LM4941

1.25 Watt Fully Differential Audio Power Amplifier With

RF Suppression and Shutdown

General Description

The LM4941 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 1.25 watts of continuous

average power to a 8

Ω load with less than 1% distortion

(THD+N) from a 5V

require output coupling capacitors or bootstrap capacitors,

and therefore is ideally suited for mobile phone and other low

voltage applications where minimal power consumption is a

primary requirement.

The LM4941 also features proprietary internal circuitry that

suppresses the coupling of RF signals into the chip. This is

important because certain types of RF signals (such as

GSM) can couple into audio amplifiers in such a way that

part of the signal is heard through the speaker. The RF

suppression circuitry in the LM4941 makes it well-suited for

portable applications in which strong RF signals generated

by an antenna from or a cellular phone or other portable

electronic device may couple audibly into the amplifier.

Other features include a low-power consumption shutdown

mode, internal thermal shutdown protection, and advanced

pop & click circuitry.

Key Specifications

95dB (typ)

Ω)

1.25W (typ)

550mW (typ)

0.1µA (typ)

Features

n

Improved RF suppression, by up to 20dB over previous

designs in selected applications

n

Fully differential amplification

n

Available in space-saving micro SMD package

n

Ultra low current shutdown mode

n

Can drive capacitive loads up to 100pF

n

Improved pop & click circuitry eliminates noises during

turn-on and turn-off transitions

n

2.4 - 5.5V operation

n

No output coupling capacitors, snubber networks or

bootstrap capacitors required

Applications

n

Mobile phones

n

PDAs

n

Portable electronic devices

Typical Application

20170303

FIGURE 1. Typical Audio Amplifier Application Circuit

June 2006

© 2006 National Semiconductor Corporation

DS201703

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