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:
Jul. 31, 2012
Filed:
Feb. 12, 2009
Morihito Hasegawa, Kasugai, JP;
Hidenobu Ito, Kasugai, JP;
Kwok Fai Hui, Hong Kong, CN;
Toshihiko Kasai, Kasugai, JP;
Katsuyuki Yasukouchi, Kasugai, JP;
Morihito Hasegawa, Kasugai, JP;
Hidenobu Ito, Kasugai, JP;
Kwok Fai Hui, Hong Kong, CN;
Toshihiko Kasai, Kasugai, JP;
Katsuyuki Yasukouchi, Kasugai, JP;
Fujitsu Semiconductor Limited, Yokohama, JP;
Abstract
A power supply circuit includes an output transistor including a source coupled to power supply voltage, and a drain from which output voltage is outputted; a first error amplifier powered by the power supply voltage and outputting a signal based on a potential difference between the output voltage and a reference voltage; a buffer transistor including a gate coupled to the output of the first error amplifier, and a source coupled via a constant current source to the power supply voltage and coupled to a gate of the output transistor; a current detection transistor coupled to the output transistor such that a gate and source are shared; and an overcurrent protection circuit configured to limit the drain current of the buffer transistor based on the increase of the drain current of the current detection transistor and thereby control the output current of the output transistor.