Constant current DC-DC LED driver delivers up to 40W

November 11, 2016 // By Julien Happich
The AL8860 hysteresis mode DC-DC step-down converter from Diodes Incorporated was designed for driving single or multiple series‑connected LEDs efficiently from a voltage source higher than the LED voltage.

With its integrated MOSFET, this product provides a low BOM cost solution for low-voltage industrial and automotive LED lighting applications, including illuminated signs and backlighting, as well as an LED retrofit for replacing low-voltage halogen lamps.
Operating from an input supply between 4.5V and 40V, the AL8860 can directly source a 1A output current in the TSOT25 package, or up to 1.5A in the more thermally efficient MSOP8-EP package. Contingent on the supply voltage and other external components, the AL8860 is capable of providing up to 40 watts of output power.
In addition to the internal 40V 0.2 ohm NDMOS power switch, the device integrates a high‑side output current sensing circuit that allows the use of a single external resistor to set the nominal average output current. Deep dimming (0% to 100%) can be applied via a CTRL pin using either a DC voltage or a PWM signal. The same pin also implements soft-start operation, with the time adjusted by an external capacitor. Applying a voltage of 0.2V or less to this pin will turn off the output and cause the device to enter a power-saving standby state.
The AL8860 includes protection against LED short and open circuits, and over-temperature to ensure reliable system operation. Offered in either the 5-pin TSOT25 package or 8-pin MSOP8‑EP package the AL8860

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