A programmable multi-output LED driver from Allegro MicroSystems, LLC suits LCD backlighting, instrument clusters, and daytime running lights. Allegro's™ A8517 integrates a current-mode boost converter with internal power switch and 10 I²C programmable current sinks, and can provide 5,000:1 contrast ratio PWM dimming at 200 Hz. 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 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 is also independently controlled for each LED channel, and each channel can be enabled/disabled independently if needed. This flexibility makes the A8517 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 A8517 provides protection against output short and overvoltage, open or shorted diode, open or shorted LED pin, shorted boost switch or inductor, and IC over-temperature. A dual level cycle-by-cycle current limit protects the internal switch against switch over-current. If needed, the IC can drive an external P-FET as input-disconnect switch that is triggered by an integrated current sense. The A8517KLPTR-T is available in a 28-pin eTSSOP package and is priced at $2.95 in quantities of 1,000.
