MIL-PRF-19500P
APPENDIX A
A.6 CLASSES OF THYRISTORS DEFINITIONS
A.6.1 Thyristor. A bi-stable semiconductor device that comprises three or more junctions and can be switched
between conducting and nonconducting status.
A.6.1.1 Bi-directional diode thyristor. A two terminal thyristor having substantially the same switching behavior in
the first and third quadrants of the principal voltage-current characteristic.
A.6.1.2 Bi-directional triode thyristor. An n-gate or p-gate thyristor having substantially the same switching
behavior in the first and third quadrants of the principal voltage-current characteristic.
A.6.1.3 N-gate thyristor. A three-terminal thyristor in which the gate terminal is connected to the n-region adjacent
to the region to which the anode terminal is connected and that is normally switched to the on-state by applying a
negative signal between gate and anode terminals.
A.6.1.4 P-gate thyristor. A three-terminal thyristor in which the gate terminal is connected to the p-region adjacent
to the region to which the cathode terminal is connected and that is normally switched to the on-state by applying a
positive signal between gate and cathode terminals.
A.6.1.5 Reverse blocking diode thyristor. A two-terminal thyristor that switches only for positive anode to cathode
voltages and exhibits a reverse blocking state for negative anode to cathode voltages.
A.6.1.6 Reverse blocking triode thyristor. An n-gate or p-gate thyristor that switches only for positive anode to
cathode voltages and exhibits a reverse blocking state for negative anode to cathode voltages.
A.6.1.7 Reverse conducting diode thyristor. A two terminal thyristor that switches only for positive anode to
cathode voltages and conducts large currents at negative anode to cathode voltages comparable in magnitude to the
on-state voltage.
A.6.1.8 Reverse conducting triode thyristor. An n-gate or p-gate thyristor that switches only for positive anode to
cathode voltages and conducts large currents at negative anode to cathode voltages comparable in magnitude to the
on-state voltages.
A.6.1.9 Turn off thyristor. A thyristor that can be switched between conducting and nonconducting states by
applying control signals of appropriate polarities to the gate terminal, with the ratio of triggering power to triggered
power appreciably less than one.
A.6.2 Physical structure terms.
A.6.2.1 Gate. An electrode connected to one of the semiconductor regions for introducing control current.
A.6.2.2 Main terminals. The two terminals through which the principal current flows.
A.6.3 Electrical characteristic and rating terms.
A.6.3.1 Anode to cathode voltage-current characteristic (anode characteristic). A function, usually represented
graphically, relating the anode to cathode voltage to the principal current, with gate current where applicable, as a
parameter.
A.6.3.2 Breakover point. Any point on the principal voltage-current characteristic for which the differential
resistance is zero and where the principal voltage reaches a maximum value.
A.6.3.3 Negative differential resistance region. Any portion of the principal voltage-current characteristic in the
switching quadrant within which the differential resistance is negative.
A.6.3.4 Off impedance. The differential impedance between the terminals through which the principal current flows
when the thyristor is in the off state.
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