In a first embodiment, an ultra-fast breakover
diode has a
turn on time TON that is less than 0.3 microseconds, where the forward breakover
voltage is greater than +400 volts and varies less than one percent per ten degrees Celsius change. In a second embodiment, a breakover
diode has a reverse
breakdown voltage that is greater, in
absolute magnitude, than the forward breakover
voltage, where the forward breakover
voltage is greater than +400 volts. In a third embodiment, a string of series-connected breakover
diode dice is provided, along with a
resistor string, in a packaged circuit. The packaged circuit acts like a single breakover diode having a large forward breakover voltage and a comparably large reverse
breakdown voltage, even though the packaged circuit includes no discrete
high voltage reverse breakdown diode. The packaged circuit is
usable to supply a triggering current to a
thyristor in a voltage protection circuit.