Led array having an active shunt arrangement

Abstract

A device, e.g., a luminaire, that includes a plurality of LEDs connected in series, and an active shunt arrangement for sensing a failure of one or more of the LEDs and for shunting current that would have otherwise flowed through a failed LED, to thereby maintain a flow of current through remaining ones of the plurality of LEDs. In one exemplary embodiment, the active shunt arrangement includes a plurality of active shunts connected in parallel across respective ones of the LEDs, and remote sense and digital control logic for detecting an open-circuit condition of the normally closed circuit, and for sequentially activating the active shunts until the normally closed circuit has been restored to a closed-circuit condition. In another exemplary embodiment, the active shunt arrangement includes a plurality of active shunts connected in parallel across respective ones of the LEDs, a plurality of sense circuits operatively associated with respective ones of the LEDs, each of the sense circuits being configured to sense a failure condition of its associated LED, and to produce a sense output signal upon sensing a failure condition of its associated LED, and a plurality of control circuits operatively associated with respective ones of the LEDs and respective ones of the sense circuits, each of the control circuits being responsive to the sense output signal produced by its associated sense circuit to activate the active shunt connected across its associated LED. Preferably, each of the active shunts is an active switching device, such as a power MOSFET, a bipolar transistor, or a micro-relay, that has a low on-resistance.