DATASHEET ISL97687 FN7714 Rev.4.00 4-Channel LED Driver with Phase Shift Control and 10-Bit Dimming Resolution Jun 7, 2019 The ISL97687 is a PWM controlled LED driver that supports Features four channels of LED current, for Monitor and TV LCD backlight 4x160mA, 75V rated channels with integrated channel applications. It is capable of driving 160mA per channel from a regulation FETs 9V to 32V input supply, with current sources rated up to 75V absolute maximum. Channels can be ganged for high current -2x350mA The ISL97687s current sources achieve typical current -1x700mA matching to 1%, while dynamically maintaining the 9V~32V input voltage minimum required V necessary for regulation. This adaptive OUT scheme compensates for the non-uniformity of forward Dimming modes: voltage variance in the LED strings. - Direct PWM dimming from 100Hz~30kHz - PWM dimming with adjustable output frequency The ISL97687 can decode both an incoming PWM signal and an analog input voltage, for DC-to-PWM dimming applications. - 10-bit dimming resolution Modes include direct PWM and several modes where the PWM -V function to synchronize PWM signal to frame SYNC frequency is synthesized on chip at 10-bit resolution. This can rate be either free running, or synchronized with the frame rate to - Phase shift give both a frequency and a phase lock, minimizing panel to - Analog to PWM dimming with 8-bit resolution panel variation and display flicker. Phase shift is supported, 2 selectable current levels for 3D applications reducing flicker and audio noise, as is multiplication of the Current matching of 1% incoming decoded analog and PWM values. Integrated fault protection features such as string open The ISL97687 has an advanced dynamic headroom control circuit protection, string short-circuit protection, overvoltage function that monitors the highest LED forward voltage string, protection, and over-temperature protection and regulates the output to the correct level to minimize power 28 Ld 5mmx5mm TQFN and 28 Ld 300mil SOIC packages loss. This proprietary regulation scheme also allows for available extremely linear PWM dimming from 0.02% to 100%. The LED current can also be switched between two current levels, giving Applications support for 3D applications. The ISL97687 incorporates Monitor/TV LED backlighting extensive protections of string open and short-circuit General/industrial/automotive lighting detections, OVP, and OTP. Related Literature For a full list of related documents, visit our website: ISL97687 device page VIN: 9V~32V FUSE 160mA MAX PER STRING D1 VIN 110 SLEW VDC Q1 100 I CH2 GD VLOGIC CS EN 90 I CH3 R STV SENSE 80 PGND EN VSYNC I CH1 EN ADIM 70 COMP PWMI I CH4 60 ACTL OVP 50 EN PS 40 CSEL ISET1 30 CH1 ISET2 CH2 20 CH3 OSC CH4 10 PWM SET/PLL 0 20 40 60 80 100 0 DIMMING DUTY CYCLE (%) FIGURE 1. ISL97687 APPLICATION DIAGRAM FIGURE 2. PWM DIMMING LINEARITY FN7714 Rev.4.00 Page 1 of 25 Jun 7, 2019 CHANNEL CURRENT (mA)ISL97687 Table of Contents Overview . 3 Block Diagram 3 Ordering Information .4 Pin Configurations .4 Pin Descriptions .5 Absolute Maximum Ratings . 6 Thermal Information . 6 Operating Conditions 6 Electrical Specifications . 6 Typical Performance Curves . 8 Theory of Operation . 11 PWM Boost Converter 11 OVP and VOUT 11 Current Matching and Current Accuracy . 11 Dynamic Headroom Control . 11 Dimming Controls . 11 LED DC Current Setting . 11 PWM Dimming Frequency Adjustment 13 Phase Shift Control 13 V Control when LEDs are Off 14 OUT Switching Frequency . 14 5V and 2.4V Low Dropout Regulators . 14 Soft-Start and Boost Current Limit . 14 Fault Protection and Monitoring . 14 Short-Circuit Protection (SCP) . 15 Open Circuit Protection (OCP) . 15 Undervoltage Lockout 15 Over-Temperature Protection (OTP) 15 Shutdown 15 Component Selections 16 Input Capacitor 16 Inductor 17 Output Capacitors . 17 Channel Capacitor . 17 Schottky Diode 17 High Current Applications . 17 PCB Layout Considerations 18 Two Layers PCB Layout with TQFN Package . 18 General Power PAD Design Considerations 18 One Layer PCB Layout with SOIC Package . 18 Equivalent Circuit Diagrams 21 Revision History 22 Package Outline Drawings . 23 FN7714 Rev.4.00 Page 2 of 25 Jun 7, 2019