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:
Apr. 06, 1999
Filed:
Jul. 07, 1998
Tadahiko Matsumoto, Yokohama, JP;
Seiichi Takahashi, Sagamihara, JP;
Yoshihiro Matsumoto, Sagamihara, JP;
Hitoshi Tsuji, Sagamihara, JP;
Abstract
An overcurrent protection circuit provided for a switching power supply has a current detector, voltage superposition device, and circuit for reducing a driving pulse. The current detector detects a circuit current in the switching power supply and converts it to a voltage. The voltage superposition device generates a constant voltage and superposes the voltage onto the detected voltage converted by the current detector. The detected voltage onto which the constant voltage has been superposed is applied between the base and the emitter of a transistor which functions as the circuit for reducing the driving pulse. If an overcurrent flows through the switching power supply, the transistor is turned on and a current flows into the transistor. As a result, a voltage applied to a maximum-duty-cycle setting terminal of a PWM IC provided for the switching power supply and used for pulse-width-modulation control of a switch device is reduced, and the overcurrent is suppressed.