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:
Oct. 08, 1985
Filed:
Feb. 08, 1984
Per Svedberg, Vallingby, SE;
ASEA Aktiebolag, Vester.ang.s, SE;
Abstract
A two-pole overcurrent protection device arranged to interrupt the current flowing in a conductor if the current exceeds a predetermined level employs a semiconductor wafer on which is formed a turn-off thyristor and a MOS transistor. The control electrode of the transistor is supplied with a voltage dependent on the on-state voltage drop of the thyristor and, therefore, on its current, and at a certain thyristor current the transistor short-circuits one of the emitter junctions of the thyristor to extinguish the thyristor. For firing the thyristor, one of the base layers thereof is supplied with a gate trigger current via a JFET transistor portion formed in the semiconductor wafer with a horizontal channel region. This transistor portion is designed so that its saturation current exceeds, with a suitable margin, the current necessary for firing the thyristor. When a high voltage exists across the thyristor, the transistor portion will limit the current flowing to the base layer to a value which is equal to the saturation current of the transistor portion.