LM4892

1 Watt Audio Power Amplifier with Headphone Sense

General Description

The LM4892 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. Switching between bridged speaker mode and

headphone (single-ended) mode is accomplished using the

headphone sense pin.

Boomer audio power amplifiers are designed specifically to

provide high quality output power with a minimal amount of

external components. The LM4892 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 LM4892 features a low-power consumption shutdown

mode, which is achieved by driving the shutdown pin with

logic low. Additionally, the LM4892 features an internal ther-

mal shutdown protection mechanism.

The LM4892 contains advanced pop & click circuitry which

eliminates noise which would otherwise occur during turn-on

and turn-off transitions.

The LM4892 is unity-gain stable and can be configured by

external gain-setting resistors.

Key Specifications

Ω Load

62dB (typ)

1.0W (typ)

400mW (typ)

0.1µA (typ)

Features

n

Available in space-saving packages: LLP, micro SMD,

MSOP, and SOIC

n

Ultra low current shutdown mode

n

BTL output can drive capacitive loads up to 500pF

n

Improved pop & click circuitry eliminates noise during

turn-on and turn-off transitions

n

2.2 - 5.5V operation

n

No output coupling capacitors, snubber networks or

bootstrap capacitors required

n

Thermal shutdown protection

n

Unity-gain stable

n

External gain configuration capability

n

Headphone amplifier mode

Applications

n

Mobile Phones

n

PDAs

n

Portable electronic devices

Typical Application

20012701

FIGURE 1. Typical Audio Amplifier Application Circuit (Pin #’s apply toM&MM packages)

October 2002

© 2002 National Semiconductor Corporation

DS200127

www.national.com