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:
Aug. 31, 2010
Filed:
May. 12, 2008
Kazuhiro Murata, Osaka, JP;
Kazuhiro Murata, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
The present invention provides a switching power supply device including a switching element, a control circuit controlling the switching element, a transformer having an auxiliary winding, a potential clamp circuit connected to one of outputs of the transformer, a delay capacitor connected to an output of the potential clamp circuit, a potential detection circuit detecting a potential at the delay capacitor, and an overload protection actuation circuit realizing overload protection. During an overload, the delay capacitor is charged only by ringing of the auxiliary winding, generated immediately after the switching element is turned off, through the potential clamp circuit. Then, the potential detection circuit supplies an actuation signal to a latch stop circuit by detecting that the potential at the delay capacitor rises. The latch stop circuit latches and stops the switching operation of the switching element to realize the overload protection when the actuation signal is fed into the latch stop circuit. Thus, the overload protection can be realized with a sufficient delay time by the relatively small delay capacitor.