LM4840

Stereo 2W Audio Power Amplifiers

with Digital Volume Control and Input Mux

General Description

The LM4840 is a monolithic integrated circuit that provides

digital volume control and stereo bridged audio power am-

plifiers capable of producing 2W into 4

Ω (Note 1) with less

than 1.0% THD or 2.2W into 3

Ω (Note 2) with less than 1.0%

THD.

to provide high quality audio while requiring a minimum

amount of external components. The LM4840 incorporates a

digital volume control, stereo bridged audio power amplifiers,

an input mux, and a last volume level memory function to

save the volume setting during shutdown. These features

make it optimally suited for multimedia monitors, portable

radios, desktop, and portable computer applications.

The LM4840 features an externally controlled, low-power

consumption shutdown mode, and both a power amplifier

and headphone mute for maximum system flexibility and

performance.

Note 1: When properly mounted to the circuit board, the LM4840LQ and

LM4840MH will deliver 2W into 4

Ω. The LM4840MT will deliver 1.1W into 8Ω.

See the Application Information section LM4840LQ and for LM4840MH us-

age information.

Note 2: An LM4840LQ and LM4840MH that have been properly mounted to

the circuit board and forced-air cooled will deliver 2.2W into 3

Ω.

Key Specifications

n

P

n

into 3

Ω (LM4840LQ, LM4840MH)

2.2W (typ)

n

into 4

Ω (LM4840LQ, LM4840MH)

2.0W (typ)

n

into 8

Ω (LM4840)

1.1W (typ)

n

Single-ended mode - THD+N at 85mW into 32

Ω

1.0%

(typ)

n

Shutdown current

0.2µA (typ)

Features

n

PC98 and PC99 Compliant

n

Digital Volume Control Interface

n

System Beep Detect

n

Stereo switchable bridged/single-ended power amplifiers

n

“Click and pop” suppression circuitry

n

Thermal shutdown protection circuitry

n

Input Mux

n

Capless headphone drivers

n

Last volume memory from shutdown

Applications

n

Portable and Desktop Computers

n

Multimedia Monitors

n

Portable Radios, PDAs, and Portable TVs

Connection Diagram

LLP Package

DS200104-35

Top View

Order Number LM4840LQ

See NS Package Number LQA028A for Exposed-DAP LLP

December 2001

© 2001 National Semiconductor Corporation

DS200104

www.national.com