Regulated auxiliary power supply

摘要

A charge pump apparatus and a method for operating a charge pump power supply (60) having an input and an output, the output coupled to a load, and the load having a bulk capacitor (30) coupled thereto for providing a voltage source for the load. A source of varying voltage (16) is provided as an input to the charge pump power supply (60). The output of the charge pump power supply (60) is coupled to the load and to the bulk capacitor (30), and the charge pump power supply (60) is operated in a first mode to provide current for charging the bulk capacitor (30) when the voltage at the load is below a predetermined voltage, and alternatively in a second mode to cease the supply of current to the bulk capacitor (30) when the voltage at the power supply is above a predetermined voltage. The charge pump comprises a capacitor-diode arrangement with a transistor switch (68) operable to control the current flow through the charge pump and to the bulk capacitor (30). <IMAGE>