Driving circuit using buck converter capable of generating sufficient voltage to power a led circuit and associated auxiliary circuitry in a normal mode of operation, and insufficient to power the led circuit but sufficient to power the associated auxiliary circuitry in an off mode of operation

Abstract

A circuit includes a voltage converter converting source voltage to supply voltage at a first node as a function of a feedback voltage at a feedback node. A first output path is coupled between first and second node nodes. Feedback circuitry couples the second node to the feedback node when a voltage at the second node exceeds a first overvoltage, in a first mode of operation. The feedback circuitry couples the second node to the feedback node when the voltage at the second node exceeds a second overvoltage less than the first overvoltage, in a second mode of operation. Impedance circuitry is coupled between the first node and a third node and generates an auxiliary supply voltage and an auxiliary ground voltage when the circuit is in both the first and second modes, the auxiliary supply voltage being less than the supply voltage in both the first and second modes.