LM4903

1 Watt Audio Power Amplifier

General Description

The LM4903 is an audio power amplifier primarily designed

for demanding applications in mobile phones and other por-

table communication device applications. It is capable of

delivering 1 watt of continuous average power to an 8

Ω BTL

load with less than 1% distortion (THD+N) from a 5V

DC

power supply.

Boomer audio power amplifiers were designed specifically to

provide high quality output power with a minimal amount of

external components. The LM4903 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 LM4903 features a low-power consumption shutdown

mode, which is achieved by driving the shutdown pin with

logic low. Additionally, the LM4903 features an internal ther-

mal shutdown protection mechanism.

The LM4903 contains advanced pop & click circuitry which

eliminates noise which would otherwise occur during turn-on

and turn-off transitions.

The LM4903 is unity-gain stable and can be configured by

external gain-setting resistors.

Key Specifications

62dB

Ω

1.07W (typ)

Ω

525mW (typ)

Ω

390mW (typ)

0.1µA (typ)

Features

n

Available in space-saving MSOP package

n

Ultra low current shutdown mode

n

BTL output can drive capacitive loads

n

Improved pop & click circuitry eliminates noise during

turn-on and turn-off transitions

n

2.0 - 5.5V operation

n

No output coupling capacitors, snubber networks or

bootstrap capacitors required

n

Unity-gain stable

n

External gain configuration capability

Applications

n

Mobile Phones

n

PDAs

n

Portable electronic devices

Typical Application

200467D3

FIGURE 1. Typical Audio Amplifier Application Circuit

February 2003

© 2003 National Semiconductor Corporation

DS200467

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