Chip-type power converter and switched capacitor conversion circuit therein

Abstract

A flyback power converter and a switched capacitor conversion circuit therein. The switched capacitor conversion circuit is used to convert a first supply voltage to generate a second supply voltage for powering the power conversion circuit. The switched capacitor conversion circuit includes: a conversion capacitor; an output capacitor; and a plurality of switches for switching the coupling between the conversion capacitor and the output capacitor according to the level of the first supply voltage of the switched capacitor conversion circuit to convert the first supply voltage to generate the second supply voltage on the output capacitor. The second supply voltage is used to supply power and control the power conversion circuit. When the first supply voltage is higher than a high threshold, the switched capacitor conversion circuit controls the second supply voltage to be lower than the first supply voltage. When the first supply voltage is lower than a low threshold, the switched capacitor conversion circuit controls the second supply voltage to be higher than the first supply voltage.

Description

Technical Field

[0001] The present invention relates to a switched capacitor converter circuit, and more particularly to a switched capacitor converter circuit capable of adjusting an output voltage level according to an input voltage level, and a flyback power converter including the switched capacitor converter circuit. Background Art

[0002] Figure 1 A conventional flyback power converter 100 is shown. The auxiliary winding NA of the transformer 10 generates an auxiliary voltage VNA via a diode 40 and a capacitor 45, which provides power to the primary-side control circuit 50 to control the flyback power converter 100. The auxiliary voltage VNA is proportional to the output voltage Vout. Specifically, the proportionality is proportional to the turns ratio between the auxiliary winding NA and the secondary winding NS. The secondary-side control circuit 60 has interface terminals CC1 and CC2 for receiving commands from a communication interface (e.g., USB PD) to program the voltage level of the output voltage Vout. Recent developments have required programming the output voltage Vout between 3.2V and 48V to cover applications ranging from charging mobile phones to charging portable power tool batteries. However, when the output voltage Vout range is too wide, the range of the auxiliary voltage VNA will also be too wide. In this case, the primary-side control circuit 50 and the secondary-side control circuit 60 will need to operate within a wider voltage range, resulting in poorer power efficiency. The object of the present invention is to solve this problem by providing a high-efficiency power supply circuit for a primary-side control circuit and / or a secondary-side control circuit.

[0003] In view of this, the present invention addresses the above-mentioned deficiencies in the prior art and proposes a novel switched capacitor conversion circuit and a power conversion circuit therein. Summary of the Invention

[0004] In one aspect, the present invention provides a switched capacitor conversion circuit for converting a first supply voltage to generate a second supply voltage to supply power to a power conversion circuit. The switched capacitor conversion circuit includes: a conversion capacitor; an output capacitor; and a plurality of switches for switching the coupling between the conversion capacitor and the output capacitor according to the level of the first supply voltage of the switched capacitor conversion circuit to convert the first supply voltage to generate the second supply voltage on the output capacitor; wherein the second supply voltage is used to supply power and control the power conversion circuit, wherein when the first supply voltage is higher than a high threshold, the switched capacitor conversion circuit controls the second supply voltage to be lower than the first supply voltage; wherein when the first supply voltage is lower than a low threshold, the switched capacitor conversion circuit controls the second supply voltage to be higher than the first supply voltage.

[0005] In another aspect, the present invention provides a flyback power converter, comprising: a controller for controlling and switching a winding of a transformer to convert an input voltage and generate an output voltage at another winding of the transformer; and a switched capacitor conversion circuit for converting a first supply voltage to generate a second supply voltage to power the controller, wherein the first supply voltage is coupled from a winding of the transformer, the switched capacitor conversion circuit comprising: a conversion capacitor; an output capacitor; and a plurality of switches for switching the coupling of the conversion capacitor and the output capacitor according to the level of the first supply voltage of the switched capacitor conversion circuit to convert the first supply voltage and generate the second supply voltage on the output capacitor; wherein when the first supply voltage is higher than a high threshold, the switched capacitor conversion circuit controls the second supply voltage to be lower than the first supply voltage; wherein when the first supply voltage is lower than a low threshold, the switched capacitor conversion circuit controls the second supply voltage to be higher than the first supply voltage.

[0006] In one embodiment, when the first supply voltage is lower than the high threshold and higher than the low threshold, the switched capacitor converter circuit controls the second supply voltage to be equal to the first supply voltage.

[0007] In one embodiment, the power conversion circuit is a flyback power converter.

[0008] In one embodiment, the second supply voltage is used to power a controller in the flyback power converter.

[0009] In one embodiment, the first supply voltage is coupled from a winding of a transformer of the flyback power converter.

[0010] In one embodiment, the first supply voltage is proportional to an output voltage of the flyback power converter.

[0011] In one embodiment, the second supply voltage is lower than an absolute maximum rating of the controller, and the absolute maximum rating is less than a maximum value of the first supply voltage.

[0012] In one embodiment, when the first supply voltage is higher than the high threshold, the second supply voltage is controlled to be 1 / 2 of the first supply voltage.

[0013] In one embodiment, the high threshold is greater than or equal to twice a minimum operating voltage of a controller of the power conversion circuit.

[0014] In one embodiment, when the first supply voltage is lower than the low threshold, the second supply voltage is controlled to be twice the first supply voltage.

[0015] In one embodiment, the lower threshold is greater than or equal to a minimum operating voltage of a controller of the power conversion circuit.

[0016] In one embodiment, the multiple switches are periodically switched in at least one of the following ways based on a switching cycle: (1) when the first supply voltage is higher than the high threshold, in the first period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in series between the first supply voltage and a ground potential, and in the second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in parallel with each other, thereby generating the second supply voltage on the output capacitor, so that the second supply voltage is controlled to be 1 / 2 of the first supply voltage; and / or (2) when the first supply voltage is lower than the low threshold, in the first period of the switching cycle, the multiple switches control the conversion capacitor to be electrically connected in parallel with the first supply voltage to charge, and in the second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in anti-phase series with each other between the first supply voltage and a ground potential, thereby generating the second supply voltage on the output capacitor, so that the second supply voltage is controlled to be twice the first supply voltage.

[0017] In one embodiment, there is a dead time between the first period and the second period of the switching cycle to prevent some of the switches from being turned on simultaneously and causing a short circuit current.

[0018] In one embodiment, the switched capacitor conversion circuit includes first to fifth switches, wherein the first switch, the second switch, the third switch, and the fourth switch are sequentially coupled in series between the first supply voltage and a ground potential, and are sequentially coupled to a first node, a second node, and a third node. The fifth switch is coupled between the first supply voltage and the third node, and the second node is coupled to the second supply voltage. The conversion capacitor is coupled between the first node and the third node, and the output capacitor is coupled between the second supply voltage and the ground potential.

[0019] In one embodiment, when the first supply voltage is lower than the upper threshold and higher than the lower threshold, the first switch and the second switch are turned on, and / or the third switch and the fifth switch are turned on, so as to control the first supply voltage and the second supply voltage to be electrically connected to each other, so that the second supply voltage is equal to the first supply voltage.

[0020] In one embodiment, each of the first switch and the second switch includes a first transistor and a second transistor connected in series, wherein a body diode of the first transistor and a body diode of the second transistor are reversely coupled to each other.

[0021] The advantages of the present invention are that the present invention can reduce the voltage that the control circuit needs to withstand, reduce power loss, and improve the power efficiency of the control circuit.

[0022] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A conventional flyback power converter is shown.

[0024] Figure 2 A circuit diagram of a switched capacitor converter circuit is shown according to an embodiment of the present invention.

[0025] Figure 3 A circuit diagram of a flyback power converter is shown according to an embodiment of the present invention.

[0026] Figure 4 A schematic diagram showing operating waveforms of a plurality of switches of a switched capacitor converter circuit according to an embodiment of the present invention is shown.

[0027] Figure 5 A specific circuit diagram of a switch of a switched capacitor converter circuit is shown according to an embodiment of the present invention.

[0028] Figure 6 A circuit diagram of a supply controller of a switched capacitor converter circuit is shown according to an embodiment of the present invention.

[0029] Explanation of symbols in the figure

[0030] 10: Transformer

[0031] 20: Primary side switch

[0032] 25: Resistors

[0033] 30, 40: diode

[0034] 35, 45: capacitors

[0035] 50: Primary side control circuit

[0036] 60: Secondary side control circuit

[0037] 100: Flyback Power Converter

[0038] 110, 120, 130: Resistors

[0039] 150, 160: Comparator

[0040] 151, 161: Inverter

[0041] 170, 180, 190: AND gate

[0042] 195: Decoding circuit

[0043] 200: Switched Capacitor Conversion Circuit

[0044] 201: Supply Controller

[0045] 2011: Mode Decision Circuit

[0046] 300: Flyback Power Converter

[0047] CC1, CC2: Interface terminals

[0048] CF: switching capacitor

[0049] Co: output capacitor

[0050] CO1, CO2: output signal

[0051] Cs1~Cs5: switch control signal

[0052] Da, Db: body diode

[0053] D2, X1, X2: signal

[0054] N1: first node

[0055] N2: Second node

[0056] N3: The third node

[0057] NA: Auxiliary winding

[0058] Np: primary winding

[0059] NS: Secondary winding

[0060] S1~S5: switch

[0061] Sa: First transistor

[0062] Sb: Second transistor

[0063] T1: The first period

[0064] T2: The second period

[0065] TD: Dwell time

[0066] TS: Switching period

[0067] VCF, VCo: cross voltage

[0068] Vin: input voltage

[0069] VNA: Voltage

[0070] Vout: output voltage

[0071] VS1: First supply voltage

[0072] VS2: Second supply voltage

[0073] VS1', VS1": proportional voltage

[0074] VTH: High threshold related signal

[0075] VTL: Low Threshold Related Signal DETAILED DESCRIPTION

[0076] The drawings in the present invention are schematic diagrams, mainly intended to illustrate the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn according to scale.

[0077] Figure 2 A circuit diagram of a switched capacitor converter circuit (switched capacitor converter circuit 200) is shown according to an embodiment of the present invention. Figure 2 As shown, the switching capacitor conversion circuit 200 of the present invention is used to convert the first supply voltage VS1 to generate a second supply voltage VS2 to supply power to the power conversion circuit. The switching capacitor conversion circuit 200 includes a conversion capacitor CF, an output capacitor Co, and a plurality of switches S1 to S5. The plurality of switches S1 to S5 are used to switch the coupling of the conversion capacitor CF and the output capacitor Co according to the level of the first supply voltage VS1 of the switching capacitor conversion circuit 200 to convert the first supply voltage VS1 and generate a second supply voltage VS2 on the output capacitor Co. The second supply voltage VS2 is used to supply power to the controller in the power conversion circuit to control the power conversion circuit to perform power conversion, the details of which will be described in detail later. Figure 2 As shown, the switched capacitor converter circuit 200 further includes a supply controller 201 that generates switch control signals Cs1-Cs5 according to the first supply voltage VS1. The switches S1-S5 are used to switch the coupling between the switching capacitor CF and the output capacitor Co according to the switch control signals Cs1-Cs5.

[0078] In one embodiment, when the first supply voltage VS1 is higher than a high threshold, the switched capacitor converter circuit 200 controls the second supply voltage VS2 to be lower than the first supply voltage VS1, such as, but not limited to, half the level of the first supply voltage VS1. In one embodiment, when the first supply voltage VS1 is lower than a low threshold, the switched capacitor converter circuit 200 controls the second supply voltage VS2 to be higher than the first supply voltage VS1, such as, but not limited to, twice the level of the first supply voltage VS1. In one embodiment, when the first supply voltage VS1 is lower than the high threshold and higher than the low threshold, the switched capacitor converter circuit 200 controls the second supply voltage VS2 to be equal to the first supply voltage VS1.

[0079] like Figure 2 As shown, in one embodiment, the switched capacitor converter circuit 200 includes switches S1 through S5. Switches S1 through S4 are sequentially coupled in series between a first supply voltage VS1 and ground, and are sequentially coupled to a first node N1, a second node N2, and a third node N3. Switch S5 is coupled between the first supply voltage VS1 and the third node N3, and the second node N2 is coupled to the second supply voltage VS2. The conversion capacitor CF is coupled between the first node N1 and the third node N3, and the output capacitor Co is coupled between the second supply voltage VS2 and ground.

[0080] Please continue to refer to Figure 2 Also refer to Figure 4 , Figure 4 According to an embodiment of the present invention, a schematic diagram of the operating waveforms of multiple switches of a switched capacitor conversion circuit is shown. Multiple switches S1 to S5 are periodically switched based on the switching period TS. In one embodiment, when the first supply voltage VS1 is higher than the high threshold, in the first time period T1 of the switching period, switches S1 and S3 are turned on and control the conversion capacitor CF and the output capacitor Co to be electrically connected in series between the first supply voltage VS1 and the ground potential, and in the second time period T2 of the switching period, switches S2 and S4 are turned on and control the conversion capacitor CF and the output capacitor Co to be electrically connected in parallel with each other, thereby generating a second supply voltage VS2 on the output capacitor Co. It should be noted that, in this embodiment, switches S2, S4 and S5 are non-conductive in the first time period T1, and switches S1, S3 and S5 are non-conductive in the second time period T2, wherein switch S5 is always non-conductive. In other words, the switch control signals Cs1 and Cs3 of switches S1 and S3 correspond to the following: Figure 4 The first phase waveform is operated, and the switch control signals Cs2 and Cs4 of the switches S2 and S4 correspond to the following: Figure 4 The second phase waveform is operated.

[0081] In another embodiment, when the first supply voltage VS1 is lower than the lower threshold, in the first period T1 of the switching cycle, switches S1 and S4 are turned on and control the conversion capacitor CF to be electrically connected in parallel to the first supply voltage VS1 for charging, and in the second period T2 of the switching cycle, switches S2 and S5 are turned on and control the conversion capacitor CF and the output capacitor Co to be electrically connected in series in anti-phase with each other between the first supply voltage VS1 and the ground potential, thereby generating a second supply voltage VS2 on the output capacitor Co. Specifically, in this embodiment, in the second period T2, the voltage across the output capacitor Co VCo is in phase with the first supply voltage VS1, and the voltage across the conversion capacitor CF VCF is in anti-phase with the voltage across the output capacitor Co VCo. In addition, it should be noted that in this embodiment, switches S2, S3 and S5 are non-conductive in the first period T1, and switches S1, S3 and S4 are non-conductive in the second period T2, wherein switch S3 is always non-conductive. In other words, the switch control signals Cs1 and Cs4 of switches S1 and S4 correspond to the following: Figure 4 The first phase waveform is operated, and the switch control signals Cs2 and Cs5 of the switches S2 and S5 correspond to the following: Figure 4 In addition, as Figure 4 As shown, there is a dead time TD between the first period T1 and the second period T2 of the switching period TS, so as to prevent some of the multiple switches from being turned on at the same time and causing a short circuit current.

[0082] In yet another embodiment, when the first supply voltage VS1 is lower than the upper threshold and higher than the lower threshold, switches S1, S2, and S4 are conductive, electrically connecting the first supply voltage VS1 and the second supply voltage VS2. In other words, the first supply voltage VS1 serves as the second supply voltage VS2. In this embodiment, switches S3 and S5 are non-conductive. In another embodiment, switches S3 and S5 can be controlled to be conductive, electrically connecting the first supply voltage VS1 and the second supply voltage VS2.

[0083] Figure 3 A circuit diagram of a power conversion circuit is shown according to an embodiment of the present invention. This embodiment exemplifies the application of the switched capacitor conversion circuit 200 to a power conversion circuit, such as but not limited to a flyback power converter. Figure 3As shown, the flyback power converter 300 includes a transformer 10, whose winding (e.g., auxiliary winding NA) generates a first supply voltage VS1 through a rectifier (e.g., formed by a diode 40 and a capacitor 45) to provide power to the switched capacitor converter circuit 200. The secondary winding NS of the transformer 10 generates an output voltage Vout through a rectifier (e.g., formed by a diode 30 and a capacitor 35). The secondary-side control circuit 60 generates a feedback signal to the primary-side control circuit 50 through an optocoupler according to the output voltage Vout. It should be noted that, in addition to the rectifier, the secondary winding NS generates a first supply voltage VS1 to provide power to the switched capacitor converter circuit 200. Figure 3 Instead of the diode 30 shown, a switch can also be implemented.

[0084] The flyback power converter 300 also includes a primary-side switch 20, whose gate terminal is coupled to the primary-side control circuit 50, whose source terminal is coupled to ground via a resistor 25, and whose drain terminal is coupled to the primary winding Np. The switched capacitor converter circuit 200 is configured to convert a first supply voltage VS1 and provide a second supply voltage VS2 to the primary-side control circuit 50 (corresponding to the aforementioned controller) to control the primary-side switch 20 of the flyback power converter 300 for power conversion. The first supply voltage VS1 is proportional to the output voltage Vout. Specifically, the proportional relationship is proportional to the turns ratio between the auxiliary winding NA and the secondary winding NS of the transformer 10. In one embodiment, the first supply voltage VS1 is proportional to the output voltage Vout. The secondary-side control circuit 60 has interface terminals CC1 and CC2 for receiving commands from a communication interface (e.g., USB PD) to program the voltage level of the output voltage Vout. In other embodiments, the second supply voltage VS2 may also be used to power the secondary-side control circuit 60.

[0085] In one embodiment, the second supply voltage VS2 is lower than the absolute maximum rating (AMR) of the controller (e.g., the primary-side control circuit 50) of the flyback power converter 300, and the AMR is lower than the maximum value of the first supply voltage VS1. In contrast to the prior art, if the primary-side control circuit 50 is directly powered by the first supply voltage VS1, then when the first supply voltage VS1 is set to its maximum value, the primary-side control circuit 50 will be damaged due to exceeding the AMR. This problem is avoided by adaptively adjusting the second supply voltage VS2 to power the primary-side control circuit 50.

[0086] In one embodiment, the upper threshold is greater than or equal to twice the minimum operating voltage of the flyback power converter 300, for example, the primary-side control circuit 50 of the flyback power converter. In another embodiment, the lower threshold is greater than or equal to the minimum operating voltage of the flyback power converter 300, for example, the primary-side control circuit 50 of the flyback power converter. The range of the upper and lower thresholds ensures that the second supply voltage VS2 does not fall below the minimum operating voltage of the primary-side control circuit 50, thereby ensuring normal operation of the primary-side control circuit 50.

[0087] Figure 5 A circuit diagram showing switches S1 and S2 of a switched capacitor converter circuit is shown according to an embodiment of the present invention. Figure 5 As shown, each of switches S1 and S2 includes a first transistor Sa and a second transistor Sb connected in series. The body diode Da of the first transistor Sa and the body diode Db of the second transistor Sb are reversely coupled to each other to prevent current that may be conducted by the body diodes when switches S1 and S2 are controlled to be non-conductive by switch control signals Cs1 and Cs2.

[0088] Figure 6 According to a specific embodiment of the present invention, a circuit diagram of a supply controller of a switched capacitor conversion circuit is shown. Figure 2 An exemplary embodiment of the supply controller 201. Figure 6 As shown, supply controller 201 includes resistors 110, 120, and 130, comparators 150 and 160, a mode determination circuit 2011, and a decoding circuit 195. Resistors 110, 120, and 130 form a voltage divider for dividing a first supply voltage VS1 to generate proportional voltages VS1′ and VS1″. Comparators 150 and 160 compare proportional voltages VS1′ and VS1″ with a high-threshold-related signal VTH and a low-threshold-related signal VTL, respectively, to generate output signals CO1 and CO2. In one embodiment, the high-threshold-related signal VTH is related to the aforementioned high threshold. In one embodiment, the low-threshold-related signal VTL is related to the aforementioned low threshold.

[0089] In one embodiment, the mode determination circuit 2011 generates signals D2, X1, and X2 based on the output signals CO1 and CO2 of the comparators 150 and 160. In one embodiment, the mode determination circuit 2011 may be, for example, but not limited to, inverters 151 and 161 and AND gates 170, 180, and 190. Signal D2 indicates that the second supply voltage VS2 is controlled to be 1 / 2 of the first supply voltage VS1. Signal X2 indicates that the second supply voltage VS2 is controlled to be twice the first supply voltage VS1. Signal X1 indicates that the first supply voltage VS1 is used as the second supply voltage VS2. In one embodiment, the comparators 150 and 160 may have hysteresis. The decoding circuit 195 generates corresponding switch control signals Cs1-Cs5 in different modes based on the signals D2, X1, and X2.

[0090] When the proportional voltage VS1′ is higher than the high-threshold-related signal VTH (indicating that the first supply voltage VS1 is higher than the high threshold), signal D2 is enabled to control the switched capacitor converter circuit 200 to generate a second supply voltage VS2 that is lower than the first supply voltage VS1, for example, at a level half that of the first supply voltage VS1. When the proportional voltage VS1″ is lower than the low-threshold-related signal VTL (indicating that the first supply voltage VS1 is lower than the low threshold), signal X2 is enabled to control the switched capacitor converter circuit 200 to generate a second supply voltage VS2 that is higher than the first supply voltage VS1, for example, at a level twice that of the first supply voltage VS1. When the proportional voltage VS1′ is lower than the high-threshold-related signal VTH and the proportional voltage VS1″ is higher than the low-threshold-related signal VTL (indicating that the voltage level of the first supply voltage VS1 is between the high threshold and the low threshold), signal X1 is enabled to control the switched capacitor converter circuit 200 to control the second supply voltage VS2 to be the same level as the first supply voltage VS1.

[0091] As described above, the present invention provides a switched capacitor conversion circuit and a power conversion circuit therein, which can reduce the voltage required to be tolerated by the primary-side control circuit and the secondary-side control circuit, reduce power loss and improve the power efficiency of the primary-side control circuit and the secondary-side control circuit.

[0092] The present invention has been described above with respect to preferred embodiments. The above description is only intended to facilitate those skilled in the art to understand the contents of the present invention and is not intended to limit the broadest scope of the present invention. The various embodiments described are not limited to individual applications, but can also be applied in combination. For example, two or more embodiments can be used in combination, and some components in one embodiment can also be used to replace corresponding components in another embodiment. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the present invention refers to "processing or calculating or generating an output result according to a certain signal", which is not limited to the signal itself, but also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and / or ratio conversion on the signal, and then processing or calculating the converted signal to generate an output result. It can be seen that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed here one by one. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A switched capacitor converter circuit for converting a first supply voltage to generate a second supply voltage for supplying power to a power conversion circuit, the switched capacitor converter circuit comprising: a switching capacitor; an output capacitor; and A plurality of switches are configured to selectively operate in the following modes according to the level of the first supply voltage to periodically switch the electrical connection between the conversion capacitor and the output capacitor to perform switched capacitor power conversion: Voltage division mode: when the first supply voltage is higher than a high threshold, the multiple switches control the conversion capacitor and the output capacitor to form a capacitive voltage divider, dividing the first supply voltage in a switched capacitor power conversion manner to generate the second supply voltage lower than the first supply voltage; and Pumping mode: When the first supply voltage is lower than a low threshold, the multiple switches control the conversion capacitor and the output capacitor to form a charge pump, pumping the first supply voltage in a switched capacitor power conversion manner to generate the second supply voltage higher than the first supply voltage.

2. The switched capacitor converter circuit according to claim 1, wherein: When the first supply voltage is lower than the high threshold and higher than the low threshold, the switches further bypass the first supply voltage to the second supply voltage, such that the second supply voltage is equal to the first supply voltage.

3. The switched capacitor conversion circuit according to claim 1, wherein: The power conversion circuit is a flyback power converter.

4. The switched capacitor conversion circuit according to claim 3, wherein: The second supply voltage is used to supply power to a controller in the flyback power converter.

5. The switched capacitor conversion circuit according to claim 3, wherein: The first supply voltage is coupled from a winding of a transformer of the flyback power converter.

6. The switched capacitor conversion circuit according to claim 5, wherein: The first supply voltage is proportional to an output voltage of the flyback power converter.

7. The switched capacitor conversion circuit according to claim 4, wherein: The second supply voltage is lower than an absolute maximum rating of the controller, and the absolute maximum rating is smaller than a maximum value of the first supply voltage.

8. The switched capacitor converter circuit according to claim 1, wherein: When the first supply voltage is higher than the high threshold, the second supply voltage is controlled to be 1 / 2 of the first supply voltage, and when the first supply voltage is lower than the low threshold, the second supply voltage is controlled to be twice the first supply voltage.

9. The switched capacitor conversion circuit according to claim 8, wherein: The high threshold is greater than or equal to twice a minimum operating voltage of a controller of the power conversion circuit.

10. The switched capacitor converter circuit according to claim 1, wherein: A portion of the plurality of switches is used to periodically switch the electrical connection relationship between the conversion capacitor and the output capacitor in both the voltage division mode and the pressure pumping mode.

11. The switched capacitor converter circuit according to claim 1, wherein: The low threshold is greater than or equal to a minimum operating voltage of a controller of the power conversion circuit.

12. The switched capacitor converter circuit according to claim 1, wherein: The plurality of switches are periodically switched based on a switching cycle to operate in the following modes: Voltage division mode: when the first supply voltage is higher than the high threshold, during a first period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in series between the first supply voltage and a ground potential, and during a second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in parallel with each other, thereby generating the second supply voltage on the output capacitor, such that the second supply voltage is controlled to be 1 / 2 of the first supply voltage; and Pumping mode: When the first supply voltage is lower than the low threshold, in the first period of the switching cycle, the multiple switches control the conversion capacitor to be electrically connected in parallel to the first supply voltage for charging, and in the second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in anti-phase series between the first supply voltage and the ground potential, thereby generating the second supply voltage on the output capacitor, so that the second supply voltage is controlled to be twice the first supply voltage.

13. The switched capacitor converter circuit according to claim 12, wherein: There is a dead time between the first period and the second period of the switching cycle to prevent a portion of the switches from being turned on at the same time to cause a short circuit current.

14. The switched capacitor converter circuit according to claim 12, wherein: The switched capacitor converter circuit includes first to fifth switches, wherein the first, second, third, and fourth switches are sequentially coupled in series between the first supply voltage and the ground potential, and are sequentially coupled to a first node, a second node, and a third node. The fifth switch is coupled between the first supply voltage and the third node, and the second node is coupled to the second supply voltage. The conversion capacitor is coupled between the first node and the third node, and the output capacitor is coupled between the second supply voltage and the ground potential.

15. The switched capacitor converter circuit according to claim 14, wherein: When the first supply voltage is lower than the high threshold and higher than the low threshold, the first switch and the second switch are turned on, and / or the third switch and the fifth switch are turned on, so as to control the first supply voltage and the second supply voltage to be electrically connected to each other, so that the second supply voltage is equal to the first supply voltage.

16. The switched capacitor converter circuit according to claim 14, wherein: Each of the first switch and the second switch includes: A first transistor and a second transistor are connected in series, wherein a body diode of the first transistor and a body diode of the second transistor are reversely coupled to each other.

17. A flyback power converter, comprising: A controller for controlling and switching a winding of a transformer to convert an input voltage and generate an output voltage at another winding of the transformer; as well as a switched capacitor conversion circuit for converting a first supply voltage to generate a second supply voltage for supplying power to the controller, wherein the first supply voltage is coupled from a winding of the transformer, the switched capacitor conversion circuit comprising: a switching capacitor; an output capacitor; and A plurality of switches are configured to selectively operate in the following modes according to the level of the first supply voltage to periodically switch the electrical connection between the conversion capacitor and the output capacitor to perform switched capacitor power conversion: Voltage division mode: when the first supply voltage is higher than a high threshold, the multiple switches control the conversion capacitor and the output capacitor to form a capacitive voltage divider, dividing the first supply voltage in a switched capacitor power conversion manner to generate the second supply voltage lower than the first supply voltage; and Pumping mode: When the first supply voltage is lower than a low threshold, the multiple switches control the conversion capacitor and the output capacitor to form a charge pump, pumping the first supply voltage in a switched capacitor power conversion manner to generate the second supply voltage higher than the first supply voltage.

18. The flyback power converter according to claim 17, wherein: When the first supply voltage is lower than the high threshold and higher than the low threshold, the switches further bypass the first supply voltage to the second supply voltage, such that the second supply voltage is equal to the first supply voltage.

19. The flyback power converter according to claim 17, wherein: The first supply voltage is proportional to the output voltage.

20. The flyback power converter according to claim 17, wherein: The second supply voltage is lower than an absolute maximum rating of the controller, and the absolute maximum rating is smaller than a maximum value of the first supply voltage.

21. The flyback power converter according to claim 17, wherein: When the first supply voltage is higher than the high threshold, the second supply voltage is controlled to be 1 / 2 of the first supply voltage, and when the first supply voltage is lower than the low threshold, the second supply voltage is controlled to be twice the first supply voltage.

22. The flyback power converter according to claim 17, wherein: The high threshold is greater than or equal to twice a minimum operating voltage of the controller.

23. The flyback power converter according to claim 17, wherein: A portion of the plurality of switches is used to periodically switch the electrical connection relationship between the conversion capacitor and the output capacitor in both the voltage division mode and the pressure pumping mode.

24. The flyback power converter according to claim 17, wherein: The low threshold is greater than or equal to a minimum operating voltage of the controller.

25. The flyback power converter according to claim 17, wherein: The plurality of switches are periodically switched based on a switching cycle to operate in the following modes: Voltage division mode: when the first supply voltage is higher than the high threshold, during a first period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in series between the first supply voltage and a ground potential, and during a second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in parallel with each other, thereby generating the second supply voltage on the output capacitor, such that the second supply voltage is controlled to be 1 / 2 of the first supply voltage; and Pumping mode: When the first supply voltage is lower than the low threshold, in the first period of the switching cycle, the multiple switches control the conversion capacitor to be electrically connected in parallel to the first supply voltage for charging, and in the second period of the switching cycle, the multiple switches control the conversion capacitor and the output capacitor to be electrically connected in anti-phase series between the first supply voltage and the ground potential, thereby generating the second supply voltage on the output capacitor, so that the second supply voltage is controlled to be twice the first supply voltage.

26. The flyback power converter according to claim 25, wherein: The switched capacitor converter circuit includes first to fifth switches, wherein the first, second, third, and fourth switches are sequentially coupled in series between the first supply voltage and the ground potential, and are sequentially coupled to a first node, a second node, and a third node. The fifth switch is coupled between the first supply voltage and the third node, and the second node is coupled to the second supply voltage. The conversion capacitor is coupled between the first node and the third node, and the output capacitor is coupled between the second supply voltage and the ground potential.

27. The flyback power converter according to claim 26, wherein: When the first supply voltage is lower than the high threshold and higher than the low threshold, the first switch and the second switch are turned on, and / or the third switch and the fifth switch are turned on, so as to control the first supply voltage and the second supply voltage to be electrically connected to each other, so that the second supply voltage is equal to the first supply voltage.

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