
Allegro MicroSystems
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.
FEATUREs and Benefits
▪ 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 30 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
APPLICATIONs include:
▪ Thin notebook displays
▪ LCD TV
▪ RGB backlight
▪ GPS systems
▪ Portable DVD players