Low-cost electrostatic discharge (ESD) protection device for high-voltage open-drain pad

摘要

A low-cost ESD protection device for high-voltage open-drain pad is disclosed, which has a first high-voltage (HV) NMOSFET coupled to a high-voltage (HV) open drain pad, a ground pad, a HV block unit and an ESD clamp unit and a low-voltage (LV) bias unit coupled to the first HV NMOSFET, a low-voltage (LV) trigger, the ESD clamp unit and the ground pad. The LV trigger is coupled to the HV block unit. The HV block unit blocks a high voltage from the HV open drain pad diode during normal operation and generates a trigger signal to the LV trigger when an ESD event is applied to the HV open drain pad. Then, the LV trigger turns on the ESD clamp unit to discharge an ESD current and switches the LV bias unit to turn off the first HV NMOSFET.