High voltage clamps with transient activation and activation release control

An active clamp control circuit for controlling a power supply clamp, wherein the active clamp control circuit comprises:

• a trigger circuit configured to detect presence of a transient overstress event between a pair of nodes of a power supply, wherein the trigger circuit comprises:
• a regulator configured to activate a regulated voltage in response to detecting presence of the transient overstress event;
• and
• a timer configured to activate a trigger signal after a time delay from activation of the regulated voltage;
• and
• a logic circuit powered by the regulated voltage, wherein the logic circuit is configured to turn on the clamp in response to activation of the regulated voltage, and to turn off the clamp in response to activation of the trigger signal.

A method of providing actively-controlling overstress protection, wherein the method comprises:

• activating a regulated voltage in response to detecting presence of a transient overstress event between a pair of nodes of a power supply;
• powering a logic circuit using the regulated voltage;
• turning on a clamp that is electrically connected between the pair of nodes using the logic circuit in response to activation of the regulated voltage;
• activating a trigger signal after a time delay from activation of the regulated voltage using a timer;
• and
• turning off the clamp using the logic circuit in response to activation of the trigger signal.