Monolithic Switching Regulator for High-Power LEDs

The new LED6000 monolithic step-down switching regulator from STMicroelectronics is optimized for use as a current source delivering up to 3A from a 4.5- to 61-V rail in Halogen-replacement and similar applications. The LED6000 is designed to be used with MLCC output capacitors and features an adjustable soft-start time and adjustable current limiting. As a result of the adjustable current limitation and switching frequency, the external inductor size can be best matched to the LED nominal current resulting in a space-optimized design also due to its compact 5 x 4.4 mm HTSSOP16 package.

The LED6000 can work with a low sensing voltage and also offers a bias switchover feature for enhanced efficiency and supports dimming and synchronization when used in a multiple-device configuration. The 250 mV typical RSENSE voltage drop enhances the efficiency. Digital dimming is implemented by driving the dedicated DIM pin. The device is fully protected against overheating, overcurrent and output short-circuit.

The adjustable current limitation, designed to select the inductor RMS in accordance with the nominal output LED current, and the adjustability of the switching frequency allow the size of the application to be compact. The embedded switchover feature on the VBIAS pin maximizes efficiency. Multiple devices can be synchronized by sharing the SYNCH pin to prevent beating noise in low-noise applications, and to reduce the input current RMS value.

The STEVAL-ILL078V1 product evaluation board is based on the LED6000 monolithic current source for high power LED driving. Digital dimming is implemented by driving the dedicated DIM pin. Low drop-out operation with almost 100% duty cycle can be achieved. The LED6000 is a 61V asynchronous switching regulator with embedded power MOSFET, designed to source up to 3A of dc current depending on the application conditions.