Switched capacitor power supply conversion circuit and conversion control circuit and control method thereof

Abstract

A switched capacitor power conversion circuit, a conversion control circuit, and a control method thereof. The switched capacitor power conversion circuit includes: a conversion capacitor; a plurality of conversion transistors; and an output capacitor coupled to an output node. In a switching conversion mode, the switched capacitor power conversion circuit converts input power using a switched capacitor to generate output power at the output node. During a first pre-charge period, the first conversion transistor is controlled to provide a first pre-charge current to pre-charge the conversion capacitor to a preset voltage level, and charging of the output capacitor is avoided during the first pre-charge period. During a second pre-charge period, the second conversion transistor is controlled to provide a second pre-charge current through the output node to pre-charge the output capacitor to a preset voltage level, and the second pre-charge current is simultaneously used to supply a load current to a load circuit.

Description

Technical Field

[0001] The present invention relates to a switched capacitor power converter circuit, and more particularly to a switched capacitor power converter circuit capable of precharging to reduce inrush current. The present invention also relates to a conversion control circuit and a control method for controlling the switched capacitor power converter circuit. Background Art

[0002] Prior documents related to this application include: "RT9758 Specification, Richtek Technology Co., Ltd.", "bq25970 Specification, TI", "NCP1764 Specification, ON Semiconductor", and "PCA9488 Specification, NXP".

[0003] Figure 1A and Figure 1B A conventional switched capacitor power converter circuit (101A-101B) is shown. The switched capacitor power converter circuit 101A-101B switches the electrical connection configuration of the switching capacitor CF through switching transistors Q1-Q4 to convert input power to generate output power.

[0004] Figure 1A-1B A disadvantage of the prior art switched capacitor power conversion circuit is that when the voltage across the conversion capacitor CF and the output capacitor Cout differs significantly from the steady-state voltage, directly performing the switched capacitor power conversion will cause a large inrush current, which may cause the conversion transistor to burn out.

[0005] Compared to Figure 1A-1B Compared with the prior art, the switched capacitor power conversion circuit of the present invention can pre-charge the conversion capacitor CF and the output capacitor Cout respectively before switching the conversion mode, thereby avoiding the aforementioned inrush current and supporting the load circuit to start up under heavy load with a smaller pre-charging current. Summary of the Invention

[0006] From one perspective, the present invention provides a switched capacitor power conversion circuit, comprising: a conversion capacitor; a plurality of conversion transistors coupled to the conversion capacitor for converting an input power supply to generate an output power supply at an output node; and an output capacitor coupled to the output node; wherein in a switching conversion mode, the plurality of conversion transistors switch the electrical connection relationship of the conversion capacitor in a time-sharing manner, so that the conversion capacitor is periodically and time-sharingly electrically connected in turn between the input power supply and a voltage-dividing node of at least one voltage-dividing node, or between a voltage-dividing node of the at least one voltage-dividing node and the ground potential, or when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power supply to generate the output power supply, wherein the output node corresponds to a node of the at least one voltage-dividing node, wherein in a steady state, the voltage of the input power supply is k times the voltage of the output power supply, and The current of the input power supply is 1 / k times the current of the output power supply, where k is a natural number greater than 1; wherein in a pre-charging mode, the switched capacitor power conversion circuit performs the following pre-charging operation: in a first pre-charging period, a first conversion transistor of the multiple conversion transistors is controlled to provide a first pre-charging current to pre-charge the conversion capacitor to a preset voltage level, and charging of the output capacitor is avoided in the first pre-charging period; and in a second pre-charging period, a second conversion transistor of the multiple conversion transistors is controlled to provide a second pre-charging current through the output node to pre-charge the output capacitor to the preset voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charging current is not greater than a first preset current level, the second pre-charging current is not greater than a second preset current level, and the load current is not less than a third preset current level.

[0007] In a preferred embodiment, the switching conversion mode is operated after the pre-charging mode.

[0008] In a preferred embodiment, the first pre-charge period is earlier than the second pre-charge period.

[0009] In a preferred embodiment, the switched capacitor power conversion circuit further controls the first conversion transistor and the second conversion transistor during a balancing period to balance the voltages of the conversion capacitor and the output capacitor to the predetermined voltage level.

[0010] In a preferred embodiment, the first conversion transistor and the second conversion transistor are connected in series, wherein the conversion capacitor, one end of the first conversion transistor and the second conversion transistor are coupled to a switching node, and the output capacitor is coupled to the other end of the second conversion transistor, wherein during the second pre-charge period, the first conversion transistor provides at least the second pre-charge current to the switching node.

[0011] In a preferred embodiment, the first preset current level is equal to the second preset current level, and the load current is smaller than the second pre-charge current.

[0012] In a preferred embodiment, in the pre-charge mode, the first transfer transistor is configured as a current source or a current clamp circuit to provide the first pre-charge current.

[0013] In a preferred embodiment, during the second pre-charging period, the second conversion transistor is configured as a current source or a current clamp circuit to provide the second pre-charging current.

[0014] In a preferred embodiment, after the first pre-charging period, whether the conversion capacitor is short-circuited or leaking is determined based on whether the voltage at the low voltage end of the conversion capacitor exceeds a voltage threshold.

[0015] In a preferred embodiment, after the second pre-charging period, whether the output voltage does not exceed a voltage threshold is used to determine whether the output capacitor is short-circuited or leaking, or whether pre-charging has failed.

[0016] In a preferred embodiment, the switched capacitor power conversion circuit is configured as follows: the first conversion transistor, the second conversion transistor, a third conversion transistor, and a fourth conversion transistor of the plurality of conversion transistors are sequentially connected in series between the input power supply and the ground potential, wherein the first conversion transistor and the second conversion transistor are coupled to one end of the conversion capacitor, the third conversion transistor and the fourth conversion transistor are coupled to the other end of the conversion capacitor, and the second conversion transistor, the third conversion transistor, and the output capacitor are coupled to the output node; wherein in the switching conversion mode, the first conversion transistor, the second conversion transistor, the third conversion transistor, and the fourth conversion transistor are switched in a time-sharing manner, so that the conversion capacitor is electrically connected between the input power supply and the output node, and between the output node and the ground potential in a time-sharing manner, thereby making the voltage of the input power supply twice the voltage of the output power supply, and the current of the input power supply 1 / 2 times the current of the output power supply.

[0017] In a preferred embodiment, in the switching conversion mode: the voltage of the input power supply is a constant voltage, and the voltage of the output power supply is also a constant voltage; or the current of the input power supply is a constant current, and the current of the output power supply is also a constant current.

[0018] From another perspective, the present invention also provides a conversion control circuit for controlling the operation of a conversion capacitor and an output capacitor, and converting an input power supply to generate an output power supply at an output node, wherein the output capacitor is coupled to the output node; the conversion control circuit includes: a plurality of conversion transistors coupled to the conversion capacitor; a precharge control circuit for controlling the plurality of conversion transistors in a precharge mode; and a switching control circuit for controlling the plurality of conversion transistors in a switching conversion mode; wherein in the switching conversion mode, the switching control circuit controls the plurality of conversion transistors to switch the electrical connection relationship of the conversion capacitor in a time-sharing manner, so that the conversion capacitor is periodically and time-sharingly electrically connected in turn between the input power supply and a voltage-dividing node among at least one voltage-dividing node, or between a voltage-dividing node among the at least one voltage-dividing node and the ground potential, or when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power supply to generate the output power supply, wherein the output node corresponds to the at least one voltage-dividing node. A node among the voltage divider nodes, wherein in steady state, the voltage of the input power supply is k times the voltage of the output power supply, and the current of the input power supply is 1 / k times the current of the output power supply, wherein k is a natural number greater than 1; wherein in the pre-charging mode, the pre-charging control circuit controls the multiple conversion transistors to perform the following pre-charging operation: in a first pre-charging period, controlling a first conversion transistor of the multiple conversion transistors to provide a first pre-charging current to pre-charge the conversion capacitor to a preset voltage level, and avoiding charging the output capacitor in the first pre-charging period; and in a second pre-charging period, controlling a second conversion transistor of the multiple conversion transistors to provide a second pre-charging current through the output node to pre-charge the output capacitor to the preset voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charging current is not greater than a first preset current level, the second pre-charging current is not greater than a second preset current level, and the load current is not less than a third preset current level.

[0019] From another perspective, the present invention also provides a control method for controlling the operation of multiple conversion transistors, a conversion capacitor and an output capacitor to convert an input power supply and generate an output power supply at an output node, and the output capacitor is coupled to the output node; the control method includes: in a switching conversion mode, the switching control circuit controls the multiple conversion transistors to switch the electrical connection relationship of the conversion capacitor in a time-sharing manner, so that the conversion capacitor is periodically and time-sharingly electrically connected between the input power supply and a voltage-dividing node of at least one voltage-dividing node, or between a voltage-dividing node of at least one voltage-dividing node and the ground potential, or when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power supply to generate the output power supply, wherein the output node corresponds to a node of the at least one voltage-dividing node, wherein in a steady state, the voltage of the input power supply is k times the voltage of the output power supply, and the output The current of the input power supply is 1 / k times the current of the output power supply, where k is a natural number greater than 1; and in a pre-charging mode, the multiple conversion transistors are controlled to perform a pre-charging operation, wherein the pre-charging operation includes the following steps: in a first pre-charging period, a first conversion transistor of the multiple conversion transistors is controlled to provide a first pre-charging current to pre-charge the conversion capacitor to a preset voltage level, and charging of the output capacitor is avoided in the first pre-charging period; and in a second pre-charging period, a second conversion transistor of the multiple conversion transistors is controlled to provide a second pre-charging current through the output node to pre-charge the output capacitor to the preset voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charging current is not greater than a first preset current level, the second pre-charging current is not greater than a second preset current level, and the load current is not less than a third preset current level.

[0020] 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

[0021] Figure 1A and Figure 1B A prior art capacitive power conversion circuit is shown.

[0022] Figure 2 A block diagram showing an embodiment of a switched capacitor power conversion circuit of the present invention is shown.

[0023] Figure 3 A schematic diagram showing a specific embodiment of the switched capacitor power conversion circuit of the present invention is shown.

[0024] Figure 4 An operation waveform diagram corresponding to an embodiment of the switched capacitor power conversion circuit of the present invention is shown.

[0025] Figure 5 A schematic diagram showing an embodiment of the switched capacitor power conversion circuit of the present invention is shown.

[0026] Figure 6 A schematic diagram showing an embodiment of a sub-conversion control circuit in the switched capacitor power conversion circuit of the present invention is shown.

[0027] Figure 7 A schematic diagram showing another specific embodiment of a pre-charge control circuit in the switched capacitor power conversion circuit of the present invention is shown.

[0028] Figure 8 A schematic diagram showing another embodiment of the switched capacitor power conversion circuit of the present invention is shown.

[0029] Explanation of symbols in the figure

[0030] 101A-101B, 102-103, 105, 108: Switched capacitor power conversion circuit

[0031] 20: Conversion control circuit

[0032] 21, 27: Precharge control circuit

[0033] 22: Switching control circuit

[0034] 26: Secondary conversion control circuit

[0035] 271: Clamping Circuit

[0036] 30: Load circuit

[0037] CF: switching capacitor

[0038] CP, CN: Switching Node

[0039] Cout: output capacitor

[0040] Icf, IQ1: current

[0041] Iin: input current

[0042] Ild: load current

[0043] Iout: output current

[0044] Iref1: reference current source

[0045] k: current amplification factor

[0046] L11, L12, L21, L22: voltage level

[0047] Lcf, Lout: current level

[0048] Lscf, Lsco: voltage threshold

[0049] Lsw: high potential

[0050] Nd1~Ndx:voltage dividing nodes

[0051] Nout: output node

[0052] Q1~Q4, Qm: conversion transistors

[0053] Q1C~Q4C: conversion control signal

[0054] Q1m, Q4m: Current control transistors

[0055] S1, S2: Selector switch

[0056] SEL: Mode switching signal

[0057] T1, T2: pre-charge period

[0058] Tbal: Balancing period

[0059] Tdet1, Tdet2: time period

[0060] Vin: input voltage

[0061] Vout: output voltage DETAILED DESCRIPTION

[0062] 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.

[0063] Figure 2 A block diagram of an embodiment of a switched capacitor power converter circuit of the present invention (switched capacitor power converter circuit 102) is shown. In one embodiment, as Figure 2 As shown, the switched capacitor power conversion circuit 102 includes a switching capacitor CF, a plurality of switching transistors (such as Figure 2 As shown in FIG, there are switching transistors Q1 to Q4) and output capacitor Cout. Figure 2 As shown, in this embodiment, the switching transistors Q1 to Q4 are sequentially connected in series between the input power supply and the ground potential, wherein the switching transistor Q1 and the switching transistor Q2 are coupled to one end of the switching capacitor CF (such as Figure 2 The switching node CP shown in FIG. 1 ), the switching transistor Q3 and the switching transistor Q4 are coupled to the other end of the switching capacitor CF (as shown in FIG. 1 ). Figure 2The switching node CN shown in FIG2 , the switching transistors Q2 and Q3 and the output capacitor Cout are coupled to the output node Nout. The switching control signals Q1C to Q4C are used to control the switching transistors Q1 to Q4 respectively.

[0064] In one embodiment, if Figure 2 As shown, the switched capacitor power conversion circuit 102 has two operation modes: a pre-charge mode and a switching conversion mode. The switching transistors (eg, Figure 2 The transistors Q1-Q4 are shown as being controlled by a precharge control circuit 21 and a switching control circuit 22 in a precharge mode and a switching mode, respectively, to implement precharge and switching power conversion operations. A mode switching signal SEL is used to control select switches S1 and S2 to determine how the switching transistors operate.

[0065] Please continue reading Figure 2 According to the present invention, in the switching conversion mode, the electrical connection configuration of the conversion capacitor CF is switched by a plurality of conversion transistors (such as conversion transistors Q1 to Q4) to convert the input power supply to generate the output power supply. Specifically, in this embodiment, in the switching conversion mode, the conversion transistor Q1, the conversion transistor Q2, the conversion transistor Q3 and the conversion transistor Q4 are switched in a time-sharing manner, so that the conversion capacitor CF is electrically connected between the input power supply and the output node Nout, and electrically connected between the output node Nout and the ground potential in a time-sharing manner, to convert the input power supply to generate the output power supply. The input power supply has an input voltage Vin and an input current Iin, and the output power supply has an output voltage Vout and an output current Iout. Specifically, in this embodiment, through the above-mentioned switching power conversion operation, the input voltage Vin is twice the output voltage Vout, and the current of the input power supply is 1 / 2 times the current of the output power supply.

[0066] Please also see Figure 2 、 Figure 3 and Figure 4 , Figure 3 A schematic diagram showing a specific embodiment of the switched capacitor power conversion circuit of the present invention (switched capacitor power conversion circuit 103) is shown. Figure 4 The operation waveform diagram of an embodiment of the switched capacitor power conversion circuit of the present invention is shown. Figure 3 As shown, in the pre-charge mode, the conversion transistor Q1 of the switched capacitor power conversion circuit 103 can be configured as a current mirror circuit for the first pre-charge period (eg Figure 4The first pre-charge current is provided to pre-charge the conversion capacitor CF to a predetermined voltage level, and the output capacitor Cout is prevented from being charged during the first pre-charge period T1. Specifically, in this embodiment, the first pre-charge current corresponds to Figure 4 The current Icf in the first pre-charge period T1, the predetermined voltage level corresponds to Figure 4 In the first pre-charge period T1, CP is pre-charged to Vin / 2.

[0067] In one embodiment, during the first pre-charging period T1, the transfer transistor Q2 is controlled to be non-conductive. Figure 4 As shown, Q2C is controlled at a low level to be non-conductive, thereby preventing the output capacitor Cout from being charged.

[0068] Then, in the second pre-charge period (such as Figure 4 T2), controls the switching transistor Q2 to provide a second pre-charge current through the output node Nout to pre-charge the output capacitor Cout to the aforementioned preset voltage level Vin / 2, and the second pre-charge current is also used to supply the load current Ild to the load circuit 30. In detail, in this embodiment, the second pre-charge current corresponds to Figure 4 Iout in the second pre-charging period T2, wherein the second pre-charging current simultaneously provides a current Icout for charging the output capacitor Cout and also supplies a load current Ild to the load circuit 30. Figure 4 As shown, the positive terminal of the output capacitor Cout (corresponding to the switching node CP) is precharged to Vin / 2 in the second precharge period T2.

[0069] Specifically, if Figure 3 As shown, in this embodiment, in the pre-charge mode, the current control transistor Q1m generates a conversion control signal Q1C (such as Figure 4 The voltage level L11 between T1) is used to control the switching transistor Q1 to generate the aforementioned first pre-charge current (such as Figure 4 In addition, the switching control signal Q2C can also control the switching transistor Q2 in the pre-charge mode in a current mirror circuit manner to generate the aforementioned second pre-charge current (such as Figure 4 Specifically, if Figure 3 As shown, in this embodiment, in the second pre-charge period T2, the conversion control signal Q2C (such as Figure 4 The voltage level L21 between T2) is from another current source mirror circuit to control the switching transistor Q2 to generate the aforementioned first pre-charge current (such as Figure 4The current Iout between T2). It should be noted that, Figure 3 For the sake of simplicity in explanation, the aforementioned selection switch is omitted in the embodiment to illustrate that the pre-charge control circuit 21 controls the conversion transistor.

[0070] In one embodiment, when the conversion capacitor CF is precharged, the current outflow end of the conversion capacitor CF may also be current limited. Specifically, Figure 3 As shown, in one embodiment, in the pre-charge mode, the current control transistor Q4m generates a switching control signal Q4C according to the reference current source to control the switching transistor Q4 to generate a current of the same level as the first pre-charge current.

[0071] According to the above-mentioned operation of the present invention divided into two pre-charging periods, in the first pre-charging period T1, since only the conversion capacitor CF is pre-charged to the preset voltage level, the output capacitor Cout is avoided from being charged. At the same time, in the first pre-charging period T1, since the output voltage Vout is still at a low potential, the load circuit 30 does not draw current. In other words, in the first pre-charging period T1, the first pre-charging current provided by the conversion transistor Q1 is completely used to pre-charge the conversion capacitor CF, and in the second pre-charging period T2, the output capacitor Cout is pre-charged at the same time, and the load current Ild is supplied to the load circuit 30.

[0072] Specifically, in one embodiment, the first pre-charge current is not greater than a first preset current level. In one embodiment, the first preset current level is related to the upper current limit of the conversion transistor Q1 in the pre-charge mode to prevent the conversion transistor Q1 from overheating or burning.

[0073] In one embodiment, the second pre-charge current is not greater than a second preset current level. In one embodiment, the second preset current level is related to the upper current limit of the switching transistor Q2 in the pre-charge mode to prevent the switching transistor Q2 from being overheated or burned.

[0074] In one embodiment, the load current Ild is not less than a third predetermined current level. The third predetermined current level is related to the current requirement of the load circuit 30 during heavy-load startup.

[0075] In one embodiment, the sum of the first pre-charging period T1 and the second pre-charging period T2 is less than the pre-charging time limit. In other words, the pre-charging needs to be completed within the aforementioned pre-charging time limit.

[0076] It is worth noting that due to the aforementioned technical features of the present invention, only the conversion capacitor CF is precharged during the first pre-charging period T1, and pre-charging of the output capacitor Cout is avoided. Therefore, the load current Ild will not be supplied to the load circuit 30 during the first pre-charging period T1. Therefore, compared with other existing technologies that pre-charge the conversion capacitor CF and the output capacitor Cout at the same time during pre-charging, and supply the load current Ild to the load circuit 30 at the same time, the present invention can complete pre-charging within the pre-charging time limit under limited pre-charging current limitations, and can also meet the requirements of heavy-load startup of the load circuit 30.

[0077] In one embodiment, the first predetermined current level (eg Figure 4 Lcf) and the second preset current level (such as Figure 4 In one embodiment, the load current Ild is less than the second pre-charge current. In this way, the second pre-charge current can not only supply the load current Ild, but also pre-charge the output capacitor Cout to a predetermined voltage level within the aforementioned pre-charge time limit.

[0078] In addition, each of the first pre-charging current and the second pre-charging current must be greater than the corresponding current lower limit level to meet the aforementioned pre-charging time limit.

[0079] Please continue reading Figure 4 In this embodiment, after the pre-charging is completed, the switching capacitor power conversion circuit (such as 103) is set to the switching conversion mode, and the input power is converted to generate the output power by switching the conversion transistors (such as Q1 to Q4) in the switching conversion mode. Figure 4 For example, the switching control signals Q1C and Q2C are switched between a low voltage and a high voltage (Lsw) in the switching conversion mode to control the switching conversion transistors Q1 and Q2 to perform switched capacitor power conversion.

[0080] In one embodiment, if Figure 4 As shown, the switched capacitor power conversion circuit (such as 103) also controls the conversion transistor Q1 and the conversion transistor Q2 in the balancing period Tbal to balance the voltage of the conversion capacitor CF and the output capacitor Cout to a predetermined voltage level (such as Vin / 2). In one embodiment, for example, the second conversion transistor Q2 is controlled to have the aforementioned second predetermined current level in the balancing period Tbal to balance the voltage of the conversion capacitor CF and the output capacitor Cout. Figure 4 For example, during the balancing period Tbal, the voltage level of the conversion control signal Q2C is controlled to be L22. In one embodiment, L22 is equal to L21.

[0081] Please continue reading Figure 2 and Figure 4 In this embodiment, the transfer transistor Q1 and the transfer transistor Q2 are connected in series. During the second pre-charging period T2, the transfer transistor Q1 also needs to provide at least the second pre-charging current to the switching node (CP) at the same time, so that the transfer transistor Q2 can provide the second pre-charging current at the output node Nout. Figure 4 For example, in the second pre-charging period T2 , the voltage level of the conversion control signal Q1C is controlled to be L12 . In one embodiment, L12 is equal to L11 .

[0082] Please continue reading Figure 4 In one embodiment, after the first pre-charging period T1, it is determined whether the switching capacitor CF is short-circuited or leaking based on whether the voltage at the low voltage end (switching node CN) of the switching capacitor CF exceeds the voltage threshold Lscf. Figure 4 As shown, in this embodiment, the voltage at the switching node CN does not exceed the voltage threshold Lscf during the time period Tdet1. Therefore, it is determined that the conversion capacitor CF is not short-circuited or leaking, and operation can continue smoothly. On the other hand, if the voltage at the switching node CN exceeds the voltage threshold Lscf during the time period Tdet1, the system can be shut down or a system or user can be notified.

[0083] Please continue reading Figure 4 In one embodiment, after the second pre-charging period T2, it is determined whether the output capacitor Cout is short-circuited or leaking, or whether pre-charging is not completed, based on whether the output voltage Vout does not exceed the voltage threshold Lsco. Figure 4 As shown, in this embodiment, the output voltage Vout exceeds the voltage threshold Lsco during the time period Tdet2. Therefore, it is determined that the output capacitor Cout is not short-circuited or leaking, and pre-charging is completed, allowing smooth operation. On the other hand, if the output voltage Vout does not exceed the voltage threshold Lscf during the time period Tdet2, the device may be shut down or a system or user may be notified.

[0084] Please continue reading Figure 2 In one embodiment, a plurality of switching transistors (such as Q1 to Q4), the precharge control circuit 21, the switching control circuit 22 and the selection switches S1 and S2 can be integrated into an integrated circuit (ie, Figure 2 In one embodiment, the output node Ncout corresponds to the output pin of the conversion control circuit 20, the switching nodes CP and CN correspond to the positive conversion pin and the negative conversion pin of the conversion control circuit 20, respectively, and the input power source (Vin) corresponds to the power input pin of the conversion control circuit 20.

[0085] Figure 5A schematic diagram showing an embodiment of a switched capacitor power conversion circuit of the present invention (switched capacitor power conversion circuit 105) is shown. In addition to the aforementioned Figure 2 and Figure 3 In addition to the embodiment shown, the scope of the present invention can be expanded. The switched capacitor power conversion circuit 105 includes at least one switching capacitor CF, a plurality of switching transistors (such as Figure 5 The switching transistors Q1-Qm (where m is a positive integer greater than 1) and the output capacitor Cout are shown. In this embodiment, in the switching conversion mode, the switching transistors Q1-Qm are periodically switched in a time-sharing manner, so that the switching capacitor CF is periodically and time-sharingly connected alternately between the input power supply and any one of the at least one voltage-dividing nodes (Nd1-Ndx), between a pair of the voltage-dividing nodes Nd1-Ndx (in an embodiment having multiple voltage-dividing nodes), or between any one of the at least one voltage-dividing nodes (Nd1-Ndx) and the ground potential, thereby converting the input power supply to generate an output power supply at the output node Nout. The output node corresponds to one of the at least one voltage-dividing nodes (Nd1-Ndx), and x is greater than or equal to 1. In this embodiment, through the switching power conversion operation described above, in steady state, the input voltage Vin is k times the output voltage Vout, and the input power current is 1 / k times the output power current, where k is a real number greater than 1.

[0086] In one embodiment, the number of conversion capacitors is not limited to one, and multiple conversion capacitors may be included, for example, interleaved to perform the capacitive power conversion described above. In this case, the pre-charging of the multiple conversion capacitors may be performed sequentially or simultaneously, depending on the actual application conditions.

[0087] Please also read back Figure 2 From one perspective, the switched capacitor power converter circuit 102 is a special case of the aforementioned switched capacitor power converter circuit 105, wherein the switched capacitor power converter circuit 102 has a voltage divider node corresponding to the aforementioned output node Nout, and the current amplification factor k of the switched capacitor power converter circuit 102 is equal to 2.

[0088] Furthermore, in one embodiment, the predetermined voltage level in the aforementioned pre-charging stage is related to the output voltage Vout and the real number k.

[0089] Figure 6 FIG. 1 is a schematic diagram showing an embodiment of a sub-conversion control circuit (sub-conversion control circuit 26) in the switched capacitor power conversion circuit of the present invention. In one embodiment, the pre-charge control circuit 21 and the switching control circuit 22 and the selection switches S1 and S2 can be integrated into an integrated circuit (i.e., as shown in FIG. 2 ). Figure 6In one embodiment, the sub-switching control circuit 26 is used to generate the aforementioned switching control signals Q1C-QmC to control the switching transistors Q1-Qm, respectively.

[0090] Figure 7 A schematic diagram showing another specific embodiment of the pre-charge control circuit (pre-charge control circuit 27) in the switched capacitor power conversion circuit of the present invention is shown. In one embodiment, Figure 7 As shown, the precharge control circuit 27 includes a clamp circuit 271 for generating a switching control signal Q1C (eg, Figure 4 The voltage level L11 or L12 in the circuit is used to control the switching transistor Q1 to generate the aforementioned pre-charge current (such as Figure 4 Other switching transistors (such as Q2) can also be controlled by the above clamping method (such as Figure 4 The voltage level L21 or L22 in the switching transistor is used to control the current flowing through the switching transistor.

[0091] Figure 8 A schematic diagram showing another embodiment of the switched capacitor power conversion circuit of the present invention (switched capacitor power conversion circuit 108) is shown. In one embodiment, in the switching conversion mode, as shown in FIG. Figure 8 As shown, the input power supply is in constant current mode (such as Figure 8 The input current Iin shown in FIG. 1 supplies power to the switched capacitor power converter circuit 108. In this case, in the switching conversion mode, the input current Iin is a constant current, and the output current Iout is also a constant current, but the aforementioned relationship of the output current Iout being k times (corresponding to 2 times in this embodiment) the input current Iin is maintained. In this embodiment, the load circuit 30 may correspond to a rechargeable battery, for example.

[0092] The present invention has been described above with respect to the preferred embodiments, but the above description is only for those skilled in the art to easily understand the content of the present invention and is not intended to limit the scope of the rights 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 part of the components in one embodiment can also be used to replace the 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-current conversion, current-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 power conversion circuit, comprising: a switching capacitor; an output capacitor coupled between an output node and a ground potential; and a plurality of switching transistors coupled to the switching capacitor and the output capacitor, configured to switch the switching capacitor and the output capacitor to convert an input power source and generate an output power source at the output node, wherein the plurality of switching transistors include a first switching transistor and a second switching transistor, wherein the first switching transistor is coupled between the input power source and the first end of the switching capacitor, and the second switching transistor is coupled between the input power source and the output node; wherein in a switching conversion mode, the plurality of conversion transistors time-share and alternately switch the electrical connection relationship of the conversion capacitor, so that the conversion capacitor is periodically and time-shared and alternately electrically connected between the input power source and one of the at least one voltage-dividing nodes, or between one of the at least one voltage-dividing nodes and the ground potential, or, when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power source to generate the output power source, wherein the output node corresponds to one of the at least one voltage-dividing nodes, wherein in a steady state, the voltage of the input power source is k times the voltage of the output power source, and the current of the input power source is 1 / k times the current of the output power source, where k is a real number greater than 1; In a pre-charging mode, the switched capacitor power conversion circuit performs the following pre-charging operations: During a first pre-charging period, controlling the first conversion transistor to convert the input power source to generate a first pre-charging current to pre-charge the conversion capacitor to a predetermined voltage level, and avoiding charging the output capacitor during the first pre-charging period; as well as During a second pre-charging period, controlling the second conversion transistor to convert the input power source to generate a second pre-charging current to pre-charge the output capacitor to the predetermined voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charge current is not greater than a first preset current level, the second pre-charge current is not greater than a second preset current level, and the load current is not less than a third preset current level; The first conversion transistor and the second conversion transistor participate in periodic switching in the switching conversion mode. 2 . The switched capacitor power converter circuit as claimed in claim 1 , wherein the switching conversion mode is operated after the pre-charging mode. 3 . The switched capacitor power conversion circuit as claimed in claim 1 , wherein the first pre-charge period is earlier than the second pre-charge period.

4. The switched capacitor power conversion circuit as claimed in claim 1 , wherein the switched capacitor power conversion circuit further controls the first switching transistor and the second switching transistor during a balancing period to balance the voltages of the switching capacitor and the output capacitor to the predetermined voltage level.

5. The switched capacitor power conversion circuit according to claim 1, The first conversion transistor is coupled between the input power supply and a switching node, the first end of the conversion capacitor is coupled to the switching node, the second conversion transistor is coupled between the switching node and the output node, and during the second pre-charging period, the first conversion transistor provides at least the second pre-charging current to the switching node. 6 . The switched-capacitor power conversion circuit as claimed in claim 1 , wherein the first preset current level is equal to the second preset current level, and the load current is smaller than the second pre-charge current. 7 . The switched-capacitor power converter circuit as claimed in claim 1 , wherein in the pre-charge mode, the first conversion transistor is configured as a current source or a current clamp circuit to provide the first pre-charge current. 8 . The switched-capacitor power converter circuit as claimed in claim 1 , wherein during the second pre-charging period, the second switching transistor is configured as a current source or a current clamp circuit to provide the second pre-charging current.

9. The switched capacitor power conversion circuit of claim 1, wherein after the first pre-charging period, whether the switching capacitor is short-circuited or leaking is determined based on whether the voltage at the low voltage end of the switching capacitor exceeds a voltage threshold.

10. The switched capacitor power conversion circuit of claim 1, wherein after the second pre-charging period, whether the output capacitor is short-circuited or leaking, or whether pre-charging is not completed, is determined based on whether the output voltage does not exceed a voltage threshold.

11. The switched capacitor power conversion circuit according to claim 1 , wherein the switched capacitor power conversion circuit is configured as follows: The first transfer transistor, the second transfer transistor, a third transfer transistor, and a fourth transfer transistor of the plurality of transfer transistors are sequentially connected in series between the input power source and the ground potential, wherein the first transfer transistor and the second transfer transistor are coupled to the first end of the transfer capacitor, the third transfer transistor and the fourth transfer transistor are coupled to a second end of the transfer capacitor, and the second transfer transistor and the third transfer transistor are coupled to the output node; In the switching conversion mode, the first conversion transistor, the second conversion transistor, the third conversion transistor and the fourth conversion transistor are switched in a time-sharing manner, so that the conversion capacitor is electrically connected between the input power supply and the output node, and between the output node and the ground potential in a time-sharing manner, thereby making the voltage of the input power supply twice the voltage of the output power supply, and the current of the input power supply 1 / 2 times the current of the output power supply.

12. The switched capacitor power converter circuit as claimed in claim 1 , wherein in the switching conversion mode: The voltage of the input power supply is a constant voltage, and the voltage of the output power supply is also a constant voltage; or The current of the input power supply is a constant current, and the current of the output power supply is also a constant current.

13. A conversion control circuit comprising: a plurality of switching transistors for switching a switching capacitor and an output capacitor to convert an input power source to generate an output power source at an output node, wherein the output capacitor is coupled between the output node and a ground potential, wherein the plurality of switching transistors include a first switching transistor and a second switching transistor, wherein the first switching transistor is coupled between the input power source and a first end of the switching capacitor, and the second switching transistor is coupled between the input power source and the output node; a precharge control circuit for controlling the plurality of switching transistors in a precharge mode; as well as a switching control circuit for controlling the plurality of switching transistors in a switching conversion mode; wherein, in the switching conversion mode, the switching control circuit controls the plurality of conversion transistors to switch the electrical connection relationship of the conversion capacitor in a time-sharing manner, so that the conversion capacitor is periodically and time-sharingly and alternately electrically connected between the input power source and one of the at least one voltage-dividing nodes, or between one of the at least one voltage-dividing node and the ground potential, or, when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power source to generate the output power source, wherein the output node corresponds to one of the at least one voltage-dividing nodes, and wherein, in a steady state, the voltage of the input power source is k times the voltage of the output power source, and the current of the input power source is 1 / k times the current of the output power source, where k is a real number greater than 1; In the pre-charging mode, the pre-charging control circuit controls the plurality of conversion transistors to perform the following pre-charging operations: During a first pre-charging period, controlling the first conversion transistor to convert the input power source to generate a first pre-charging current to pre-charge the conversion capacitor to a predetermined voltage level, and avoiding charging the output capacitor during the first pre-charging period; as well as During a second pre-charging period, controlling the second conversion transistor to convert the input power source to generate a second pre-charging current to pre-charge the output capacitor to the predetermined voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charge current is not greater than a first preset current level, the second pre-charge current is not greater than a second preset current level, and the load current is not less than a third preset current level; The first conversion transistor and the second conversion transistor participate in periodic switching in the switching conversion mode. 14 . The conversion control circuit as claimed in claim 13 , wherein the switching conversion mode is operated after the pre-charging mode. 15 . The conversion control circuit as claimed in claim 13 , wherein the first pre-charge period is earlier than the second pre-charge period. 16 . The conversion control circuit as claimed in claim 13 , further controlling the first conversion transistor and the second conversion transistor to balance the voltages of the conversion capacitor and the output capacitor to the predetermined voltage level during a balancing period.

17. A conversion control circuit as described in claim 13, wherein the first conversion transistor is coupled between the input power supply and a switching node, wherein the first end of the conversion capacitor is coupled to the switching node, and the second conversion transistor is coupled between the switching node and the output node, wherein in the second pre-charge period, the first conversion transistor provides at least the second pre-charge current to the switching node. 18 . The conversion control circuit as claimed in claim 13 , wherein the first preset current level is equal to the second preset current level, and the load current is smaller than the second pre-charge current. 19 . The conversion control circuit of claim 13 , wherein in the pre-charge mode, the first conversion transistor is configured as a current source or a current clamp circuit to provide the first pre-charge current. 20 . The conversion control circuit of claim 13 , wherein during the second pre-charging period, the second conversion transistor is configured as a current source or a current clamp circuit to provide the second pre-charging current. 21 . The conversion control circuit of claim 13 , wherein after the first pre-charging period, whether the conversion capacitor is short-circuited or leaking is determined based on whether the voltage at the low voltage end of the conversion capacitor exceeds a voltage threshold.

22. The conversion control circuit of claim 13, wherein after the second pre-charging period, whether the output capacitor is short-circuited or leaking, or whether pre-charging is not completed, is determined based on whether the output voltage does not exceed a voltage threshold.

23. The conversion control circuit according to claim 13, wherein the conversion control circuit is configured as follows: The first transfer transistor, the second transfer transistor, a third transfer transistor, and a fourth transfer transistor of the plurality of transfer transistors are sequentially connected in series between the input power source and the ground potential, wherein the first transfer transistor and the second transfer transistor are coupled to the first end of the transfer capacitor, the third transfer transistor and the fourth transfer transistor are coupled to a second end of the transfer capacitor, and the second transfer transistor and the third transfer transistor are coupled to the output node; In the switching conversion mode, the first conversion transistor, the second conversion transistor, the third conversion transistor and the fourth conversion transistor are switched in a time-sharing manner, so that the conversion capacitor is electrically connected between the input power supply and the output node, and between the output node and the ground potential in a time-sharing manner, thereby making the voltage of the input power supply twice the voltage of the output power supply, and the current of the input power supply 1 / 2 times the current of the output power supply.

24. The conversion control circuit as claimed in claim 13, wherein in the switching conversion mode: The voltage of the input power supply is a constant voltage, and the voltage of the output power supply is also a constant voltage; or The current of the input power supply is a constant current, and the current of the output power supply is also a constant current.

25. A control method for controlling the operation of a plurality of switching transistors, a switching capacitor, and an output capacitor to convert an input power source to generate an output power source at an output node, wherein the output capacitor is coupled between the output node and a ground potential, wherein the plurality of switching transistors include a first switching transistor and a second switching transistor, wherein the first switching transistor is coupled between the input power source and a first end of the switching capacitor, and the second switching transistor is coupled between the input power source and the output node; the control method comprising: In a switching conversion mode, the plurality of conversion transistors are controlled to time-share and alternately switch the electrical connection relationship of the conversion capacitor, so that the conversion capacitor is periodically and time-shared and alternately electrically connected between the input power source and one of the at least one voltage-dividing nodes, or between one of the at least one voltage-dividing node and the ground potential, or, when there are multiple voltage-dividing nodes, electrically connected between a pair of the at least one voltage-dividing nodes, thereby converting the input power source to generate the output power source, wherein the output node corresponds to one of the at least one voltage-dividing node, and in a steady state, the voltage of the input power source is k times the voltage of the output power source, and the current of the input power source is 1 / k times the current of the output power source, where k is a real number greater than 1; as well as In a pre-charge mode, the plurality of transfer transistors are controlled to perform a pre-charge operation, wherein the pre-charge operation includes the following steps: During a first pre-charging period, controlling the first conversion transistor to convert the input power source to generate a first pre-charging current to pre-charge the conversion capacitor to a predetermined voltage level, and avoiding charging the output capacitor during the first pre-charging period; as well as During a second pre-charging period, controlling the second conversion transistor to convert the input power source to generate a second pre-charging current to pre-charge the output capacitor to the predetermined voltage level, and the second pre-charging current is simultaneously used to supply a load current to a load circuit; wherein the first pre-charge current is not greater than a first preset current level, the second pre-charge current is not greater than a second preset current level, and the load current is not less than a third preset current level; The first conversion transistor and the second conversion transistor participate in periodic switching in the switching conversion mode. 26 . The control method as claimed in claim 25 , wherein the switching conversion mode is operated after the pre-charging mode. 27 . The control method as claimed in claim 25 , wherein the first pre-charge period is earlier than the second pre-charge period.

28. The control method according to claim 25, wherein the pre-charge operation further comprises the following steps: During a balancing period, the first switching transistor and the second switching transistor are controlled to balance the voltages of the switching capacitor and the output capacitor to the predetermined voltage level.

29. The control method of claim 25, wherein the first preset current level is equal to the second preset current level, and the load current is smaller than the second pre-charge current.

30. The control method according to claim 25, wherein the pre-charge operation further comprises the following steps: After the first pre-charging period, whether the conversion capacitor is short-circuited or leaking is determined based on whether the voltage at the low voltage end of the conversion capacitor exceeds a voltage threshold.

31. The control method according to claim 25, wherein the pre-charge operation further comprises the following steps: After the second pre-charging period, whether the output voltage does not exceed a voltage threshold is determined to determine whether the output capacitor is short-circuited or leaking, or whether the pre-charging operation is not completed.

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