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. 27, 1979
Filed:
Sep. 16, 1977
Robert C Dobkin, Hillsborough, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system for limiting power dissipation in a power transistor to less than a destructive level is disclosed. The power transistor includes a base and a power emitter in the base. The system includes a sense emitter positioned close to the power emitter in the base and a reference emitter positioned in a base at a remote position that would not be heated by the heat dissipated by the power emitter for providing an indication of the temperature gradient between the power emitter and the remote position induced by power dissipated in the power emitter by sensing the voltage difference between the sense emitter and the reference emitter. The system further includes a differential amplifier responsive to the indication of the temperature gradient for limiting power dissipation in the power transistor by reducing the power provided to the power transistor when the indication reaches a predetermined level.