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:
Nov. 05, 1996
Filed:
Jan. 06, 1995
Minoru Hirahara, Kawasaki, JP;
Fujitsu Limited, Kanagawa, JP;
Abstract
A primary control type switching power supply circuit includes a transformer having a primary side and a secondary side, a control circuit generating a control signal based on a detection signal, a circuit for switching a current flowing through the primary side in response to the control signal so as to generate an A.C. voltage on the secondary side, a rectifying and smoothing circuit for rectifying and smoothing the A.C. voltage to generate an output voltage across first and second terminals, an output voltage detection circuit including a circuit part for comparing a reference voltage and a detection voltage that is based on the output voltage, and a detection signal transmitting part supplying to the control circuit the detection signal which is indicative of an error between the reference voltage and the detection voltage so that the output voltage is maintained constant based on the control signal, and a circuit including a choke coupled to one of the first and second terminals for turning the output voltage ON/OFF via the choke at a switching frequency and for obtaining a D.C. voltage by rectifying and smoothing an induced voltage of the choke caused by the ON/OFF of the output voltage. The D.C. voltage is supplied to the detection signal transmitting part of the output voltage detection circuit as a driving voltage from a driving power supply for the detection signal transmitting part.