AN-1442| Application Note

Design and Programming Examples for Lighting Management Unit LP5526

Design and Programming Examples for Lighting Management Unit LP5526
Introduction
This document provides information for customers who are using LP5526. The document is written to help design, layout and software engineers and thus reduce the time needed for successful design. The first chapter describes the basic ideas of LP5526 with a few example solutions that utilize the main features. Example LED configurations are presented. The functionality of the part is introduced in the default and programmable modes together with example schematics and programming examples.

National Semiconductor Application Note 1442 Tomi Koskela January 2007

The second chapter introduces the layout guide. A 4-layer layout is shown and the critical layout rules are explained. Chapter three presents the recommended external components and constraints. An Evaluation Kit including the evaluation board and the PC interface software is available.

1. LP5526 Application
GENERAL SYSTEM OVERVIEW LP5526 is a Lighting Management Unit for portable applications. It is used to drive display backlight, keypad LEDs, color LEDs and Flash LEDs. The device can drive 2 separately connected strings of LEDs with high voltage boost converter. The RGB driver allows driving either individual color LEDs or RGB LED from separate supply voltage, or it can be used to drive FLASH LEDs. The MAIN and SUB outputs are high resolution current mode drivers. RGB outputs can be used in switch mode and current mode. PWM control can be used for any selected outputs. The device is controlled through 2-wire low voltage I2C compatible interface that reduces the number of required connections. LP5526 is offered in a tiny microSMD-25 package (2.54 mm x 2.54 mm). FEATURES High efficiency high voltage boost converter with programmable output voltage 2 individual drivers for serial display backlight LEDs Automatic dimming controller Stand alone RGB controller Dedicated FLASH function Safety feature to
avoid prolonged Flash 3 general purpose IO pins microSMD-25 Package: (2.54 mm x 2.54 mm x 0.6 mm) APPLICATIONS Cellular Phones and PDAs MP3 players Digital cameras

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Fig 1. LP5526 Typical Application. RGB drivers driving FLASH LED.

2007 National Semiconductor Corporation

201798

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