The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 08, 1994
Filed:
Feb. 07, 1992
Richard A Keller, Palo Alto, CA (US);
Power Integrations, Inc., Mountain View, CA (US);
Abstract
An embodiment of the present invention is a switching power supply comprising a transformer with a primary and two secondaries, a switching transistor in series with the primary, a rectifier and filter on one secondary to provide regulated output power, a feedback control circuit that monitors the secondary and adjusts the duty cycle of an on-off control signal to the switching transistor to maintain a constant output at the terminals, and a monitor that detects when the power level flowing through the switching regulator has dropped to a predetermined minimum and then linearly turns on a load to the transformer. Transistor is typically a power MOSFET. The monitor tracks a summing junction current before any slope compensation is added. Load is a shunt regulator that is activated when the summing junction current falls below 12% of full scale. Alternatively, the predetermined value of 12% is adjustable. The shunt regulator load increases the load on secondary until the summing junction current returns to 12% of full scale. The feedback control circuit and monitor are preferably fabricated on a single monolithic integrated circuit which increases its power dissipation when the monitor activates the shunt regulator load.