Led driver circuit with step configurable output

Abstract

An LED driver apparatus provides discrete output current configuration. User interfaces such as dip switches enable user selection of output current settings. LED driver circuitry includes an inverter, a primary transformer winding coupled to the inverter switches and providing resonant inductance, and a secondary transformer winding coupled on a first end to an output rectifier. Various circuit branches are coupled in parallel between the output rectifier and the secondary winding, each including a switching element driven between open and closed states associated with the user-selected output current setting. The circuit branches may be coupled to respective secondary winding taps, wherein output current is regulated according to an effective turns ratio defined by the closed circuit branch. Alternatively, the circuit branches may be coupled to one end of the secondary winding but include current limiting capacitors, wherein one or more closed circuit branches define an equivalent capacitance and associated output current.