Electrostatic discharge protective circuit having rise time detector and discharge sustaining circuitry

Abstract

Methods and devices of the invention include an electrostatic discharge (ESD) protection circuit. This circuit includes rise time dependent activation circuitry capable of detecting a slew rate of an input signal and capable of determining whether the slew rate of the input signal is greater than a threshold value. For an ESD event said activation circuitry generates a trigger signal. Additionally, the activation circuitry is coupled with the ESD dissipation duration control circuitry which is further coupled with an ESD dissipation circuit. This arrangement enabling the duration control circuit to be activated by the trigger signal which responds by producing an activation signal that activates the ESD dissipation circuitry and that controls the length of time the dissipation circuit remains active. The ESD dissipation circuitry includes a shunt that redirects the ESD energy away from the protected internal circuit. The ESD dissipation duration circuitry further configured to maintain shunting of the energy for a period of time sufficient to discharge of the ESD energy without damaging the protected circuitry.