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High-Performance Power ICs and Hall-Effect Sensors

A8500
Flexible WLED/RGB Backlight Driver for Medium Size LCDs

Pin-Out or Package

Features

  • Active current sharing between LED strings for ±1.5% typical current matching and ±1.2% typical accuracy
  • Drive up to 12 series × 8 parallel = 96 LEDs (Vf = 3.2 V, If = 20 mA)
  • Flexible dimming, using alternative methods:
    • LED duty cycle control (PWM pin)
    • DC current using serial programming (EN pin)
    • DC current using external PWM signal (APWM pin)
    • An external resistor
  • Boost converter with integrated 50 V, 2 A DMOS
  • LED sinks rated for 25 mA
  • 200 kHz to 2 MHz switching frequency
  • Open LED disconnect
  • Boost current limit, thermal shutdown, and soft start
  • No audible ceramic capacitor noise during PWM dimming
  • Adjustable overvoltage protection (OVP)
  • No pull-up resistors required for LED modules that use ESD capacitors

Pb (lead) free

Description

The A8500 is a multi-output WLED driver for medium display backlighting. The A8500 integrates a boost converter and eight current-sinks to provide a flexible WLED/RGB backlight driver. The boost converter can provide output voltage up to 47 V. The flexible channel selection control and high voltage capability allow a wide range of LED backlight applications. The A8500 can support any application requiring 4 to 96 WLEDs. The boost converter is a constant frequency current-mode converter.

Each LED channel can sink 25 mA, and channels can be paralleled for higher currents. Flexible dimming allows output channels to either run at an adjustable DC value or with externally controlled PWM duty cycles.

The A8500 is available in a 26 pin, 4 mm × 4 mm QFN/MLP package that is only 0.75 mm nominal in height. Applications include:

  • Thin notebook displays
  • LCD TV
  • RGB backlight
  • GPS systems
  • Portable DVD players

Functional Block Diagram

Functional Block Diagram

Complete Part Numbers
Part Number Package Type RoHS
Compliant
Part Composition/
RoHS Data
Temperature Comments Samples Distributor Stock
A8500EECTR-T 26-lead QFN/MLP Yes view data -40 °C to  85 °C contact factory   Contact Marketing Representative

Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system.

Copyright © 2008 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Worcester, MA 01606 USA Phone: 1.508.853.5000 Fax: 1.508.853.7895