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. 10, 1998
Filed:
Jun. 02, 1997
William J Scheraga, Warwick, RI (US);
Cherry Semiconductor Corporation, East Greenwich, RI (US);
Abstract
A control circuit for providing fast turn on of a PNP transistor in which a capacitor charging current is boosted and provided to the base of the PNP transistor. An embodiment of the invention provides a current amplifier in parallel with a current source for coupling to the base of the PNP transistor. The PNP transistor is connected to a positive voltage supply. A capacitor is also coupled to the positive voltage supply for delivering a charging current amplifier. In a further embodiment, an NPN transistor has its base coupled to the capacitor and its collector coupled to the base of the PNP transistor for providing the drive current boost. A diode may be coupled to the capacitor for passing a discharge current to the capacitor when the PNP transistor is off and to block the capacitor current when the PNP transistor is being switched on. A PNP drive transistor may be coupled between the collector of the NPN transistor and the base of the PNP transistor.