Electronic apparatus, voltage detector and voltage detection method thereof

A voltage detector, comprising:

• a rectifying and filtering circuit, receiving an alternating current input voltage, and performing a rectifying and filtering operation on the alternating current input voltage to generate a processed voltage;
• a comparison circuit, coupled to the rectifying and filtering circuit, and comparing the processed voltage with a reference voltage to generate a comparison signal;
• and
• a detection signal generator, having a first side and a second side, the first side coupled to the comparison circuit to receive the comparison signal, the first side generating an induction signal according to the comparison signal, and the second side receiving the indication signal to generate a detection signal,
• wherein the first side and the second side are isolated,
• wherein the detection signal generator comprises:
• an optical coupler, having a light-emitting element and a phototransistor, wherein the light-emitting element is arranged on the first side, and the phototransistor is arranged on the second side;
• and
• a first resistor, coupled between the phototransistor and a reference grounding voltage end,
• wherein an end point, coupled to the phototransistor, of the first resistor generates the detection signal, a first end of the light-emitting element receives a power voltage, and a second end of the light-emitting element receives the comparison signal.