Patent Number: 7,133,301

Title: Method and apparatus for balancing active capacitor leakage current

Abstract: A circuit that provides a method and apparatus to actively balance capacitor leakage current from series stacked capacitors and disconnects itself when stacked capacitors are configured for doubler operation. In one embodiment, the active circuit includes high voltage low current transistors, such as for example a PNP bipolar transistor and an NPN bipolar transistor, that are configured in a sink-source voltage follower arrangement with the bases of the transistors connected to a voltage divider network and referenced to a fraction of a DC input voltage with a very high impedance, low dissipative resistor divider network. In one embodiment, the emitters of the PNP and NPN transistors are both tied to the connection point between capacitors in the stack and provide an active sink-source drive, which maintains the voltage at this point to be bounded by the input reference voltages of sink-source followers.

Inventors: Odell; Arthur B. (Cupertino, CA)

Assignee: Power Integrations, Inc.

International Classification: H02M 7/04 (20060101)

Expiration Date: 2019-11-07 0:00:00