Start-up circuit for switched mode power supply
AssigneeKoninklijke Philips Electronics N.V.
InventorHubertus Cornelis Miermans
Life of this patent
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Abstract
A switched mode power supply apparatus is equipped with a start-up device supplying electrical energy to a controller which controls the switching of a switching transistor. The start-up device is bypassed by a bypass device. During start-up of the power supply, the bypass device is open. After a successful start-up, the bypass device is closed, eliminating further dissipation in the start-up device, and, therefore, increasing the overall energy efficiency of the power supply. By connecting the start-up device to a stand-by power supply or to a primary voltage, use of an additional winding on the transformer to supply the controller is obviated. The power supply has an electronic overload protection, and will stop and periodically attempt a restart when an overload condition occurs.
Claims7
A switched mode power supply for conversion of an input voltage into at least one output voltage, comprising:
- an inductive device for transforming the input voltage into the at least one output voltage;
- a switching device for periodically coupling the inductive. device to the input voltage;
- a controller for controlling the switching of the switching device;
- a start-up device for supplying electrical energy to the controller in a start-up phase;
- and
- a bypass device coupled in parallel to the start-up device for bypassing the start-up device when the switched mode power supply is in regulation,
- characterized in that the switched mode power supply further comprises:
- a detection device for detecting whether an output quantity of the switched mode power supply indicates that the switched mode power supply is in regulation;
- and
- a control circuit for controlling the bypass device to be closed when the detection device detects that the switched mode power supply is in regulation.
A switched mode power supply for conversion of an input voltage into at least one output voltage, comprising:
- an inductive device for transforming the input voltage into the at least one output voltage;
- a switching device for Periodically coupling the inductive device to the input voltage;
- a controller for controlling the switching of the switching device;
- a start-up device for supplying electrical energy to the controller in a start-up phase;
- and
- a bypass device coupled in parallel to the start-up device for bypassing the start-up device when the switched mode power supply is in regulation,
- characterized in that the bypass device is a controllable semiconductor switch.
A switched mode power supply for conversion of an input voltage into at least one output voltage, comprising:
- an inductive device for transforming the input voltage into the at least one output voltage;
- a switching device for periodically coupling the inductive device to the input voltage;
- a controller for controlling the switching of the switching device;
- a start-up device for supplying electrical energy to the controller in a start-up phase;
- a bypass-device coupled in parallel to the start-up device for bypassing the start-up device when the switched mode power supply is in regulation;
- a detection device for detecting whether an output quantity of the switched mode power supply indicates that the switched mode power Supply is in regulation;
- and
- a control circuit for controlling the bypass device to be closed when the detection device detects that the switched mode power supply is in regulation,
- characterized in that the controller the bypass device the detection device detects that the at least one output voltage drops below a predetermined value.
A method of starting up a switched mode power supply for conversion of an input voltage into at least one output voltage, the switched mode power supply comprising:
- an inductive device for transforming the input voltage into the at least one output voltage;
- a switching device for periodically coupling the primary winding to the input voltage;
- a controller for controlling the switching of the switching device;
- and
- a start-up device for supplying electrical energy to the controller in a start-up phase, characterized in that the method further comprises the steps:
- supplying electrical energy to the controller from the start-up device in a start-up phase;
- detecting when the switched mode power supply is in regulation;
- and
- bypassing the start-up device, when the switched mode power supply is detected to be in regulation.
Dependencies are inferred from the claim text.