Capacitance discrimination circuit and touch switch equipped with the same

A capacitance discrimination circuit comprising:

• a first capacitor;
• a second capacitor;
• a comparator configured to compare a first voltage of the first capacitor and a second voltage of the second capacitor;
• a counter circuit configured to perform a count operation based on a comparison result of the comparator;
• a charge circuit configured to charge the first capacitor and the second capacitor;
• and
• a control circuit configured to control the charge circuit so as to charge either the first capacitor or the second capacitor based on a comparison result of the comparator, wherein capacitance discrimination of the first capacitor and the second capacitor is performed based on count values of the counter circuit;
• wherein the counter circuit includes:
• a first counter configured to perform a count operation when the comparison result of the comparator is a first value;
• a second counter configured to perform a count operation when the comparison result of the comparator is not the first value;
• and
• a third counter configured to count a predetermined time period,
• wherein, when it is discriminated by the third counter that the predetermined time period has passed, the capacitance discrimination of the first capacitor and the second capacitor is performed based on the count values of the first counter and the second counter.

A capacitance discrimination method of discriminating capacitance of a plurality of capacitors, the method comprising the steps of:

• comparing voltages of the plurality of capacitors;
• performing a count operation on one of the plurality of capacitors lowest in voltage based on a comparison result of the voltages of the plurality of capacitors to obtain a count value on each of the plurality of capacitors;
• charging one of the plurality of capacitors lowest in voltage based on the comparison result of the voltages of the plurality of capacitors;
• and
• discriminating capacitance of the plurality of capacitors based on the count values of the count operation.