Patent ID: 8947014
Filing Date: 2015-02-03
Classification: H05B

Abstract:
1. An LED array switching apparatus, comprising: a plurality of LED arrays arranged in a serial path, each LED array having a forward voltage; a voltage supply coupled to the plurality of LED arrays; a plurality of current sources selectively coupled to the LED arrays, each of the current sources being switchable between a current regulating state and an open state; and a controller that outputs at least one control signal generated based on at least one of: (a) at least one comparison between the voltage of the voltage supply and at least one reference voltage, and (b) currents through one or more of the current sources, the control signals controlling the turning on and off of at least one switch and a current source associated with the at least one switch, the controller, the at least one switch and current sources cooperating together such that: when the voltage of the voltage source is below the at least one reference voltage, and/or when a predetermined level of current passes through the one or more current sources, at least one switch is closed and one or more associated current sources are controlled so as to break the serial path into one or more parallel paths each including less than all of the LED arrays, wherein the LED arrays in the one or more parallel paths are on, wherein each current source comprises: a first transistor having a gate, a drain, and a source, wherein the drain of the first transistor is coupled to its respective LED array; a second transistor having a base, collector, and emitter, wherein the base is coupled to the source of the first transistor, the collector is coupled to the gate of the first transistor, and the emitter is coupled to ground; and a zener diode coupled between the collector and emitter of the second transistor.