LP3936

Lighting Management System for Six White LEDs and

One RGB or FLASH LED

General Description

LP3936 is a complete lighting management system de-

signed 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 sub-LCD panel and

1 set of RGB LED drivers.

Both WLED groups have 8-bit programmable constant cur-

rent drivers that are separately adjustable and matched to

1% (typ.). For efficient backlighting the backlight intensity

can be adjusted using the 8-bit ADC with ambient light

detection circuit.

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 converter provides the required

bias operating from a single Li-Ion battery. The DC/DC con-

verter output voltage is user programmable for adapting to

different LED types and for efficiency optimization. All func-

tions

are

software

controllable

through

an

I

MicroWire/SPI compatible interface and 16 internal regis-

ters.

Features

n

High Efficiency 250 mA Magnetic Boost DC-DC

Converter with Programmable Output Voltage

n

PWM controlled RGB LED drivers with programmable

color, brightness, turn on/off slopes and blinking

n

FLASH function with 3 drivers, each up to 120 mA

current

n

4 constant current White LED drivers with

programmable 8-bit adjustment (0 … 25 mA/LED)

n

2 constant current White LED drivers with

programmable 8-bit adjustment (0 … 25 mA/LED)

n

8-bit ADC for ambient light sensor with averaging

n

Combined MicroWire/SPI and I

interface

n

Low current Standby mode (software controlled)

n

Low voltage digital interface down to 1.8V

n

Space efficient 32-pin thin CSP laminate package

Applications

n

Cellular Phones

n

PDAs

Typical Application

20081401

June 2004

© 2004 National Semiconductor Corporation

DS200814

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