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US 5,552,695 AGranted
Synchronously rectified buck-flyback DC to DC power converter
AssigneeLinear Technology Corporation
InventorPeter H. Schwartz
Life of this patent
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Abstract
A synchronously rectified buck-flyback converter is described which provides multiple synchronous regulated outputs. A synchronous buck converter provides the main output and a synchronous flyback converter, utilizing the primary inductor of the buck converter, provides the secondary output. The converter utilizes a split-feedback signal, whereby each of the regulated outputs provides a component of the signal and a switch controller synchronously activates and deactivates rectification switches based on the feedback signal, required output levels and load. The switches are synchronously controlled such that a power input switch is operated in anti-phase to a control switch for each regulated output.
Claims62
A circuit for providing a plurality of regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element having a first end coupled to a node between said first and second switches, and a second end coupled to produce a first output;
- a second inductive element having a first end coupled to produce a second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to turn current flow through said second inductive element ON and OFF;
- and
- a control circuit coupled to synchronously control the ON and OFF duty cycles of said first, second and third switches to regulate said first and second outputs, such that said second and third switches operate in substantial phase with one another, and in substantial anti-phase with said first switch.
3 more elements
A circuit for providing a plurality of regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element having a first end coupled to a node between said first and second switches, and a second end coupled to produce a first output;
- a second inductive element having a first end coupled to produce a second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to turn current flow through said second inductive element ON and OFF;
- a control circuit coupled to synchronously control the ON and OFF duty cycles of said first, second and third switches such that said second and third switches operate in substantial phase with one another, and in substantial anti-phase with said first switch;
- and
- a circuit for sensing said first and second outputs, for producing feedback signals indicative of the magnitudes of said first and second outputs, and for coupling said feedback signals to said control circuit to regulate said first and second outputs.
4 more elements
A circuit for regulating a plurality of output voltages, said circuit comprising:
- first and second means, coupled in series with each other across a source of electrical potential, for turning a first current ON and OFF;
- a first inductive means coupled to a node between said first and second means, and coupled to produce a first output;
- a second inductive means coupled to produce a second output, and magnetically coupled with said first inductive means;
- a third means, coupled in series with said second inductive means, for turning a second current through said second inductive means ON and OFF;
- and
- means for synchronously controlling the ON and OFF duty cycles of said first, second and third means such that said second and third means operate in substantial phase with one another, and in substantial anti-phase with said first means, to cause said first and second outputs to be regulated.
3 more elements
In a circuit adapted to be coupled to first and second terminals providing a source of electrical potential, a method for producing regulated first and second output voltages comprising the steps of:
- forming a current path between said first terminal and said first output through a first switch and a first inductive element;
- forming a current path between said second terminal and said first output through a second switch and said first inductive element;
- forming a current path between said second terminal and said second output through a third switch and a second inductive element, wherein said third switch turns current flow through said second inductive element ON and OFF;
- magnetically coupling said first and second inductive elements;
- and
- synchronously controlling the ON and OFF duty cycles of said first, second and third switches such that said second and third switches are operated in substantial phase with one another, and in substantial anti-phase with said first switch, to cause said first and second outputs to be regulated.
3 more elements
In a circuit adapted to be coupled to first and second terminals providing a source of electrical potential, a method for producing regulated first and second output voltages comprising the steps of:
- forming a current path between said first terminal and said first output through a first switch and a first inductive element;
- forming a current path between said second terminal and said first output through a second switch and said first inductive element;
- forming a current path between said second terminal and said second output through a third switch and a second inductive element, wherein said third switch turns current flow through said second inductive element ON and OFF;
- magnetically coupling said first and second inductive elements;
- and
- synchronously controlling the ON and OFF duty cycles of said first, second and third switches to cause said first and second outputs to be regulated.
3 more elements
A circuit for providing first and second regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element coupled at a first end to a node between said first and second switches, and coupled at a second end to produce said first output;
- a second inductive element coupled at a first end to produce said second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to turn current flow through said second inductive element ON and OFF;
- and
- means for synchronously controlling the ON and OFF duty cycles of said first, second and third switches to cause said first and second outputs to be regulated.
3 more elements
A circuit for providing a plurality of regulated output voltages, said circuit comprising:
- a first switching voltage regulator circuit in a buck configuration providing a buck regulated output, said first regulator circuit being synchronously controlled by first and second switches;
- a second switching voltage regulator circuit in a flyback configuration providing a flyback regulated output, said second regulator circuit being synchronously controlled by said first switch and a third switch, and said regulator circuits being magnetically coupled;
- means for synchronously controlling the 0N and OFF duty cycles of said first, second and third switches to cause said buck and flyback outputs to be simultaneously regulated.
In a circuit adapted to be coupled to first and second terminals providing a source of electrical potential, a method of producing synchronously regulated buck and flyback output voltages comprising the steps of:
- forming a current path between said first terminal and said buck output through a first switch and a first inductive element;
- forming a current path between said second terminal and said buck output through a second switch and said first inductive element;
- forming a current path through a second inductive element and a third switch to said flyback output;
- magnetically coupling said buck and flyback outputs;
- and
- synchronously controlling the ON and OFF duty cycles of said first, second and third switches such that said first and second switches operate in substantial anti-phase with one another to generate said buck output and said first and third switches operate in substantial anti-phase with one another to generate said flyback output.
3 more elements
A circuit for providing a plurality of regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element having a first end coupled to a node between said first and second switches, and a second end coupled to produce a first output;
- a second inductive element having a first end coupled to produce a second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to control current flow through said second inductive element;
- a control circuit coupled to synchronously control the ON and OFF duty cycles of said first, second and third switches to regulate said first and second outputs, such that said second and third switches operate in substantial phase with one another, and in substantial anti-phase with said first switch;
- a first feedback circuit coupled to provide a first feedback signal indicative of the magnitude of said first output;
- and
- a second feedback circuit coupled to provide a second feedback signal indicative of the magnitude of said second output, wherein said first and second feedback signals are combined into a single feedback signal which is coupled to said control circuit to responsively vary the ON and OFF duty cycles of said switches.
5 more elements
A circuit for providing a plurality of regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element having a first end coupled to a node between said first and second switches, and a second end coupled to produce a first output;
- a second inductive element having a first end coupled to produce a second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to control current flow through said second inductive element;
- a control circuit coupled to synchronously control the ON and OFF duty cycles of said first, second and third switches such that said second and third switches operate in substantial phase with one another, and in substantial anti-phase with said first switch;
- and
- a circuit for sensing said first and second outputs, for producing feedback signals indicative of the magnitudes of said first and second outputs, and for coupling said feedback signals to said control circuit to regulate said first and second outputs, wherein said feedback signals are combined into a single feedback signal that is coupled to said control circuit.
4 more elements
In a circuit adapted to be coupled to first and second terminals providing a source of electrical potential, a method for producing regulated first and second output voltages comprising the steps of:
- forming a current path between said first terminal and said first output through a first switch and a first inductive element;
- forming a current path between said second terminal and said first output through a second switch and said first inductive element;
- forming a current path between said second terminal and said second output through a third switch and a second inductive element, wherein said third switch controls current flow through said second inductive element;
- magnetically coupling said first and second inductive elements;
- synchronously controlling the ON and OFF duty cycles of said first, second and third switches such that said second and third switches are operated in substantial phase with one another, and in substantial anti-phase with said first switch, to cause said first and second outputs to be regulated;
- providing first and second feedback signals indicative of said first and second outputs, respectively, to responsively vary the ON and OFF duty cycles of said switches;
- combining said first and second feedback signals into a single feedback signal;
- and
- coupling said single feedback signal such that said step of controlling responsively varies the ON and OFF duty cycles of said switches, at least in part, based on said single feedback signal.
6 more elements
In a circuit adapted to be coupled to first and second terminals providing a source of electrical potential, a method for producing regulated first and second output voltages comprising the steps of:
- forming a current path between said first terminal and said first output through a first switch and a first inductive element;
- forming a current path between said second terminal and said first output through a second switch and said first inductive element;
- forming a current path between said second terminal and said second output through a third switch and a second inductive element, wherein said third switch controls current flow through said second inductive element;
- magnetically coupling said first and second inductive elements;
- and
- synchronously controlling the ON and OFF duty cycles of said first, second and third switches to cause said first and second outputs to be regulated;
- providing first and second feedback signals indicative of said first and second outputs, respectively, to responsively vary the ON and OFF duty cycles of said switches;
- combining said first and second feedback signals into a single feedback signal;
- and
- coupling said single feedback signal such that said step of controlling responsively varies the ON and OFF duty cycles of said switches, at least in part, based on said single feedback signal.
7 more elements
A circuit for providing first and second regulated output voltages, said circuit comprising:
- first and second switches coupled in series between a source of electrical potential;
- a first inductive element coupled at a first end to a node between said first and second switches, and coupled at a second end to produce said first output;
- a second inductive element coupled at a first end to produce said second output, and magnetically coupled with said first inductive element;
- a third switch coupled in series with said second inductive element to control current flow through said second inductive element;
- means for synchronously controlling the ON and OFF duty cycles of said first, second and third switches to cause said first and second outputs to be regulated;
- and
- first and second feedback circuits coupled to produce feedback signals indicative of said first and second outputs, respectively, to responsively vary the ON and OFF duty cycles of said switches, wherein said feedback signals are combined into a single feedback signal that is coupled to said means for controlling.
4 more elements
Dependencies are inferred from the claim text.