DATASHEET ISL97635 FN6434 Rev.3.00 SMBus 8-Channel LED Driver Sep 26, 2017 The ISL97635 is a digitally controlled LED driver that controls 8 Features channels of LED current for LCD backlight applications. The 8 channels ISL97635 is capable of driving typically 72 (8x9) pieces of 3.5V/30mA or 80 (8x10) pieces of 3.2V/20mA LEDs. The 6V to 24V input ISL97635s 8 channels of voltage controlled current sources 34.5V output maximum with typical currents matching of 1%, which compensate for Drive maximally 72 (3.5V/30mA each) or 80 (3.2V/20mA the non-uniformity effect of forward voltages variance in the each) LEDs LED stacks. To minimize the voltage headroom and power loss in the typical multi-strings operation, the ISL97635 features a Current matching 1% typical dynamic headroom control that monitors the highest LED Dynamic headroom control forward voltage string and uses its feedback signal for output regulation. Dimming controls - SMBus 8-bit PWM current control The LED dimming control can be achieved through a SMBus, - SMBus 8-bit DC current control an external PWM, or a variable DC (analog light sensor) input. SMBus controlled dimming allows 256 levels each of PWM - External PWM input up to 20kHz dimming and DC current adjustments. The SMBus PWM dimming - SMBus and external PWM DPST dimming control frequency can be adjusted from 100Hz to 5kHz by an external - DC-to-PWM dimming control capacitor. External PWM input allows up to 20kHz audio noise Protections free PWM dimming. The SMBus PWM setting and an external PWMI signal can also be combined to provide a dynamic PWM - String open circuit detection dimming that complies with Intels DPST (Display Power - String short-circuit detection with selectable thresholds Saving Technology) requirement. - Over-temperature protection One or more channels can be selected sequentially in any - Overvoltage protection order, allowing scrolling in RGB LED backlighting applications. - Input overcurrent protection with disconnect switch The ISL97635 features extensive protection functions that 600kHz/1.2MHz selectable f SW include string open and short-circuit detections, OVP, OTP, Selectable channels allows scrolling backlight thermal shutdown, and an optional input overcurrent protection with master fault disconnect switch. The fault 24 Ld (4mmx4mm) QFN package conditions will be recorded in the Fault/Status register. There Pb-free (RoHS compliant) are selectable short-circuit thresholds and the switching frequency can be programmed between 600kHz and 1.2MHz. Applications Available in the 24 Ld 4mmx4mm QFN, the ISL97635 Notebook displays WLED or RGB LED backlighting operates from -40C to +85C with input voltage ranging from LCD monitor LED backlighting 6V to 24V. Automotive displays LED backlighting Related Literature Automotive or traffic lighting For a full list of related documents, visit our website - ISL97635 product page FN6434 Rev.3.00 Page 1 of 28 Sep 26, 2017ISL97635 Ordering Information PACKAGE PKG. PART NUMBER (Notes 1, 2, 3)PART MARKING (RoHS COMPLIANT) DWG. ISL97635IRZ 976 35IRZ 24 Ld 4x4 QFN L24.4x4D NOTES: 1. Add -T suffix for 6k unit or -TK suffix for 1k unit tape and reel options. Refer to TB347 for details on reel specifications. 2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 3. For Moisture Sensitivity Level (MSL), see product information page for ISL97635. For more information on MSL, see tech brief TB363. Typical Application Circuit VBL+ = 6V TO 24V V = 34.5V, 30mA PER STRING OUT ISL97635 LX 19 21 FAULT LX 20 23 OVP 16 VIN 24 PGND VDC 17 PGND 18 22 IIN0 15 COMP 1 SMBCLK IIN1 14 2 SMBDAT IIN2 13 6 IIN3 PWMI/EN 12 PWMO 4 IIN4 10 11 IIN5 9 RSET IIN6 8 3 FPWM IIN7 7 5 GND FIGURE 1. Typical Application Circuit FN6434 Rev.3.00 Page 2 of 28 Sep 26, 2017