Two-stage LED driver with selectable dual output current

摘要

A two-stage LED driver for providing a substantially constant output current to an LED load, and related methods and systems. The first stage of the LED driver includes a conventional power factor correction (PFC) circuit that outputs a direct current (DC) voltage and a DC current. The second stage of the LED driver includes a low voltage flyback circuit that receives the DC voltage and the DC current. The low voltage flyback circuit includes a flyback transformer and a switch circuit that selectably toggles the substantially constant output current provided by the low voltage flyback circuit to the LED load between a first and a second, preset constant current. The secondary windings of the flyback transformer are split into two sections, and the switch circuit toggles the two sections of the secondary windings between a series and a parallel configuration to provide the first and second, preset constant currents.

主权项

1. A light emitting diode (LED) driver for providing a substantially constant output current to an LED load, comprising:
a power factor correction (PFC) circuit, the PFC circuit connected to an alternating current (AC) power supply and configured to output a direct current (DC) voltage and a DC current; and a low voltage flyback circuit, the low voltage flyback circuit receiving the DC voltage and the DC current output by the PFC circuit, wherein the low voltage flyback circuit includes a flyback transformer and a switch circuit that selectably toggles the substantially constant output current provided by the low voltage flyback circuit to the LED load between a first, preset constant current and a second, preset constant current.