Patent ID: 8139331

Claim:
An electrostatic discharge (ESD) protection circuit, comprising: a first clamp connected between a first power line and a ground line; a second clamp connected between the ground line and a second power line; a first output buffer connected between the first power line and the ground line, and providing a first operating voltage to an input/output pad; a second output buffer connected between the ground line and the second power line, and providing a second operating voltage to the input/output pad; a first switch unit configured to transfer the first operating voltage to the input/output pad; a second switch unit configured to transfer the second operating voltage to the input/output pad; a first transfer unit comprising one or more diodes having a breakdown voltage higher than the first operating voltage and connected in series between the first power line and the input/output pad; and a second transfer unit comprising one or more diodes having a breakdown voltage higher than the second operating voltage and connected in series between the input/output pad and the second power line.