Methods and apparatus for power switch fault protection

Apparatus, comprising:

• a current source terminal;
• a switch having:
• a first switch terminal coupled to the current source terminal;
• a second switch terminal;
• and a control terminal;
• an over-current protection circuit configured to detect an over-current condition through the switch and to output a signal to the control terminal to open the switch responsive to the over-current condition being a malign event;
• a first reverse current protection circuit configured to detect a first reverse current from the second switch terminal to the first switch terminal and to output a signal to the control terminal to open the switch responsive to the first reverse current being a malign event;
• and
• a second reverse current protection circuit configured to detect a second reverse current from the first switch terminal to the second switch terminal and to output a signal to the control terminal to open the switch responsive to the second reverse current being a malign event;
• wherein the first reverse current protection circuit includes:
• a comparator having:
• an inverting input coupled to the first switch terminal;
• a non-inverting input;
• and a comparator output;
• a first voltage reference terminal coupled to the second switch terminal;
• a second voltage reference terminal coupled to the non-inverting input of the comparator;
• a slew rate detector having:
• an input coupled to the first switch terminal;
• and an output;
• and
• a switch controller having:
• a first input coupled to the comparator output;
• a second input coupled to the output of the slew rate detector;
• and a switch controller output coupled to the control terminal;
• the switch controller being configured to provide a signal on the switch controller output to cause the switch to open responsive to a malign event indicated by:
• the comparator detecting a reverse current from the second switch terminal into the switch;
• and the slew rate detector detecting a positive slew rate.

A method, comprising:

• detecting whether a current through a switch positioned between a supply source and an output terminal exceeds a current limit;
• detecting a sign of a slew rate of a voltage on the output terminal;
• and
• opening the switch to decouple the output terminal from the supply source in response to the current through the switch exceeding the current limit while the sign of the slew rate of the voltage on the output terminal is negative.