A8521 datasheet(12/35 Pages) ALLEGRO

Part #	A8521

Description	The A8521 is a multi-output white LED driver for small-size LCD backlighting.

PDF	35 Pages

Scroll/Zoom	100%

Manufacturer	ALLEGRO [Allegro MicroSystems]

Direct Link	http://www.allegromicro.com

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12 / 35 page

Wide Input Voltage Range, High Efficiency

Fault Tolerant LED Driver

A8521

Allegro MicroSystems, Inc.

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

4A. An LED detect occurring when both LED pins are selected to be used;

shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.), ISET (ch3,

1 V/div.), and PWM/EN (ch4, 5 V/div.) pins, time = 500 μs/div.

4B. Example with LED2 pin not being used; the detect voltage is

about 150 mV; shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.),

ISET (ch3, 1 V/div.), and PWM/EN (ch4, 5 V/div.) pins, time = 500 μs/div.

4C. Example with one LED shorted to ground. The IC will not proceed with

power-up until the shorted LED pin is released, at which point the LED is

checked to see if it is being used; shows LED1 (ch1, 500 mV/div.), LED2 (ch2,

500 mV/div.), ISET (ch3, 1 V/div.), and PWM/EN (ch4, 5 V/div.) pins,

time = 1 ms/div.

LED detection period

PWM/EN

LED2

LED1

ISET

Pin shorted

Short removed

PWM/EN

LED2

LED1

ISET

LED detection period

PWM/EN

LED2

LED1

ISET

A8521 Datasheet(PDF) 12 Page - Allegro MicroSystems