LM4817

1W Stereo Audio Amplifier Plus Adjustable Output

Limiter Plus Adjustable LDO

General Description

The LM4817 combines a bridge-connected (BTL) stereo

audio power amplifier with a low dropout voltage regulator

(LDO). The audio amplifier delivers 1.0W to a 8

Ω load with a

less than 1.0% THD+N while operating on a 5V power

supply. With V

clamped to 6V

With the LM4817’s adjustable low-dropout (LDO) CMOS

linear regulator delivers an output current of up to 300mA,

has shutdown mode (1nA, typ) low quiescent current (90µA,

typ) and LDO voltage (120mV, typ). The regulator is stable

with small ceramic capacitive load (2.2µF, typ). The regulator

includes regulation fault detection, a bandgap voltage refer-

ence, and constant current limiting. It is designed for low

power, low current applications that can take advantage of

its 300mA output current capability.

The LM4817 features an externally controlled micropower

shutdown mode and thermal shutdown protection. It also

utilizes circuitry that reduces "clicks and pops" during device

turn-on and return from shutdown.

Boomer audio power amplifiers are designed specifically to

use few external components and provide high quality output

power in a surface mount package.

Key Specifications

n

P

≤ 1%, R

Ω 1.0W(typ)

n

Power supply range (amplifier)

3.0V to 5.5V

n

Power supply range (LDO)

2.5V to 6.0V

n

Shutdown current

0.07µA (typ)

n

LDO output current

300mA (min)

n

LDO dropout voltage (I

120mV (typ)

n

LDO quiescent supply current

90µA (typ)

n

LDO shutdown supply current

1nA (typ)

n

LDO PSRR

60dB

n

LDO turn-on time

120ms (typ)

n

LDO ouput noise-voltage

37µV

Features

n

Stereo BTL amplifier

n

Adjustable output voltage magnitude limiter

n

Adjustable LDO regulator

n

“Click and pop” suppression circuitry

n

LDO is stable with small-value ceramic output capacitors

n

Unity-gain stable audio amplifiers

n

LDO has over-current protection

n

Thermal shutdown protection circuitry

n

TSSOP (MH) package

Applications

n

Multimedia monitors

n

Portable and desktop computers

n

Portable televisions

Connection Diagram

20078129

Top View

Order Number LM4817MH

See NS Package Number MXA28A for TSSOP

March 2004

© 2004 National Semiconductor Corporation

DS200781

www.national.com