POWER SUPPLY CIRCUIT AND POWER SUPPLY SYSTEM
First Claim
1. A power supply circuit configured to self-oscillate by supply of power from a power supply section, the power supply circuit being comprising:
- a resonance section including a resonance capacitor and a resonance coil, and adapted for supplying power to a load device;
an oscillation section including a first switching element connected in series to said resonance section and a feedback coil magnetically coupled to said resonance coil, and adapted for turning on and off said first switching element to cause said resonance section to self-oscillate;
a turn-off section including a second switching element and a turn-off capacitor connected between a control terminal of said second switching element and a negative electrode of the power supply section, wherein when an on-current which flows when said first switching element turns on reaches a predetermined level, said second switching element turns on to cause said first switching element to turn off; and
a first charging section including a diode of which anode is connected to said feedback coil side, and a zener diode of which cathode is connected to the cathode of said diode and of which anode is connected to said turn-off capacitor side.
1 Assignment
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Accused Products
Abstract
To provide a power supply circuit which can be applied worldwide without using a high withstand voltage switching element and can supply a load device with stable power. A charging section is arranged between a turn-off capacitor and a load coil. The charging section has the anode connected to the positive terminal of a feedback coil and the cathode connected to the cathode of a zener diode. Thus, when a voltage of a commercial power supply is high, the charging section operates, the turn-off capacitor is quickly charged, an on-period of a transistor is shortened, and an excessive voltage is prevented from being applied between the drain and the source of the transistor. At the same time, an output characteristic indicating relationship between the voltage of the commercial power supply and a current flowing in the load device is permitted to be flat.
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Citations
18 Claims
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1. A power supply circuit configured to self-oscillate by supply of power from a power supply section, the power supply circuit being comprising:
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a resonance section including a resonance capacitor and a resonance coil, and adapted for supplying power to a load device; an oscillation section including a first switching element connected in series to said resonance section and a feedback coil magnetically coupled to said resonance coil, and adapted for turning on and off said first switching element to cause said resonance section to self-oscillate; a turn-off section including a second switching element and a turn-off capacitor connected between a control terminal of said second switching element and a negative electrode of the power supply section, wherein when an on-current which flows when said first switching element turns on reaches a predetermined level, said second switching element turns on to cause said first switching element to turn off; and a first charging section including a diode of which anode is connected to said feedback coil side, and a zener diode of which cathode is connected to the cathode of said diode and of which anode is connected to said turn-off capacitor side. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification