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. 20, 2001
Filed:
Jun. 02, 2000
Akira Matsumoto, Nagano, JP;
Nagano Japan Radio Co., Ltd., Nagano, JP;
Abstract
A switching power supply is provided which is capable of preventing abnormal operation of a synchronous rectifier circuit thereof, which is caused by a discontinuous current mode, and capable of enhancing an input power factor thereof. A transformer has a primary winding and a secondary winding. A first switching element is connected in series with the primary winding of the transformer, for switching an input voltage. A diode rectifies an induced voltage induced in the secondary winding of the transformer to generate a rectified current. A control signal is generated which has a current value or a voltage value approximately proportional to a current value of the rectified current. A second switching element is connected in parallel with the diode in an equivalent fashion and has a control terminal to which the control signal is input. The second switching element operates in response to the control signal for rectifying the induced voltage. A current is prevented from flowing into the primary winding during an OFF period of the first switching element.