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US 8,576,588 B2Granted
Switching mode power supply with primary side control
AssigneeMonolithic Power Systems, Inc.
InventorsNaixing Kuang, Lei Du, Junming Zhang, Yuancheng Ren
Life of this patent
Estimating the term…
Abstract
The present technology are directed to switching mode power supplies with primary side control. In one embodiment, the switching mode power supply provides an equivalent current signal which represents a load current. The equivalent current signal is then used to control a switching circuit in the switching mode power supply.
Claims20
A switching mode power supply, comprising:
- a transformer having a primary winding, a secondary winding, and an auxiliary winding;
- a switching circuit coupled to the primary winding, the switching circuit having a switch coupled to the primary winding to control current flow through the primary winding;
- a calculator configured to receive a switching control signal and a current sense signal, wherein the current sense signal represents a current flow through the primary winding, and wherein based on the switching control signal and the current sense signal, the calculator is configured to provide an equivalent current signal;
- a zero-crossing detector coupled to the auxiliary winding, wherein the zero-crossing detector provides a zero detected signal when a voltage across the auxiliary winding first crosses zero;
- and
- a controller configured to receive the equivalent current signal, the zero detected signal, the current sense signal, and a reference signal, and to provide the switching control signal to the switching circuit based thereon.
3 more elements
A switching mode power supply, comprising:
- a transformer having a primary winding and a secondary winding;
- a switching circuit coupled to the primary winding, the switching circuit having a switch coupled to the primary winding to control current flow through the primary winding;
- a calculator configured to receive a switching control signal and a current sense signal, wherein the current sense signal represents a current flow through the primary winding, and wherein based on the switching control signal and the current sense signal, the calculator is configured to provide an equivalent current signal;
- a detecting capacitor coupled to the primary winding for sensing an oscillation between a magnetizing inductor of the primary winding and a parasitic capacitor of the switching circuit;
- a zero-crossing detector coupled to the detecting capacitor, wherein the zero-crossing detector is configured to provide a zero detected signal in response to a reverse current flow through the detecting capacitor;
- and
- a controller configured to receive the equivalent current signal, the zero detected signal, the current sense signal, and a reference signal, and to provide the switching control signal based thereon.
4 more elements
A switching mode power supply, comprising:
- a transformer having a primary winding and a secondary winding;
- means for controlling the current flow through the primary winding;
- means for providing an equivalent current signal in response to a switching control signal and a current sense signal;
- means for sensing an oscillation between a magnetizing inductor of the primary winding and a parasitic capacitor;
- means for providing a zero detected signal in response to a first zero-crossing of the oscillation;
- and
- means for providing the switching control signal in response to the equivalent current signal, the zero detected signal, the current sense signal, and a reference signal.
4 more elements
A method used in a switching mode power supply, comprising:
- sensing a current flow through a primary winding of a transformer and generating a current sense signal, the transformer having a switching circuit coupled to the primary winding and configured to controllably charge/discharge the primary winding;
- sensing an oscillation between a magnetizing inductor of the primary winding of the transformer and a parasitic capacitor of the switching circuit;
- generating a zero detected signal when the oscillation first crosses zero;
- generating an equivalent current signal in response to a switching control signal and the current sense signal, wherein the switching control signal is coupled to control the switching circuit;
- and
- generating the switching control signal in response to the equivalent current signal, the zero detected signal, the current sense signal, and a reference signal.
3 more elements
Dependencies are inferred from the claim text.