Patent ID: 7848125

Claim:
A keep alive circuit for a bootstrap capacitive element providing a higher base or gate voltage than an active switching device switches for use with a multiple switch node power conversion system having the active switching device comprising at least one N-channel field effect transistor switching device or at least one NPN transistor switching device, the circuit comprising: a controllable current or voltage blocking device that is adapted to selectively block current or voltage from escaping from the circuit and to selectively deliver current or voltage to the circuit; an active switching device having a control terminal, a first conduction terminal, and a second conduction terminal, the conduction terminals of the active switching device being disposed between the blocking device and a capacitive element and the control terminal adapted to selectively control current flow between said conduction terminals; and a voltage regulator that is electrically coupled to the control terminal of the active switching device for clamping said control terminal, wherein a first keep alive circuit at a first switching node receives a regulated floating voltage generated by switching action at a second switching node when a switching device at the first switching node is in substantially continuous operation.