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:
Apr. 29, 1997
Filed:
Jun. 28, 1995
Hiroyuki Kawakami, Kawasaki, JP;
Noriho Terasawa, Kawasaki, JP;
Fuji Electric Co., Ltd., Kanagawa, JP;
Abstract
A control circuit for an insulated-gate semiconductor device (IGBT) 1 has a drive circuit 2, which is a series circuit constructed of an npn transistor 3 and a pnp transistor 4, and controls the switching operation of the IGBT 1 in response to an on/off signal 9S from a switching signal source 9. The control circuit includes a switching speed control means 10, a gate potential stabilizing npn transistor 20, and a stable operation extending means 30. The switching speed control means 10 gives predetermined slops to the rise and fall of the on/off signal 9S. The gate potential stabilizing npn transistor 20 is Darlington-connected to the pnp transistor 4 of the drive circuit 2 and has the emitter thereof connected to the source of the IGBT 1. The stable operation extending means 30 generates an on signal to the base of the gate potential stabilizing npn transistor 20 upon sensing a drop in the gate potential of the IGBT 1 to a threshold voltage thereof or less.