Switched current regulator with improved power switch control mechanism
AssigneeSGS-Thomson Microelectronics S.A.
InventorAntoine Pavlin
Life of this patent
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Abstract
A flyback-type switched current regulator, comprising first and second coupled windings and a circuit for connecting the first winding to a voltage source as soon as the windings are demagnetized. The regulator further comprises a current sensor that senses the current flowing through the first winding; a switch that disconnects the first winding from the voltage source when the first current in the first winding reaches a reference value, whereby the first winding is switched according to a duty cycle; and a circuit that varies the reference value in accordance with the duty cycle.
Claims36
A flyback-type switched current regulator, comprising:
- a first winding;
- a second winding coupled to the first winding;
- a current sensor, coupled to the first winding, that senses an instantaneous current flowing through the first winding and outputs a current sensor signal indicative of the instantaneous current;
- connecting means for connecting the first winding to a voltage source when a second current flowing through the second winding is substantially zero;
- disconnecting means for disconnecting the first winding from the voltage source when the current sensor signal indicates that the instantaneous current flowing through the first winding is greater than or equal to a variable reference value, whereby the first winding is connected to and disconnected from the voltage source according to a switching duty cycle;
- and
- varying means, coupled to a supply voltage, for varying the variable reference value with variations of the switching duty cycle.
A switched current regulator, comprising:
- a first winding;
- a second winding coupled to the first winding;
- a current sensor, coupled to the first winding, that senses a first instantaneous current flowing through the first winding and that outputs a current sensor signal having a first state when the first instantaneous current flowing through the first winding is greater than or equal to a reference value;
- a demagnetization sensor, coupled to a winding core located between the first winding and the second winding, that senses a second current flowing through the second winding and that outputs a demagnetization sensor signal having a first state when the second current flowing through the second winding is substantially zero;
- and
- a connection circuit, responsive to the current sensor signal and the demagnetization sensor signal, that connects the first winding to a voltage source when the demagnetization sensor signal is in the first state and that disconnects the first winding from the voltage source when the current sensor signal is in the first state.
A method for regulating current in a current regulator having a first winding and a second winding coupled to the first winding, the method comprising the steps of:
- A. determining an instantaneous amount of a first current flowing through the first winding;
- B. comparing the instantaneous amount of the first current flowing through the first winding with a variable reference value;
- C. coupling the first winding to a voltage source when the instantaneous amount of the first current in the first winding is less than the variable reference value;
- and
- D. decoupling the first winding from the voltage source when the instantaneous amount of the first current in the first winding is greater than or equal to the variable reference value.
A method for self-oscillation of a switched current regulator having a power switch disposed in series with a current sensor between a first winding and a terminal of a voltage supply, a winding core disposed between the first winding and a second winding, a demagnetization circuit coupled to the winding core and a reference switch disposed between a terminal of a current source and ground, the method comprising the steps of:
- A. determining a value of a second current flowing through the second winding;
- B. closing the power switch when the second current flowing through the second winding is substantially zero such that a first current flows through the first winding;
- C. opening the reference switch when the second current flowing through the second winding is substantially zero to generate a variable reference signal;
- and
- D. opening the power switch according to the generated variable reference signal and an instantaneous amount of the first current.
Dependencies are inferred from the claim text.