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TPA6138A2PW Headphone Driver

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TPA6138A2PW is Texas Instruments DirectPat Technology based Headphone Driver that has an adjustable gain functionality. It is a pop-free stereo headphone amplifier featuring a built-in active-mute control for audio on/off control in a pop-free manner. This is done by an under-voltage detector that mutes the output if the power supply is removed, resulting in a pop-free output shutdown.


It is a successful stereo headphone amplifier that is designed in a way that the output dc-blocking capacitors are not required and component count and production cost can be drastically reduced. TPA6138A2PW is capable of driving 25mW, 32-Ohms load from a 3.3V supply voltage.


TPA6138A2PW Op-Amp Pin Description

Pin Number

Pin Name




Right-channel OPAMP positive input



Right-channel OPAMP negative input



Right-channel OPAMP output



Power GND



Mute, Active LOW



Negative Supply voltage



Charge-Pump flying capacitor negative rail



Charge-Pump flying capacitor positive rail



Positive Supply



Power GND



Under Voltage Protection



Left-Channel OPAMP Out



Left-channel OPAMP negative input



Left-channel OPAMP positive input


The pinout is shown in the below image-

TPA6138A2PW Pinout


Features and Specification of TPA6138A2PW Amplifier

  • 40 mW Into 32 Ω With 3.3-V Supply
  • Low THD+N < 0.01% at 10 mW Into 32 Ω
  • Differential Input and Single-Ended Output
  • Adjustable Gain by External Gain-Setting Resistor
  •  Ground-Referenced Outputs Eliminate DC Blocking capacitors
  • External Undervoltage Mute
  • Supply voltage: 3.3V (NOM) (MIN: 3V, MAX: 3.6V)
  • Load Impedance: 16 Ohms (MIN), 32 Ohms (NOM)


Note: Complete technical details can be found in the TPA6138A2PW Datasheet linked at the bottom of this page.


Alternative Product of TPA6138A2PW Amplifier

Replacement of this TPA6138A2PW Amplifier-

  1. TS482
  2. MAX13330
  3. TPA6139A2
  4. TPA6133A2


TPA6138A2PW Amplifier - Overview

TPA6138A2PW Stereo Headphone amplifier is capable of driving 16 Ohms - 32 Ohms Load and provides up to 40mW power from 3.3V supply voltage. The advantage of this stereo headphone amplifier IC is that it does not require the output DC blocking capacitor and split-rail power supply. However, it integrates its own charge pump to generate a negative supply rail that is clean and could produce a pop-free ground-biased audio signal. Thus, it reduces the component count and total BOM cost.


The gain can be set individually using an external resistor and can be also configured as a second-order low-pass filter that is very useful to interface the PWM based audio sources. TPA6138A2PWM Audio output compiles with ±8-kV IEC ESD protection, requiring just a simple resistor-capacitor ESD protection circuit.


 How to Choose a Headphone Amplifier

  1. Choose the headphone amplifier that is required for the application. Calculate the maximum power output that is required for the application. TPA6138A2PW supports a maximum of 40mW power output.
  2. Be sure about the availability of the Voltage. Choose an amplifier that works on the supported voltage. TPA6138A2PW requires a 3.0V minimum to 3.6V maximum input voltage.
  3. Choose an amplifier that supports the targeted headphone impedance that is required for the applications. TPA6138A2PW supports 16 Ohms and 32 Ohms headphone impedance as load.


TPA6138A2 Application Circuit

The below image is showing the standard interfacing TPA6138A2.

TPA6138A2 Application Circuit


Applications of TPA6138A2PW MOSFET

  • Sound Card
  • LCD and TVs
  • Mobile phones
  • Laptops
  • Set-Top Boxes


2D Model and Dimensions of TPA6138A2PW

TPA6138A2PW Dimensions

Component Datasheet

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