IGBT/MOSFET desaturation circuity w/ reverse polarity protection

A system for desaturation protection of a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT), the system comprising:

• first and second input nodes configured to sense a voltage difference across first and second conduction terminals of the MOSFET or the IGBT connected thereto;
• an output node configured to indicate whether the voltage difference exceeds a desaturation condition;
• a Zener-diode-resistor network conductively coupled, via a rectifying diode configured to block reverse-polarity current conduction through the Zener-diode-resistor network, between the first and the second input nodes and comprising a pull-up network connected to a pull-down network at a first control node, wherein, the Zener-diode-resistor network is configured to generate a first control voltage at the first control node based on the voltage difference;
• a signal isolation device having a device-input current path and a device-output current path conductively isolated from one another, the signal isolation device configured to generate an output signal, via the device-output current path, at the output node in response to current conduction through the device-input current path;
• a first switch having a first-switch input control terminal coupled to the first control node and a first-switch output conduction path coupled to both the device-input current path and a control network, wherein the first switch is configured to turn on in response to the first control voltage exceeding a first-switch threshold voltage, thereby conducting current through the device-input current path and generating a second control voltage in the control network;
• and
• a second switch having a second-switch input control terminal coupled to the control network and a second-switch output conduction path conductively coupled to the pull-up network, wherein the second switch is configured to conduct current through the pull-up network in response to the second control voltage exceeding a second-switch threshold voltage, thereby causing negative feedback control of the current conducted through the device-input current path.