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High-Performance Power and Hall-Effect Sensor ICs

A8503
High Efficiency 6-Channel, 2 MHz, WLED/RGB Driver for Medium Displays, with Integrated 55 V Power Switch

Pin-Out or Package

Features

  • Active current sharing between LED strings for ±0.6% accuracy and matching
  • Drives up to 12 series × 6 parallel = 72 LEDs (Vf = 3.2 V, If = 20 mA) at 5 V
  • Each individual current sink is capable of 32 mA
  • Adjustable overvoltage protection (OVP)
  • 600 kHz to 2 MHz adjustable switching frequency
  • Open or shorted LED string protection
  • Open Schottky diode protection
  • Overtemperature, cycle-by-cycle current limit, undervoltage, and soft start time-out protections
  • Selectable latched/auto-restart protection modes
  • No audible MLCC noise during PWM dimming
  • No pull-up resistors required for LED modules that use ESD capacitors
  • Extends battery life
  • Efficiency optimized for 3-cell notebooks
  • 0.1 µA shutdown current
  • Unique architecture eliminates external voltage divider and associated battery drain
  • Rugged and small footprint solution
  • 55 V, 2 A DMOS switch in 4 mm × 4 mm package—allows IPC-2221/2 / IPC-D-275 compliant PCB layout

Applications

  • Notebook and sub-notebook displays
  • LCD monitors
  • LCD panels

Description

The A8503 is a multi-output WLED/RGB LED driver for medium-size LCD backlighting. It integrates a current-mode boost converter with internal power switch and six current sinks. The boost converter can provide output voltages up to 47 V. The boost converter can drive up to 72 LEDs at 20 mA per LED with a battery voltage down to 5 V. The LED sinks are capable of sinking up to 32 mA each, and can also be paralleled together to achieve even higher LED currents. The A8503 provides protection against overvoltage, open diode, open or shorted LED string, and overtemperature. A dual level cycle-by-cycle current limit function provides soft start and protects against overloads. A soft start timeout monitor is provided to enhance protection when starting up into a fault condition.

When the MODE pin is set low, the A8503 latches on a fault, and can be re-enabled only by cycling the input voltage, VIN, or by toggling the EN pin. Connecting the MODE pin high provides auto-restart after fault events. The A8503 features EN (enable) and PWM (dimming) pins to comply with popular notebook backlight control interfaces.

The device package is a 26-contact, 4 mm × 4 mm, 0.75 mm nominal overall height QFN, with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating.

Functional Block Diagram

Functional Block Diagram

Complete Part Numbers
Part Number Package Type RoHS
Compliant
Part Composition/
RoHS Data
Temperature Comments Samples Distributor Stock
A8503GECTR-T 26-lead QFN/MLP Yes view data -40 °C to  105 °C new   Contact Local Sales Representative
or check distributor stock
 

Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system.

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