Switch mode power supply and control method thereof

摘要

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.

主权项

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; wherein the 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 wherein the control circuit is configured to provide the control signal responsive to the first comparing signal and the second comparing signal.