
Allegro MicroSystems
Description
The A8501 is a multioutput WLED/RGB driver for backlighting medium-size displays. The A8501 integrates a boost converter and four 100 mA current sinks. LED channels can be tied together for up to 400 mA sink capability. It can work from a single power supply of 8 to 21 V and withstand up to 40 V. The boost converter is a constant frequency, current-mode converter
FEATUREs and Benefits
▪ 600 kHz to 2.2 MHz switching frequency—ability to operate above the AM band
▪ Internal bias supply for single-supply operation (VIN = 8 to 21 V)
▪ Boost converter with integrated 40 V DMOS switch and OVP–load-dump protection
▪ 3.5 μA shutdown current—limits battery drain
▪ Active current sharing between LED strings for 0.8% current matching and 0.7% accuracy
▪ Drive up to 9 series LEDs in 4 parallel strings, 36 LEDs maximum (Vf = 3.5 V, If = 100 mA)
▪ LED sinks rated for 100 mA each (400 mA total)
▪ PWM dimming with LED PWM duty cycle control
▪ 4000:1 dimming range
▪ Extensive fault mode protection schemes:
▫ Shorted LED protection against misconnected loads—with true output disconnect
▫ Open LED disconnect protects against LED failures
▫ External thermistor sensing to limit LED temperature
▫ Output overvoltage protection (OVP): 19.5 V default can be adjusted as high as 38 V
▫ Open Schottky and open OVP resistor protection against external component failure
▫ Input under- and overvoltage protection (UVLO and OVLO) against VIN variation
▫ Boost current limit, output short circuit limit, overtemperature protection (OTP), and soft start
APPLICATIONs include:
▪ GPS navigation systems
▪ Automotive infotainment
▪ Back-up camera displays
▪ Cluster backlighting
▪ Portable DVD players
▪ Industrial LCD displays