Sgs-thomson Microelectronics S.a.

Albert Senes

Robert Pezzani

A protection device against overvoltages liable to occur between two supply terminals (A, B) comprises between the supply terminals, an avalanche triggered thyristor (6) having a determined break-over voltage (V.sub.BO) This system further comprises a zener diode (4) in parallel and reversely connected with the thyristor; the diode is selected so that its avalanche voltage (V.sub.BR) is lower than the break-over voltage of the thyristor and gets higher only for overvoltages having a higher duration or amplitude than a predetermined threshold.

Monolithic overvoltage protection device

A protection device against overvoltages liable to occur between two supply terminals (A, B) comprises between the terminals, on the one hand, a thyristor (Th) and, on the other hand, first and second zener diodes in series. The anode of the first diode (D1) is connected to the cathode of the thyristor and the cathode of the second diode (D2) is connected to the anode of the thyristor, and a third zener diode (D3) is placed between the thyristor gate and the junction (10) of the first and second diodes. The third diode has an avalanche voltage higher than that of the first diode.

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Saint Cyr Sur Loire, France

Albert Senes