SINGLE STAGE SWITCHING POWER CONVERTER WITH IMPROVED PRIMARY ONLY FEEDBACK
First Claim
Patent Images
1. A method of controlling a switching power converter, comprising:
- comparing an on-time current produced from each cycle of a power switch to a current threshold to determine whether a sense voltage pulse produced on an auxiliary winding from each cycle of the power switch is trustable or non-trustable, and wherein consecutive cycles of a rectified input voltage are separated by a dead period in which the sense voltage pulses are non-trustable;
during each trustable sense voltage pulse, adjusting a reference voltage responsive to the trustable sense voltage pulse;
during each rectified input voltage cycle, determining a first trustable value of the voltage reference resulting from an initial one of the trustable sense voltage pulses in the rectified input voltage cycle and determining a last trustable value of the voltage reference resulting from a final one of the trustable sense voltage pulses in the rectified input voltage cycle;
for each dead period, extrapolating from the first trustable value of the reference voltage and the last trustable value to produce an extrapolated reference voltage; and
controlling the cycling of the power switch during each dead period responsive to the extrapolated reference voltage.
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Abstract
A switching power converter is provided that extrapolates from a reference voltage during dead periods of a rectified input voltage as determined from a comparison of an Isense voltage to a current threshold.
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Citations
20 Claims
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1. A method of controlling a switching power converter, comprising:
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comparing an on-time current produced from each cycle of a power switch to a current threshold to determine whether a sense voltage pulse produced on an auxiliary winding from each cycle of the power switch is trustable or non-trustable, and wherein consecutive cycles of a rectified input voltage are separated by a dead period in which the sense voltage pulses are non-trustable; during each trustable sense voltage pulse, adjusting a reference voltage responsive to the trustable sense voltage pulse; during each rectified input voltage cycle, determining a first trustable value of the voltage reference resulting from an initial one of the trustable sense voltage pulses in the rectified input voltage cycle and determining a last trustable value of the voltage reference resulting from a final one of the trustable sense voltage pulses in the rectified input voltage cycle; for each dead period, extrapolating from the first trustable value of the reference voltage and the last trustable value to produce an extrapolated reference voltage; and controlling the cycling of the power switch during each dead period responsive to the extrapolated reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A switching power converter, comprising:
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a comparator configured to compare an Isense signal representative of an on-time current from each cycle of a power switch to a current threshold to determine whether a sense voltage pulse produced on an auxiliary winding from the cycle of the power switch is a trustable sense voltage pulse or a non-trustable sense voltage pulse; a tracking circuit configured to adjust a reference voltage responsive to each trustable sense voltage; and an extrapolator configured to determine for each cycle of a rectified input voltage a first trustable value of the voltage reference resulting from an initial one of the trustable sense voltage pulses in the rectified input voltage cycle and to determine a last trustable value of the voltage reference resulting from a final one of the trustable sense voltage pulses in the rectified input voltage cycle, wherein the extrapolator is further configured to extrapolate from the first trustable value of the reference voltage and the last trustable value of the reference voltage to produce an extrapolated reference voltage during a dead period of each rectified input voltage cycle in which the sense voltage pulses are non-trustable, - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification