Patent ID: 7545616
Filing Date: 2009-06-09
Classification: H02H

Abstract:
1. A circuit for discharging static electricity, comprising: a plurality of input/output pads; a plurality of switching units connected to the input/output pads, each switching unit connected to one corresponding input/output pad, wherein the switching units are configured to be turned on in response to a low voltage state relative to an external power voltage; a plurality of resistors connected between the input/output pads and the switching units, each resistor connected to one corresponding input/output pad and to one corresponding switching unit; and a charge device model (CDM) discharge unit serially connected to the plurality of the switching units, wherein the CDM discharge unit providing a part of a ground path, wherein each switching unit includes: a PMOS transistor having a gate connected to the external power voltage, configured to be turned on at a lower potential than the potential of the external power voltage, thereby forming part of the ground path; and a NMOS transistor connected in parallel to the PMOS transistor, the NMOS transistor having a gate connected to one of the input/output pads, configured to be turned on at lower potential than the potential of the external power voltage, thereby forming part of the ground path.