Overcurrent protective device for power device

U.S. Patent Number: 5394287

Abstract: A TSD (8) is provided in the vicinity of an IGBT (1), and reference voltages (VR1 to VR5) are provided to the negative inputs of comparators (51 to 55) as a function of a temperature detection signal (S8). A sense terminal (3) of the IGBT is connected to the positive inputs of the comparators (51 to 55) in common. An output signal (S51) of the comparator (51) and output signals (S72 to S75) of signal judging circuits (72 to 75) having received the output signals (S52 to S55) are applied to the input of an NOR gate (6) for on/off control of the IGBT. The signal judging circuits (72 to 75) normally output an L-level judgment signal (S7) and output an H-level judgment signal (S7) when the input signal is at the H level for periods of time that are not shorter than allowable durations (.DELTA.t2 to .DELTA.t5 ), respectively. This provides an overcurrent protective device for a power device which performs overcurrent protective operation adapted for a practical safe operating area of the power device.

Inventors: Sakata; Hiroshi (Fukuoka, JP), Fukunaga; Masanori (Fukuoka, JP)

Assignee: Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)

Application Number: 08/010,756

Issued: 1995-02-28

Expired: 2007-02-28

Classes: 361/18 ; 361/103; 361/57; 361/98

Field of search: 361/103,106,93,94,97,98,18,24,25,37,54,56,57,46,100 323/284,285,312

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