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:
Feb. 17, 1987
Filed:
Aug. 20, 1984
Sivakumar Sivasothy, Mountain View, CA (US);
Ramanatha V Balakrishnan, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A circuit (100) is shown which provides a large turn-on current drive to the base of a lateral PNP transistor (218) by forcing a large voltage drop across the base-emitter junction of the lateral PNP transistor in order to quickly turn on the PNP transistor. A current sensing circuit (203, 166) determines when the collector current in the PNP transistor is sufficient for proper operation of the rest of the circuitry dependent upon this PNP transistor. The current sensing circuitry then limits the base drive applied to the PNP transistor to the current level necessary to maintain the required quiescent collector current in the PNP transistor. In addition, means (190, 200) are provided to quickly clamp the base of the PNP transistor to the emitter of the PNP transistor thereby quickly turning off the PNP transistor.