LM4875

750 mW Audio Power Amplifier with DC Volume Control

and Headphone Switch

General Description

The LM4875 is a mono bridged audio power amplifier with

DC voltage volume control. The LM4875 is capable of deliv-

ering 750mW of continuous average power into an 8

Ω load

with less than 1% THD when powered by a 5V power supply.

Switching between bridged speaker mode and headphone

(single ended) mode is accomplished using the headphone

sense pin. To conserve power in portable applications, the

LM4875’s micropower shutdown mode (I

activated when less than 300mV is applied to the DC Vol/SD

pin.

Boomer audio power amplifiers are designed specifically to

provide high power audio output while maintaining high fidel-

ity. They require few external components and operate on

low supply voltages.

Applications

n

GSM phones and accessories, DECT, office phones

n

Hand held radio

n

Other portable audio devices

Key Specifications

Ω

750mW (typ)

Ω

1W (typ)

0.7µA(typ)

2.7V to 5.5V

Features

n

Precision DC voltage volume control

n

Headphone amplifier mode

n

“Click and pop” suppression

n

Shutdown control when volume control pin is low

n

Thermal shutdown protection

Typical Application

Connection Diagram

Small Outline Package (SO)

Mini Small Outline Package (MSOP)

10104202

Top View

Order Number LM4875M, LM4875MM

See NS Package Number M08A, MUA08A

10104201

FIGURE 1. Typical Audio Amplifier

Application Circuit

January 2002

© 2004 National Semiconductor Corporation

DS101042

www.national.com