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:
Jan. 17, 1995
Filed:
May. 15, 1992
Yuji Nishizawa, Aichi, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A circuit for providing an overcurrent protection for a power element, such as an IGBT, MOSFET or bipolar transistor, which is inserted between the power supply and a load, the protection circuit comprising a control circuit that provides an input to a gate amplifier at the power element gate. The gate amplifier comprises a photodiode that is connected between the amplifier power supply and the power element gate. The photodiode provides a clamp of the gate voltage in the event of an overcurrent and communicates optically with a phototransistor to provide a detection signal that can modify the control circuit operation. Specifically, the detection circuit can modify the input to the control circuit or control the output of the control circuit so that the energization of the power element is stopped or limited. The control can be through Darlington-connected transistors at the output of the phototransistor.