TPA6138A2PW Headphone Driver

28 July 2020 - 0 Comments

TPA6138A2PW Headphone Driver

TPA6138A2PW Pinout

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	Description
1	+INR	Right-channel OPAMP positive input
2	-INR	Right-channel OPAMP negative input
3	OUTR	Right-channel OPAMP output
4	GND	Power GND
5	_MUTE	Mute, Active LOW
6	VSS	Negative Supply voltage
7	CN	Charge-Pump flying capacitor negative rail
8	CP	Charge-Pump flying capacitor positive rail
9	VDD	Positive Supply
10	GND	Power GND
11	UVP	Under Voltage Protection
12	OUTL	Left-Channel OPAMP Out
13	-INL	Left-channel OPAMP negative input
14	+INL	Left-channel OPAMP positive input

The pinout is shown in the below image-

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-

TS482
MAX13330
TPA6139A2
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

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.
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.
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.