Overview

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 are 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. The ISL97678 is available in the 32 Ld QFN 5mmx5mm and operates from -40°C to +85°C with input voltage ranges from 4. 75V to 26V.

ISL97678 Functional Diagram
ISL97678 Functional Diagram
  • 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
  • Protections
  • String open circuit and short circuit detections, OVP, and OTP
  • Adjustable dimming frequency
  • Adjustable switching frequency
  • 32 Ld (5mmx5mm) QFN package

Applications

  • Notebook Displays WLED or RGB LED Backlighting
  • LCD Monitor LED Backlighting

Design & Development

ECAD Models

Schematic symbols, PCB footprints, and 3D CAD models from SamacSys can be found by clicking on products in the Product Options table. If a symbol or model isn't available, it can be requested directly from the website.

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Product Options

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    Pkg. Type
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    Price (USD) | 1ku
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    Part Number
    ISL97678IRZ
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    		 QFN Tube 3 4.18 Get Samples,
    ISL97678IRZ-T
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    		 QFN Reel 3 Get Samples,
    ISL97678IRZ-TK
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    Samples Available
    		 QFN Reel 3 Get Samples,
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