8-Channel 45V, 50mA LED Driver

The ISL97678 is an 8-channel PWM dimming LED driver for LCD backlight applications. The ISL97678 is capable of driving up to 96 pieces of 3.4V/50mA LEDs but larger numbers of LEDs are possible if the LED forward voltage combined is less than 45V. The ISL97678 has 8 channels of voltage controlled current sources with typical currents matching to ±1, which compensate for the non-uniformity effect of forward voltages variance in the LED strings. To minimize the voltage headroom and power loss in the typical multi-string operation, the ISL97678 features dynamic headroom control that monitors the highest LED forward voltage string and uses its feedback signal for output regulation.

Features

• 8 channels

• 4.75V ~ 26V input

• 45V maximum output

• Drive typically 96 LEDs (3.4V/50mA each)

• External PWM input up to 20kHz dimming

• Dimming range 0.4~100 up to 30kHz

• Current matching ±0.7 typical

• Protections

- String open circuit and short circuit detections, OVP, and OTP

• Adjustable dimming frequency

• Adjustable switching frequency

• 32 Ld (5mmx5mm) QFN package

Applications

• Notebook displays WLED or RGB LED backlighting

• LCD monitor LED backlighting