Product Folder Order Now Support & Community Tools & Software Technical Documents LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 LM48511 3-W, Ultra-Low EMI, Filterless, Mono, Class D Audio Power Amplifier With Spread Spectrum 1 Features * * * * 1 * * * * * * 3-W Output into 8 at 5 V With THD+N = 1% Selectable Spread Spectrum Mode Reduces EMI 80% Efficiency Independent Regulator and Amplifier Shutdown Controls Dynamically Selectable Regulator Output Voltages Filterless Class D 3-V to 5.5-V Operation Low Shutdown Current Click and Pop Suppression Key Specifications - Quiescent Power Supply Current - VDD = 3 V 9 mA (Typical) - VDD = 5 V 13.5 mA (Typical) - PO at VDD = 5 V, PV1 = 7.8 V, RL = 8 , THD+N = 1% 3 W (Typical) - PO at VDD = 3 V, PV1 = 4.8 V, RL = 8 , THD+N = 1% 1 W (Typical) - PO at VDD = 5 V, PV1 = 7.8 V, RL = 4 , THD+N = 1% 5.4 W (Typical) - Shutdown Current at VDD = 3 V, 0.01 A (Typical) 2 Applications * * * * * GPS Portable media Cameras Mobile Phones Handheld games 3 Description The switching regulator of the LM48511 is a currentmode boost converter operating at a fixed frequency of 1 MHz. Two selectable feedback networks allow the LM48511 regulator to dynamically switch between two different output voltages, improving efficiency by optimizing the amplifier's supply voltage based on battery voltage and output power requirements. The LM48511 is designed for use in portable devices, such as GPS, mobile phones, and MP3 players. The high, 80% efficiency at 5 V, extends battery life when compared to Boosted Class AB amplifiers. Independent regulator and amplifier shutdown controls optimize power savings by disabling the regulator when high-output power is not required. The gain of the LM48511 is set by external resistors, which allows independent gain control from multiple sources by summing the signals. Output short circuit and thermal overload protection prevent the device from damage during fault conditions. Superior click and pop suppression eliminates audible transients during power-up and shutdown. Device Information(1) PART NUMBER LM48511 PACKAGE WQFN (24) BODY SIZE (NOM) 5.00 mm x 4.00 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. EMI Graph: LM48511 RF Emissions -- 3-Inch Cable 55.0 FCC Class B Limit 50.0 AMPLITUDE (dBPV/m) The LM48511 device integrates a boost converter with a high-efficiency Class D audio power amplifier to provide 3-W continuous power into an 8- speaker when operating from a 5-V power supply. When operating from a 3-V to 4-V power supply, the LM48511 can be configured to drive 1 to 2.5 W into an 8- load with less than 1% distortion (THD+N). The Class D amplifier features a low-noise PWM architecture that eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design. A selectable spread spectrum modulation scheme suppresses RF emissions, further reducing the need for output filters. 45.0 40.0 LM45811 EMI Spectrum 35.0 30.0 25.0 20.0 30.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 FREQUENCY (MHz) 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. LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 4 5 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 5 5 5 5 6 7 8 9 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics VDD = 5 V.......................... Electrical Characteristics VDD = 3.6 V....................... Electrical Characteristics VDD = 3 V.......................... Typical Characteristics .............................................. Detailed Description ............................................ 13 7.1 Overview ................................................................. 13 7.2 Functional Block Diagram ....................................... 13 7.3 Feature Description................................................. 14 7.4 Device Functional Modes........................................ 15 8 Application and Implementation ........................ 16 8.1 Application Information............................................ 16 8.2 Typical Application ................................................. 16 9 Power Supply Recommendations...................... 22 10 Layout................................................................... 22 10.1 Layout Guidelines ................................................. 22 10.2 Layout Example .................................................... 22 11 Device and Documentation Support ................. 23 11.1 11.2 11.3 11.4 11.5 Receiving Notification of Documentation Updates Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 23 23 23 23 23 12 Mechanical, Packaging, and Orderable Information ........................................................... 23 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision I (August 2017) to Revision J Page * Changed Pin 20 From: FB_GND0 To: FB_GND1 in the Pin Image and Pin Functions table................................................ 4 * Changed Pin 21 From: FB_GND1 To: FB_GND0 in the Pin Image and Pin Functions table................................................ 4 Changes from Revision H (August 2015) to Revision I Page * Changed Pin 20 From: FB_GND1 To: FB_GND0 in the Pin Image and Pin Functions table................................................ 4 * Changed Pin 21 From: FB_GND0 To: FB_GND1 in the Pin Image and Pin Functions table................................................ 4 Changes from Revision G (May 2013) to Revision H * Added Pin Configuration and Functions section, 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 Changes from Revision F (October 2012) to Revision G * 2 Page Deleted the Typical limits (Vih and Vil) EC table.................................................................................................................... 6 Changes from Revision C (November 2007) to Revision D * Page Changed layout of National Data Sheet to TI format ........................................................................................................... 20 Changes from Revision D (February 2012) to Revision E * Page Page Deleted the "Build of Materials" (BOM) table........................................................................................................................ 20 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 Changes from Revision B (September 2007) to Revision C * Page Edited the Notes section and added another PO (@VDD = 5 V, RL = 4 ) section in the Key Specification division. ............ 1 Changes from Revision A (July 2007) to Revision B * Page Changed the Amplifier Voltage (Operating Ratings section) from 5 V to 4.8 V. .................................................................... 5 Changes from Original (July 2007) to Revision A * Page Input some text edits .............................................................................................................................................................. 1 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 3 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 5 Pin Configuration and Functions REGGND FB_GND0 FB_GND1 24 REGGND SD_BOOST NHZ Package 24-Pin WQFN Top View 23 22 21 20 18 VDD 3 17 VGO- SOFTSTART 4 16 IN+ SD_AMP 5 15 IN- SS/FF 6 14 VGO+ GND 7 13 V1 8 9 10 11 12 LS- 2 SW LSGND SW PV1 19 FB LSGND 1 LS+ FB_SEL Pin Functions PIN NAME NO. I/O DESCRIPTION DAP - -- To be soldered to board for enhanced thermal dissipation. Connect to GND plane. FB 19 -- Regulator feedback input Connect FB to an external resistive voltage divider to set the boost output voltage. FB_GND0 21 -- Ground return for R3, R1 resistor divider FB_GND1 20 -- Ground return for R3, R2 resistor divider FB_SEL 1 I GND 7 -- IN- 15 I Amplifier inverting input IN+ 16 I Amplifier noninverting input LS+ 8 O Amplifier noninverting output LS- 12 O Amplifier inverting output 9, 11 -- Amplifier H-Bridge ground 10 -- Amplifier H-Bridge power supply Connect to V1. REGGND 22, 23 -- Power ground (booster) SD_AMP 5 I Amplifier active-low shutdown Connect to VDD for normal operation. Connect to GND to disable amplifier. SD_BOOST 24 I Regulator active-low shutdown. Connect to VDD for normal operation. Connect to GND to disable regulator. SOFT-START 4 -- SS/FF 6 I 2, 3 -- Drain of the internal FET switch 13 -- Amplifier supply voltage Connect to PV1 VDD 18 -- Power supply VG0+ 14 O Amplifier noninverting gain output VG0- 17 O Amplifier inverting gain output LSGND PV1 SW V1 4 Regulator feedback select Connect to VDD to select feedback network connected to FB_GND1. Connect to GND to select feedback network connected to FB_GND0. Signal ground Soft-start capacitor Modulation mode select. Connect to VDD for spread spectrum mode (SS). Connect to GND for fixed frequency mode (FF). Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2). MIN MAX UNIT 9 V VDD + 0.3 V Supply voltage (VDD, PV1, V1) -0.3 Input voltage Power dissipation (3) Internally limited Junction temperature 150 Storage temperature -65 (1) (2) (3) C 150 C Absolute Maximum Ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in the Recommended Operating Conditions is not implied. TheRecommended Operating Conditions indicate conditions at which the device is functional and the device must not be operated beyond such conditions. All voltages are measured with respect to the ground pin, unless otherwise specified. If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications. The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, JJA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / JA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM48511, see Figure 20 for additional information. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) 2000 Machine model (2) 200 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Machine model, applicable std. JESD22-A115-A. 6.3 Recommended Operating Conditions Temperature range TMIN TA TMAX Supply voltage (VDD) Amplifier voltage (PV1, V1) MIN MAX -40 85 UNIT C 3 5.5 V 4.8 8 V 6.4 Thermal Information LM48511 THERMAL METRIC (1) NHZ (WQFN) UNIT 24 PINS RJA Junction-to-ambient thermal resistance 32.8 C/W RJC(top) Junction-to-case (top) thermal resistance 3.8 C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 5 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 6.5 Electrical Characteristics VDD = 5 V The following specifications apply for VDD = 5 V, PV1 = 7.8 V (continuos mode), AV = 2 V/V, R3 = 25.5 k, RLS = 4.87 k, RL = 8 , f = 1 kHz, SS/FF = GND, unless otherwise specified. Limits apply for TA = 25C. (1) PARAMETER TEST CONDITIONS IDD Quiescent Power Supply VIN = 0, RLOAD = Current ISD Shutdown Current (3) VIH Logic Voltage Input High VIL Logic Voltage Input Low TWU Wake-up Time CSS = 0.1 F VOS Output Offset Voltage See PO Output Power THD+N Total Harmonic Distortion + Noise Output Noise OS PSRR Power Supply Rejection Ratio (Input Referred) 14.5 22 mA 0.11 1 mA A 1.4 V 0.4 49 (4) 0.04 RL = 8 f = 1 kHz, BW = 22 kHz THD+N = 1% FF RL = 8 f = 1 kHz, BW = 22 kHz THD+N = 10% FF 3.8 SS 3.8 RL = 4 f = 1 kHz, BW = 22 kHz THD+N = 1% FF 5.4 SS 5.4 RL = 4 f = 1 kHz, BW = 22 kHz THD+N = 10% FF 6.7 SS 6.7 PO = 2 W, f = 1 kHz, RL = 8 FF 0.03% SS 0.03% PO = 3 W, f = 1 kHz, RL = 4 FF 0.04% SS 0.05% f = 20 Hz to 20 kHz Inputs to AC GND, No weighting FF 32 SS 32 f = 20 Hz to 20 kHz Inputs to AC GND, A weighted FF 22 SS 22 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 217 Hz FF 88 SS 87 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 1 kHz FF 88 SS 85 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 10 kHz FF 77 SS 76 SS Efficiency f = 1 kHz, RL = 8 , PO = 1 W VFB Feedback Pin Reference Voltage (5) 6 UNIT Spread Spectrum Mode (SS) VSD_BOOST = VSD_AMP = SS = FB_SEL = GND VRIPPLE = 1 VP-P, fRIPPLE = 217 Hz (3) (4) (5) MAX 13.5 Common-Mode Rejection Ratio (Input Referred) (2) TYP (2) Fixed Frequency Mode (FF) CMRR (1) MIN V ms 3 mV 3 2.6 3 73 W W W W VRMS VRMS dB dB dB dB 80% 1.23 V RL is a resistive load in series with two inductors to simulate an actual speaker load for RL = 8, the load is 15H+8+15H. For RL = 4 , the load is 15 H + 4 + 15 H. Typical values represent most likely parametric norms at TA = +25C, and at the Recommended Operation Conditions at the time of product characterization and are not specified. Shutdown current is measured with components R1 and R2 removed. Offset voltage is determined by: (IDD (with load) -- IDD (no load)) x RL. Feedback pin reference voltage is measured with the Audio Amplifier disconnected from the Boost converter (the Boost converter is unloaded). Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 6.6 Electrical Characteristics VDD = 3.6 V The following specifications apply for VDD = 3.6 V, PV1 = 7 V (continuous mode), AV = 2 V/V, R3 = 25.5 k, RLS = 5.36 k, RL = 8 , f = 1 kHz, SS/FF = GND, unless otherwise specified. Limits apply for TA = 25C. (1) PARAMETER TEST CONDITIONS Quiescent Power Supply VIN = 0, RLOAD = Current IDD MIN Fixed Frequency Mode (FF) TYP (2) 16 Spread Spectrum Mode (SS) mA 0.03 1 A VIH Logic Voltage Input High 1.4 0.96 VIL Logic Voltage Input Low 0.4 0.84 TWU Wake-up Time CSS = 0.1 F VOS Output Offset Voltage See PO Output Power THD+N Total Harmonic Distortion + Noise Output Noise OS PSRR Power Supply Rejection Ratio (Input Referred) 2.5 RL = 8 , f = 1 kHz, BW = 22 kHz THD+N = 10% FF 3 SS 3 RL = 4 , f = 1 kHz, BW = 22 kHz THD+N = 1% FF 4.3 SS 4.2 RL = 4 , f = 1 kHz, BW = 22 kHz THD+N = 10% FF 5.4 SS 5.3 PO = 1.5 W, f = 1 kHz, RL = 8 FF 0.03% SS 0.03% PO = 3 W, f = 1 kHz, RL = 4 FF 0.04% SS 0.05% f = 20 Hz to 20 kHz Inputs to AC GND, No weighting FF 35 SS 36 f = 20 Hz to 20 kHz Inputs to AC GND, A weighted FF 25 SS 26 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 217 Hz FF 85 SS 86 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 1 kHz FF 87 SS 86 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 10 kHz FF 78 SS 77 Efficiency f = 1 kHz, RL = 8 , PO = 1 W VFB Feedback Pin Reference Voltage (5) (2) (3) (4) (5) mV SS (1) 0.04 2.5 VRIPPLE = 1 VP-P, fRIPPLE = 217 Hz V ms FF Common-Mode Rejection Ratio (Input Referred) V 50 RL = 8 , f = 1 kHz, BW = 22 kHz THD+N = 1% CMRR mA 26.6 Shutdown Current (3) VSD_BOOST = VSD_AMP = SS = FB_SEL = GND UNIT 17.5 ISD (4) MAX 73 W W W W VRMS VRMS dB dB dB dB 77% 1.23 V RL is a resistive load in series with two inductors to simulate an actual speaker load for RL = 8, the load is 15H+8+15H. For RL = 4 , the load is 15 H + 4 + 15 H. Typical values represent most likely parametric norms at TA = +25C, and at the Recommended Operation Conditions at the time of product characterization and are not specified. Shutdown current is measured with components R1 and R2 removed. Offset voltage is determined by: (IDD (with load) -- IDD (no load)) x RL. Feedback pin reference voltage is measured with the Audio Amplifier disconnected from the Boost converter (the Boost converter is unloaded). Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 7 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 6.7 Electrical Characteristics VDD = 3 V The following specifications apply for VDD = 3 V, PV1 = 4.8 V (continuos mode), AV = 2V/V, R3 = 25.5 k, RLS = 9.31 k, RL = 8 , f = 1 kHz, SS/FF = GND, unless otherwise specified. Limits apply for TA = 25C. (1) PARAMETER TEST CONDITIONS MIN Fixed Frequency Mode (FF) TYP (2) MAX 9 UNIT mA IDD Quiescent Power Supply VIN = 0, RLOAD = Current ISD Shutdown Current (3) VIH Logic Voltage Input High 0.91 V VIL Logic Voltage Input Low 0.79 V TWU Wake-up Time VOS Output Offset Voltage (4) PO Output Power THD+N Total Harmonic Distortion + Noise Output Noise OS PSRR Power Supply Rejection Ratio (Input Referred) Spread Spectrum Mode (SS) FF 1.3 SS 1.3 RL = 4 , f = 1 kHz, BW = 22 kHz THD+N = 1% FF 1.8 SS 1.8 RL = 4 , f = 1 kHz, BW = 22 kHz THD+N = 10% FF 2.2 SS 2.2 PO = 500 mW, f = 1 kHz, FF RL = 8 SS 0.02% PO = 500 mW, f = 1 kHz, FF RL = 4 SS 0.04% 0.84 1 SS 35 f = 20 Hz to 20 kHz Inputs to AC GND, A weighted FF 25 SS 25 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 217 Hz FF 89 SS 89 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 1 kHz FF 88 SS 88 VRIPPLE = 200 mVP-P Sine, fRIPPLE = = 10 kHz FF 78 SS 78 f = 1 kHz, RL = 8 , PO = 1 W VFB W W W 0.06% 35 Feedback Pin Reference Voltage (5) W 0.03% FF Efficiency 8 1 f = 20Hz to 20kHz Inputs to AC GND, No weighting (3) (4) (5) ms mV RL = 8 , f = 1 kHz, BW = 22 kHz THD+N = 10% VRIPPLE = 1 VP-P, fRIPPLE = 217 Hz A 49 FF SS mA 1 0.04 RL = 8 , f = 1 kHz, BW = 22 kHz THD+N = 1% Common-Mode Rejection Ratio (Input Referred) (2) 0.01 CSS = 0.1F CMRR (1) 9.5 VSD_BOOST = VSD_AMP = SS = FB_SEL = GND 71 VRMS VRMS dB dB dB dB 75% 1.23 V RL is a resistive load in series with two inductors to simulate an actual speaker load for RL = 8, the load is 15H+8+15H. For RL = 4 , the load is 15 H + 4 + 15 H. Typical values represent most likely parametric norms at TA = +25C, and at the Recommended Operation Conditions at the time of product characterization and are not specified. Shutdown current is measured with components R1 and R2 removed. Offset voltage is determined by: (IDD (with load) -- IDD (no load)) x RL. Feedback pin reference voltage is measured with the Audio Amplifier disconnected from the Boost converter (the Boost converter is unloaded). Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 10 10 1 1 FIXED FREQUENCY FIXED FREQUENCY THD+N (%) THD+N (%) 6.8 Typical Characteristics 0.1 0.1 0.01 0.01 SPREAD SPECTRUM SPREAD SPECTRUM 0.001 20 200 2k 20k 0.001 20 FREQUENCY (Hz) Figure 1. THD+N vs Frequency VDD = 5 V, RL = 8 PO = 2 W, Filter = 22 kHz, PV1 = 7.8 V 2k 20k Figure 2. THD+N vs Frequency VDD = 3.6 V, RL = 8 PO = 500 mW, Filter = 22 kHz, PV1 = 4.8 V 10 10 SPREAD SPECTRUM, CIN = 180 nF 1 1 FIXED FREQUENCY, CIN = 180 nF THD+N (%) THD+N (%) 200 FREQUENCY (Hz) 0.1 SPREAD SPECTRUM 0.1 0.01 SPREAD SPECTRUM, CIN = 1 PF FIXED FREQUENCY, CIN = 1 PF 0.001 20 200 2k 0.01 10m 20k 100m 1 5 OUTPUT POWER (W) FREQUENCY (Hz) Figure 3. THD+N vs Frequency VDD = 3 V, RL = 8 PO = 1.5 W, Filter = 22 kHz, PV1 = 7 V Figure 4. THD+N vs Output Power VDD = 5 V, RL = 8 PO = 1.5 W, f = 1 kHz, Filter = 22 kHz, PV1 = 7.8 V 10 10 1 THD+N (%) FIXED FREQUENCY 1 THD+N (%) FIXED FREQUENCY SPREAD SPECTRUM 0.1 FIXED FREQUENCY SPREAD SPECTRUM 0.1 0.01 10m 100m 1 5 0.01 10m OUTPUT POWER (W) 100m 1 5 OUTPUT POWER (W) Figure 5. THD+N vs Output Power VDD = 3.6 V, RL = 8 f = 1 kHz, Filter = 22 kHz, PV1 = 7 V Figure 6. THD+N vs Output Power VDD = 3 V, RL = 8 f = 1 kHz, Filter = 22 kHz, PV1 = 4.8 V Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 9 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com Typical Characteristics (continued) 10 10 3V 9.31 k: THD+N (%) 1 THD+N (%) 1 3.6V 5.35 k: 0.1 4.87 k: 0.1 5V 0.01 10m 100m 1 0.01 10m 5 100m OUTPUT POWER (W) Figure 8. THD+N vs Output Power VDD = 3.6 V, RL = 8 Filter = 22 kHz, PV1 = 7.8 V, PV1 = 7 V, PV1 = 4.8 V, FF 100 100 90 90 80 80 70 70 EFFICIENCY (%) EFFICIENCY (%) 5 OUTPUT POWER (W) Figure 7. THD+N vs Output Power VDD = 3 V, 3.6 V, 5 V, RL = 8 f = 1kHz, Filter = 22 kHz, R1 = 4.87 k, FF 60 50 40 30 60 50 40 30 20 20 10 10 0 1 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 4.0 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT POWER (W) OUTPUT POWER (W) Figure 9. Boost Amplifier vs Output Power VDD = 5 V, RL = 8 f = 1 kHz, PV1 = 7.8 V Figure 10. Boost Amplifier vs Output Power VDD = 3.6 V, RL = 8 f = 1 kHz, PV1 = 7 V 0 100 90 -20 70 PSRR (dB) EFFICIENCY (%) 80 60 50 40 -40 FIXED FREQUENCY -60 SPREAD SPECTRUM 30 -80 20 10 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 -100 20 2k 20k FREQUENCY (Hz) OUTPUT POWER (W) Figure 11. Boost Amplifier vs Output Power VDD = 3 V, RL = 8 f = 1 kHz, PV1 = 4.8 V 10 200 Submit Documentation Feedback Figure 12. PSRR vs Frequency VDD = 5 V, RL = 8 VRIPPLE = 200 mVPP, PV1 = 7.8 V Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 0 0 -20 -20 -40 -60 PSRR (dB) PSRR (dB) Typical Characteristics (continued) FIXED FREQUENCY SPREAD SPECTRUM -40 -60 SPREAD SPECTRUM -80 -80 -100 20 200 2k FIXED FREQUENCY -100 20 20k 200 2k 20k FREQUENCY (Hz) FREQUENCY (Hz) Figure 13. PSRR vs Frequency VDD = 3.6 V, RL = 8 VRIPPLE = 200 mVPP, PV1 = 7 V Figure 14. PSRR vs Frequency VDD = 3 V, RL = 8 VRIPPLE = 200 mVPP, PV1 = 4.8 V 30 23 SPREAD SPECTRUM SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 21 25 20 15 FIXED FREQUENCY 10 SPREAD SPECTRUM 19 17 15 13 11 FIXED FREQUENCY 9 7 5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 5 2.5 6.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) Figure 15. Supply Current vs Supply Voltage PV1 = 7.8 V Figure 16. Supply Current vs Supply Voltage PV1 = 7 V 11 1.8 1.6 POWER DISSIPATION (W) 10 SUPPLY CURRENT (mA) 3.0 SPREAD SPECTRUM 9 8 7 6 3.0 3.5 4.0 4.5 1.2 1.0 0.8 0.6 0.4 0.2 FIXED FREQUENCY 5 2.5 1.4 5.0 5.5 0 6.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT POWER (W) SUPPLY VOLTAGE (V) Figure 17. Supply Current vs Supply Voltage PV1 = 4.8 V Figure 18. Power Dissipation vs Output Power VDD = 5 V, RL = 8 PV1 = 7.8 V, FF Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 11 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com Typical Characteristics (continued) 1.8 0.5 0.4 POWER DISSIPATION (W) POWER DISSIPATION (W) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.3 0.2 0.1 0.2 0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 3.5 0 0.2 OUTPUT POWER (W) 0.6 0.8 1.0 1.2 1.4 1.6 OUTPUT POWER (W) Figure 19. Power Dissipation vs Output Power VDD = 3.6 V, RL = 8 PV1 = 7 V, FF Figure 20. Power Dissipation vs Output Power VDD = 3 V, RL = 8 PV1 = 4.8 V, FF 100 100 90 90 80 80 70 70 EFFICIENCY (%) EFFICIENCY (%) 0.4 60 50 40 30 60 50 40 30 20 20 10 10 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 0 LOAD CURRENT (A) 0.2 0.3 0.4 0.5 0.6 LOAD CURRENT (A) Figure 21. Boost Converter Efficiency vs ILOAD(DC) VDD = 5 V, PV1 = 7.8 V Figure 22. Boost Converter Efficiency vs ILOAD(DC) VDD = 3.6 V, PV1 = 7 V 100 90 EFFICIENCY (%) 80 70 60 50 40 30 20 10 0 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.4 LOAD CURRENT (A) Figure 23. Boost Converter Efficiency vs ILOAD(DC) VDD = 3 V, PV1 = 4.8 V 12 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 7 Detailed Description 7.1 Overview The LM48511 integrates a boost converter with a high-efficiency Class D audio power amplifier, which features a low-noise PWM architecture that eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design. A selectable spread spectrum modulation scheme suppresses RF emissions, further reducing the need for output filters. Two selectable feedback networks allow the LM48511 regulator to dynamically switch between two different output voltages, improving efficiency by optimizing the amplifier's supply voltage based on battery voltage and output power requirements. The gain of the LM48511 is set by external resistors, which allows independent gain control from multiple sources by summing the signals. Output short circuit and thermal overload protection prevent the device from damage during fault conditions. 7.2 Functional Block Diagram +3.0V to +5.5V L1 6.8 PH CS1 10 PF VDD D1 C2 100 PF SW C1 280 pF R3 25.5 k: SD_BOOST REGGND R4 2.5 k: MODULATOR FB SOFTSTART R2 9.31 k: CSS 0.1 PF R1 4.87 k: FB_GND1 OSCILLATOR FB_SEL FB_GND0 V1 SD_AMP PV1 C4 1 PF VGOCIN VIN + R5 20 k: R6 20 k: IN+ R7 20 k: LS+ MODULATOR H-BRIDGE IN- VINCIN C3 1 PF R8 20 k: LS- VGO+ OSCILLATOR SS/FF GND LSGND Copyright (c) 2017, Texas Instruments Incorporated Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 13 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 7.3 Feature Description 7.3.1 General Amplifier Function The LM48511 features a Class D audio power amplifier that uses a filterless modulation scheme, reducing external component count, conserving board space and reducing system cost. The outputs of the device transition from PV1 to GND with a 300-kHz switching frequency. With no signal applied, the outputs (VLS+ and VLS-) switch with a 50% duty cycle, in phase, causing the two outputs to cancel. This cancellation results in no net voltage across the speaker, thus there is no current to the load in the idle state. With the input signal applied, the duty cycle (pulse width) of the LM48511 outputs changes. For increasing output voltage, the duty cycle of VLS+ increases, while the duty cycle of VLS-decreases. For decreasing output voltages, the converse occurs. The difference between the two pulse widths yields the differential output voltage. 7.3.2 Differential Amplifier Explanation The LM48511 includes fully differential amplifier that features differential input and output stages. A differential amplifier amplifies the difference between the two input signals. Traditional audio power amplifiers have typically offered only single-ended inputs resulting in a 6dB reduction in signal to noise ratio relative to differential inputs. The LM48511 also offers the possibility of DC input coupling which eliminates the two external AC coupling, DC blocking capacitors. The LM48511 can be used, however, as a single-ended input amplifier while still retaining the fully differential benefits of the device. In fact, completely unrelated signals may be placed on the input pins. The LM48511 simply amplifies the difference between the signals. A major benefit of a differential amplifier is the improved common-mode rejection ratio (CMRR) over single input amplifiers. The common-mode rejection characteristic of the differential amplifier reduces sensitivity to ground offset related noise injection, especially important in high noise applications. 7.3.3 Audio Amplifier Power Dissipation and Efficiency The major benefit of a Class D amplifier is increased efficiency versus a Class AB. The efficiency of the LM48511 is attributed to the region of operation of the transistors in the output stage. The Class D output stage acts as current steering switches, consuming negligible amounts of power compared to their Class AB counterparts. Most of the power loss associated with the output stage is due to the IR loss of the MOSFET ONresistance, along with switching losses due to gate charge. 7.3.4 Regulator Power Dissipation At higher duty cycles, the increased ON-time of the switch FET means the maximum output current will be determined by power dissipation within the LM48511 FET switch. The switch power dissipation from ON-time conduction is calculated by: PD(SWITCH) = DC x (IINDUCTOR(AVE))2 x RDS(ON) (W) where * DC is the duty cycle. (1) 7.3.5 Shutdown Function The LM48511 features independent amplifier and regulator shutdown controls, allowing each portion of the device to be disabled or enabled independently. SD_AMP controls the Class D amplifiers, while SD_BOOST controls the regulator. Driving either inputs low disables the corresponding portion of the device, and reducing supply current. When the regulator is disabled, both FB_GND switches open, further reducing shutdown current by eliminating the current path to GND through the regulator feedback network. Without the GND switches, the feedback resistors as shown in Figure 1 would consume an additional 165 A from a 5-V supply. With the regulator disabled, there is still a current path from VDD, through the inductor and diode, to the amplifier power supply. This allows the amplifier to operate even when the regulator is disabled. The voltage at PV1 and V1 will be: (VDD - [VD + (IL x DCR)] Where * * * 14 VD is the forward voltage of the Schottky diode VD is the forward voltage of the Schottky diode IL is the current through the inductor Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 Feature Description (continued) * DCR is the DC resistance of the inductor (2) Additionally, when the regulator is disabled, an external voltage from 5 V to 8 V can be applied directly to PV1 and V1 to power the amplifier. It is best to switch between ground and VDD for minimum current consumption while in shutdown. The LM48511 may be disabled with shutdown voltages in between GND and VDD, the idle current will be greater than the typical 0.1-A value. Increased THD+N may also be observed when a voltage of less than VDD is applied to SD_AMP . 7.3.6 Regulator Feedback Select The LM45811 regulator features two feedback paths as shown in Figure 1, which allow the regulator to easily switch between two different output voltages. The voltage divider consists of the high side resistor, R3, and the low side resistors (RLS), R1 and R2. R3 is connected to the output of the boost regulator, the mid-point of each divider is connected to FB, and the low side resistors are connected to either FB_GND1 or FB_GND0. FB_SEL determines which FB_GND switch is closed, which in turn determines which feedback path is used. For example if FB_SEL = VDD, the FB_GND1 switch is closed, while the FB_GND0 switch remains open, creating a current path through the resistors connected to FB_GND1. Conversely, if FB_SEL = GND, the FB_GND0 switch is closed, while the FB_GND1 switch remains open, creating a current path through the resistors connected to FB_GND0. FB_SEL can be susceptible to noise interference. To prevent an accidental state change, either bypass FB_SEL with a 0.1F capacitor to GND, or connect the higher voltage feedback network to FB_GND0, and the lower voltage feedback network to FB_GND1. Because the higher output voltage configuration typically generates more noise on VDD, this configuration minimizes the VDD noise exposure of FB_SEL, as FB_SEL = GND for FB_GND0 (high voltage output) and FB_SEL = VDD for FB_GND1 (low voltage output). The selectable feedback networks maximize efficiency in two ways. In applications where the system power supply voltage changes, such as a mobile GPS receiver, that transitions from battery power, to AC line, to a car power adapter, the LM48511 can be configured to generate a lower voltage when the system power supply voltages is lower, and conversely, generate a higher voltage when the system power supply is higher. See the Setting the Regulator Output Voltage (PV1) section. In applications where the same speaker/amplifier combination is used for different purposes with different audio power requirements, such as a cell phone ear piece/speaker phone speaker, the ability to quickly switch between two different voltages allows for optimization of the amplifier power supply, increasing overall system efficiency. When audio power demands are low (ear piece mode) the regulator output voltage can be set lower, reducing quiescent current consumption. When audio power demands increase (speaker phone mode), a higher voltage increases the amplifier headroom, increasing the audio power delivered to the speaker. 7.4 Device Functional Modes The LM48511 features two modulations schemes, a fixed frequency mode (FF) and a spread spectrum mode (SS). 7.4.1 7.4.1 Fixed Frequency Select the fixed frequency mode by setting SS/FF = GND. In fixed frequency mode, the amplifier outputs switch at a constant 300 kHz. In fixed frequency mode, the output spectrum consists of the fundamental and its associated harmonics (see Typical Characteristics). 7.4.2 7.4.2 Spread Spectrum Mode Set SS/FF = VDD for spread spectrum mode. The logic selectable spread spectrum mode eliminates the need for output filters, ferrite beads or chokes. In spread spectrum mode, the switching frequency varies randomly by 10% about a 330-kHz center frequency, reducing the wideband spectral contend, improving EMI emissions radiated by the speaker and associated cables and traces. Where a fixed frequency class D exhibits large amounts of spectral energy at multiples of the switching frequency, the spread spectrum architecture of the LM48511 spreads that energy over a larger bandwidth (see Typical Characteristics). The cycle-to-cycle variation of the switching period does not affect the audio reproduction, efficiency, or PSRR. Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 15 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 8 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. 8.1 Application Information The LM48511 integrates a boost converter with a high-efficiency Class D audio power amplifier, which uses a filterless modulation scheme, reducing external component count, board area consumption and system cost. The major benefit of a Class D amplifier is increased efficiency versus a Class AB. The LM48511 regulator has two selectable feedback paths, which allow the regulator to dynamically switch between two different output voltages easily. In addition, the LM48511 regulator features two different switching modes, improving light load efficiency by minimizing losses due to MOSFET gate charge. The amplifier gain of the LM48511 is set by four external resistors. Careful matching of those resistor pairs is required for optimum performance. 8.2 Typical Application VDD 4 19 20 21 GND2 1 VDD 24 5 17 GND2 Audio Input 1 1 GND2 2 2 3 3 4 4 GND2 CIN+ R5 20k CIN- R7 180 nF 20k 16 15 14 GND1 GND 2 GND3 3 GND2 C4 1 PF GND1 3 GND3 FB_GND1 FB_SEL V1 LM48511SQ /SD_Boost 22 GND3 23 PV1 13 10 /SD_Amp VGO- LS+ 8 Speaker 2 IN+ INVGO+ VDD SS_EN 1 C3 1 PF FB_GND0 R8 20k GND2 GND3 FB 6 180 nF R6 20k Softstart GND2 + R2 9.31k 100 nF SW R1 4.87k GND3 GND2 2 CSoftstart GND2 FB_SEL VDD 1 1 2 2 3 3 GND2 +C2 100 PF LS- 12 1 7 GND3 1 PF CS3 SW GND3 1 PF CS2 GND1 SD_Amp 1 1 2 2 3 3 10 PF CS1 D1 6.8 PH 9 SD_Boost 1 1 2 2 3 3 VDD + 18 GND1 (Class D GND) GND2 (AGND) GND3 (Switch GND) L1 VDD VDD GND2 GND1 2 11 + C1 280 pF R3 25.5k R4 2.5k 1 SS-EN VDD GND1 GND1 GND2 1 2 3 GND2 Copyright (c) 2017, Texas Instruments Incorporated Figure 24. Typical LM48511 Audio Amplifier Application Circuit 16 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 Typical Application (continued) 8.2.1 Design Requirements Table 1 lists the design parameters for this example. Table 1. Design Parameters PARAMETERS VALUES Supply voltage range 3.0 V to 5.5 V Amplifier range 4.8 V to 8 V Temperature range -40C to 85C 8.2.2 Detailed Design Procedure 8.2.2.1 Proper Selection of External Components Proper selection of external components in applications using integrated power amplifiers, and switching DC-DC converters, is critical for optimizing device and system performance. Consideration to component values must be used to maximize overall system quality. The best capacitors for use with the switching converter portion of the LM48511 are multi-layer ceramic capacitors. They have the lowest ESR (equivalent series resistance) and highest resonance frequency, which makes them optimum for high-frequency switching converters. When selecting a ceramic capacitor, only X5R and X7R dielectric types must be used. Other types such as Z5U and Y5F have such severe loss of capacitance due to effects of temperature variation and applied voltage, they may provide as little as 20% of rated capacitance in many typical applications. Always consult capacitor manufacturer's data curves before selecting a capacitor. High-quality ceramic capacitors can be obtained from Taiyo-Yuden and Murata. 8.2.2.2 Power Supply Bypassing As with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. The capacitor location on both PV1, V1 and VDD pins must be as close to the device as possible. 8.2.2.3 Audio Amplifier Gain Setting Resistor Selection The amplifier gain of the LM48511 is set by four external resistors, the input resistors, R5 and R7, and the feed back resistors R6 and R8.. The amplifier gain is given by: Where RIN is the input resistor and RF is the feedback resistor. AVD = 2 x RF / RIN (3) Careful matching of the resistor pairs, R6 and R8, and R5 and R7, is required for optimum performance. Any mismatch between the resistors results in a differential gain error that leads to an increase in THD+N, decrease in PSRR and CMRR, as well as an increase in output offset voltage. Resistors with a tolerance of 1% or better are recommended. The gain setting resistors must be placed as close to the device as possible. Keeping the input traces close together and of the same length increases noise rejection in noisy environments. Noise coupled onto the input traces which are physically close to each other will be common mode and easily rejected. 8.2.2.4 Audio Amplifier Input Capacitor Selection Input capacitors may be required for some applications, or when the audio source is single-ended. Input capacitors block the DC component of the audio signal, eliminating any conflict between the DC component of the audio source and the bias voltage of the LM48511. The input capacitors create a highpass filter with the input resistors RIN. The -3dB point of the highpass filter is found by: f = 1 / 2RINCIN (4) In single-ended configurations, the input capacitor value affects click-and-pop performance. The LM48511 features a 50-mg turnon delaly. Choose the input capacitor / input resistor values such that the capacitor is charged before the 50-ms turnon delay expires. A capacitor value of 0.18 F and a 20-k input resistor are recommended. In differential applications, the charging of the input capacitor does not affect click-and-pop significantly. Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 17 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com The input capacitors can also be used to remove low-frequency content from the audio signal. Highpass filtering the audio signal helps protect speakers that can not reproduce or may be damaged by low frequencies. When the LM48511 is using a single-ended source, power supply noise on the ground is seen as an input signal. Setting the highpass filter point above the power supply noise frequencies, 217 Hz in a GSM phone, for example, filters out the noise such that it is not amplified and heard on the output. Capacitors with a tolerance of 10% or better are recommended for impedance matching and improved CMRR and PSRR. 8.2.2.5 Selecting Regulator Output Capacitor A single 100-F low ESR tantalum capacitor provides sufficient output capacitance for most applications. Higher capacitor values improve line regulation and transient response. Typical electrolytic capacitors are not suitable for switching converters that operate above 500 kHz because of significant ringing and temperature rise due to self-heating from ripple current. An output capacitor with excessive ESR reduces phase margin and causes instability. 8.2.2.6 Selecting Regulating Bypass Capacitor A supply bypass capacitor is required to serve as an energy reservoir for the current which must flow into the coil each time the switch turns on. This capacitor must have extremely low ESR, so ceramic capacitors are the best choice. A nominal value of 10 F is recommended, but larger values can be used. Because this capacitor reduces the amount of voltage ripple seen at the input pin, it also reduces the amount of EMI passed back along that line to other circuitry. 8.2.2.7 Selecting the Soft-Start (CSS) Capacitor The soft-start function charges the boost converter reference voltage slowly. This allows the output of the boost converter to ramp up slowly thus limiting the transient current at start-up. Selecting a soft-start capacitor (CSS) value presents a trade off between the wake-up time and the start-up transient current. Using a larger capacitor value will increase wake-up time and decrease start-up transient current while the apposite effect happens with a smaller capacitor value. A general guideline is to use a capacitor value 1000 times smaller than the output capacitance of the boost converter (C2). A 0.1-uF soft-start capacitor is recommended for a typical application. Table 2 shows the relationship between CSS start-up time and surge current. Table 2. Soft-Start Capacitor Start-Up Time and Surge Current CSS (F) (1) (1) BOOST SET-UP TIME (ms) INPUT SURGE CURRENT (mA) 0.1 5.1 330 0.22 10.5 255 0.47 21.7 220 VDD = 5 V, PV1 = 7.8 V (continuous mode) 8.2.2.8 Selecting Diode (D1) Use a Schottkey diode, as shown in Figure 1. A 30-V diode such as the DFLS230LH from Diodes Incorporated is recommended. The DFLS230LH diodes are designed to handle a maximum average current of 2 A. 8.2.2.9 Duty Cycle The maximum duty cycle of the boost converter determines the maximum boost ratio of output-to-input voltage that the converter can attain in continuous mode of operation. The duty cycle for a given boost application is defined by: Duty Cycle = (PV1 + VD - VDD) / (PV1 + VD - VSW) (5) This applies for continuous mode operation. 18 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 8.2.2.10 Selecting Inductor Value Inductor value involves trade-offs in performance. Larger inductors reduce inductor ripple current, which typically means less output voltage ripple (for a given size of output capacitor). Larger inductors also mean more load power can be delivered because the energy stored during each switching cycle is: E = L / 2 x (IP)2 Where * IP is the peak inductor current (6) The LM48511 will limit its switch current based on peak current. With IP fixed, increasing L will increase the maximum amount of power available to the load. Conversely, using too little inductance may limit the amount of load current which can be drawn from the output. Best performance is usually obtained when the converter is operated in "continuous" mode at the load current range of interest, typically giving better load regulation and less output ripple. Continuous operation is defined as not allowing the inductor current to drop to zero during the cycle. Boost converters shift over to discontinuous operation if the load is reduced far enough, but a larger inductor stays continuous over a wider load current range. 8.2.2.11 Inductor Supplies The recommended inductor for the LM48511 is the IHLP-2525CZ-01 from Vishay Dale. When selecting an inductor, the continuous current rating must be high enough to avoid saturation at peak currents. A suitable core type must be used to minimize switching losses, and DCR losses must be considered when selecting the current rating. Use shielded inductors in systems that are susceptible to RF interference. 8.2.2.12 Setting the Regulator Output Voltage (PV1) The output voltage of the regulator is set through one of two external resistive voltage-dividers (R3 in combination with either R1 or R2) connected to FB (Figure 1). The resistor, R4 is only for compensation purposes and does not affect the regulator output voltage. The regulator output voltage is set by the following equation: PV1 = VFB [1 + R3 / RLS] Where * VFB is 1.23 V, and RLS is the low side resistor (R1 or R2) (7) To simplify resistor selection: RLS = (R3VFB) / (PV1 - VFB) (8) A value of approximately 25.5 k is recommended for R3. The quiescent current of the boost regulator is directly related to the difference between its input and output voltages, the larger the difference, the higher the quiescent current. For improved power consumption the following regulator input/output voltage combinations are recommended: Table 3. Recommended Regulator Input and Output Voltages (1) (1) VDD (V) PV1 (V) R3 (k) RLS (k) 3.0 4.8 25.5 9.31 POUT into 8 (W) 1 3.6 7.1 25.5 5.35 2.5 5 7.8 25.5 4.87 3 The values of PV1 are for continuous mode operation. For feedback path selection, see Regulator Feedback Select. 8.2.2.13 Discontinuous and Continuous Operation The LM48511 regulator features two different switching modes. Under light-load conditions, the regulator operates in a variable frequency, discontinuous, pulse-skipping mode, that improves light load efficiency by minimizing losses due to MOSFET gate charge. Under heavy loads, the LM48511 regulator automatically switches to a continuous, fixed-frequency PWM mode, improving load regulation. In discontinuous mode, the regulator output voltage is typically 400 mV higher than the expected (calculated) voltage in continuous mode. Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 19 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 8.2.2.14 ISW Feed-Forward Compensation for Boost Converter Although the LM48511 regulator is internally compensated, an external feed-forward capacitor, (C1) may be required for stability. The compensation capacitor places a zero in regulator loop response. The recommended frequency of the zero (fZ) is 22.2 kHz. The value of C1 is given by: C1 = 1 / 2R3fZ (9) In addition to C1, a compensation resistor, R4 is required to cancel the zero contributed by the ESR of the regulator output capacitor. Calculate the zero frequency of the output capacitor by: fCO = 1 / 2RCOCO where * R CO is the ESR of the output capacitor (10) The value of RFB3 is given by: R4 = 1 / 2fCOC1 (11) 8.2.2.15 Calculating Regulator Output Current The load current of the boost converter is related to the average inductor current by the relation: IAMP = IINDUCTOR(AVE) x (1 - DC) (A) where * DC is the duty cycle of the application (12) The switch current can be found by: ISW = IINDUCTOR(AVE) + 1/2 (IRIPPLE) (A) (13) Inductor ripple current is dependent on inductance, duty cycle, supply voltage and frequency: IRIPPLE = DC x (VDD - VSW) / (f x L) (A) where * f = switching frequency = 1MHz (14) combining all terms, we can develop an expression which allows the maximum available load current to be calculated: IAMP(max) = (1-DC) x [ISW(max)- DC (V - VSW)] / 2fL (A) (15) The equation shown to calculate maximum load current takes into account the losses in the inductor or turnoff switching losses of the FET and diode. 8.2.2.16 Design Parameters VSW and ISW The value of the FET "ON" voltage (referred to as VSW in Equation 9 thru Equation 12) is dependent on load current. A good approximation can be obtained by multiplying the ON-resistance (RDS(ON) of the FET times the average inductor current. The maximum peak switch current the device can deliver is dependent on duty cycle. 20 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 8.2.3 Application Curve POUT (W) IDD (A) K (%) 100 10 1 POUT (W) THD+N (%) IDD (A) K (%) 0.1 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 VDD (V) 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 D001 Figure 25. VDD vs POUT, IDD, and Efficiency With 4- Load Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 21 LM48511 SNAS416J - JULY 2007 - REVISED OCTOBER 2017 www.ti.com 9 Power Supply Recommendations The devices are designed to operate from an input supply voltage (VDD) operating range from 3 V to 5.5 V, but the absolute maximum rating is 9 V. As with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. The capacitor location on both PV1, V1 and VDD pins must be as close to the device as possible. 10 Layout 10.1 Layout Guidelines This section provides general practical guidelines for PCB layouts that use various power and ground traces. Designers must note that these are only rule-of-thumb recommendations and the actual results are predicated on the final layout. 10.1.1 Power and Ground Circuits Star trace routing techniques can have a major positive impact on low-level signal performance. Star trace routing refers to using individual traces that radiate from a signal point to feed power and ground to each circuit or even device. 10.1.2 Layout Helpful Hints * Avoid routing traces under the inductor. * Use three separate grounds that eventually connect to one point: - Signal or quiet ground (GND) - Ground for the LM48511 device (LSGND) - SW (REGGND) (switch ground). This trace for the switch ground carries the heaviest current (3 A) and therefore is the nosiest. Make this trace as wide and short as possible and keep at a distance from the quiet ground and device ground. Give distance priority to the quiet ground. 10.2 Layout Example Figure 26. Layout Example 22 Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 LM48511 www.ti.com SNAS416J - JULY 2007 - REVISED OCTOBER 2017 11 Device and Documentation Support 11.1 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. 11.2 Community Resources 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. 11.3 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 11.4 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. 11.5 Glossary SLYZ022 -- TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 12 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. Submit Documentation Feedback Copyright (c) 2007-2017, Texas Instruments Incorporated Product Folder Links: LM48511 23 PACKAGE OPTION ADDENDUM www.ti.com 16-Oct-2017 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) LM48511SQ/NOPB ACTIVE WQFN NHZ 24 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 48511SQ LM48511SQX/NOPB ACTIVE WQFN NHZ 24 4500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 48511SQ (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (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. 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Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 16-Oct-2017 Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 19-Aug-2018 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM48511SQ/NOPB Package Package Pins Type Drawing WQFN NHZ 24 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 1000 178.0 12.4 Pack Materials-Page 1 4.3 B0 (mm) K0 (mm) P1 (mm) 5.3 1.3 8.0 W Pin1 (mm) Quadrant 12.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 19-Aug-2018 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM48511SQ/NOPB WQFN NHZ 24 1000 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA NHZ0024B SQA24B (Rev A) 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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