Patent ID: 7839131

Claim:
A circuit for driving a switching stage including control and sync switches series connected at a switching node, at least one of the control and sync switches being a normal ON depletion mode device, the circuit comprising: a gate driver including first and second switching stages for generating gate drive signals for the sync and control switches, respectively, the first switching stage having a first driver output node and the second switching stage having a second driver output node, a signal from the first node driving the sync switch and a signal from the second node driving the control switch; and a circuit connected to the first and second switching stages, the circuit comprising a first circuit providing a first voltage source, the first circuit being coupled to the first switching stage and to the sync switch, a first bias voltage from said first voltage source being switched by said first switching stage, said first switching stage having a first state wherein said sync switch is on, and a second state wherein said first bias voltage is switched to the gate of said sync switch to turn said sync switch off; and a second circuit including a first energy storage device for charging with a second bias voltage, the second switching circuit having a first state, wherein said control switch is on when said sync switch is off and having a second state wherein said control switch is switched off when said sync switch is on by switching said second bias voltage to the gate of said control switch.