LM4929

Stereo 40mW Low Noise Headphone Amplifier

with OCL Output

General Description

The LM4929 is an stereo audio power amplifier capable of

delivering 40mW per channel of continuous average power

into a 16

Ω load or 25mW per channel into a 32Ω load at 1%

THD+N from a 3V power supply.

Boomer audio power amplifiers were designed specifically to

provide high quality output power with a minimal amount of

external components. Since the LM4929 does not require

bootstrap capacitors or snubber networks, it is optimally

suited for low-power portable systems. The LM4929 is con-

figured for OCL (Output Capacitor-Less) outputs, operating

with no DC blocking capacitors on the outputs.

The LM4929 features a low-power consumption shutdown

mode with a faster turn on time. Additionally, the LM4929

features an internal thermal shutdown protection mecha-

nism.

The LM4929 is unity gain stable and may be configured with

external gain-setting resistors.

Key Specifications

65dB (typ)

1% THD+N into a 16

Ω load

25mW (typ)

1% THD+N into a 16

Ω load

40mW (typ)

2.0µA (max)

from Shutdown V

Ω

1mV (max)

Features

n

OCL outputs — No DC Blocking Capacitors

n

External gain-setting capability

n

Available in space-saving MSOP package

n

Ultra low current shutdown mode

n

2V - 5.5V operation

n

Ultra low noise

Applications

n

Portable CD players

n

PDAs

n

Portable electronics devices

Block Diagram

20132441

FIGURE 1. Block Diagram

December 2004

© 2004 National Semiconductor Corporation

DS201324

www.national.com