An interface circuit of an electronic device includes one or more pins, an internal circuit, an over-voltage protection circuit and a monitoring circuit. The pins are selectively connected to an external circuit. The over-voltage protection circuit is coupled between the internal circuit and at least one pin to prevent the internal circuit from being damaged by a voltage spike or a current surge received at the pin. The monitoring circuit is configured to monitor one or more electrical characteristics of at least one critical component in the internal circuit or the over-voltage protection circuit by monitoring the value of at least one parameter related to the electrical characteristics of the critical component. When the value of the parameter is outside of a safety range, the monitoring circuit outputs a warning signal.