Method and apparatus to limit output power in a switching power supply
First Claim
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1. A switching regulator circuit, comprising:
- a switch to be coupled to an energy transfer element of a power supply;
a controller to generate a drive signal coupled to control switching of the switch to regulate an output of the power supply;
a current limiter included in the controller to adjust the drive signal to limit a current through the switch to a variable current limit value, wherein the variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.
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Abstract
Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.
33 Citations
30 Claims
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1. A switching regulator circuit, comprising:
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a switch to be coupled to an energy transfer element of a power supply;
a controller to generate a drive signal coupled to control switching of the switch to regulate an output of the power supply;
a current limiter included in the controller to adjust the drive signal to limit a current through the switch to a variable current limit value, wherein the variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method, comprising:
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switching a switch coupled to an energy transfer element to regulate a transfer of energy through the energy transfer element;
limiting a current through the switch to a first current limit value if there is a nominal or relatively low input line voltage coupled to the energy transfer element; and
limiting the current through the switch to a second current limit value if there is a relatively high input line voltage coupled to the energy transfer element. - View Dependent Claims (13, 14, 15)
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16. A power supply, comprising:
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an energy transfer element coupled between an input line voltage and an output of the power supply;
a switch coupled to the input of the energy transfer element to regulate a transfer of energy from the input of the power supply to the output of the power supply;
a controller coupled to the switch to control switching of the switch; and
a current limiter included in the controller to limit a current though the switch to a variable current limit value, wherein the variable current limit value is set by the current limiter in response to the input line voltage to be coupled to the energy transfer element. - View Dependent Claims (17, 18, 19, 20)
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21. A switching regulator circuit, comprising:
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a switch to be coupled to an energy transfer element of a power supply;
a controller coupled to the switch to control a switching of the switch to regulate an output, the controller to switch the switch periodically in switching periods; and
a current limiter included in the controller and coupled to the switch to turn off the switch when a current in the switch exceeds a variable current limit, the current limiter to adjust the variable current limit in response to a measurement of time between values of the current in the switch. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method, comprising:
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switching a switch coupled to an energy transfer element to regulate a transfer of energy through the energy transfer element;
measuring an amount of time for a current in the switch to rise from a first current value to a second current value within a switching period; and
adjusting a variable current limit in response to the measured amount of time. - View Dependent Claims (28, 29, 30)
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Specification