BJT driver with dynamic adjustment of storage time versus input line voltage variations
First Claim
1. A method of dynamically adjusting a storage time of a bipolar junction transistor (BJT) in a switched mode power converter during a switching cycle, the method comprising:
- generating a storage time reference signal in response to an input voltage signal;
generating a collector off signal in response to a first comparison of a current sense signal to a collector off reference threshold signal, wherein the current sense signal is representative of a switch current of the BJT, and wherein generating the collector off signal in response to the first comparison of the current sense signal to the collector off reference threshold signal comprises;
generating the collector off reference threshold signal using an input current peak regulator circuit;
generating a base off reference threshold signal in response to the storage time reference signal and the collector off signal;
generating a base off signal in response to a second comparison of the current sense signal and the base off reference threshold signal;
discontinuing charging a base terminal of the BJT in response to the base off signal; and
discharging the base terminal of the BJT in response to the collector off signal.
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Abstract
A method of dynamically adjusting a storage time of a bipolar junction transistor (BJT) in a switched mode power converter during a switching cycle includes generating a storage time reference signal responsive to an input voltage signal. A collector off signal is generated responsive to a comparison of a current sense signal to a collector off reference threshold signal. The current sense signal is representative of a switch current of the BJT. A base off reference threshold signal is generated responsive to the storage time reference signal and the collector off signal. A base off signal is generated responsive to a comparison of the current sense signal and the base off reference threshold signal. Charging of a base terminal of the BJT is discontinued responsive to the base off signal, and the base terminal of the BJT is discharged responsive to the collector off signal.
29 Citations
18 Claims
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1. A method of dynamically adjusting a storage time of a bipolar junction transistor (BJT) in a switched mode power converter during a switching cycle, the method comprising:
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generating a storage time reference signal in response to an input voltage signal; generating a collector off signal in response to a first comparison of a current sense signal to a collector off reference threshold signal, wherein the current sense signal is representative of a switch current of the BJT, and wherein generating the collector off signal in response to the first comparison of the current sense signal to the collector off reference threshold signal comprises; generating the collector off reference threshold signal using an input current peak regulator circuit; generating a base off reference threshold signal in response to the storage time reference signal and the collector off signal; generating a base off signal in response to a second comparison of the current sense signal and the base off reference threshold signal; discontinuing charging a base terminal of the BJT in response to the base off signal; and discharging the base terminal of the BJT in response to the collector off signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of controlling a transfer of power in a switched mode power converter from a primary side of an energy transfer element to a secondary side of the energy transfer element, the method comprising:
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switching a bipolar junction transistor (BJT) in response to an output signal representative of an output of the switched mode power converter; generating a storage time reference signal in response to a signal representative of an input of the switch mode power converter; generating a collector off signal in response to a first comparison of a switch current sense signal and a collector off reference signal; generating a base off reference signal in response to the storage time reference signal and the collector off signal; generating a base off signal in response to a second comparison of the switch current sense signal and the base off reference signal; discontinuing charging a base terminal of the BJT in response to the base off signal; and discharging the base terminal of the BJT in response to the collector off signal during a switching cycle of the BJT. - View Dependent Claims (15, 16, 17)
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18. A method of dynamically adjusting a storage time of a bipolar junction transistor (BJT) in a switched mode power converter during a switching cycle, the method comprising:
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generating a storage time reference signal in response to an input voltage signal; generating a collector off signal in response to a first comparison of a current sense signal to a collector off reference threshold, wherein generating the collector off signal comprises; generating the collector off reference threshold based on the current sense signal against a predefined current limit threshold, wherein the current sense signal is representative of a switch current of the BJT; generating a base off reference threshold signal in response to the storage time reference signal and the collector off signal; generating a base off signal in response to a second comparison of the current sense signal and the base off reference threshold signal; discontinuing charging a base terminal of the BJT in response to the base off signal; and discharging the base terminal of the BJT in response to the collector off signal.
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Specification