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:
Sep. 24, 1996
Filed:
Mar. 01, 1995
Tomoyuki Yamazaki, Nagano, JP;
Masahito Otsuki, Nagano, JP;
Fuji Electronic Co., Ltd., Tokyo, JP;
Abstract
An insulated gate-type bipolar transistor with an overcurrent limiting function that is capable of keeping the ratio of a main current to a detection current constant even under different operating conditions, and capable of suppressing the voltage dependence of the limited-current value to perform stable overcurrent protection. P-wells are formed so that they are incorporated between main cell IGBTs as sensing cells for current detection on part of the semiconductor substrate on which a large number of main cells are formed integratedly, and current-detecting emitter electrodes connected to the P-wells are connected to an overcurrent-protection circuit and separated from the main emitter electrodes connected to the main IGBT cells. Given such a configuration, the overcurrent flowing into the main cells during a load short circuit in an inverter device is detected as a hole current from the P-wells with a high accuracy of keeping the current ratio to the current in the main cells constant, and moreover, stable overcurrent protection is performed keeping the limited current values suppressed below the short-circuit withstand capability without dependence on the power supply voltage.