SENSORS: Allegro MicroSystems Inc. introduced a high power LED driver with output disconnect for backlighting medium LCD displays. This new driver is a robust solution targeting numerous applications within the automotive market. Typical applications include in-dash navigation systems, automotive infotainment, and back-up camera displays. A commercial version is also available for industrial and consumer applications.
Allegro’s A8501 integrates a boost converter and four 100mA current sinks. LED channels can be tied together for up to 40mA sink capability. It can work from a single power supply of 8 to 21 V and withstand up to 40V. The boost converter is a constant frequency, current-mode converter.
Operating frequency can be set up to 2MHz in order to avoid interference with the AM radio band in automotive applications. The integrated boost DMOS switch is rated for 40V at 3.6A. PWM dimming allows LED currents to be controlled at up to a 1000:1 ratio. Additional 4:1 dimming can be achieved by using the DIM pin. As part of an extensive list of protection features, the A8501 provides protection against output connector shorts through an integrated output disconnect switch. It also includes adjustable overvoltage protection (OVP) and protects against open or shorted LEDs and an open OVP resistor or boost diode.
The device is supplied in a surface mount, 28-pin TSSOP package (suffix LP), with exposed thermal pad for enhanced thermal dissipation. It is available with an ambient operating temperature of either 125C or 85C maximum, for automotive or industrial/consumer applications. The device is lead free, with a lead frame plating choice of 100 percent matte-tin (suffix T) or tin-bismuth (suffix B). It is priced at $2.36 in quantities of 1,000 and has a 16 week typical lead-time to market.
-Edited by Kelsey Anderson