LM4915

Pseudo-Differential Mono Headphone Amplifier with

Fixed 6dB Gain

General Description

The LM4915 is a pseudo-differential audio power amplifier

primarily designed for demanding applications in mobile

phones and other portable audio device applications with

mono headphones. It is capable of delivering 90 miliwatts of

continuous average power to a 32

Ω BTL load with less than

1% distortion (THD+N) from a 3V

Boomer audio power amplifiers were designed specifically to

provide high quality output power with a minimal amount of

external components. The LM4915 does not require output

coupling capacitors or bootstrap capacitors, and therefore is

ideally suited for mobile phone and other low voltage appli-

cations where minimal power consumption is a primary re-

quirement.

The LM4915 features a low-power consumption shutdown

mode. To facilitate this, Shutdown may be enabled by driving

the shutdown pin low. Additionally, the LM4915 features an

internal thermal shutdown protection mechanism.

The LM4915 contains advanced pop & click circuitry which

virtually eliminates noises which would otherwise occur dur-

ing turn-on and turn-off transitions.

The LM4915 has an internally fixed gain of 6dB.

Key Specifications

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Improved PSRR at 217Hz and 1kHz

75dB (typ)

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Power Output at 5.0V & 1% THD into 32

Ω 280mW (typ)

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Power Output at 3.0V & 1% THD into 32

Ω 90mW (typ)

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Output Noise, A-weighted

20µV (typ)

Features

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Pseudo-differential amplification

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Internal gain-setting resistors

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Available in space-saving LLP package

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Ultra low current shutdown mode

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Can drive capacitive loads up to 500pF

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Improved pop & click circuitry virtually eliminates noises

during turn-on and turn-off transitions

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2.2 - 5.5V operation

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No output coupling capacitors, snubber networks,

bootstrap capacitors or gain-setting resistors required

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Ultra low noise

Applications

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Mobile phones

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PDAs

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Portable electronics devices

Typical Application

200482B4

FIGURE 1. Typical Audio Amplifier Application Circuit

May 2003

© 2003 National Semiconductor Corporation

DS200482

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