Switching mode power supplies
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Accused Products
Abstract
In a switching mode power supply, an input received from the secondary side of the transformer 7 and indicative of the power being drawn by the loads is used to control the timing of bursts. The input is compared with two threshold different threshold values V2, V3, and switching is enabled if the input rises above a first higher threshold value V2, and disabled if it falls below a second lower threshold value V3. A memory device FF1 controls a current limitation circuit which limits currents in the primary of the transformer when the switching mode power supply is operating in the burst mode.
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Citations
33 Claims
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1-13. -13. (canceled)
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14. A switching mode power supply comprising:
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a transformer, a transistor operably coupled to switch current through a primary of the transformer, and a control unit configured to control the switching of the transistor to generate current pulses through the transformer, the control unit further configured to receive a signal from a secondary side of the transformer and compare the signal with two threshold levels defining a range, the control unit configured to enable switching of the transistor in the case that a characteristic of the signal is outside the range in a first direction, and disabling switching of the transistor in the case that the characteristic of the signal is outside the range in a second direction. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A switching mode power supply comprising:
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a transformer, a transistor coupled to control the current through a primary of the transformer, a control unit configured to control switching of the transistor to generate current pulses in the transformer, a memory device for storing data indicating whether the switching mode power supply is operating in a first power supply mode, and a current limitation circuit arranged to receive a first signal indicative of the current through the primary of the transformer and to limit the current pulses if the first signal indicates that the current is above a threshold value and the memory device indicates that the switching mode power supply is operating in the first power supply mode. - View Dependent Claims (23, 24, 25)
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26. A method of operating a power supply, the power supply having a transformer, a transistor controlling the current through the primary of the transformer, and a control unit for controlling the switching of the transistor to generate current pulses in the transformer, the method including:
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a) receiving a signal from a secondary side of the transformer and comparing a characteristic of the signal with two threshold levels, the two threshold levels defining a range therebetween, and b) enabling switching of the transistor in the case that the characteristic of the signal is outside the range in a first direction, and disabling switching to the transistor in the case that the characteristic of the signal is outside the range in a second direction. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. A method of operating a power supply having a transformer, a transistor controlling the current through a primary of the transformer, and a control unit for controlling the switching of the transistor to generate current pulses in the transformer, the method comprising:
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a) receiving a signal indicative of the current through the primary of the transformer, and b) limiting the current pulses if the signal indicates that the current is above a threshold value and if the power supply is operating in a first power supply mode of a plurality of power supply modes.
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Specification