LP55271

Tiny LED Driver for Camera Flash and 4 LEDs with I

Programmability, Connectivity Test and Audio

Synchronization

General Description

The LP55271 is a lighting management unit for handheld

devices with I

has a step-up DC/DC converter with high current output and

it drives display and keypad backlights and powers the cam-

era flash LED. In addition the DC/DC converter has the

output current to power for example an audio amplifier si-

multaneously. The chip has four 8-bit programmable high

efficiency constant current LED drivers and a FLASH LED

driver. Built-in audio synchronization feature allows the user

to synchronize one of the LEDs to audio input.

The LP55271 has an integrated 370 mA flash driver with a

safety stop feature and 46 mA torch mode. An external

enable pin is provided for the synchronizing the flash with the

camera action. An external software independent test inter-

face provides a fast way to find a broken path or short on

LED circuits. Very small microSMD package together with

minimum number of external components is a best fit for

handheld devices.

Features

n

High current boost DC-DC converter (up to 1A output

current)

n

Programmable boost output voltage

n

370 mA flash LED constant current driver with low

tolerance and a safety circuit

n

Synchronization pin for the flash timing

n

Two single-ended audio inputs with gain control

n

Four constant current 15 mA LED drivers with 8-bit

programmable brightness control

n

Audio synchronization feature

n

I

n

Built-in LED connectivity test to maximize manufacturing

yield

n

Small microSMD-30 package (2.5 mm x 3.0 mm x 0.6

mm)

Applications

n

Camera FLASH, funlight and backlight driving in battery

powered devices

Typical Application

20202401

September 2006

© 2006 National Semiconductor Corporation

DS202024

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