LED backlight driver IC for large displays

26th May 2010

ES Admin

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Datasheet

The new A8512 from Allegro MicroSystems Europe is a multi-output white LED RGB driver IC for the LED backlighting of large-area LCD monitors and television screens. The new device integrates a scalable-output boost controller operating in constant-frequency current mode control - adjustable between 300 kHz and 1 MHz - driving an external MOSFET. It integrates six internal current sinks each capable of sinking up to 80 mA, which can be combined together to achieve even higher currents. PWM dimming allows LED currents to be precisely controlled over a 500:1 ratio as a percentage of the maximum setpoint determined by the user.

Multiple A8512 devices can be connected in parallel, with one master controller controlling the boost stage and up to five slave controllers acting as LED sinks. This configuration allows up to 36 LED strings to be powered by a single boost converter, significantly reducing the number of external components required.

Other features include controlled start-up using enable, PWM signal or battery voltage ramp, and active current sharing between LED strings with ±0.6% accuracy and matching. There is no audible MLCC noise during PWM dimming.

The A8512 operates from a single supply of 8-24 V. It provides protection against overvoltage, open or short-circuited LED string, and overtemperature. A dual-level cycle-by-cycle current limit function provides soft start and protects against overloads.

The A8512 is available in a 28-contact 5 mm x 5 mm QFN package (ET), with an exposed thermal pad for enhanced thermal dissipation. For single-sided PCB manufacturing capability, the device is also available in a 24-pin SOICW package (LB), with internally fused pins for enhanced thermal dissipation. Both packages are lead (Pb) free, with 100% matt tin lead-frame plating.