Switch mode power supply and control method thereof
First Claim
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1. A switch mode power supply, comprising:
- a first switch having a first terminal, a second terminal and a control terminal;
an energy storage component having a first terminal and a second terminal, wherein the second terminal is coupled to the first terminal of the first switch, and wherein the energy storage component is configured to store energy when the first switch is turned ON and the energy storage component is configured to output energy when the first switch is turned OFF;
a first current sampling circuit having an input terminal and an output terminal, wherein the input terminal is coupled to the second terminal of the first switch, and the output terminal is configured to provide a first current sampling signal indicating a current flowing through the first switch from the first terminal of the first switch to the second terminal of the first switch;
a first voltage sampling circuit having an input terminal and an output terminal, wherein the input terminal is configured to sample a voltage on the first terminal of the first switch, and the output terminal is configured to provide a first voltage sampling signal indicating a voltage across the first switch; and
a control circuit having a first input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the first current sampling circuit and the output terminal of the first voltage sampling circuit via a multi-function pin, and the output terminal is configured to provide a control signal coupled to the control terminal of the first switch;
whereinthe control circuit is configured to provide a first comparing signal by comparing a signal on the multi-function pin with a first threshold signal when the first switch is turned OFF;
the control circuit is configured to provide a second comparing signal by comparing the signal on the multi-function pin with a second threshold signal when the first switch is turned ON; and
whereinthe control circuit is configured to provide the control signal responsive to the first comparing signal and the second comparing signal.
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Abstract
In one embodiment, a switch mode power supply comprising a switch and a control circuit is disclosed. The control circuit may comprise a multi-function pin configured to receive a first current sampling signal and a first voltage sampling signal. A first comparing signal may be provided by comparing the first voltage sampling signal with a first threshold signal when the switch is turned OFF, and a second comparing signal may be provided by comparing the first current sampling signal with a second threshold signal when the switch is turned ON. The control circuit may be configured to control the switch in accordance with the first comparing signal and the second comparing signal.
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Citations
19 Claims
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1. A switch mode power supply, comprising:
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a first switch having a first terminal, a second terminal and a control terminal; an energy storage component having a first terminal and a second terminal, wherein the second terminal is coupled to the first terminal of the first switch, and wherein the energy storage component is configured to store energy when the first switch is turned ON and the energy storage component is configured to output energy when the first switch is turned OFF; a first current sampling circuit having an input terminal and an output terminal, wherein the input terminal is coupled to the second terminal of the first switch, and the output terminal is configured to provide a first current sampling signal indicating a current flowing through the first switch from the first terminal of the first switch to the second terminal of the first switch; a first voltage sampling circuit having an input terminal and an output terminal, wherein the input terminal is configured to sample a voltage on the first terminal of the first switch, and the output terminal is configured to provide a first voltage sampling signal indicating a voltage across the first switch; and a control circuit having a first input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the first current sampling circuit and the output terminal of the first voltage sampling circuit via a multi-function pin, and the output terminal is configured to provide a control signal coupled to the control terminal of the first switch;
whereinthe control circuit is configured to provide a first comparing signal by comparing a signal on the multi-function pin with a first threshold signal when the first switch is turned OFF; the control circuit is configured to provide a second comparing signal by comparing the signal on the multi-function pin with a second threshold signal when the first switch is turned ON; and
whereinthe control circuit is configured to provide the control signal responsive to the first comparing signal and the second comparing signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A control circuit for a switch mode power supply comprising a first switch, the control circuit comprising:
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a multi-function pin, coupled to receive a first current sampling signal indicating a current flowing through the first switch and a first voltage sampling signal indicting a voltage across the first switch; a first comparison circuit, having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the multi-function pin, and the second input terminal is configured to receive a first threshold signal; a second comparison circuit, having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is selectively coupled to the multi-function pin, and the second input terminal is configured to receive a second threshold signal; a logic circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the first comparison circuit, the second input terminal is coupled to the output terminal of the second comparison circuit, and the output terminal is configured to provide a control signal, and wherein the control signal is configured to control the first switch, and wherein the logic circuit is configured to turn ON the first switch when the first voltage sampling signal is less than the first threshold signal, and wherein the logic circuit is configured to provide an over-current protection when the first current sampling signal is larger than the second threshold signal; and a signal transmission circuit having an input terminal, a control terminal, a first output terminal and a second output terminal, wherein the input terminal is coupled to the multi-function pin, the control terminal is coupled to the output terminal of the logic circuit to receive the control signal, the first output terminal is coupled to the first input terminal of the first comparison circuit, and the second output terminal is coupled to the first input terminal of the second comparison circuit. - View Dependent Claims (13, 14, 15, 16)
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17. A control method for controlling a switch mode power supply comprising a first switch, the method comprising:
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providing a first current sampling signal, wherein the first current sampling signal is configured to indicate a current flowing through the first switch; providing a first voltage sampling signal, wherein the first voltage sampling signal is configured to indicate a voltage across the first switch; receiving the first current sampling signal and the first voltage sampling signal via a multi-function pin; providing a first comparing signal by comparing a signal on the multi-function pin with a first threshold signal when the switch is turned OFF; providing a second comparing signal by comparing a signal on the multi-function pin with a second threshold signal when the switch is turned ON; and controlling the first switch in accordance with the first comparing signal and the second comparing signal. - View Dependent Claims (18, 19)
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Specification