Electrostatic discharge protection device and method thereof

An electrostatic discharge protection device for protecting an inner circuit, the inner circuit operated in a source voltage and receiving an input voltage through a pad, the electrostatic discharge protection device comprising:

• a protection unit providing a discharge path transmitting an electrostatic signal from the pad to a ground line, the protection unit having a control end and adjusting a holding voltage and a triggering voltage for determining whether to conduct the discharge path based on a voltage level at the control end;
• and
• a control unit transmitting the input voltage to the control end of the protection unit when the source voltage is supplied, such that the protection unit raises the holding voltage and the triggering voltage, the control unit switching the control end of the protection unit to a floating condition or a ground condition by the electrostatic signal when the source voltage is not supplied, such that the protection unit lowers the holding voltage and the triggering voltage.