Envelope-Tracking Power Supply Reference Design for Audio Power Amplifiers
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Key Document


This envelope-tracking power reference design maintains helps extend battery life in a portable audio applications, such as Bluetooth® or Wi-Fi speakers. The low-power step-down converter in the design features envelope-tracking capability to an audio power amplifier, maintaining high efficiency across the output voltage range. By adding an audio envelope signal to the FB pin of TI’s TPS61178 device, the output voltage can change in accordance with the envelope of the audio signal thus dynamically adapting the TPA3128D2 power amplifier’s supply and optimizing its power consumption.

  • 5.4V to 8.4V input voltage range
  • 2X20W into a 8-Ω load at Vin=7.2V
  • Programmable power limit
  • Isolate the input battery from the output side when shut down
  • High efficiency and small solution size

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Schematic/Block Diagram

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Design Files

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(Output Voltage 1)
Vin (Min) (V)5.4
Vin (Max) (V)8.4
Vout (Nom) (V)18
Iout (Max) (A)1.5
Output Power (W)27
Input TypeDC
TopologyBoost- Synchronous

TI Devices (3)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
OPA4377  Quad Low-Cost, Low Noise, 5.5MHz CMOS Operational Amplifier   Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
TPA3128D2  30-W stereo, 60-W mono, 4.5- to 26-V, analog input Class-D audio amplifier w/ low idle current  Audio amplifiers  Sample & Buy View Design Kits & Evaluation Modules
TPS61178  20-V Fully Integrated Sync Boost with Load Disconnect  Step-up (boost) regulators  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
OPA4377 Download Download
TPA3128D2 Download
TPS61178 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 643 25 Sep 2017
Design files (6)
Title Type Size (KB) Date
ZIP 1103 25 Sep 2017
ZIP 1360 25 Sep 2017
PDF 714 25 Sep 2017
PDF 212 25 Sep 2017
PDF 79 25 Sep 2017
PDF 259 25 Sep 2017

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