RD-168: Ambient Light Adaptive, 100mA @ 20V Max, 6 ~ 12V in

Summary

The ambient light adaptive LED driver automatically adjusts display brightness for changing ambient light conditions, providing a more viewable display with better contrast. The design drives five series connected LEDs from an input voltage of 4.5V to 12V. The LED current is nominally 100mA and the output voltage is 15 to 20V.

The heart of the design is National’s PowerWise® LM3423 LED driver which has all the features needed to implement a boost converter with output current regulation and PWM dimming of the current. The LM3423 achieves output current regulation by sensing and appropriately adjusting the voltage across a resistor connected in series with the LED string.

Specifications

Manufacturer Texas Instruments
Category Lighting
Sub-Category LED Drivers - DC In
Eval Board Board not Stocked
Voltage In 6 ~ 12 V
Topology Step Up
Current Out 100 mA
Voltage Out (Max) 20 V
Outputs and Type 1 Non-Isolated
Efficiency @ Conditions >84%, 6 ~ 12V in, 15 ~ 20 @ 100 mA
Features Ambient Light Adaptive
Switching Frequency 300 kHz
Component Count + Extras 55 + 4
Design Author Texas Instruments
Application / Target Market Audio: MP3 Players
Cell Phones
Portable Devices
Main I.C. Base Part LM3423
Date Created By Author
Date Added To Library 2011-03

Support Documents & Media

RD-168 - User Guilde LM3423 - User Guide - App Note AN-1872 Ultra Librarian Software:CAD Symbols and Footprints (Zip File) TI's CAD/CAE Symbols and Footprint Search

Media

RD_168_Schematic.JPG RD_168_Board.JPG