Power conversion circuit with multi-functional pin and conversion control circuit thereof

Abstract

A conversion control circuit for controlling at least one switch of a power conversion circuit to periodically switch the electrical connection of an inductor according to a duty cycle, includes: a multiplexing pin coupled to a temperature sensing element; a temperature sensing circuit for providing a temperature sensing current to the temperature sensing element through the multiplexing pin during temperature sensing to generate a multiplexing signal, and generating an over-temperature protection signal based on the multiplexing signal; and a feedback control circuit for receiving the multiplexing signal during feedback control to generate a feedback output signal. The duty cycle of the at least one switch is determined according to the feedback output signal. During temperature sensing, the multiplexing signal corresponds to a temperature sensing voltage to indicate a temperature level, wherein the temperature sensing voltage is related to the voltage across the temperature sensing element. During feedback control, the multiplexing signal corresponds to the feedback voltage.

Claims

1. A conversion control circuit for controlling a power conversion circuit to convert an input voltage to generate an output voltage, wherein the power conversion circuit includes a power stage circuit and a temperature sensing element, wherein the power stage circuit includes at least one switch and an inductor; wherein the conversion control circuit is an integrated circuit for controlling the at least one switch to periodically switch the electrical connection relationship of the inductor according to a duty cycle, the conversion control circuit including: a multiplexing pin, wherein the temperature sensing element is coupled between the multiplexing pin and a feedback voltage, thereby generating a multiplexing signal on the multiplexing pin, wherein the feedback voltage is related to the output voltage; A temperature sensing circuit is configured to, during a temperature sensing period, provide a temperature sensing current to a temperature sensing element through a multiplexing pin to generate the multiplexing signal, and generate an over-temperature protection signal based on the multiplexing signal; and a feedback control circuit is configured to, during a feedback control period, receive the multiplexing signal to generate a feedback output signal, wherein the duty cycle of the at least one switch is determined based on the feedback output signal; wherein during the temperature sensing period, the multiplexing signal corresponds to a temperature sensing voltage to indicate a temperature level, wherein the temperature sensing voltage is related to a voltage across the temperature sensing element; wherein during the feedback control period, the multiplexing signal corresponds to the feedback voltage; wherein during the feedback control period, the feedback control circuit is configured to track the feedback voltage; wherein during the temperature sensing period, the feedback control circuit is further configured to hold the feedback voltage to generate a feedback holding voltage, and generate the feedback output signal based on the feedback holding voltage; The temperature sensing period includes a first sensing period and a second sensing period, the temperature sensing voltage includes a first sensing voltage and a second sensing voltage, and the temperature sensing current includes a first sensing current and a second sensing current. The first sensing voltage and the second sensing voltage are generated through the multiplexing pin during the first sensing period and the second sensing period, respectively. The over-temperature protection signal is generated based on the difference between the second sensing voltage and the first sensing voltage and a temperature sensing threshold.

2. The switching control circuit as claimed in claim 1, wherein the temperature sensing circuit further includes a comparator for comparing the second sensing voltage with a second threshold-related voltage during the second sensing period to generate the over-temperature protection signal, wherein the second threshold-related voltage includes the first sensing voltage.

3. The conversion control circuit as claimed in claim 2, wherein the comparator has a common-mode voltage; wherein the power conversion circuit further includes a clamping element for clamping the feedback voltage to a clamping voltage during the temperature sensing period, such that the common-mode voltage includes the clamping voltage; wherein both the first sensing current and the second sensing current are sufficiently large such that the clamping element clamps during both the first sensing period and the second sensing period, thereby causing the feedback voltage to correspond to the clamping voltage.

4. The conversion control circuit as claimed in claim 2, wherein the power conversion circuit further includes a voltage regulator capacitor coupled to the feedback voltage to ensure that the variation range of the feedback voltage during the temperature sensing period is less than a preset range.

5. The conversion control circuit as described in claim 1, wherein the power conversion circuit is configured as a power factor correction (PFC) circuit.

6. The conversion control circuit as described in claim 5, wherein one of the bandwidths of the power factor correction circuit is less than one-tenth of a preset frequency, wherein the preset frequency is related to an AC frequency of a mains power supply.

7. A power conversion circuit for converting an input voltage to generate an output voltage, comprising: a power stage circuit including at least one switch and an inductor; a temperature sensing element coupled between a multiplexer pin and a voltage divider node, wherein the voltage divider node is coupled to the output voltage; and a conversion control circuit configured as an integrated circuit for controlling the at least one switch to periodically switch the electrical connection of the inductor according to a duty cycle; wherein the conversion control circuit includes: A multiplexing pin, wherein the temperature sensing element is coupled between the multiplexing pin and a feedback voltage, thereby generating a multiplexing signal at the multiplexing pin, wherein the feedback voltage is related to the output voltage; a temperature sensing circuit for providing a temperature sensing current to the temperature sensing element through the multiplexing pin during a temperature sensing period to generate the multiplexing signal, and generating an over-temperature protection signal based on the multiplexing signal; and a feedback control circuit for receiving the multiplexing signal during a feedback control period to generate a feedback output signal, wherein the duty cycle of the at least one switch is determined based on the feedback output signal; wherein during the temperature sensing period, the multiplexing signal corresponds to a temperature sensing voltage to indicate a temperature level, wherein the temperature sensing voltage is related to a voltage across the temperature sensing element; wherein during the feedback control period, the multiplexing signal corresponds to the feedback voltage; During the feedback control period, the feedback control circuit tracks the feedback voltage; during the temperature sensing period, the feedback control circuit holds the feedback voltage to generate a feedback holding voltage, and generates the feedback output signal based on the feedback holding voltage; the temperature sensing period includes a first sensing period and a second sensing period, the temperature sensing voltage includes a first sensing voltage and a second sensing voltage, and the temperature sensing current includes a first sensing current and a second sensing current, the first sensing voltage and the second sensing voltage are generated through the multiplexing pin during the first sensing period and the second sensing period, respectively; the over-temperature protection signal is generated based on the difference between the second sensing voltage and the first sensing voltage and a temperature sensing threshold.

8. The power conversion circuit as claimed in claim 7, wherein the temperature sensing circuit further includes a comparator for comparing the second sensing voltage with a second threshold-related voltage during the second sensing period to generate the over-temperature protection signal, wherein the second threshold-related voltage includes the first sensing voltage.

9. The power conversion circuit as claimed in claim 8 further includes a clamping element; wherein the comparator has a common-mode voltage; wherein the clamping element is used to clamp the feedback voltage to a clamping voltage during the temperature sensing period, such that the common-mode voltage includes the clamping voltage; wherein both the first sensing current and the second sensing current are sufficiently large such that the clamping element clamps during both the first sensing period and the second sensing period, thereby causing the feedback voltage to correspond to the clamping voltage.

10. The power conversion circuit as claimed in claim 8 further includes a voltage regulator coupled to the feedback voltage to make the variation range of the feedback voltage during the temperature sensing period less than a preset range.

11. The power conversion circuit as described in claim 7 is further configured as a power factor correction (PFC) circuit.

12. The power conversion circuit as claimed in claim 11, wherein one of the bandwidths of the power factor correction circuit is less than one-tenth of a preset frequency, wherein the preset frequency is related to an AC frequency of a mains power supply.

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