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:
Mar. 13, 2001
Filed:
Oct. 12, 1999
Hirohisa Warita, Nara, JP;
Akio Nakajima, Nara, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A current detection resistance such as a metal resistance is formed in series with a power transistor, and in response to an output voltage of the current detection resistance, an overcurrent protective circuit performs an overcurrent suppressing operation with high accuracy without being affected by irregularity of a current multiplication factor, etc.; thus, it is possible to realize a smaller chip area so as to reduce the cost. Furthermore, a short-circuit protective circuit returns a terminal voltage of a referenced resistance, that appears in accordance with a partial pressure value of an output voltage, at the transistor, a partial pressure resistance, and a current mirror circuit. And the short-circuit protective circuit controls a potential of a base resistance and suppresses a base current. Hence, it is not necessary to dispose the transistor for suppressing a current between base lines, so that a low-voltage operation can be realized. In a direct-current stabilization power supply device having a two-chip structure of a PNP power transistor and a control IC, it is possible to achieve a smaller chip area and a low-voltage operation.