Input-voltage-off detection apparatus and power supply with input-voltage-off detection apparatus

A power supply comprising:

• an input-voltage-off detection apparatus;
• an auxiliary voltage winding electrically connected to the input-voltage-off detection apparatus;
• a main converter electrically connected to the auxiliary voltage winding;
• a pulse width modulation controller electrically connected to the auxiliary voltage winding and the main converter;
• a primary side filtering capacitor electrically connected to the main converter;
• a bridge rectifier electrically connected to the primary side filtering capacitor, the pulse width modulation controller and the auxiliary voltage winding;
• an output side filter electrically connected to the main converter and an electronic apparatus;
• and
• a feedback circuit electrically connected to the output side filter, the electronic apparatus and the pulse width modulation controller,
• wherein the input-voltage-off detection apparatus comprises:
• a voltage adjustment unit receiving an input voltage;
• a time delay unit electrically connected to the voltage adjustment unit and utilizing the input voltage to generate a direct current voltage;
• a voltage clamp unit electrically connected to the voltage adjustment unit and the time delay unit;
• an auxiliary voltage discharge switch unit electrically connected to the voltage adjustment unit, the time delay unit, the voltage clamp unit and the auxiliary voltage winding;
• and
• an isolation notification unit electrically connected to the auxiliary voltage winding, the auxiliary voltage discharge switch unit and the electronic apparatus,
• wherein after the input voltage is cut off, the direct current voltage stored in the time delay unit discharges to the voltage adjustment unit;
• when the direct current voltage reduces to a predetermined voltage, the auxiliary voltage discharge switch unit is turned on, so that the auxiliary voltage winding sends a working voltage to the isolation notification unit;
• after the isolation notification unit receives the working voltage, the isolation notification unit notifies the electronic apparatus that the input voltage is cut off.