High voltage clamps with active activation and activation-release control are provided herein. In certain configurations, a clamp can have scalable operating clamping voltage level and can be used to protect the electrical circuit connected to a power supply of a semiconductor chip from damage from an overstress event, such as electrostatic discharge (ESD) events. The pins of the power supply are actively monitored to detect when an overstress event is present, and the clamp is turned-on in response to detecting the overstress event. A timer is used to shut down the clamp after a time delay from detecting the overstress event, thereby providing a false detection shutdown mechanism that prevents the protection clamp from getting falsely activated and remain in the on-state during normal circuit operation.