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The ISL97635 is a digitally controlled LED driver thatcontrols 8 channels of LED current for LCD backlightapplicaTIons. The ISL97635 is capable of driving typically 72(8x9) pieces of 3.5V/30mA or 80 (8x10) pieces of3.2V/20mA LEDs. The ISL97635’s 8 channels of voltagecontrolled current sources with typical currents matching of±1%, which compensate for the non-uniformity effect offorward voltages variance in the LED stacks. To minimize thevoltage headroom and power loss in the typical mulTI-stringsoperaTIon, the ISL97635 features a dynamic headroomcontrol that monitors the highest LED forward voltage stringand uses its feedback signal for output regulaTIon.The LED dimming control can be achieved through aSMBus, an external PWM, or a variable DC (analog lightsensor) input. SMBus controlled dimming allows 256 levelseach of PWM and DC current adjustments. The SMBusPWM dimming frequency can be adjusted from 100Hz to5kHz by an external capacitor. External PWM input allows upto 20kHz audio noise free PWM dimming. The SMBus PWMsetting and an external PWMI signal can also be combinedto provide a dynamic PWM dimming that complies withIntel’s DPST (Display Power Saving Technology)requirement.
