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 is 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. The ISL97678 features PWM dimming up to 30kHz with 0.4%~100% duty cycle and maintains ±1% current matching across all ranges. The PWM dimming frequency can be adjusted between 100Hz and 30kHz. The boost switching frequency can also be adjusted between 600kHz and 1.5MHz. The ISL97678 features extensive protection functions that include string open and short circuit detections, OVP, and OTP. ISL97678 is available in the 32 Leads QFN 5mmx5mm and operate from -40°C to +85°C with input voltage ranges from 4.75V to 26V.
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
String Open Circuit and Short Circuit Detections, OVP, and OTP