any clock output operating at any frequency to achieve a 0 time/phase offset from the qualifying clock. Therefore the calculated time shift table will also be the same as in Table 115 9.1.7.1 Example Consider a system with: * A VCO frequency of 2000 MHz. * The VCO divider is bypassed, therefore the clock distribution path frequency is 2000 MHz. * CLKout0_DIV = 10 resulting in a 200 MHz frequency on CLKout0. 94 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com * SNAS589F - JUNE 2012 - REVISED AUGUST 2017 CLKout2_DIV = 20 resulting in a 100 MHz frequency on CLKout2. For this system the minimum time adjustment is 0.25 ns, which is 0.5 / (2000 MHz). Since the higher frequency is 200 MHz, phase adjustments will be calculated with respect to the 200 MHz frequency. The 0.25 ns minimum time adjustment results in a minimum phase adjustment of 18 degrees, which is 360 degrees / 200 MHz * 0.25 ns. To calculate the digital delay value to achieve a 0 time/phase shift of CLKout2 when CLKout0 is the qualifying clock. Solve Equation 5 using the divide value of 10. To solve the equation 16/10 = 1.6, the ceiling of 1.6 is 2. Then to finish solving the equation solve (2 + 0.5) * 10 - 11.5 = 13.5. A digital delay value of 13.5 is programmed by setting CLKout2_DDLY = 14 and CLKout2_HS = 1. To calculate the digital delay value to achieve a 0 time/phase shift of CLKout0 when CLKout2 is the qualifying clock, solve Equation 5 using the divide value of CLKout2, which is 20. This results in a digital delay of 18.5 which is programmed as CLKout0_DDLY = 19 and CLKout0_HS = 1. Once the 0 time/phase shift digital delay programming value is known a table can be constructed with the digital delay value to be programmed for any time/phase offset by decrementing or incrementing the digital delay value by 0.5 for the minimum time/phase adjustment. A complete filled out table for use of CLKout0 as the qualifying clock is shown in Table 115. It was created by entering a digital delay of 13.5 for 0 degree phase shift, then decrementing the digital delay down to the minimum value of 4.5. Since this did not result in all the possible phase shifts, the digital delay was then incremented from 13.5 to 14.0 to complete all possible phase shifts. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 95 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 115. Example Digital Delay Calculation DIGITAL DELAY CALCULATED TIME SHIFT (ns) RELATIVE TIME SHIFT TO 200 MHz (ns) PHASE SHIFT OF 200 MHZ (DEGREES) 4.5 -4.5 0.5 36 5 -4.25 0.75 54 5.5 -4 1 72 6 -3.75 1.25 90 6.5 -3.5 1.5 108 7 -3.25 1.75 126 7.5 -3 2 144 8 -2.75 2.25 162 8.5 -2.5 2.5 180 9 -2.25 2.75 198 9.5 -2 3 216 10 -1.75 3.25 234 10.5 -1.5 3.5 252 11 -1.25 3.75 270 11.5 -1 4 288 12 -0.75 4.25 306 12.5 -0.5 4.5 324 13 -0.25 4.75 342 13.5 0 0 0 14 0.25 0.25 18 14.5 0.5 0.5 36 Observe that the digital delay value of 4.5 and 14.5 will achieve the same relative time shift/phase delay. However programming a digital delay of 14.5 will result in a clock off time for the synchronizing clock to achieve the same phase time shift/phase delay. Digital delay value is programmed as CLKoutX_DDLY -- (0.5 x CLKoutX_HS). So to achieve a digital delay of 13.5, program CLKoutX_DDLY = 14 and CLKoutX_HS = 1. To achieve a digital delay of 14, program CLKoutX_DDLY = 14 and CLKoutX_HS = 0. 9.1.8 Optional Crystal Oscillator Implementation (OSCin/OSCin*) The LMK04906 family features supporting circuitry for a discretely implemented oscillator driving the OSCin port pins. Figure 35 illustrates a reference design circuit for a crystal oscillator: 96 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 OSCin* Copt CC1 = 2.2 nF R1 = 4.7k SMV1249-074LF R3 = 10k LMK04906 XTAL 1 nF R2 = 4.7k CC2 = 2.2 nF OSCin CPout1 Copt PLL1 Loop Filter Figure 35. Reference Design Circuit for Crystal Oscillator Option This circuit topology represents a parallel resonant mode oscillator design. When selecting a crystal for parallel resonance, the total load capacitance, CL, must be specified. The load capacitance is the sum of the tuning capacitance (CTUNE), the capacitance seen looking into the OSCin port (CIN), and stray capacitance due to PCB parasitics (CSTRAY), and is given by Equation 7. CSTRAY CL = CTUNE + CIN + (7) 2 CTUNE is provided by the varactor diode shown in Figure 35, Skyworks model SMV1249-074LF. A dual diode package with common cathode provides the variable capacitance for tuning. The single diode capacitance ranges from approximately 31 pF at 0.3 V to 3.4 pF at 3 V. The capacitance range of the dual package (anode to anode) is approximately 15.5 pF at 3 V to 1.7 pF at 0.3 V. The desired value of VTUNE applied to the diode should be VCC/2, or 1.65 V for VCC = 3.3 V. The typical performance curve from the data sheet for the SMV1249-074LF indicates that the capacitance at this voltage is approximately 6 pF (12 pF / 2). The nominal input capacitance (CIN) of the LMK04906 family OSCin pins is 6 pF. The stray capacitance (CSTRAY) of the PCB should be minimized by arranging the oscillator circuit layout to achieve trace lengths as short as possible and as narrow as possible trace width (50- characteristic impedance is not required). As an example, assume that CSTRAY is 4 pF. The total load capacitance is nominally: Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 97 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 CL = 6 + 6 + www.ti.com 4 = 14 pF 2 (8) Consequently the load capacitance specification for the crystal in this case should be nominally 14 pF. The 2.2-nF capacitors shown in the circuit are coupling capacitors that block the DC tuning voltage applied by the 4.7-k and 10-k resistors. The value of these coupling capacitors should be large, relative to the value of CTUNE (CC1 = CC2 >> CTUNE), so that CTUNE becomes the dominant capacitance. For a specific value of CL, the corresponding resonant frequency (FL) of the parallel resonant mode circuit is: 1 FL = FS A C1 2(C0 + CL1) + 1 = FS A C0 2 (c) C1 + CL * +1 C1 where * * * * FS = Series resonant frequency C1 = Motional capacitance of the crystal CL = Load capacitance C0 = Shunt capacitance of the crystal, specified on the crystal datasheet (9) The normalized tuning range of the circuit is closely approximated by: 1 'F FCL1 - FCL2 C1 = = F 2 FFCL1 A 1 1 1 = (C0 + CL1) (C0 + CL2) 2 A C0 C1 (c) + - C0 C1 (c) C1 CL1* 1 + CL2* C1 (10) CL1, CL2 = The endpoints of the circuit's load capacitance range, assuming a variable capacitance element is one component of the load. FCL1, FCL2 = parallel resonant frequencies at the extremes of the circuit's load capacitance range. A common range for the pullability ratio, C0/C1, is 250 to 280. The ratio of the load capacitance to the shunt capacitance is approximately (n x 1000), n < 10. Hence, picking a crystal with a smaller pullability ratio supports a wider tuning range because this allows the scale factors related to the load capacitance to dominate. Examples of the phase noise and jitter performance of the LMK04906 with a crystal oscillator are shown in Table 116. This table illustrates the clock output phase noise when a 20.48-MHz crystal is paired with PLL1. 98 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Table 116. Example RMS Jitter and Clock Output Phase Noise for LMK04906 With a 20.48-MHz Crystal Driving OSCin (T = 25 C, VCC = 3.3 V) (1) INTEGRATION BANDWIDTH CLOCK OUTPUT TYPE PLL2 PDF = 20.48 MHz (EN_PLL2_REF2X = 0, XTAL_LVL = 3) PLL2 PDF = 40.96 MHz (EN_PLL2_REF2X = 1, XTAL_LVL = 3) fCLK = 245.76 MHz fCLK = 122.88 MHz fCLK = 245.76 MHz LVCMOS 374 412 382 LVDS 419 421 372 LVPECL 1.6 Vpp 460 448 440 LVCMOS 226 195 190 LVDS 231 205 194 LVPECL 1.6 Vpp 226 191 188 Clock Output Type PLL2 PDF = 20.48 MHz (EN_PLL2_REF2X = 0, XTAL_LVL = 3) RMS JITTER (ps) 100 Hz - 20 MHz 10 kHz - 20 MHz PHASE NOISE (dBc/Hz) Offset 100 Hz 1 kHz 10 kHz 100 kHz 1 MHz 40 MHz (1) PLL2 PDF = 40.96 MHz (EN_PLL2_REF2X = 1, XTAL_LVL = 3) fCLK = 245.76 MHz fCLK = 122.88 MHz fCLK = 245.76 MHz LVCMOS -87 -93 -87 LVDS -86 -91 -86 LVPECL 1.6 Vpp -86 -92 -85 LVCMOS -115 -121 -115 LVDS -115 -123 -116 LVPECL 1.6 Vpp -114 -122 -116 LVCMOS -117 -128 -122 LVDS -117 -128 -122 LVPECL 1.6 Vpp -117 -128 -122 LVCMOS -130 -135 -129 LVDS -130 -135 -129 LVPECL 1.6 Vpp -129 -135 -129 LVCMOS -150 -154 -148 LVDS -149 -153 -148 LVPECL 1.6 Vpp -150 -154 -148 LVCMOS -159 -162 -159 LVDS -157 -159 -157 LVPECL 1.6 Vpp -159 -161 -159 Performance data and crystal specifications contained in this section are based on Vectron model VXB1-1150-20M480, 20.48 MHz. PLL1 has a narrow loop bandwidth, PLL2 loop parameters are: C1 = 150 pF, C2 = 120 nF, R2 = 470 , Charge Pump current = 3.2 mA, Phase detector frequency = 20.48 MHz or 40.96 MHz, VCO frequency = 2949.12 MHz. Loop filter was optimized for 40.96-MHz phase detector performance. Example crystal specifications are presented in Table 117. Table 117. Example Crystal Specifications PARAMETER VALUE Nominal Frequency (MHz) 20.48 Frequency Stability, T = 25 C 10 ppm Operating temperature range -40 C to +85 C Frequency Stability, -40 C to +85 C 15 ppm Load Capacitance 14 pF Shunt Capacitance (C0) 5 pF Maximum Motional Capacitance (C1) 20 fF 30% Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 99 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Table 117. Example Crystal Specifications (continued) PARAMETER VALUE Equivalent Series Resistance 25 Maximum Drive level 2 mWatts Maximum C0/C1 ratio 225 typical, 250 Maximum See Figure 36 for a representative tuning curve. 180 140 100 PPM 60 20 -20 -60 -100 -140 -180 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 VTUNE(V) Figure 36. Example Tuning Curve, 20.48-MHz Crystal The tuning curve achieved in the user's application may differ from the curve shown above due to differences in PCB layout and component selection. This data is measured on the bench with the crystal integrated with the LMK04906 family. Using a voltmeter to monitor the VTUNE node for the crystal, the PLL1 reference clock input frequency is swept in frequency and the resulting tuning voltage generated by PLL1 is measured at each frequency. At each value of the reference clock frequency, the lock state of PLL1 should be monitored to ensure that the tuning voltage applied to the crystal is valid. The curve shows over the tuning voltage range of 0.3 VDC to 3.0 VDC, the frequency range is -140 to 91 ppm; or equivalently, a tuning range of -2850 Hz to 1850 Hz. The measured tuning voltage at the nominal crystal frequency (20.48 MHz) is 1.7 V. Using the diode data sheet tuning characteristics, this voltage results in a tuning capacitance of approximately 6.5 pF. The tuning curve data can be used to calculate the gain of the oscillator (KVCO). The data used in the calculations is taken from the most linear portion of the curve, a region centered on the crossover point at the nominal frequency (20.48 MHz). For a well designed circuit, this is the most likely operating range. In this case, the tuning range used for the calculations is 1000 Hz ( 0.001 MHz), or 81.4 ppm. The simplest method is to calculate the ratio: KVCO = 'F = 'V 'F2 - 'F1 * MHz VTUNE2 - VTUNE1 , V (c) (11) F2 and F1 are in units of MHz. Using data from the curve this becomes: 0.001 - (-0.001) MHz = 0.00164 2.03 - 0.814 V (12) A second method uses the tuning data in units of ppm: FNOM A ('ppm2 - 'ppm1) KVCO = 6 'V A 10 (13) FNOM is the nominal frequency of the crystal and is in units of MHz. Using the data, this becomes: 100 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 12.288 A (81.4 - (-81.4)) (2.03 - 0.814) A 10 6 = 0.00164, MHz V (14) In order to ensure startup of the oscillator circuit, the equivalent series resistance (ESR) of the selected crystal should conform to the specifications listed in Electrical Characteristics. It is also important to select a crystal with adequate power dissipation capability, or drive level. If the drive level supplied by the oscillator exceeds the maximum specified by the crystal manufacturer, the crystal will undergo excessive aging and possibly become damaged. Drive level is directly proportional to resonant frequency, capacitive load seen by the crystal, voltage and equivalent series resistance (ESR). For more complete coverage of crystal oscillator design, see AN-1939 Crystal Based Oscillator Design with the LMK04000 Family (SNAA065). 9.2 Typical Application Normal use case of the LMK04906 device is as a dual loop jitter cleaner. This section will discuss a design example to illustrate the various functional aspects of the LMK04906 device. R N Phase Detector PLL1 PLL2 External VCXO or Tunable Crystal External Loop Filter OSCout0 OSCout0* 1 output OSCin CLKinX CLKinX* 3 inputs CPout1 PLL1 External Loop Filter CPout2 R Input Buffer N Phase Detector PLL2 Divider Digital Delay Analog Delay Partially Integrated Loop Filter Internal VCO CLKoutX CLKoutX* 6 outputs 6 blocks LMK04906 Copyright (c) 2016, Texas Instruments Incorporated Figure 37. Simplified Functional Block Diagram for Dual Loop Mode 9.2.1 Design Requirements Given a remote radio head (RRU) type application which needs to clock some ADCs, DACs, FPGA, SERDES, and an LO. The input clock will be a recovered clock which needs jitter cleaning. The FPGA clock should have a clock output on power up. A summary of clock input and output requirements are as follows: Clock Input: * 30.72 MHz recovered clock. Clock Outputs: * 2x 245.76 MHz * 4x 983.04 MHz * 1x 122.88 MHz * 1x 122.88 MHz * 2x 122.88 MHz clock clock clock clock clock for ADC, LVPECL for DAC, LVPECL for FPGA, LVPECL. POR clock for SERDES, LVPECL for LO, LVCMOS It is also desirable to have the holdover feature engage if the recovered clock reference is ever lost. The following information reviews the steps to produce this design. 9.2.2 Detailed Design Procedure Design of all aspects of the LMK04906 are quite involved and software has been written to assist in part selection, part programming, loop filter design, and simulation. This design procedure will give a quick outline of the process. Note that this information is current as of the date of the release of this datasheet. Design tools receive continuous improvements to add features and improve model accuracy. Refer to software instructions or training for latest features. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 101 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Typical Application (continued) 1. Device Selection - the key to device selection is required VCO frequency given required output frequencies. The device must be able to produce the VCO frequency that can be divided down to required output frequencies. - The software design tools will take inot account VCO frequency range for specific devices based on the application's required output frequencies. Using an external VCO provides increased flexibility regarding valid designs. - To understand the process better, refer to Frequency Planning With the LMK04906 Family for more detail on calculating valid VCO frequency when using integer dividers using the least common multiple (LCM) of the output frequencies. 2. Device Configuration - There are many possible permutations of dividers and other registers to get same input and output frequencies from a device. However there are some optimizations and trade-offs to be considered. - If more than one divider is in series, for instance VCO divider to CLKout divider, or VCO divider to PLL prescaler to PLL N. It is possible although not assured that some crosstalk/mixing could be created when using some divides. - The design software normally attempts to maximize phase detector frequency, use smallest dividers, and maximizes PLL charge pump current. - When an external VCXO or crystal is used for jitter cleaning, the design software will choose the maximum frequency value, depending on design software options, this max frequency may be limited to standard value VCXOs/Crystals. Note, depending on application, different frequency VCXOs may be chosen to generate some of the required output frequencies. - Refer to PLL Programming for divider equations need to ensure PLL is locked. The design software is able to configure the device for most cases, but at this time for advanced features like 0-delay, the user must take care to ensure proper PLL programming. - These guidelines may be followed when configuring PLL related dividers or other related registers: - For lowest possible in-band PLL flat noise, maximize phase detector frequency to minimize N divide value. - For lowest possible in-band PLL flat noise, maximize charge pump current. The highest value charge pump currents often have similar performance due to diminishing returns. - To reduce loop filter component sizes, increase N value and/or reduce charge pump current. - Large capacitors help reduce phase detector spurs at phase detector frequency caused by external VCOs/VCXOs with low input impedance. - As rule of thumb, keeping the phase detector frequency approximately between 10 * PLL loop bandwidth and 100 * PLL loop bandwidth. A phase detector frequency less than 5 * PLL bandwidth may be unstable and a phase detector frequency > 100 * loop bandwidth may experience increased lock time due to cycle slipping. 3. PLL Loop Filter Design - It is recommended to use Clock Design Tool or Clock Architect to design your loop filter. - Best loop filter design and simulation can be achieved when: - Custom reference and VCXO phase noise profiles are loaded into the software. - VCO gain of the external VCXO or possible external VCO device are entered. - The Clock Design Tool will return solutions with high reference/phase detector frequencies by default. In the Clock Design Tool the user may increase the reference divider to reduce the frequency if desired. Due to the narrow loop bandwidth used on PLL1, it is common to lower the phase detector frequency on PLL1 to reduce component size. - While designing loop filter, adjusting the charge pump current or N value can help with loop filter component selection. Lower charge pump currents and larger N values result in smaller component values but may increase impacts of leakage and reduce PLL phase noise performance. - More detailed understanding of loop filter design can found in Dean Banerjee's PLL Performance, Simulation, and Design (www.ti.com/tool/pll_book). 102 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Typical Application (continued) 4. Clock Output Assignment - At this time the design software does not take into account frequency assignment to specific outputs except to ensure that the output frequencies can be achieved. It is best to consider proximity of each clock output to each other and other PLL circuitry when choosing final clock output locations. Here are some guidelines to help achieve best performance when assigning outputs to specific CLKout/OSCout pins. - Group common frequencies together. - PLL charge pump circuitry can cause crosstalk at charge pump frequency. Place outputs sharing charge pump frequency or lower priority outputs not sensitive to charge pump frequency spurs together. - Muxes can create a path for noise coupling. Consider all frequencies which may have some bleed through from non-selected mux inputs. - For example, LMK04906 CLKout6/7 and CLKout8/9 share a mux with OSCin. - Some clock targets require low close-in phase noise. If possible, use a VCXO based PLL1 output for such a clock target. An example is a clock to a PLL reference. - Some clock targets require excellent noise floor performance. Outputs driven by the internal VCO have the best noise floor performance. An example is an ADC or DAC. 5. Other device specific configuration. For LMK04906, consider the following: - PLL lock time based on programming: - In addition to the time it takes the device to lock to frequency, there is a digital filter to avoid false lock time detects which can also be used to ensure a specific PPM frequency accuracy. This also impacts the time it takes for the digital lock detect (DLD) pin to be asserted. Refer to Digital Lock Detect Frequency Accuracy for more information. - Holdover configuration: - Specific PPM frequency accuracy required to exit holdover can be programmed. Refer to Holdover Mode - Automatic Exit of Holdover for more information. - Digital delay: phase alignment of the output clocks. - Analog delay: another method to shift phases of clocks with finer resolution with the penalty of increase noise floor. Clock Design Tool can simulate analog delay impact on phase noise floor. - Dynamic digital delay: ability to shift phase alignment of clocks with minimum disruption during operation. 6. Device Programming - The software tool CodeLoader for EVM programming can be used to setup the device in the desired configuration, then export a hex register map suitable for use in application. 9.2.2.1 Device Selection Use the WEBENCH Clock Architect Tool or Clock Design Tool. Enter the required frequencies and formats into the tool. To use this device, find a solution using the LMK04906. 9.2.2.1.1 Clock Architect When viewing resulting solutions, it is possible to narrow the parts used in the solution by setting a filter. Under advanced tab, filtering of specific parts can be done using regular expressions in the Part Filter box. "LMK04906" will filter for only the LMK04906 device (without quotes). Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 103 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Typical Application (continued) 9.2.2.1.2 Clock Design Tool In wizard-mode, select Dual Loop PLL to find the LMK04906 device. If a high frequency and clean reference is available, Although dual loop mode is selected as a customer requirement, it is not required to use dual loop; PLL1 can be powered down and input is then provided via the OSCin port. When simulating single loop solutions, set PLL1 loop filter block to "0 Hz LBW" and use VCXO as the reference block. 9.2.2.1.3 Calculation Using LCM In this example, the LCM(245.76 MHz, 983.04 MHz, 122.88 MHz) = 983.04 MHz. A valid VCO frequency for LMK04906 is 2949.12 MHz = 3 * 983.04 MHz. Therefore the LMK0480B may be used to produce these output frequencies. 9.2.2.2 Device Configuration The tools automatically configure the simulation to meet the input and output frequency requirements given and make assumptions about other parameters to give some default simulations. The assumptions made are to maximize input frequencies, phase detector frequencies, and charge pump currents while minimizing VCO frequency and divider values. For this example, when using the clock design tool, the reference would have been manually entered as 30.72 MHz according to input frequency requirements, but the tool allows VCXO1 frequency either to be set manually, auto-selected according to standard frequencies, or auto-selected for best frequency. With the best frequency option, the highest possible VCXO frequency which gives the highest possible PLL2 PDF frequency is recommended first. In this case: 421 + 53/175 MHz VCXO resulting in a 140 + 76/175 MHz phase detector frequency. This is a high phase detector frequency, but the VCXO is likely going to be a custom order. The select configuration page just before simulation shows before some different configurations possible with different VCO divider values. For example, a more common 491.52 MHz frequency provides a 122.88 MHz PDF. This is a more logical configuration. From the simulation page of clock design tool, it can be seen that the VCXO frequency of 491.52 MHz is too high for feedback into the PLL1_N divider. Reducing the VCXO frequency to 245.76 MHz resolves the PLL1_N divider max input frequency problem. The PLL2 R divider must be updated to 2 so that the VCO of PLL2 is still at 2949.12 MHz. At this point the design meets all input and output frequency requirements and it is possible to design a loop filter for system and simulate performance on CLKouts. However, consider also the following: * At this time the clock design tool doesn't assign outputs strategically for jitter, such as PLL1 vs PLL2. If PLL1 output frequency is high enough, it may have improved jitter performance depending on the noise floor and application required integration range. * The clock design tool does not consider power on reset clocks in the clock requirements or assignments. * The clock design tool simplifies the LMK04906 architecture not showing the mux complexity around OSCout0/1 and not showing OSCout1. Simulation of OSCout0 is equivalent to OSCout1. The next section addresses how the user may alter the design when considering these items. 9.2.2.2.1 PLL LO Reference PLL1 outputs have the best phase noise performance for LO references. As such OSCout0 can be used to provide the 122.88 MHz LO reference clock. To achieve this with the 245.76 MHz VCXO the OSCout_DIV can be set to 2 to provide 122.88 MHz at OSCout0. However in the next section it is determined that for the POR clock, a 122.88 MHz VCXO will be chosen which results not needing to change this parameter. 104 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Typical Application (continued) 9.2.2.2.2 POR Clock If OSCout1 is to be used for LVPECL POR 122.88 MHz clock, the POR value of the OSCout_DIV is 1, so a 122.88 MHz VCXO frequency must be chosen. This may be desired anyway since the phase detector frequency is limited to 122.88 MHz and lower frequency VCXOs tend to cost less. With this change the OSCin frequency and phase detector frequency are the same, so the doubler must be enabled and the PLL2 R divider programmed = 2 to follow the rule stated in PLL Programming. Since the clock design tool does not show the doubler, PLL2_R will still reflect the value 1 one for the simulation purposes. If LVDS was required for POR clock, a voltage divider could be used to convert from LVPECL to LVDS. Note: it is possible to set the PLL2 R = 0.5 to simulate the doubler in-case lower frequency VCXOs would like to be simulated. For example a 61.44 MHz VCXO could be used while retaining a 122.88 MHz phase detector frequency. However, it would reduce the LO reference frequency and POR clock frequency to 61.44 MHz. At this time the main design updates have been made to support the POR clock and loop filter design may begin. 9.2.2.3 PLL Loop Filter Design The PLL structure for the LMK04906 is illustrated in Figure 37. At this time the user may choose to make adjustments to the simulation tools for more accurate simulations to their application. For example: * Clock Design Tool allows loading a custom phase noise plot for any block. Typically, a custom phase noise plot is entered for CLKin to match the reference phase noise to the device; a phase noise plot for the VCXO can additionally be provided to match the performance of VCXO used. For improved accuracy in simulation and optimum loop filter design, be sure to load these custom noise profiles for use in application. After loading a phase noise plot, user should recalculate the recommended loop filter design. * The Clock Design Tool will return solutions with high reference/phase detector frequencies by default. In the Clock Design Tool the user may increase the reference divider to reduce the frequency if desired. Due to the narrow loop bandwidth used on PLL1, it is common to reduce the phase detector frequency on PLL1 by increasing PLL1 R. For this example, for PLL1 to perform jitter cleaning and to minimize jitter from PLL2 used for frequency multiplication: * PLL1: A narrow loop bandwidth PLL1 filter was design by updating the loop bandwidth to 50 Hz and phase margin to 50 degrees. * PLL2: - VCXO noise profile is measured, then loaded into VCXO block in clock design tool. - The recommended loop filter is redesigned. Updates to the PLL1 loop filter and VCXO phase noise may change the loop filter recommendation. The next two sections will discuss PLL1 and PLL2 loop filter design specific to this example using default phase noise profiles. NOTE Clock Design Tool provides some recommend loop filters upon first load of the simulation. Anytime PLL related inputs change like an input phase noise, charge pump current, divider values, and so forth. it is best to re-design the PLL1 loop filter to the recommended design or your desired parameters. After PLL1, then update the PLL2 loop filter in the same way to keep the loop filters designed and optimized for the application. Since PLL1 loop filter design may impact PLL2 loop filter design, be sure to update the designs in order. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 105 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Typical Application (continued) 9.2.2.3.1 PLL1 Loop Filter Design For this example, in the clock design tool simulator click on the PLL1 loop filter design button, then update the loop bandwidth for 0.05 kHz and the phase margin for 50 degrees and press calculate. With the 30.72 MHz phase detector frequency and 1.6 mA charge pump; the designed loop filter's largest capacitor, C2, is 27 F. Supposing a goal of < 10 F; setting PLL1 R = 4 and pressing the calculate again shows that C2 is 6.8 F. Suppose that a reduction to < 1 F is desired, continuing to increase the PLL1 R to 8 resulting in a phase detector frequency of 3.84 MHz and reducing the charge pump current from 1.6 mA to 0.4 mA and calculating again shows that C2 is 820 nF. As N was increased and charge pump decreased, this final design has R2 = 12 k. The first design with low N value and high charge pump current result in R2 = 390 . The impact of the thermal resistance is calculated in the tool. Viewing the simulation of the loop filter with the 12-k resistor shows that the thermal noise in the loop is not impacting performance. It may be desired to design a 3rd order loop filter for additional attenuation input noise and spurs With the PLL1 loop filter design complete, PLL2's loop filter is ready to be designed. 9.2.2.3.2 PLL2 Loop Filter Design In the clock design tool simulator, click on the PLL2 loop filter design button, then press recommend design. For PLL2's loop filter maximum phase detector frequency and maximum charge pump current are typically used. Typically the jitter integration bandwidth includes the loop filter bandwidth for PLL2. The recommended loop filter by the tools are designed to minimize jitter. The integrated loop filter components are minimized with this recommendation as to allow maximum flexibility in achieve wide loop bandwidths for low PLL noise. With the recommended loop filter calculated, this loop filter is ready to be simulated. If using integrated components is desired, open the bode plot for the PLL2 Loop Filter, then make adjustments to the integrated components. The effective loop bandwidth and phase margin with these updates is calculated. The integrated loop filter components are good to use when attempting to eliminate some spurs since they provide filtering after the bond wires. The recommended procedure is to increase C3/C4 capacitance, then R3/R4 resistance. Large R3/R4 resistance can result in degraded VCO phase noise performance. 9.2.2.4 Clock Output Assignment At this time the Clock Design Tool and Clock Architect only assign outputs to specific clock outputs numerically; not necessarily by optimum configuration. The user may wish to make some educated re-assignment of outputs. During device configuration, some output assignment was discussed since it impacted the part's configuration relating to loop filter design, such as: * In this example, OSCout1 can be used to provide the power on reset (POR) start-up clock to the FPGA at 122.88 MHz since the VCXO frequency is the required output frequency. * Since PLL1 outputs have best in-band noise, OSCout0 is used to provide LVCMOS output to the PLL reference for the LO. LVCMOS (Norm/Inv) is used instead of LVCMOS (Norm/Norm) to reduce crosstalk. It is also possible to use CLKout6/7 or CLKout8/9 for a PLL reference being driven from the VCXO. The noise floor will be higher, but close-in noise is typically of more concern since noise above the loop bandwidth of the LO will be dominated by the VCO of the LO. See Figure 38. Since CLKout6/7 and CLKout8/9 have a mux allowing them to be driven by the VCXO and due there is a chance for some 122.88 MHz crosstalk from the VCXO. The 122.88 MHz SERDES clock will be placed on CLKout6 since it will not be sensitive to crosstalk as it is operating at the same frequency. The two 245.76 MHz clocks and four 983.04 MHz clocks for the converters need to be discussed. There is some flexibility in assignment. For example CLKout0/1 could operate at 245.76 MHz for the ADCs and then CLKout2/3 and CLKout4/5 could operate at 983.04 MHz for the DAC. It is also possible to consider CLKout2/3 for the ADC and position CLKout0/1 and CLKout10/11 for the DAC. The ADCs clock was placed as far as possible from other clock which could result in sub-harmonic spurs since the ADC clock is often the most sensitive. 106 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Typical Application (continued) 9.2.2.5 Other Device Specific Configuration 9.2.2.5.1 Digital Lock Detect Digital lock time for PLL1 will ultimately depend upon the programming of the PLL1_DLD_CNT register as discussed in Digital Lock Detect Frequency Accuracy. Since the PLL1 phase detector frequency in this example is 3.84 MHz, the lock time will = 1 / (PLL1_DLD_CNT * 3.84 MHz) Digital lock time for PLL1 if PLL1_DLD_CNT = 10000 is just over 2.6 ms. When using holdover, it is very important to program the PLL1_DLD_CNT to a value large enough to prevent false digital lock detect signals. If PLL1_DLD_CNT is too small, when the device exits holdover and is re-locking, the DLD will go high while the phase of the reference and feedback are within the specified window size because the programmed PLL1_DLD_CNT will be satisfied. However, if the loop has not yet settled to without the window size, when the phases of the reference and feedback once again exceed the window size, the DLD will return low. Provided that DISABLE_DLD1_DET = 0, the device once again enter holdover. Assuming that the reference clock is valid because holdover was just exited, the exit criteria will again be met, holdover will exit, and PLL1 will start locking. Unfortunately, the same sequence of events will repeat resulting in oscillation out-of and back-into holdover. Setting the PLL1_DLD_CNT to an appropriately large value prevents chattering of the PLL1 DLD signal and stable holdover operation can be achieved. Refer to Holdover Mode - Automatic Exit of Holdover for more detail on calculating exit times and how the PLL1_DLD_CNT and PLL1_WND_SIZE work together. 9.2.2.5.2 Holdover For this example, when the recovered clock is lost, the goal is to set the VCXO to Vcc/2 until the recovered clock returns. Holdover Mode contains detailed information on how to program holdover. To * * * * * achieve the above goal, fixed holdover will be used. Program: HOLDOVER_MODE = 2 (Holdover enabled) EN_TRACK = 0 (Tracking disabled) EN_MAN_DAC = 1 (Use manual DAC for holdover voltage value) MAN_DAC = 512 (Approximately Vcc/2) DISABLE_DLD1_DET = 0 (Use PLL1 DLD = Low to start holdover) 9.2.2.6 Device Programming The CodeLoader software is used to program the LMK04906 evaluation board using the LMK04906 profile. It also allows the exporting of a register map which can be used to program the device to the user's desired configuration. Once a configuration of dividers has been achieved using the Clock Design Tool to meet the requested input/output frequencies with the desired performance, the CodeLoader software is manually updated with this information to meet the required application. At this time no automatic import exists. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 107 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Typical Application (continued) 9.2.3 Application Curve -130 VCO CLKoutX VCXO CLKout6/7/8/9 VCXO OSCout0/1 VCXO Direct Phase Noise (dBc/Hz) -135 -140 -145 -150 -155 -160 -165 -170 1k 10k 100k 1M Frequency Offset (Hz) 10M D001 Figure 38. LVPECL Phase Noise, 122.88 MHz Illustration of Different Performance Depending on Signal Path. 9.3 System Examples 9.3.1 System Level Diagram Figure 39 and Figure 40 show an LMK04906 family device with external circuitry for clocking and for power supply to serve as a guideline for good practices when designing with the LMK04906 family. See Pin Connection Recommendations for more details on the pin connections and bypassing recommendations. Also refer to the evaluation board. PCB design will also play a role in device performance. 108 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 System Examples (continued) Status_CLKin0 240: Status_CLKin1 CLKout0*, 1* Status_HOLDOVER To Host processor 0.1 PF CLKout0, 1 Status_LD 0.1 PF SYNC 2x LVPECL output clocks to DAC 240: LEuWire CLKuWire 240: DATAuWire 0.1 PF CLKout2, 3 0.1 PF CLKout2*,3* CLKin0 0.1 PF CLKin0* Recovered Reference Clocks 50: 2x LVPECL output clocks to ADC 240: 0.1 PF CLKin1 LMK04906 0.1 PF CLKout4 CLKout4 active at startup CLKout4* 100: CLKin1* LVDS clock to FPGAs or microcontroller 0.1 PF CLKin2 0.1 PF 100: CLKin2* 0.1 PF Rterm LVDS Low Frequency System Synchronization Clock CLKout5 CLKout5* OSCin 0.1 PF OSCin* 0.1 PF 240: LDObyp1 0.1 PF OSCout0 LDObyp2 OSCout0* CPout2 0.1 PF CPout1 0.1 PF 10 PF LVPECL OSCout clocks to PLL references 240: OSCout0 on at startup PLL1 Loop Filter Up to 7 total differential clocks PLL2 External Loop Filter Figure 39. Example Application - System Schematic Except for Power Figure 39 shows the primary reference clock input is at CLKin0/0*. A secondary reference clock is driving CLKin1/1*. Both clocks are depicted as AC coupled differential drivers. The VCXO attached to the OSCin/OSCin* port is configured as an AC coupled single-ended driver. Any of the input ports (CLKin0/0*, CLKin1/1*, CLKin2/2*or OSCin/OSCin*) may be configured as either differential or single-ended. These options are discussed later in the data sheet. See Loop Filter for more information on PLL1 and PLL2 loop filters. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 109 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com System Examples (continued) The clock outputs are all AC coupled with 0.1 F capacitors. Some clock outputs are depicted as LVPECL with 240 emitter resistors and some clock outputs as LVDS. However, the output format of the clock outputs will vary by user programming, so the user should use the appropriate source termination for each clock output. Later sections of this data sheet illustrate alternative methods for AC coupling, DC coupling and terminating the clock outputs. PCB design will influence crosstalk performance. Tightly coupled clock traces will have less crosstalk than loosely coupled clock traces. Also proximity to other clocks traces will influence crosstalk. PLL Supply Plane Vcc1 FB Vcc4 Vcc5 10 PF, 1 PF, 0.1 PF 1 PF, 0.1 PF, 10 nF Vcc7 Vcc9 LDO LP3878-ADJ Vcc6 FB 0.1 PF 0.1 PF Digital CLKin/OSCout1 OSCin/OSCout0/ PLL2 Circuitry PLL2 N Divider PLL1 CP 0.1 PF PLL2 CP FB FB = Ferrite bead VCO LDO 0.1 PF Vcc8 LMK04906 Clock Supply Plane FB FB 10 PF, 1 PF, 0.1 PF FB Vcc13 Vcc2 Vcc3 FB Vcc10 Vcc11 Vcc12 CLKout0 CLKout1 CLKout2 CLKout3 CLKout4 CLKout5 Figure 40. Example Application - Power System Schematic Figure 40 shows an example decouping and bypassing scheme for the LMK04906. Components drawn in dotted lines are optional. Two power planes are used in this design, one for the clock outputs and one for other PLL circuits. PCB design will influence impedance to the supply. Vias and traces will increase the impedance to the power supply. Ensure good direct return current paths. 110 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 9.4 Do's and Don'ts 9.4.1 LVCMOS Complementary vs. Non-Complementary Operation * * * It is recommended to use a complementary LVCMOS output format such as LVCMOS (Norm/Inv) to reduce switching noise and crosstalk when using LVCMOS. If only a single LVCMOS output is required, the complementary LVCMOS output format can still be used by leaving the unused LVCMOS output floating. A non-complimentary format such as LVCMOS (Norm/Norm) is not recommended as increased switching noise is present. 9.4.2 LVPECL Outputs When using an LVPECL output it is not recommended to place a capacitor to ground on the output as might be done when using a capacitor input LC lowpass filter. The capacitor will appear as a short to the LVPECL output drivers which are able to supply large amounts of switching current. The effect of the LVPECL sourcing large switching currents can result in: 1. Large switching currents through the Vcc pin of the LVPECL power supply resulting in more Vcc noise and possible Vcc spikes. 2. Large switching currents injected into the ground plane through the capacitor which could couple onto other Vcc pins with bypass capacitors to ground resulting in more Vcc noise and possible Vcc spikes. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 111 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 10 Power Supply Recommendations 10.1 Pin Connection Recommendations 10.1.1 Vcc Pins and Decoupling All Vcc pins must always be connected. Integrated capacitance on the LMK04906 makes external high frequency decoupling capacitors ( 1 nF) unnecessary. The internal capacitance is more effective at filtering high frequency noise than off device bypass capacitance because there is no bond wire inductance between the LMK04906 circuit and the bypass capacitor. 10.1.1.1 Vcc2, Vcc3, Vcc10, Vcc11, Vcc12, Vcc13 (CLKout Vccs) Each of these pins has an internal 200 pF of capacitance. Ferrite beads may be used to reduce crosstalk between different clock output frequencies on the same LMK04906 device. Ferrite beads placed between the power supply and a clock Vcc pin will reduce noise between the Vcc pin and the power supply. When several output clocks share the same frequency a single ferrite bead can be used between the power supply and each same frequency CLKout Vcc pin. When using ferrite beads on CLKout Vcc pins, care must be taken to ensure the power supply can source the needed switching current. * In most cases a ferrite bead may be placed and the internal capacitance is sufficient. * If a ferrite bead is used with a low frequency output (typically 10 MHz) and a high current switching clock output format such as non-complementary LVCMOS or high swing LVPECL is used, then... - the ferrite bead can be removed to the lower impedance to the main power supply and bypass capacitors, or - localized capacitance can be placed between the ferrite bead and Vcc pin to support the switching current. - Note that decoupling capacitors used between the ferrite bead and a CLKout Vcc pin can permit high frequency switching noise to couple through the capacitors into the ground plane and onto other CLKout Vcc pins with decoupling capacitors. This can degrade crosstalk performance. 10.1.1.2 Vcc1 (VCO), Vcc4 (Digital), and Vcc9 (PLL2) Each of these pins has internal bypass capacitance. Ferrite beads should not be used between these pins and the power supply/large bypass capacitors because these Vcc pins don't produce much noise or a ferrite bead can cause phase noise disturbances and resonances. The typical application diagram in Figure 40 shows all these Vccs connected to together to Vcc without a ferrite bead. 10.1.1.3 Vcc6 (PLL1 Charge Pump) and Vcc8 (PLL2 Charge Pump) Each of these pins has an internal bypass capacitor. Use of a ferrite bead between the power supply/large bypass capacitors and PLL1 is optional. PLL1 charge pump can be connected directly to Vcc along with Vcc1, Vcc4, and Vcc9. Depending on the application, a 0.1 uF capacitor may be placed close to PLL1 charge pump Vcc pin. A ferrite bead should be placed between the power supply/large bypass capacitors and Vcc8. Most applications have high PLL2 phase detector frequencies and (> 50 MHz) such that the internal bypassing is sufficient and a ferrite bead can be used to isolate this switching noise from other circuits. For lower phase detector frequencies a ferrite bead is optional and depending on application a 0.1 uF capacitor may be added on Vcc8. 10.1.1.4 Vcc5 (CLKin), Vcc7 (OSCin & OSCout0) Each of these pins has an internal 100 pF of capacitance. No ferrite bead should be placed between the power supply/large bypass capacitors and Vcc5 or Vcc7. These pins are unique since they supply an output clock and other circuitry. Vcc5 supplies CLKin. 112 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Pin Connection Recommendations (continued) Vcc7 supplies OSCin, OSCout0, and PLL2 circuitry. 10.1.2 Unused Clock Outputs Leave unused clock outputs floating and powered down. 10.1.3 Unused Clock Inputs Unused clock inputs can be left floating. 10.1.4 LDO Bypass The LDObyp1 and LDObyp2 pins should be connected to GND through external capacitors, as shown in the diagram. 10.2 Current Consumption and Power Dissipation Calculations From Table 118 the current consumption can be calculated for any configuration. For example, the current for the entire device with 1 LVDS (CLKout0) and 1 LVPECL 1.6 Vpp /w 240 ohm emitter resistors (CLKout1) output active with a clock output divide = 1, and no other features enabled can be calculated by adding up the following blocks: core current, clock buffer, one LVDS output buffer current, and one LVPECL output buffer current. There will also be one LVPECL output drawing emitter current, which means some of the power from the current draw of the device is dissipated in the external emitter resistors which doesn't add to the power dissipation budget for the device but is important for LDO ICC calculations. For total current consumption of the device, add up the significant functional blocks. In this example, 228.1 mA = * 140 mA (core current) * 17.3 mA (base clock distribution) * 25.5 mA (CLKout0 & 1 divider) * 14.3 mA (LVDS buffer) * 31 mA (LVPECL 1.6 Vpp buffer /w 240 ohm emitter resistors) Once total current consumption has been calculated, power dissipated by the device can be calculated. The power dissipation of the device is equation to the total current entering the device multiplied by the voltage at the device minus the power dissipated in any emitter resistors connected to any of the LVPECL outputs. If no emitter resistors are connected to the LVPECL outputs, this power will be 0 watts. Continuing the above example which has 228.1 mA total Icc and one output with 240 ohm emitter resitors. Total IC power = 717.7 mW = 3.3 V * 228.1 mA - 35 mW. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 113 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Current Consumption and Power Dissipation Calculations (continued) Table 118. Typical Current Consumption for Selected Functional Blocks (TA = 25 C, VCC = 3.3 V) BLOCK TYPICAL ICC (mA) CONDITION POWER POWER DISSIPATE DISSIPATE D D IN EXTERNAL DEVICE LY (1) (mW) (mW) CORE AND FUNCTIONAL BLOCKS Core MODE = 0: Dual Loop, Internal VCO PLL1 and PLL2 locked 140 462 -- MODE = 2: Dual Loop, Internal VCO, 0-Delay PLL1 and PLL2 locked; Includes EN_FEEDBACK_MUX = 1 155 512 -- MODE = 3: Dual Loop, External VCO PLL1 and PLL2 locked 127 419 -- MODE = 5: Dual Loop, External VCO, PLL1 and PLL2 locked; Includes 0-Delay EN_FEEDBACK_MUX = 1 142 469 -- MODE = 6: Single Loop (PLL2), Internal VCO PLL2 locked 116 383 -- MODE = 11: Single Loop (PLL2), External VCO PLL2 locked 103 340 -- PD_OSCin = 0 42 139 -- PD_OSCin = 1 34.5 114 -- 2 6.6 -- 17.3 57.1 -- MODE = 16: Clock Distribution EN_TRACK Tracking is enabled (EN_TRACK = 1) Base Clock Distribution At least 1 CLKoutX_PD = 0 CLKout Outputs Each CLKout Output 2.8 9.2 -- Clock Divider/ Digital Delay When a clock output is enabled, this contributes the divider/delay block 25.5 84.1 -- Divider / digital delay in extended mode 29.6 97.7 -- VCO Divider VCO Divider current 7.7 25.4 -- HOLDOVER mode When in holdover mode 2.2 7.2 -- Feedback Mux Feedback mux must be enabled for 0-delay modes and digital delay mode (SYNC_QUAL = 1) 4.9 16.1 -- SYNC Asserted While SYNC is asserted, this extra current is drawn 1.7 5.6 -- EN_SYNC = 1 Required for SYNC functionality. May be turned off once SYNC is complete to save power. 6 19.8 -- SYNC_QUAL = 1 Delay enabled, delay > 7 (CLKout_MUX = 2, 3) 8.7 28.7 -- XTAL_LVL = 0 1.8 5.9 -- XTAL_LVL = 1 2.7 9 -- XTAL_LVL = 2 3.6 12 -- XTAL_LVL = 3 4.5 15 -- 2.8 9.2 -- CLKoutX_ANLG_DLY = 0 to 3 3.4 11.2 -- CLKoutX_ANLG_DLY = 4 to 7 3.8 12.5 -- CLKoutX_ANLG_DLY = 8 to 11 4.2 13.9 -- CLKoutX_ANLG_DLY = 12 to 15 4.7 15.5 -- CLKoutX_ANLG_DLY = 16 to 23 5.2 17.2 -- 2.8 9.2 -- Crystal Mode Enabling the Crystal Oscillator OSCin Doubler EN_PLL2_REF_2X = 1 Analog Delay Value Analog Delay Clock Output Has Analog Delay Selected. Example: CLKout0_ADLY_SEL = 1 (1) 114 Power is dissipated externally in LVPECL emitter resistors. The externally dissipated power is calculated as twice the DC voltage level of one LVPECL clock output pin squared over the emitter resistance. That is to say power dissipated in emitter resistors = 2 * Vem2 / Rem. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 Current Consumption and Power Dissipation Calculations (continued) Table 118. Typical Current Consumption for Selected Functional Blocks (TA = 25 C, VCC = 3.3 V) (continued) BLOCK TYPICAL ICC (mA) CONDITION POWER POWER DISSIPATE DISSIPATE D D IN EXTERNAL DEVICE LY (1) (mW) (mW) CLOCK OUTPUT BUFFERS LVDS LVPECL LVCMOS 100- differential termination 14.3 47.2 -- LVPECL 2.0 Vpp, AC coupled using 240- emitter resistors 32 70.6 35 LVPECL 1.6 Vpp, AC coupled using 240- emitter resistors 31 67.3 35 LVPECL 1.6 Vpp, AC coupled using 120- emitter resistors 46 91.8 60 LVPECL 1.2 Vpp, AC coupled using 240- emitter resistors 30 59 40 LVPECL 0.7 Vpp, AC coupled using 240- emitter resistors 29 55.7 40 LVCMOS Pair (CLKoutX_TYPE = 6 to 9) CL = 5 pF 3 MHz 24 79.2 -- 30 MHz 26.5 87.5 -- 150 MHz 36.5 120.5 -- LVCMOS Single (CLKoutX_TYPE = 10 to 13) CL = 5 pF 3 MHz 15 49.5 -- 30 MHz 16 52.8 -- 150 MHz 21.5 71 -- 11 Layout 11.1 Layout Guidelines Power consumption of the LMK04906 can be high enough to require attention to thermal management. For reliability and performance reasons the die temperature should be limited to a maximum of 125C. That is, as an estimate, TA (ambient temperature) plus device power consumption times JA should not exceed 125C. The package of the device has an exposed pad that provides the primary heat removal path as well as excellent electrical grounding to a printed circuit board. To maximize the removal of heat from the package a thermal land pattern including multiple vias to a ground plane must be incorporated on the PCB within the footprint of the package. The exposed pad must be soldered down to ensure adequate heat conduction out of the package. A recommended land and via pattern is shown in Figure 41. More information on soldering WQFN packages can be obtained: http://www.ti.com/packaging. To minimize junction temperature it is recommended that a simple heat sink be built into the PCB (if the ground plane layer is not exposed). This is done by including a copper area of about 2 square inches on the opposite side of the PCB from the device. This copper area may be plated or solder coated to prevent corrosion but should not have conformal coating (if possible), which could provide thermal insulation. The vias shown in Figure 41 should connect these top and bottom copper layers and to the ground layer. These vias act as "heat pipes" to carry the thermal energy away from the device side of the board to where it can be more effectively dissipated. Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 115 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com Layout Guidelines (continued) 7.2 mm 0.2 mm 1.46 mm 1.15 mm Figure 41. Recommended Land and Via Pattern 116 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 LMK04906 www.ti.com SNAS589F - JUNE 2012 - REVISED AUGUST 2017 11.2 Layout Example CLKin and OSCin path if differential input (preferred) route trace tightly coupled like clock outputs. If single ended, have at least 3 trace width (of CLKin/OSCin trace) separation from other RF traces. Example shown is hybrid for both differential and single ended not tightly couple to compromise for both configurations. RF Terminations should be placed as close to IC as possible. When using CLKin1 for high frequency input for external VCO or distribution, a 3 dB pi pad is suggested for termination. )RU &/.RXW 9FFV SODFH IHUULWH EHDGV RQ WRS OD\HU FORVH WR SLQV WR FKRNH high frequency noise from via. Charge pump output shorter traces are better. Place all resistors and caps closer to IC except for a single capacitor next to VCXO. In a 2nd order filter place C1 close to VCXO Vtune pin. In a 3rd and 4th order filter place C3 or C4 respectively close to VCXO. Clock outputs differential signals, should be routed tightly coupled to minimize PCB crosstalk. Trace impedance and terminations should be designed according to output type being used (i.e. LVDS, LVPECL...) Figure 42. LMK04906 Layout Example Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 117 LMK04906 SNAS589F - JUNE 2012 - REVISED AUGUST 2017 www.ti.com 12 Device and Documentation Support 12.1 Device Support * * * * Clock Design Tool Clock Architect Packaging Information Clock and Timing 12.2 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper right corner, click on Alert me to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 12.3 Community Resource The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2ETM Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 12.4 Trademarks PLLatinum, E2E are trademarks of Texas Instruments. All other trademarks are the property of their respective owners. 12.5 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 12.6 Glossary SLYZ022 -- TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 118 Submit Documentation Feedback Copyright (c) 2012-2017, Texas Instruments Incorporated Product Folder Links: LMK04906 PACKAGE OPTION ADDENDUM www.ti.com 26-Jan-2016 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LMK04906BISQ/NOPB ACTIVE WQFN NKD 64 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K04906BISQ LMK04906BISQE/NOPB ACTIVE WQFN NKD 64 250 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K04906BISQ LMK04906BISQX/NOPB ACTIVE WQFN NKD 64 2000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K04906BISQ (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 26-Jan-2016 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 13-Aug-2017 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LMK04906BISQ/NOPB WQFN NKD 64 LMK04906BISQE/NOPB WQFN NKD LMK04906BISQX/NOPB WQFN NKD SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 330.0 16.4 9.3 9.3 1.3 12.0 16.0 Q1 64 250 178.0 16.4 9.3 9.3 1.3 12.0 16.0 Q1 64 2000 330.0 16.4 9.3 9.3 1.3 12.0 16.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 13-Aug-2017 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMK04906BISQ/NOPB WQFN NKD 64 1000 367.0 367.0 38.0 LMK04906BISQE/NOPB WQFN NKD 64 250 210.0 185.0 35.0 LMK04906BISQX/NOPB WQFN NKD 64 2000 367.0 367.0 38.0 Pack Materials-Page 2 PACKAGE OUTLINE NKD0064A WQFN - 0.8 mm max height SCALE 1.600 WQFN 9.1 8.9 B A PIN 1 INDEX AREA 0.5 0.3 9.1 8.9 0.3 0.2 DETAIL OPTIONAL TERMINAL TYPICAL 0.8 MAX C SEATING PLANE (0.1) TYP 7.2 0.1 SEE TERMINAL DETAIL 32 17 60X 0.5 33 16 4X 7.5 1 PIN 1 ID (OPTIONAL) 48 64 49 64X 0.5 0.3 64X 0.3 0.2 0.1 0.05 C A C B 4214996/A 08/2013 NOTES: 1. All linear dimensions are in millimeters. Dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT NKD0064A WQFN - 0.8 mm max height WQFN ( 7.2) SYMM 64X (0.6) 64X (0.25) 64 SEE DETAILS 49 1 48 60X (0.5) SYMM (8.8) (1.36) TYP ( 0.2) VIA TYP 8X (1.31) 16 33 32 17 (1.36) TYP 8X (1.31) (8.8) LAND PATTERN EXAMPLE SCALE:8X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND METAL SOLDER MASK OPENING SOLDER MASK OPENING NON SOLDER MASK DEFINED (PREFERRED) METAL SOLDER MASK DEFINED SOLDER MASK DETAILS 4214996/A 08/2013 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, refer to QFN/SON PCB application note in literature No. SLUA271 (www.ti.com/lit/slua271). www.ti.com EXAMPLE STENCIL DESIGN NKD0064A WQFN - 0.8 mm max height WQFN SYMM 64X (0.6) 64X (0.25) (1.36) TYP 64 49 1 48 (1.36) TYP 60X (0.5) SYMM (8.8) METAL TYP 33 16 32 17 25X (1.16) (8.8) SOLDERPASTE EXAMPLE BASED ON 0.125mm THICK STENCIL EXPOSED PAD 65% PRINTED SOLDER COVERAGE BY AREA SCALE:10X 4214996/A 08/2013 NOTES: (continued) 5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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