US Patent 10163888 Self-biased bidirectional ESD protection circuit

Disclosed examples provide an ESD protection circuit including a protection structure to selectively conduct current between a first terminal at a protected node and a second terminal at a reference node in response to the protected node voltage and a control voltage signal rising above a trigger voltage during an ESD event, and a bias circuit configured to bias a protection structure control terminal at a control voltage corresponding to a higher one of a first voltage of the first terminal and a second voltage of the second terminal to control the trigger voltage of the ESD protection structure to keep the ESD protection structure off during normal operation.