POWER SUPPLY CONTROL SYSTEM
First Claim
1. A control system for a switch mode power supply (SMPS), the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the control system having two operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer, said control system having a feedback input to receive a said feedback signal, a control output for regulating said output voltage, and a mode selector coupled to said feedback input to select one of said first and second control system operating modes responsive to said feedback signal.
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Abstract
This invention relates to improved control systems and methods for switch mode power supplies. A control system for a switch mode power supply (SMPS), the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the control system having two operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer, said control system having a feedback input to receive a said feedback signal, a control output for regulating said output voltage, and a mode selector coupled to said feedback input to select one of said first and second control system operating modes responsive to said feedback signal.
43 Citations
26 Claims
- 1. A control system for a switch mode power supply (SMPS), the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the control system having two operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer, said control system having a feedback input to receive a said feedback signal, a control output for regulating said output voltage, and a mode selector coupled to said feedback input to select one of said first and second control system operating modes responsive to said feedback signal.
- 9. A control system for a switch mode power supply, the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the control system having a feedback input to receive a feedback signal (FB) responsive to a voltage in said output side of said SMPS, and a control output to provide a control signal (DEMAND) for, regulating said dc output voltage, the control system further comprising a first comparator coupled to said feedback input to compare a signal from said feedback input with a first reference level to provide a first digitised signal (FLY), and a second comparator with a second reference level to provide a second digitised signal (FBD), and a control system to provide said control signal responsive to said first and second digitised signals.
- 11. A control system as claimed in claim 11 further comprising a first store coupled to an output of said first comparator to store a history of said first digitised signal, and wherein said sampling time is dependent upon said first digitised signal history.
- 15. A switch mode power supply (SMPS) controller for a SMPS having an input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output sides of said SMPS being coupled by a transformer, the controller having two operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer.
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18. A method of implementing a control system for a switch mode power supply (SMPS), the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the method comprising:
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providing two control system operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer; receiving a said feedback signal; selecting one of said first and second control system operating modes responsive to said feedback signal; and outputting a control signal for regulating said SMPS output voltage to implement said control system in accordance with said selected operating mode.
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- 19. A control system for a switch mode power supply (SMPS), the SMPS having an input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output sides of said SMPS being coupled by an energy transfer device, said control system having a feedback input to receive a feedback signal responsive to said dc output voltage, and a control output for regulating said output voltage, said control system further comprising a current sense input to receive a current sense signal, and wherein said control system is configured to output a control signal dependent upon a combination of said feedback signal and said current sense signal for regulating said output voltage.
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25. A method of controlling a switch mode power supply (SMPS), the SMPS having an input side for receiving a power supply input and an output side for providing a de output voltage, said input and output sides of said SMPS being coupled by an energy transfer device, the method comprising:
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receiving a feedback signal responsive to said de output voltage; receiving a current sense signal responsive to a current flowing in said SMPS input side and providing power to said energy transfer device; and controlling said SMPS output voltage responsive to a combination of said feedback signal and said current sense signal. - View Dependent Claims (26)
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Specification