1 Features

1• Stereo DirectPath™ Headphone Amplifier

– 40 mW Into 32 Ω With 3.3-V Supply

• Low THD+N < 0.01% at 10 mW Into 32 Ω

• High SNR, >90 dB

• Differential Input and Single-Ended Output

• Adjustable Gain by External Gain-Setting

Resistors

• Configurable as a Second-Order Low-Pass Filter

– Ideal for PWM Audio Sources

• Low DC Offset, <1 mV

• Ground-Referenced Outputs Eliminate DC-

Blocking Capacitors

– Reduce Board Area

– Reduce Component Cost

– Improve THD+N Performance

– No Degradation of Low-Frequency Response

Due to Output Capacitors pop•

Short-Circuit Protection

• Click- and Pop-Reduction Circuitry

• External Undervoltage Mute

• Active Mute Control for Pop-Free Audio On/Off

Control

• Space-Saving TSSOP Package

2 Applications

• LCD and PDP TV

• Blu-ray Disc™, DVD Players

• Set-Top Boxes

• Mini/Micro Combo Systems

• Sound Cards

• Laptops

3 Description

The TPA6138A2 is a pop-free stereo headphone

amplifier designed to allow the removal of the output dc-blocking capacitors for reduced component count

and cost. The device is ideal for single-supply

electronics where size and cost are critical design

parameters.

Designed using TI’s patented DirectPath™

technology, The TPA6138A2 is capable of driving 25

mW into a 32-Ω load with 3.3-V supply voltage. The device has differential inputs and uses external gain-

setting resistors that supports a gain range of ±1 V/V

to ±10 V/V. Gain can be configured individually for

each channel. The device can also be configured as

a second-order low-pass filter and is ideal for interfacing with PWM audio sources. Audio output

compiles with ±8-kV IEC ESD protection, requiring

just a simple resistor-capacitor ESD protection circuit.

The TPA6138A2 has built-in active-mute control for pop-free audio on/off control. The TPA6138A2 has an

external undervoltage detector that mutes the output

when the power supply is removed, ensuring a pop•

free shutdown.

Using the TPA6138A2 in audio products can reduce

component count considerably compared to

traditional headphone amplifiers. The TPA6138A2 does not require a split-rail power supply or a dc

blocking capacitor. The TPA6138A2 integrates its

own charge pump to generate a negative supply rail

that provides a clean, pop-free ground-biased audio

signal.

The TPA6138A2 is available in a 14-pin TSSOP.