The ISL97635A is a digitally controlled LED driver that
controls 6 channels of LED current for LCD backlight
applications. The ISL97635A is capable of driving typically
54 (6x9) pieces of 3.5V/30mA or 60 (6x10) pieces of
3.2V/20mA LEDs. The ISL97635A contains 6 channels of
voltage controlled current sources with typical currents
matching of ±1%, which compensate for the non-uniformity
effect of forward voltages variance in the LED stacks. To
minimize the voltage headroom and power loss in the typical
multi-strings operation, the ISL97635A features a dynamic
headroom control that monitors the highest LED forward
voltage string and uses its feedback signal for output
regulation.
The LED dimming control can be achieved through a
SMBus, an external PWM, or a variable DC (analog light
sensor) input. SMBus controlled dimming allows 256 levels
each of PWM and DC current adjustments. The SMBus
PWM dimming frequency can be adjusted from 100Hz to
5kHz by an external capacitor. External PWM input allows up
to 20kHz audio noise free PWM dimming. The SMBus PWM
setting and an external PWMI signal can also be combined
to provide a dynamic PWM dimming that complies with
Intel’s DPST (Display Power Saving Technology)
requirement.
One or more channels can be selected sequentially in any
order allowing scrolling in RGB LED backlighting
applications.
The ISL97635A features extensive protection functions that
include string open and short circuit detections, OVP, OTP,
thermal shutdown and an optional input overcurrent
protection with master fault disconnect switch. The fault
conditions will be recorded in the Fault/Status register. There
are selectable short-circuit thresholds and the switching
frequency can be programmed between 600kHz and
1.2MHz.
Available in the 24 Ld 4mmx4mm QFN, the ISL97635A
operates from -40°C to +85°C with input voltage ranging
from 6V to 24V for high LEDs count applications.

Features
• 6 Channels
• 6V to 24V Input
• 34.5V Output Max
• Drive Maximally 54 (3.5V/30mA each) or 60 (3.2V/20mA
each) LEDs
• Current Matching ±1% Typ
• Dynamic Headroom Control
• Dimming Controls
- SMBus 8-Bit PWM Current Control
- SMbus 8-Bit DC Current Control
- External PWM Input up to 20kHz Dimming
- SMBus and External PWM DPST Dimming Control
- DC-to-PWM Dimming Control
• Protections
- String Open Circuit Detection
- String Short Circuit Detection with Selectable
Thresholds
- Over-Temperature Protection
- Overvoltage Protection
- Input Overcurrent Protection with Disconnect Switch
• 600kHz/1.2MHz Selectable fSW
• Selectable Channels Allows Scrolling Backlight
• 24 Ld (4mmx4mm) QFN Package
• Pb-Free (RoHS Compliant)

Applications
• Notebook Displays WLED or RGB LED Backlighting
• LCD Monitor LED Backlighting
• Automotive Displays LED Backlighting
• Automotive or Traffic Lighting