Dimmable step-down LED driver for lighting products

March 14, 2014 // By Graham Prophet
Diodes Inc. has added a dimmable buck LED driver enabling a reduction in component count and PCB size in 12V and 24V LED lighting systems and MR16-type LED lamps. AL8807B is a hysteretic driver with an integrated power switch and operates at a switching frequency of 1 MHz.

Output current is set using a single external sense resistor. Dimming is achieved by applying a fast digital PWM signal to the driver’s control input. A low voltage, applied to the same input, turns the output power switch off. Lamp reliability is ensured by the driver’s built-in over-temperature, LED open-circuit and short-circuit protection features.

By packaging the driver in a small footprint, low thermal-resistance MSOP-8EP package, a higher power density is achieved, maximising the permissible LED current over a wider ambient temperature range. The AL8807B delivers an LED drive current up to 1.3A and operates between -40ºC to +125ºC with an efficiency of 96%.

From voltage sources between 6V and 36V, the driver will produce a constant current for a chain of high brightness LEDs. Average LED current accuracy is better than 5%, helping to improve channel-to-channel matching and meeting the requirements of most medium voltage LED lighting products.

The AL8807B costs $0.32 (10,000)

Diodes; www.diodes.com