Power holdup circuit with increased power factor

An input circuit adapted for maintaining power factor during voltage dropout of an input power source, the input circuit comprising:

• holdup means having stored power for use during voltage dropout;
• and
• control means for monitoring a difference between the voltage of the input power source and the voltage of the holdup means, and adapted for switching power from the input power source to the holdup means when the difference exceeds a predetermined value.

A method of maintaining power factor when voltage temporarily decreases from a power source, the method comprising the steps of:

• monitoring the voltage difference between an input source and a holdup capacitor;
• switching power from the input source to the holdup capacitor when the difference exceeds a predetermined amount defined by the voltage rating of a diode plus the turn-on voltage of a transistor.

A power holdup circuit comprising:

• a monitoring circuit for monitoring a difference between a power supply voltage and an energy storage element;
• and
• a switch circuit, the switch circuit turning on to release energy from the energy storage element when the difference between the power supply voltage and an energy storage element voltage exceeds a predetermined threshold level.