Appeal No. 95-0648
Application 08/001,199
13. A short protective circuit comprising:
a control terminal;
a first switching element having a control electrode, a first electrode and a second
electrode, said first switching element being driven by a signal applied from the control terminal to
the control electrode;
a second switching element for current detection having a control electrode, a first
electrode and a second electrode, the control electrode and the first electrode of the second
switching element being respectively connected to the control electrode and the first electrode of
the first switching element, the second electrode of the second switching element being connected
to the second electrode of the first switching element through a current detecting resistor;
a branch circuit having a discharge switching element, said branch circuit connected to a
circuit connection between the control terminal and the control electrode of the first switching
element;
means for reducing a drive signal of the first switching element by activating the discharge
switching element when an excessive current flows through a current detecting resistor, said
discharge switching element maintaining the reduced drive signal when the excessive current
flowing through the first switching element is suppressed as the drive signal decreases; and
means for deactivating the discharge switching element when a signal applied to the
control terminal becomes zero or opposite in polarity from the drive signal after the drive signal is
reduced.
The references relied upon by the examiner are:
Okado et al. (Okado) 4,719,531 Jan. 12, 1988
Mihara et al. (Mihara) 4,893,158 Jan. 09, 1990
Kumagai 5,303,110 Apr. 12, 1994
(filed Mar. 19, 1992)
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