Detection circuit for an active discharge circuit of an X-capacitor, related active discharge circuit, integrated circuit and method

A method, comprising:

• detecting an AC oscillation at a capacitor by:
• comparing a sensor signal, indicative of a voltage at the capacitor, with a lower threshold value and determining whether the sensor signal is greater than the lower threshold value:
• comparing the sensor signal with an upper threshold value and determining whether the sensor signal is lower than the upper threshold value;
• increasing a first value of a smaller one of the lower threshold value and the upper threshold value to a first new value that is greater than a second value of a larger one of the lower threshold value and the upper threshold value in response to a first control signal indicating a sensor signal is greater than the values of the upper threshold value and the lower threshold value;
• and
• decreasing a third value of the greater one of the lower threshold value and the upper threshold value to a second new value that is less than the value of the larger one of the lower threshold value and the upper threshold value in response to a second control signal indicating the sensor signal is less than the values of the upper threshold value and the lower threshold value.

A device, comprising:

• a discharge capacitor;
• a voltage sensor coupled to the discharge capacitor and configured to output a signal representative of a voltage of the discharge capacitor;
• a first comparator coupled to the voltage sensor and configured to compare the signal to a first threshold;
• a second comparator coupled to the voltage sensor and configured to compare the signal to a second threshold;
• an elaboration circuit coupled to the first and second comparators, the elaboration circuit including:
• an AND gate coupled to the first and second comparators;
• and
• a NOR gate coupled to the first and second comparators, wherein the AND gate and the NOR gate together indicate whether the signal is greater than, less than or between the first and second thresholds;
• and
• a dynamic threshold generator circuit coupled to the first and second comparators and to the elaboration circuit.