Abstract: In described examples, a switch has: a first current handling terminal coupled to a supply source terminal; and a second current handling terminal coupled to an output terminal. A comparator has: a first input coupled to the second current handling terminal; and a second input. A voltage reference source has: a first terminal coupled to the first current handling terminal; and a second terminal coupled to the second input of the comparator. A slew rate detector has an input coupled to the second current handling terminal. A switch controller has: a first input coupled to the comparator output; and a second input coupled to an output of the slew rate detector. The switch controller is coupled to output a signal to cause the switch to open when the comparator detects an over-current condition through the switch while the slew rate detector detects a negative slew rate.

Abstract: Protection circuits, USB interface integrated circuits, and methods for protecting host circuitry from USB port pin overvoltages, in which a switch is connected between a USB port pin and a middle node, and a detection circuit compares the middle node voltage with a reference voltage. A control circuit turns off the switch and turns on a clamp circuit to conduct pull down current from the middle node in response to the middle node voltage exceeding the reference voltage to mitigate overvoltage conditions on a host pin coupled to the middle node. When the middle node voltage falls below the reference voltage, the control circuit delays for a predetermined time and then turns off the clamp circuit and turns on the switch.