Patent ID: 9692300
Date: 2017-06-27
CPC Classifications: H02M

Claim:
1. A regulated voltage system, comprising: a direct current power source; a regulated voltage supply circuit including a regulated voltage supply output and a charging capacitor coupled to the direct current power source, the regulated voltage supply output supplying power to an electrical load; a shunt transistor having a gate, a drain coupled to the direct current power source and the regulated voltage supply circuit, and a source coupled to ground; a shunt control circuit to operate the shunt transistor between an open and closed state, the shunt control circuit including a cross-coupled bias circuit coupled to the gate of the shunt transistor; and a controller having an output port coupled to the cross-coupled bias circuit and an input port coupled the regulated voltage supply output, the controller controlling the shunt transistor according to a state machine having a first state to close the shunt transistor when the regulated supply voltage reaches or exceeds a maximum hysteresis value and a second state to open the shunt transistor when the regulated supply voltage is equal to or less than a minimum hysteresis value, the controller periodically sampling the regulated voltage supply output and sending a control signal to the cross-coupled bias circuit; and wherein the cross-coupled bias circuit includes a first bias transistor having a gate coupled to the controller and a first bias resistor, a source coupled to ground and a drain coupled to the gate of a second bias transistor, the second bias transistor having a drain coupled to a second bias resistor and a source coupled to the regulated supply voltage output, wherein the second bias resistor is coupled to the gate of the first bias transistor, the first bias resistor and the controller, and wherein a third bias resistor is coupled between the gate of the second bias transistor and the regulated supply voltage output.