Buck-Flyback Converter
AssigneeInfineon Technologies North America Corp.
InventorsMladen Ivankovic, Fred Sawyer
Life of this patent
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Abstract
A two-transistor flyback converter includes a transformer having a primary side and a secondary side, a first transistor connected between an input voltage source and a first terminal of the primary side, a second transistor connected between ground and a second terminal of the primary side, and a diode directly connected between the first terminal of the primary side and ground. The first and second transistors are operable to switch on and off simultaneously and with no current return from the primary side to the input voltage source when the input voltage source is less than a reflected voltage from the secondary side.
Claims20
A two-transistor flyback converter, comprising:
- a transformer having a primary side and a secondary side;
- a first transistor connected between an input voltage source and a first terminal of the primary side;
- a second transistor connected between ground and a second terminal of the primary side;
- a diode directly connected between the first terminal of the primary side and ground;
- and
- wherein the first and second transistors are operable to switch on and off simultaneously and with no current return from the primary side to the input voltage source when the input voltage source is less than a reflected voltage from the secondary side.
A method of operating a two-transistor flyback converter including a transformer with a primary side and a secondary side, the method comprising:
- simultaneously switching on a first transistor connected between an input voltage source and a first terminal of the primary side, and a second transistor connected between ground and a second terminal of the primary side to energize the transformer through the primary side;
- simultaneously switching off the first and second transistors to transfer the energy stored in the transformer to a load connected to the secondary side;
- and
- connecting the first terminal of the primary side to ground only through a diode when the first and second transistors are switched off and with no current return from the primary side to the input voltage source when the input voltage source is less than a reflected voltage from the secondary side.
A two-transistor flyback converter, comprising:
- a transformer having a primary side and a secondary side;
- a first MOSFET having a drain connected to an input voltage source and a source connected to a first terminal of the primary side;
- and
- a second MOSFET having a drain connected to a second terminal of the primary side and a source connected to ground so that the primary side is decoupled from the input voltage source by only the first MOSFET and energy is transferred to the secondary side independent of the primary side voltage when the first and second MOSFETs are switched off.
A method of operating a two-transistor flyback converter including a transformer with a primary side and a secondary side, the method comprising:
- switching on a first MOSFET having a drain connected to an input voltage source and a source connected to a first terminal of the primary side, and a second MOSFET having a drain connected to a second terminal of the primary side and a source connected to ground to energize the transformer through the primary side;
- switching off the first and second MOSFETs to transfer the energy stored in the transformer to a load connected to the secondary side;
- decoupling the primary side from the input voltage source by only the first MOSFET when the first and second MOSFETs are switched off;
- and
- transferring energy from the primary side to the secondary side independent of the primary side voltage when the first and second MOSFETs are switched off.
Dependencies are inferred from the claim text.