LP3933

Lighting Management System for Six White LEDs and

Two RGB or FLASH LEDs

General Description

The LP3933 is a complete lighting management system

designed for portable wireless applications. It contains a

boost DC/DC converter, 4 white-LED drivers to drive the

main LCD panel backlight, 2 white-LED drivers for the sub-

LCD panel and two sets of RGB/FLASH LED drivers.

Both backlight drivers have 8-bit constant current drivers that

are separately adjustable and matched to 0.5% (typ.). The

RGB LED drivers are PWM-driven with programmable color,

intensity and blinking patterns. In addition, they feature a

FLASH function to support picture taking with camera-

enabled cellular phones.

An efficient magnetic boost DC/DC converter provides the

required bias for LEDs, operating from a single Li-Ion bat-

tery. The DC/DC converter output voltage is user program-

mable from 4.1V to 5.3V for adapting to different LED types

and for efficiency optimization. All functions are software

controllable through a SPI interface and 19 internal registers.

Features

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High Efficiency Programmable 300 mA Magnetic Boost

DC-DC converter

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2 separately controlled PWM RGB LED drivers with

programmable color, brightness, turn on/off slopes and

blinking patterns

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FLASH function with up to 6 outputs, each up to 120

mA

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4 constant current LED drivers with programmable 8-bit

adjustment (0 … 25 mA/LED)

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2 constant current LED drivers with programmable 8-bit

adjustment (0 … 25 mA/LED)

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Functions software controlled through SPI interface

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Additional LED on/off and dimming hardware control

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Programmable low current Standby mode

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Low voltage digital interface down to 1.8V

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Space efficient 32-pin thin CSP laminate package

Applications

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Cellular Phones

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PDAs

Typical Application

20080505

March 2004

© 2004 National Semiconductor Corporation

DS200805

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