Auxiliary power supply circuit operating within a wide input voltage range

An auxiliary power supply circuit operating within a wide input voltage range, applied to be electrically connected to a working voltage conversion circuit of a wide input voltage range direct-current (DC) power converter, and comprising:

• a voltage follower unit comprising:
• an electronic switch comprising:
• a first terminal electrically connected to a voltage input terminal of the working voltage conversion circuit;
• a second terminal electrically connected to a voltage output terminal of the working voltage conversion circuit;
• and
• a control terminal;
• a resistor electrically connected between the first terminal of the electronic switch and the control terminal of the electronic switch;
• and
• a Zener diode having a cathode electrically connected to the control terminal of the electronic switch;
• and
• a voltage comparison unit comprising:
• a detecting terminal electrically connected to the voltage input terminal of the working voltage conversion circuit;
• and
• an output terminal electrically connected to the control terminal of the electronic switch,
• wherein the electronic switch of the voltage follower unit is defined as a first electronic switch;
• wherein a breakdown voltage of the Zener diode is lower than a threshold voltage;
• wherein the threshold voltage is equal to a steady-state output voltage of the working voltage conversion circuit;
• wherein the breakdown voltage of the Zener diode is lower than the steady-state output voltage,
• wherein the voltage comparison unit comprises:
• a comparator having:
• a non-inverting input terminal deemed as the detecting terminal of the voltage comparison unit;
• an inverting input receiving a reference voltage correlating with a protection voltage higher than the threshold voltage;
• and
• an output terminal;
• and
• a second electronic switch comprising:
• a first terminal deemed as the output terminal of the voltage comparison unit;
• a second terminal provided to be grounded;
• and
• a control terminal electrically connected to the output terminal of the comparator.