- 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
- String Open Circuit and Short Circuit Detections, OVP, and OTP
- Adjustable Dimming Frequency
- Adjustable Switching Frequency
- 32 Ld (5mmx5mm) QFN Package
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.
- Notebook Displays WLED or RGB LED Backlighting
- LCD Monitor LED Backlighting
|# of Devices/ Channels||8||6||6||8|
|Total Current for DC/DC Lighting||400 mA||300 mA||300 mA||280 mA|
|Output Current Max/Channel||50 mA||50 mA||50 mA||35 mA|
|VOUT (max) (V)||45||45||45||34.5|
|VIN (max) (V)||26||26.5||26.5||24|
|VIN (min) (V)||4.75||4.5||4.5||6|
|Backlight for LCD Size (min)||0 in||0 in||0 in||0 in|
|Backlight for LCD Size (max)||17 in||17 in||17 in||17 in|
|Peak Efficiency (%)||93.4||92.9||92.9||91|
|# of LEDs (max)||96||78||78||80|
|Frequency||1.5 MHz||0.6/1.2 MHz||0.6/1.2 MHz||1.2 MHz|
|IS (max)||10 mA||5 mA||5 mA||10 mA|
|IQ (max)||5 µA||5 µA||5 µA||20 µA|
|ISW (typ)||3800 mA||2000 mA||2000 mA||2500 mA|
|Over Voltage Protection||Yes||Yes||Yes||Yes|
|Topologies||Inductor Boost||Inductor Boost||Inductor Boost||Inductor Boost|