SY58608U 3.2Gbps Precision, 1:2 LVDS Fanout Buffer with Internal Termination and Fail Safe Input General Description Features The SY58608U is a 2.5V, high-speed, fully differential 1:2 LVDS fanout buffer optimized to provide two identical output copies with less than 20ps of skew and 130fsRMS typical additive phase jitter. The SY58608U can process clock signals as fast as 2GHz or data patterns up to 3.2Gbps. The differential input includes Micrel's unique, 3-pin input termination architecture that interfaces to LVPECL, LVDS or CML differential signals, (AC- or DC-coupled) as small as 100mV (200mVPP) without any level-shifting or termination resistor networks in the signal path. For AC-coupled input interface applications, an integrated voltage reference (VREF-AC) is provided to bias the VT pin. The outputs are 325mV LVDS, with rise/fall times guaranteed to be less than 100ps. The SY58608U operates from a 2.5V 5% supply and is guaranteed over the full industrial temperature range (- 40C to +85C). For applications that require CML or LVPECL outputs, consider Micrel's SY58606U and SY58607U, 1:2 fanout buffers with 400mV and 800mV output swings respectively. The SY58608U is part of Micrel's high-speed, Precision Edge(R) product line. Data sheets and support documentation can be found on Micrel's web site at: www.micrel.com. * Precision 1:2, 325mV LVDS fanout buffer * Guaranteed AC performance over temperature and voltage: - DC-to > 3.2Gbps throughput - <300ps propagation delay (IN-to-Q) - <20ps within-device skew - <100ps rise/fall times * Fail Safe Input - Prevents outputs from oscillating when input is invalid * Ultra-low jitter design - 130fsRMS typical additive phase jitter - High-speed LVDS outputs * 2.5V 5% power supply operation * Industrial temperature range: -40C to +85C * Available in 16-pin (3mm x 3mm) QFN package Functional Block Diagram Applications * * * * All SONET clock and data distribution Fibre Channel clock and data distribution Gigabit Ethernet clock and data distribution Backplane distribution Markets * * * * * DataCom Telecom Storage ATE Test and Measurement Precision Edge is a registered trademark of Micrel, Inc. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com May 29, 2014 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Ordering Information(1) Part Number Package Type Operating Range Package Marking Lead Finish SY58608UMG QFN-16 Industrial 608U with Pb-Free bar-line indicator NiPdAu Pb-Free SY58608UMGTR(2) QFN-16 Industrial 608U with Pb-Free bar-line indicator NiPdAu Pb-Free Notes: 1. Contact factory for die availability. Dice are guaranteed at TA = 25C, DC Electricals only. 2. Tape and Reel. Pin Configuration 16-Pin QFN Pin Description Pin Number Pin Name 1, 4 IN, /IN 2 VT 3 VREF-AC 5, 8,13, 16 VCC 6, 7, 14, 15 GND, Exposed pad 9, 10 /Q1, Q1 11, 12 /Q0, Q0 May 29, 2014 Pin Function Differential Inputs: This input pair is the differential signal input to the device. Input accepts DC-coupled differential signals as small as 100mV (200mVPP). Each pin of this pair internally terminates with 50 to the VT pin. If the input swing falls below a certain threshold (typical 30mV), the Fail Safe Input (FSI) feature will guarantee a stable output by latching the outputs to its last valid state. See "Input Interface Applications" section for more details. Input Termination Center-Tap: Each input terminates to this pin. The VT pin provides a center-tap for each input (IN, /IN) to a termination network for maximum interface flexibility. See "Input Interface Applications" section. Reference Voltage: This output bias to VCC-1.2V. It is used for AC-coupling inputs IN and /IN. Connect VREF-AC directly to the VT pin. Bypass with 0.01F low ESR capacitor to VCC. Maximum sink/source current is 1.5mA. See "Input Interface Applications" section for more details. Positive Power Supply: Bypass with 0.1F//0.01F low ESR capacitors as close to the VCC pins as possible. Ground. Exposed pad must be connected to a ground plane that is the same potential as the ground pin. LVDS Differential Output Pairs: Differential buffered output copy of the input signal. The output swing is typically 325mV. Normally terminated 100 across the output pairs (Q and /Q). See "LVDS Output Termination" section. 2 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Absolute Maximum Ratings(3) Operating Ratings(4) Supply Voltage (VCC) ............................... -0.5V to +4.0V Input Voltage (VIN) ............................ -0.5V to VCC +0.3V LVDS Output Current (IOUT) .................................. 10mA Input Current Source or Sink Current on (IN, /IN) ............... 50mA Current (VREF) Source or sink current on VREF-AC(6) ............... 1.5mA Maximum Operating Junction Temperature .......... 125C Lead Temperature (soldering, 20sec.) .................. 260C Storage Temperature (Ts) .................... -65C to +150C Supply Voltage (VIN) ...................... +2.375V to +2.635V Ambient Temperature (TA) ................... -40C to +85C Package Thermal Resistance(5) QFN Still-air (JA) ........................................... 60C/W Junction-to-board (JB) ......................... 33C/W DC Electrical Characteristics(7) TA = -40C to +85C, unless otherwise stated. Symbol Parameter Condition Min Typ Max Units VCC Power Supply Voltage Range 2.375 2.5 2.625 V ICC Power Supply Current RDIFF_IN Differential Input Resistance (IN-to-/IN) 55 75 mA 90 100 110 VIH Input HIGH Voltage (IN, /IN) IN, /IN 1.2 VCC V VIL Input LOW Voltage (IN, /IN) IN, /IN 0 VIH-0.1 V VIN Input Voltage Swing (IN, /IN) see Figure 4, Note 8 0.1 1.7 V VDIFF_IN Differential Input Voltage Swing (|IN - /IN|) see Figure 6 0.2 VIN_FSI Input Voltage Threshold that Triggers FSI VREF-AC Output Reference Voltage IN to VT Voltage from Input to VT No load, max. VCC VCC-1.3 V 30 100 mV VCC-1.2 VCC-1.1 V 1.28 V Notes: 3. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum ratings conditions for extended periods may affect device reliability. 4. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. 5. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the device's most negative potential on the PCB. JB and JA values are determined for a 4-layer board in still-air number, unless otherwise stated. 6. Due to the limited drive capability, use for input of the same package only. 7. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. 8. VIN (max) is specified when VT is floating. May 29, 2014 3 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U LVDS Outputs DC Electrical Characteristics(9) VCC = +2.5V 5%, RL = 100 across the output pairs; TA = -40C to +85C, unless otherwise stated. Symbol Parameter Condition Min Typ VOUT Output Voltage Swing See Figure 4, 5 250 325 Max Units mV VDIFF_OUT Differential Output Voltage Swing See Figure 6 500 650 mV VOCM Output Common Mode Voltage See Figure 7 1.125 1.20 VOCM Change in Common Mode Voltage See Figure 7 -50 1.275 V 50 mV Notes: 9. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. May 29, 2014 4 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U AC Electrical Characteristics(10) VCC = +2.5V 5%, RL = 100 across the output pairs, Input tr/tf: 300ps; TA = -40C to +85C, unless otherwise stated. Symbol Parameter fMAX Maximum Frequency tPD Propagation Delay tSkew Condition Min Typ NRZ Data 3.2 4.25 Gbps 2 3 GHz VIN: 100mV-200mV 170 280 420 ps VIN: 200mV-800mV 130 200 300 ps 5 20 ps 135 ps VOUT > 200mV IN-to-Q Within Device Skew Note 11 Part-to-Part Skew Note 12 Clock Carrier = 622MHz tJitter Additive Phase Jitter tr, tf Output Rise/Fall Time (20% to 80%) At full output swing. 35 Duty Cycle Differential I/O 47 Max 130 Integration Range: 12kHz - 20MHz 60 Units fsRMS 100 ps 53 % Notes: 10. These high-speed parameters are guaranteed by design and characterization. 11. Within-device skew is measured between two different outputs under identical input transitions. 12. Part-to-part skew is defined for two parts with identical power supply voltages at the same temperature and no skew at the edges at the respective inputs. May 29, 2014 5 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Input Clock Failure Case If the input clock fails to a floating, static, or extremely low signal swing such that the differential voltage across the input pair is less than 100mV, the FSI function will eliminate a metastable condition and latch the outputs to the last valid state. No ringing and no indeterminate state will occur at the output under these conditions. The output recovers to normal operation once the input signal returns to a valid state with a differential voltage 100mV. Note that the FSI function will not prevent duty cycle distortion in case of a slowly deteriorating (but still toggling) input signal. Due to the FSI function, the propagation delay will depend on rise and fall time of the input signal and on its amplitude. Refer to "Typical Characteristics" for detailed information. Functional Description Fail-Safe Input (FSI) The input includes a special fail-safe circuit to sense the amplitude of the input signal and to latch the outputs when there is no input signal present, or when the amplitude of the input signal drops sufficiently below 100mVPK (200mVPP), typically 30mVPK. Maximum frequency of SY58608U is limited by the FSI function. Timing Diagrams Figure 1. Propagation Delay Figure 2. Fail Safe Feature May 29, 2014 6 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. May 29, 2014 SY58608U 7 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Typical Characteristics VCC = 2.5V, GND = 0V, VIN = 100mV, RL = 100 across the output pairs, TA = 25C, unless otherwise stated. May 29, 2014 8 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Functional Characteristics VCC = 2.5V, GND = 0V, VIN = 250mV, Data Pattern: 223-1, RL = 100 across the outputs, TA = 25C, unless otherwise stated. May 29, 2014 9 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Functional Characteristics (continued) VCC = 2.5V, GND = 0V, VIN = 250mV, RL = 100 across the outputs, TA = 25C, unless otherwise stated. May 29, 2014 10 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Additive Phase Noise Plot VCC = +3.3V, TA = 25C May 29, 2014 11 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Input Stage Figure 3. Simplified Differential Input Buffer May 29, 2014 Figure 4. Single-Ended Swing Figure 5. LVDS Differential Measurement Figure 6. Differential Swing Figure 7. LVDS Common Mode Measurement 12 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Input Interface Applications Figure 8. CML Interface (DC-Coupled) Figure 11. LVPECL Interface (AC-Coupled) May 29, 2014 Figure 9. CML Interface (AC-Coupled) Figure 10. LVPECL Interface (DC-Coupled) Figure 12. LVDS Interface (DC-Coupled) 13 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY58608U Package Information 16-Pin (3mm x 3mm) QFN MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2006 Micrel, Incorporated. May 29, 2014 14 M9999-052914-A hbwhelp@micrel.com or (408) 955-1690