LM4895

1 Watt Fully Differential Audio Power Amplifier With

Shutdown Select and Fixed 6dB Gain

General Description

The LM4895 is a fully differential audio power amplifier

primarily designed for demanding applications in mobile

phones and other portable communication device applica-

tions. It is capable of delivering 1 watt of continuous average

power to an 8

Ω load with less than 1% distortion (THD+N)

from a 5V

Boomer audio power amplifiers were designed specifically to

provide high quality output power with a minimal amount of

external components. The LM4895 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 LM4895 features a low-power consumption shutdown

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

logic high or low depending on mode selection. Driving the

shutdown mode pin either high or low enables the shutdown

select pin to be driven in a likewise manner to enable Shut-

down. Additionally, the LM4895 features an internal thermal

shutdown protection mechanism.

The LM4895 contains advanced pop & click circuitry which

eliminates noises which would otherwise occur during

turn-on and turn-off transitions.

The LM4895 has an internally fixed gain of 6dB.

Key Specifications

80dB

1.0W(typ.)

400mW(typ.)

0.1µA(typ.)

Features

n

Fully differential amplification

n

Internal-gain-setting resistors

n

Available in space-saving packages micro SMD, MSOP

and LLP

n

Ultra low current shutdown mode

n

Can drive capacitive loads up to 500 pF

n

Improved pop & click circuitry eliminates noises 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

Shutdown high or low selectivity

Applications

n

Mobile phones

n

PDAs

n

Portable electronic devices

Typical Application

20023201

FIGURE 1. Typical Audio Amplifier Application Circuit

October 2002

© 2002 National Semiconductor Corporation

DS200232

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