Low impedance, high voltage protection circuit.

摘要

A low impedance ovevoltage protection circuit includes a first MOSFET having a drain connected to an input signal and a source connected to a drain of a second MOSFET, the source of the second MOSFET being coupled to the output. The gates of the first and second MOSFETs are connected to voltage supplies which float relative to the input signal values so as to maintain the gates of the respective MOSFETs biased to a conducting state. The maximum and minimum values to which the floating voltage supplies will float are defined by clamping diodes and clamp voltage sources. When the input signal value exceeds a desired positive maximum value, the first MOSFET is no longer biased to an on state whereby the MOSFET turns off, shunting the input signal through a high impedance for limiting input current and removing the input signal from the output. Negative going peak values are removed in a like manner by the second MOSFET. Bipolar transistors are coupled to each MOSFET to allow quick turn off in the event of rapid rise time transient input values.