Power supply circuit
A power supply circuit includes: a coil having a first end that receives an input voltage and a second end; a transistor connected to the second end of the coil; a first capacitor connected to the second end of the coil; and a surge protection circuit connected to the second end of the coil in parallel with the first capacitor. The surge protection circuit includes a diode, a second capacitor, and a resistance. The diode, the second capacitor, and the resistance are connected in series to the second end of the coil.
1. A power supply circuit comprising:
a coil having a first end that receives an input voltage and a second end;
a switching element connected to the second end of the coil;
a first capacitor connected to the second end of the coil; and
a surge protection circuit connected to the second end of the coil in parallel with the first capacitor, wherein
the surge protection circuit comprises
a diode,
a second capacitor, and
a resistance, and
the diode, the second capacitor, and the resistance are connected in series to the second end of the coil.
2. The power supply circuit according to claim 1 , wherein a capacitance of the second capacitor is greater than a capacitance of the first capacitor.
3. The power supply circuit according to claim 2 , wherein
the diode comprises a Zener diode,
the Zener diode comprises a cathode electrically connected to the second end of the coil, and
the second capacitor and the resistance are connected in series to an anode of the Zener diode.
4. The power supply circuit according to claim 3 , wherein an operating voltage of the Zener diode is lower than a rated voltage of the switching element.
5. The power supply circuit according to claim 3 , wherein an operating voltage of the Zener diode exceeds a design value of the input voltage.
6. The power supply circuit according to claim 4 , wherein an operating voltage of the Zener diode exceeds a design value of the input voltage.
7. The power supply circuit according to claim 2 , wherein the diode comprises an anode connected to the second end of the coil.
8. The power supply circuit according to claim 7 , wherein
the diode comprises an anode connected to the second end of the coil,
the surge protection circuit further includes a Zener diode, and
the Zener diode, the second capacitor and the resistance are connected in series to a cathode of the diode.
9. The power supply circuit according to claim 1 , wherein
the diode comprises a Zener diode,
the Zener diode comprises a cathode electrically connected to the second end of coil, and
the second capacitor and the resistance are connected in series to an anode of the Zener diode.
10. The power supply circuit according to claim 9 , wherein an operating voltage of the Zener diode is lower than a rated voltage of the switching element.
11. The power supply circuit according to claim 9 , wherein an operating voltage of the Zener diode exceeds a design value of the input voltage.
12. The power supply circuit according to claim 10 , wherein an operating voltage of the Zener diode exceeds a design value of the input voltage.
13. The power supply circuit according to claim 1 , wherein the diode comprises an anode connected to the second end of the coil.
14. The power supply circuit according to claim 13 , wherein
the diode comprises an anode connected to the second end of the coil,
the surge protection circuit further includes a Zener diode, and
the Zener diode, the second capacitor and the resistance are connected in series to a cathode of the diode.