LM4873

Dual 2.1W Audio Amplifier Plus Stereo Headphone

Function

General Description

The LM4873 is a dual bridge-connected audio power ampli-

fier which, when connected to a 5V supply, will deliver 2.1W

toa4

Ω load (Note 1) or 2.4W to a 3Ω load (Note 2)with less

than 1.0% THD+N. In addition, the headphone input pin al-

lows the amplifiers to operate in single-ended mode to drive

stereo headphones. A Mux Control pin toggles between the

two stereo sets of amplifier inputs, allowing for two select-

able amplifier closed-loop responses.

Boomer audio power amplifiers were designed specifically to

provide high quality output power from a surface mount

package while requiring few external components. To sim-

plify audio system design, the LM4873 combines dual bridge

speaker amplifiers and stereo headphone amplifiers on one

chip.

The LM4873 features an externally controlled, low-power

consumption shutdown mode, a stereo headphone amplifier

mode, and thermal shutdown protection. It also utilizes cir-

cuitry to reduce “clicks and pops” during device turn-on.

Note 1: An LM4873MTE-1 which has been properly mounted to the circuit

board will deliver 2.1W into 4

Ω. The other package options for the LM4873

will deliver 1.1W into 8

Ω. See the Application Information section for

LM4873MTE-1 usage information.

Note 2: An LM4873MTE-1 which has been properly mounted to the circuit

board and forced-air cooled will deliver 2.4W into 3

Ω.

Key Specifications

n

P

into 3

Ω (LM4873MTE-1)

2.4W(typ)

into 4

Ω (LM4873MTE-1)

2.1W(typ)

into 4

Ω (LM4873MTE)

1.9W(typ)

into 8

Ω (LM4873)

1.1W(typ)

n

Single-ended mode - THD+N

at 75mW into 32

Ω

0.5%(max)

n

Shutdown current

0.7µA(typ)

Features

n

Input mux control and two separate inputs per channel

n

Stereo headphone amplifier mode

n

“Click and pop” suppression circuitry

n

Thermal shutdown protection circuitry

n

Exposed-DAP TSSOP and TSSOP packaging available

Applications

n

Multimedia monitors

n

Portable and desktop computers

n

Portable audio systems

Typical Application

DS100993-31

FIGURE 1. Typical Audio Amplifier Application Circuit

April 2000

© 2000 National Semiconductor Corporation

DS100993

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