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Wide Input Voltage, Fault Tolerant, Independently Controlled Multi-Channel LED Driver with I²C Interface

A8522

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Description

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The A8522 is a programmable multi-output LED driver for LCD backlighting. It integrates a current-mode boost converter with internal power switch and 8 current sinks. The IC operates from 4.5 to 36 V, and is able to withstand up to 40 V load-dump conditions encountered in automotive systems.

The control loop is optimized to eliminate night flash in display backlight applications.

The I2C interface allows the user to set the LED currents individually, up to 60 mA per LED channel. Adjacent channels may be combined to drive higher-current LED strings. The PWM dimming duty cycle also is independently controlled for each LED channel. This flexibility makes the A8522 a single solution for a wide range of LED applications. Two-way communication allows fault status to be reported.

PWM dimming duty cycle also is independently controlled for each LED channel. This flexibility makes the A8522 a single solution for a wide range of LED applications, in some cases offering the ability to replace two or more LED driver ICs with a single device.

The A8522 detects and protects against a wide variety of fault conditions, and two-way communication allows fault status to be reported. It provides protection against output short and overvoltage, open or shorted diode, open or shorted LED pin, shorted boost switch or inductor, and IC overtemperature. A dual cycle-by-cycle current limit protects the internal switch against switch overcurrent. If required, the IC can drive an external PFET as an input-disconnect switch that is triggered by integrated current sense.

ACE Award 2014 Finalist

 

  • AEC-Q100 qualified
  • Wide input voltage range of 4.5 to 36 V
  • Operates down to 3.9 V (VIN falling) for idle stop, and up to 40 V for load dump
  • Integrated boost converter with DMOS switch and OVP protection up to 39 V
  • 8 fully integrated LED current sinks, with individually programmable current up to 60 mA per channel
  • I2C™ interface for programming LED current, PWM dimming, and various protection thresholds per channel
  • Ability to drive multiple loads from a single IC
  • Extensive PWM dimming (up to 10,000:1 at 100 Hz), individually programmable for each channel
  • Extensive diagnostics and fault reporting
  • Thermal warning and derating of LED current at higher temperatures
  • Buffered PWM dimming control for all channels to facilitate localized dimming applications
  • Polyphase PWM dimming: LED currents staggered to reduce light flickering and input ripple current
  • Synchronize boost switching frequency: 400 kHz to 2.3 MHz to allow operation below or above the AM band
  • Programmable frequency dithering to reduce EMI
  • Typical LED current accuracy of 0.7%, and LED-to-LED matching accuracy of 0.8%
  • Protection Features
    • Open/shorted LED pin detection
    • Programmable LED string short detection
    • Open/shorted external components (including boost inductor, Schottky diode, FSET resistor and so forth)
    • Input overcurrent protection against output to GND short
    • Cycle-by-cycle switch current limit
    • Overtemperature, and output overvoltage and undervoltage protection

Typical Applications

  • Infotainment
  • Cluster
  • Center-Stack Lighting
  • Head-Up Display (HUD)
  • Daytime Running Lights (DRL)
28-pin TSSOP with exposed thermal pad (suffix LP)
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