Multiple-output automotive LED driver IC with I²C interface

July 17, 2013 // By Graham Prophet
This 10-channel device features wide input voltage range, fault tolerance and independent control of each channel.

The A8517 from Allegro MicroSystems Europe is a programmable multiple-output LED driver IC incorporating an I 2C interface and designed for automotive applications such as LCD backlighting, instrument clusters, and daytime running lights. It integrates a current-mode boost converter with an internal power switch and ten I²C programmable current sinks, and can provide a 5000:1 contrast ratio with PWM dimming at 200 Hz. It operates over a voltage range from 4.5 to 36V, and is able to withstand up to 40V for the load-dump conditions encountered in automotive systems.

The I²C interface allows the user to set the LED currents individually at 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 or 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-circuits and over-voltage, 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 an input-disconnect switch that is triggered by an integrated current sense resistor.