System and method providing reliable over current protection for power converter
First Claim
1. A system controller for protecting a power converter, the system controller comprising:
- a first controller terminal configured to output a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the power converter further including a secondary winding coupled to the primary winding, the drive signal being associated with one or more switching periods; and
a second controller terminal configured to receive a sensing voltage from a sensing resistor, the sensing voltage representing a magnitude of the current flowing through the primary winding of the power converter;
wherein the system controller is configured to;
in response to an average output current of the power converter being larger than a current threshold, generate the drive signal to cause the switch to open and remain open to protect the power converter;
wherein the current threshold is equal to a first ratio multiplied by a second ratio, the first ratio being equal to a first number of turns of the primary winding divided by a second number of turns of the secondary winding, the second ratio being equal to a reference voltage divided by a resistance of the sensing resistor.
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Accused Products
Abstract
System controller and method for protecting a power converter. The system controller includes a first controller terminal configured to output a drive signal to a switch to affect a first current flowing through a primary winding of a power converter. The power converter further includes a secondary winding coupled to the primary winding, and the drive signal is associated with one or more switching periods. Additionally, the system controller includes a second controller terminal configured to receive a sensing voltage from a sensing resistor. The sensing voltage represents a magnitude of the first current flowing through the primary winding of the power converter. The system controller is configured to process information associated with the sensing voltage and a reference voltage, and determine whether an average output current of the power converter is larger than a current threshold.
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Citations
34 Claims
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1. A system controller for protecting a power converter, the system controller comprising:
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a first controller terminal configured to output a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the power converter further including a secondary winding coupled to the primary winding, the drive signal being associated with one or more switching periods; and a second controller terminal configured to receive a sensing voltage from a sensing resistor, the sensing voltage representing a magnitude of the current flowing through the primary winding of the power converter; wherein the system controller is configured to; in response to an average output current of the power converter being larger than a current threshold, generate the drive signal to cause the switch to open and remain open to protect the power converter; wherein the current threshold is equal to a first ratio multiplied by a second ratio, the first ratio being equal to a first number of turns of the primary winding divided by a second number of turns of the secondary winding, the second ratio being equal to a reference voltage divided by a resistance of the sensing resistor. - View Dependent Claims (2, 3)
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4. A system controller for protecting a power converter, the system controller comprising:
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an over-current-protection signal generator configured to receive a drive signal from a modulation and drive signal generator, receive a sensing voltage from a sensing resistor, receive a demagnetization signal, and generate a protection signal based at least in part on the drive signal, the sensing voltage, and the demagnetization signal, the sensing voltage representing a magnitude of a first current flowing through a primary winding of the power converter, the power converter further including a secondary winding coupled to the primary winding, the demagnetization signal being associated with one or more demagnetization periods; wherein; the over-current-protection signal generator is further configured to determine whether an average output current of the power converter is larger than a current threshold based at least in part on the drive signal, the sensing voltage, and the demagnetization signal, and in response to the average output current of the power converter being determined to be larger than the current threshold, change the protection signal from a first logic level to a second logic level; and the modulation and drive signal generator is configured to receive the protection signal, and in response to the protection signal being at the second logic level, generate the drive signal to cause a switch to open and remain open to protect the power converter; wherein the average output current of the power converter is related to a second current flowing through the secondary winding. - View Dependent Claims (5, 6, 7, 8)
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9. A system controller for a power converter, the system controller comprising:
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a first controller terminal configured to provide a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the drive signal being associated with one or more switching periods; and a second controller terminal configured to receive one or more input signals during the one or more switching periods; wherein the system controller is configured to; in response to a temperature associated with the power converter being larger than a predetermined temperature threshold, generate the drive signal to cause the switch to open and remain open to protect the power converter; wherein the system controller is further configured to; in response to an output voltage associated with a secondary winding of the power converter being larger than a predetermined voltage threshold, generate the drive signal to cause the switch to open and remain open to protect the power converter; wherein the system controller is further configured to; generate a demagnetization signal based at least in part on the one or more input signals; wherein, for each switching period of the one or more switching periods, the demagnetization signal represents a demagnetization period related to a demagnetization process; and the demagnetization signal is at a first logic level during the demagnetization period and at a second logic level outside the demagnetization period. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A system controller for a power converter, the system controller comprising:
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a modulation signal generator configured to generate a modulation signal, the modulation signal being associated with one or more switching periods; and a demagnetization signal generator configured to receive the modulation signal from the modulation signal generator, output a current to a controller terminal, and generate a demagnetization signal based at least in part on the modulation signal and the current; wherein, for each switching period of the one or more switching periods, the demagnetization signal represents a demagnetization period related to a demagnetization process; and the demagnetization signal is at a first logic level during the demagnetization period and at a second logic level outside the demagnetization period. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for protecting a power converter, the method comprising:
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outputting a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the power converter further including a secondary winding coupled to the primary winding, the drive signal being associated with one or more switching periods; receiving a sensing voltage from a sensing resistor, the sensing voltage representing a magnitude of the current flowing through the primary winding of the power converter; and in response to an average output current of the power converter being larger than a current threshold, generating the drive signal to cause the switch to open and remain open to protect the power converter; wherein the current threshold is equal to a first ratio multiplied by a second ratio, the first ratio being equal to a first number of turns of the primary winding divided by a second number of turns of the secondary winding, the second ratio being equal to a reference voltage divided by a resistance of the sensing resistor.
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32. A method for protecting a power converter, the method comprising:
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receiving a drive signal, a sensing voltage, and a demagnetization signal, the sensing voltage being generated by a sensing resistor and representing a magnitude of a current flowing through a primary winding of the power converter, the power converter further including a secondary winding coupled to the primary winding, the demagnetization signal being associated with one or more demagnetization periods; generating a protection signal based at least in part on the drive signal, the sensing voltage, and the demagnetization signal, wherein the generating a protection signal includes; determining whether an average output current of the power converter is larger than a current threshold based at least in part on the drive signal, the sensing voltage, and the demagnetization signal, and in response to the average output current of the power converter being determined to be larger than the current threshold, changing the protection signal from a first logic level to a second logic level; receiving the protection signal; and in response to the protection signal being at the second logic level, generating the drive signal to cause a switch to open and remain open to protect the power converter; wherein the average output current of the power converter is related to a second current flowing through the secondary winding.
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33. A method for a power converter, the method comprising:
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providing a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the drive signal being associated with one or more switching periods; receiving one or more input signals during the one or more switching periods; in response to a temperature associated with the power converter being larger than a predetermined temperature threshold, generating the drive signal to cause the switch to open and remain open to protect the power converter; in response to an output voltage associated with a secondary winding of the power converter being larger than a predetermined voltage threshold, generating the drive signal to cause the switch to open and remain open to protect the power converter; and generating a demagnetization signal based at least in part on the one or more input signals; wherein, for each switching period of the one or more switching periods, the demagnetization signal represents a demagnetization period related to a demagnetization process; and the demagnetization signal is at a first logic level during the demagnetization period and at a second logic level outside the demagnetization period.
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34. A method for a power converter, the method comprising:
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generating a modulation signal associated with one or more switching periods; outputting a current based at least in part on the modulation signal; and generating a demagnetization signal based at least in part on the modulation signal and the current; wherein, for each switching period of the one or more switching periods, the demagnetization signal represents a demagnetization period related to a demagnetization process; and the demagnetization signal is at a first logic level during the demagnetization period and at a second logic level outside the demagnetization period.
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Specification