MOS transistor circuit with breakdown protection.

摘要

A protected MOS transistor circuit includes an input (or output) MOS transistor (1) and a protective circuit (10) including a depletion mode MOS transistor (TrP) having a drain-source current path connected between ground and the gate of the MOS transistor and arranged to prevent breakdown of the gate oxide of the protected MOS transistor when power is off as a consequence of stray voltages. When power is on, the depletion mode MOS transistor's gate receives a control signal which renders the depletion mode MOS transistor non-conductive but, when power is off, the depletion mode transistor is conductive so as to ground currents caused by the stray voltages.