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US 9,882,497 B2Granted
Soft switching synchronous quasi resonant converter
AssigneeMicrochip Technology Incorporated
InventorsTerry L. Cleveland, Jeffrey L. Dann, Scott Dearborn
Life of this patent
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Abstract
A switching circuit including a transformer having a primary and a secondary side; a first MOSFET switch coupled with the primary side; a primary current sensing device; a second MOSFET switch coupled with the secondary side; a secondary current sensing device; and a control circuit for driving the first and second MOSFET switches, wherein first and second switch are complementarily driven and wherein switching of the first and second MOSFET switches is controlled by the primary and secondary current sensing devices.
Claims19
A switching circuit comprising:
- a transformer having a primary and a secondary winding wherein the secondary winding is coupled with a load;
- a first MOSFET switch coupled with the primary winding;
- a primary current sensing device configured to measure a current at an output of the first MOSFET;
- a second MOSFET switch coupled in series with the secondary winding;
- a secondary current sensing device coupled in series with the second MOSFET configured to measure a current at an output of the second MOSFET;
- a control circuit for driving said first MOSFET switch and said second MOSFET switch, wherein a driving signal of said first MOSFET switch is inverse to a driving signal of said second MOSFET switch;
- and
- a comparator having a first input, a second input and an output, wherein a signal from the first current sensing device is fed to the first input and a signal from the second current sensing device is fed to the second input and a resulting output signal from said output of said comparator is fed to a pulse width modulator generating the driving signals for said first MOSFET switch and said second MOSFET switch.
5 more elements
A power supply circuit comprising:
- a control circuit;
- and
- a quasi-resonant flyback circuit including:
- a primary circuit controlled by a first transistor switch and including a first current sensing device;
- a secondary circuit controlled by a second transistor switch and including a second current sensing device coupled in series with the second transistor;
- and
- a transformer having a primary and a secondary winding, wherein the primary winding is coupled with the first transistor switch and the secondary winding is coupled in series with the second transistor and with a load;
- wherein the control circuit is configured to drive said first transistor switch and said second transistor switch, wherein a driving signal for said first transistor switch is inverse with respect to a driving signal for said second transistor switch and wherein signals from the first and second current sensing devices are fed to a comparator and compared with each other and a resulting output signal of the comparator is fed to a pulse width modulator generating the driving signals for said first transistor switch and said second transistor switch.
5 more elements
A method, comprising:
- charging an output capacitor through a secondary winding of a flyback transformer with a primary switch, wherein a primary winding of the flyback transformer and the primary switch are coupled to a power source;
- discharging the output capacitor through a secondary winding of the flyback transformer with a secondary switch into a load, the secondary winding of the flyback transformer and the secondary switch being coupled to the output capacitor and the load;
- sensing a current of the primary switch;
- sensing a current of the secondary switch;
- comparing a first current sense signal with a second current sense signal and feeding a resulting control signal to a pulse width modulator generating driving signals for said primary switch and said secondary switch;
- and
- driving said primary switch and said secondary switch with said driving signals, wherein a driving signal for said primary switch is inverse to a driving signal for said secondary switch.
4 more elements
Dependencies are inferred from the claim text.