Patent ID: 6944286

Claim:
A circuit for interference-proof detection in the operation of a grounding key, the circuit comprising: a current detection device configured to detect a current flowing when the grounding key is in operation; a comparator configured to compare the detected current with at least one threshold value, wherein the comparator includes: a first comparator circuit configured to compare the detected current with an upper threshold value; and a second comparator circuit configured to compare the detected current with a lower threshold value; a monitoring circuit configured to: detect a first period when the current exceeds the upper threshold value; and detect a second period when the current drops below the lower threshold value; output a grounding key detection signal when the first period is greater than the second period, wherein the monitoring circuit includes at least one internal counter configured to count up when the upper threshold value has been exceeded by the current and at least one internal counter configured to count down when the lower threshold value has not been exceeded by the current.