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. 01, 1983
Filed:
Oct. 13, 1981
Hideji Sumi, Yokohama, JP;
Masayuki Kokado, Kawasaki, JP;
Fujitsu Limited, Kanagawa, JP;
Abstract
A line driver circuit having a protective circuit against excess currents, which includes a protective transistor for limiting the output current of an output-stage emitter-follower transistor. A detecting means for detecting the output current of the emitter-follower transistor and a pull-up transistor for pulling up the base potential of the protective transistor are provided. Before the output current becomes too large, the detecting means detects the output current to turn on the pull-up transistor. Then the base potential of the protective transistor is pulled up to turn on the protective transistor. As a result the base current of the emitter-follower transistor is decreased, so that the emitter-follower transistor is protected from being thermally destroyed.