Switched capacitor power converter and method of operation thereof

Abstract

A method of operating a switched capacitor power converter is disclosed. The method includes controlling a plurality of switches during a first on-time to couple a first inductor, a second inductor, and at least two flying capacitors in series between an input node and an output node. The method also includes controlling the plurality of switches during a second on-time to couple the at least two flying capacitors in parallel with each other and in series with the second inductor between the output node and a ground terminal.

Description

Technical Field

[0001] This disclosure describes a switching capacitor power converter and its operation method, particularly a resonant switching capacitor power converter having at least two inductors and its operation method. Background Technology

[0002] Power converters are used in electronic devices that receive power at one voltage level and supply power at another voltage level for circuit operation. For example, power converters can be used in mobile devices, computing devices, communication devices, or other electronic systems with limited circuit area and thermal budgets. With the increasing demand for higher power density, power converters are expected to provide conversion that reduces circuit area, component size, and temperature rise while maintaining stable electrical behavior.

[0003] A switching capacitor power converter transfers energy by selectively connecting a flying capacitor via a switch. The conversion ratio of the switching capacitor power converter is related to the series-parallel connection relationship of the flying capacitors. Resonant operation can be introduced by incorporating an inductor in the current path of the switching capacitor power converter. Resonant operation can shape the current waveforms of the flying capacitors and inductors and can be coordinated with the switching timing of the switches.

[0004] During transitions between switching states, voltage deviations accumulated on the flying capacitors can generate transient currents via the internal capacitor path. When multiple flying capacitors are connected in series, their voltage deviations can accumulate. These accumulated voltage deviations can cause peak switching currents, power losses, and thermal stress. The position of the inductor in the resonant path and the on-time control of the switch affect whether the transient current is distributed along the resonant path. Therefore, switching capacitor power converters and operating methods that support resonant operation, multiple switching modes, and zero-current switching remain design challenges. Summary of the Invention

[0005] In one embodiment, a method for operating a switching capacitor power converter is disclosed, the switching capacitor power converter being used to convert power between an input node and an output node. The switching capacitor power converter includes a controller, a plurality of switches, a first inductor, a second inductor, and at least two flying capacitors. The method includes controlling the plurality of switches by the controller during a first on-time to couple the first inductor, the second inductor, and at least two flying capacitors in series between the input node and the output node; and controlling the plurality of switches by the controller during a second on-time to connect the at least two flying capacitors in parallel with each other and in series with the second inductor between the output node and ground.

[0006] In another embodiment, a switching capacitor power converter is disclosed. The switching capacitor power converter includes an input node, an output node, a power stage, and a controller. The power stage is coupled between the input node and the output node. The power stage includes multiple switches, a first inductor, a second inductor, and at least two flying capacitors. The controller is coupled to the multiple switches and is used to control the multiple switches during a first on-time to couple the first inductor, the second inductor, and at least two flying capacitors in series between the input node and the output node, and during a second on-time to control the multiple switches to couple the at least two flying capacitors in parallel with each other and in series with the second inductor between the output node and ground. Attached Figure Description

[0007] Figure 1 This is a circuit diagram of a switching capacitor power converter according to an embodiment of the present disclosure.

[0008] Figure 2 This is a circuit diagram of the power stage of a 4:1 resonant switching capacitor power converter according to an embodiment of the present disclosure.

[0009] Figure 3 This is a circuit diagram of another power stage of a 4:1 resonant switching capacitor power converter according to an embodiment of the present disclosure.

[0010] Figure 4A This is an equivalent circuit diagram of a switching capacitor power converter operating during a first conduction time according to an embodiment of the present disclosure.

[0011] Figure 4B This is an equivalent circuit diagram of a switching capacitor power converter operating during a second conduction time according to an embodiment of the present disclosure.

[0012] Figure 5 This is a circuit diagram of a two-phase resonant switching capacitor power converter according to an embodiment of the present disclosure.

[0013] Figure 6 This is a circuit diagram of another power stage of a dual-phase resonant switching capacitor power converter according to an embodiment of the present disclosure.

[0014] Figure 7A This is a circuit diagram of the first switching state of a biphase resonant switching capacitor power converter operating in 4:1 resonant mode according to an embodiment of the present disclosure.

[0015] Figure 7B This is a circuit diagram of the second switching state of a biphase resonant switching capacitor power converter operating in 4:1 resonant mode according to an embodiment of the present disclosure.

[0016] Figure 8 This is a circuit diagram of a zero-current switching detection circuit and a conduction time generator according to an embodiment of the present disclosure.

[0017] Figure 9 This is a waveform diagram of the switching signal and waveform of a dual-phase resonant switching capacitor power converter operating in 4:1 resonant mode according to an embodiment of the present disclosure.

[0018] Figure 10A This is a circuit diagram of the third switching state of a dual-phase resonant switching capacitor power converter operating in 3:1 resonant mode according to an embodiment of the present disclosure.

[0019] Figure 10B This is a circuit diagram of the fourth switching state of a dual-phase resonant switching capacitor power converter operating in 3:1 resonant mode according to an embodiment of the present disclosure.

[0020] Figure 11 This is a waveform diagram of the switching signal and waveform of a dual-phase resonant switching capacitor power converter operating in 3:1 resonant mode according to an embodiment of the present disclosure.

[0021] Figure 12 This is a simulated waveform diagram of a biphase resonant switching capacitor power converter operating in 4:1 resonant mode and having a first inductor and a second inductor, according to an embodiment of the present disclosure.

[0022] Figure 13 This is a simulated waveform diagram of a two-phase resonant switching capacitor power converter operating in 4:1 resonant mode and without a first inductor, according to an embodiment of the present disclosure.

[0023] Figure 14 This is a flowchart of a method for operating a switching capacitor power converter according to an embodiment of the present disclosure.

[0024] Explanation of symbols in the attached drawings:

[0025] 100: Switching Capacitor Power Converter

[0026] 10, 200, 300, 410, 500: Power stages

[0027] 20, 420: Controller

[0028] 400: Two-phase resonant switching capacitor power converter

[0029] 420a: NOR gate

[0030] 420b: On-time generator

[0031] 420c: Zero-current switching detection circuit

[0032] C1 to C6: Flying Capacitors

[0033] Ceq1: Series equivalent capacitance

[0034] Ceq2: Parallel equivalent capacitance

[0035] Cout: Output capacitor

[0036] CP1, CP2: Comparators

[0037] dVcf: Flying capacitor voltage ripple

[0038] Ic1, Ic4, ic1, ic4: Flying capacitor current

[0039] IL1, iL1: First inductor current

[0040] IL2, iL2: Second inductor current

[0041] L1: First Inductor

[0042] L2: Second Inductor

[0043] Q1 to Q20: Switches

[0044] R1 to R3, Rd1, Rd2: Resistors

[0045] S1 to S20: Switching signals

[0046] Sst: Status signal

[0047] Sst1 to Sst3: Switching status signals

[0048] Svx: Sensing voltage signal

[0049] t: time

[0050] t0 to t4: Time points

[0051] Ton1: First conduction time

[0052] Ton2: Second conduction time

[0053] Tsw: Switching cycle

[0054] Vc1, Vc4: Voltage of the flying capacitor

[0055] Vin: Input voltage

[0056] Vout, VOUT: Output voltage

[0057] Vref1, Vref2: Reference voltages

[0058] Vx: Voltage for switching nodes

[0059] Vx1: First switching node

[0060] Vx2: Second Switching Node

[0061] S1401 to S1402: Steps Detailed Implementation

[0062] Figure 1 This is a circuit diagram of a switching capacitor power converter 100 according to an embodiment of the present disclosure. Figure 1 The switching capacitor power converter 100 can operate in a 3:1 resonant mode using two flying capacitors C1 and C2. Because the switching capacitor power converter 100 can operate in resonant mode, it can also be called a resonant switching capacitor power converter 100. For simplicity, it will be referred to as the switching capacitor power converter 100 below. The switching capacitor power converter 100 includes a power stage 10 and a controller 20. The power stage 10 is coupled between an input node receiving the input voltage Vin and an output node providing the output voltage Vout. The power stage 10 includes multiple switches Q1 to Q7, a first inductor L1, a second inductor L2, two flying capacitors C1 and C2, and an output capacitor Cout. The two flying capacitors C1 and C2 correspond to at least two flying capacitors of the switching capacitor power converter 100. The output capacitor Cout is coupled between the output node and ground, and it stabilizes the output voltage Vout. The controller 20 is coupled to the multiple switches Q1 to Q7 and is used to generate switching signals for controlling the multiple switches Q1 to Q7. The controller 20 can receive the input voltage Vin, the output voltage Vout, and the voltage of the switching node Vx. The switching node Vx can be either the first switching node Vx1 or the second switching node Vx2.

[0063] Switches Q1 through Q7 selectively configure flying capacitors C1 and C2 to different connection states. During the first on-time, controller 20 controls switches Q1 through Q7 such that flying capacitors C1 and C2 are coupled in series. First inductor L1 and second inductor L2 are also located in the first on-time current path. Therefore, the first on-time current path extends from the input node through flying capacitors C1 and C2, first inductor L1, and second inductor L2 towards the output node. The first on-time current path corresponds to the series charging path of flying capacitors C1 and C2. The resonant path during the first on-time includes first inductor L1, second inductor L2, and the series-connected flying capacitors C1 and C2.

[0064] During the second on-time, controller 20 controls switches Q1 to Q7, causing flying capacitors C1 and C2 to be coupled in parallel. The parallel-connected flying capacitors C1 and C2 are coupled in series with the second inductor L2 between the output node and ground. Therefore, flying capacitors C1 and C2 discharge toward the output node via the second inductor L2. The first inductor L1 is not included in the equivalent resonant path during the second on-time. Therefore, the resonant path during the first on-time includes both the first inductor L1 and the second inductor L2, while the resonant path during the second on-time includes the second inductor L2 but not the first inductor L1.

[0065] In the 3:1 resonant mode, the equivalent capacitance of the first on-time resonant path is related to the series-connected flying capacitors C1 and C2, and the equivalent inductance of the first on-time resonant path is related to the first inductor L1 and the second inductor L2. The equivalent capacitance of the second on-time resonant path is related to the parallel-connected flying capacitors C1 and C2, and the equivalent inductance of the second on-time resonant path is related to the second inductor L2. The first and second on-times can be determined based on the corresponding resonant periods. The controller 20 can adjust the first and second on-times based on the zero-current switching detection results, so that the inductor current of the second inductor L2 reaches zero current level during the dead time after the first and second on-times.

[0066] The voltage at switching node Vx can be used for zero-current switching detection. Controller 20 can sense the voltage at switching node Vx and generate a sensed voltage signal based on the voltage at switching node Vx. Controller 20 can compare the sensed voltage signal with a reference voltage generated based on the output voltage Vout and determine whether the current switching sequence is too early, too late, or close to a zero-current switching state. Controller 20 can then adjust the on-time of subsequent switching cycles. The first inductor L1 and the second inductor L2 are not limited to discrete inductor components. At least one of the first inductor L1 and the second inductor L2 can be formed by conductive paths on a printed circuit board, conductive paths on an integrated circuit, package wires, or other conductive structures with inductive effects.

[0067] Figure 2 This is a circuit diagram of the power stage 200 of a 4:1 resonant switching capacitor power converter according to an embodiment of the present disclosure. Figure 2 show Figure 1 The 3:1 resonant mode shown can be extended to a 4:1 resonant mode by increasing the number of flying capacitors from two to three. Power stage 200 includes switches Q1 to Q10, a first inductor L1, a second inductor L2, flying capacitors C1 to C3, and an output capacitor Cout. Power stage 200 is coupled between the input node receiving the input voltage Vin and the output node providing the output voltage Vout. The output capacitor Cout is coupled between the output node and ground. Power stage 200 can be controlled by a controller, for example... Figure 1 The controller 20 shown.

[0068] Power stage 200 includes a series-parallel switching capacitor network formed by flying capacitors C1 to C3 and switches Q1 to Q10. Switch Q1 is coupled between the input node and one side of flying capacitor C1. Switch Q5 is coupled between the other side of flying capacitor C1 and one side of flying capacitor C2. Switch Q6 is coupled between the other side of flying capacitor C2 and one side of flying capacitor C3. Switch Q7 is coupled between the other side of flying capacitor C3 and a node coupled to a first inductor L1. The first inductor L1 is coupled between the node connected to switch Q7 and the second switching node Vx2. The second inductor L2 is coupled between the second switching node Vx2 and the output node. Switches Q2, Q3, and Q4 are configured to couple the corresponding capacitor nodes to the upper bus leading to the second switching node Vx2 during parallel discharge. Switches Q8, Q9, and Q10 are configured to couple the corresponding capacitor nodes to ground during parallel discharge.

[0069] During the first on-time of power stage 200, switches Q1, Q5, Q6, and Q7 are turned on, and switches Q2, Q3, Q4, Q8, Q9, and Q10 are turned off. The current path during the first on-time extends from the input node through switch Q1, flying capacitor C1, switch Q5, flying capacitor C2, switch Q6, flying capacitor C3, switch Q7, first inductor L1, second switching node Vx2, and second inductor L2 to the output node. Flying capacitors C1 to C3 are connected in series and coupled in series with first inductor L1 and second inductor L2 between the input and output nodes. Therefore, flying capacitors C1 to C3 are charged in series via a resonant path including first inductor L1 and second inductor L2.

[0070] During the second conduction time of power stage 200, switches Q2, Q3, Q4, Q8, Q9, and Q10 are turned on, and switches Q1, Q5, Q6, and Q7 are turned off. Switches Q2, Q3, and Q4 couple the upper ends of flying capacitors C1 to C3 to the upper bus and the second switching node Vx2. Switches Q8, Q9, and Q10 couple the lower ends of flying capacitors C1 to C3 to ground. Therefore, flying capacitors C1 to C3 are coupled in parallel to each other. The parallel-connected flying capacitors C1 to C3 are coupled in series with the second inductor L2 between the output node and ground. During the second conduction time, flying capacitors C1 to C3 discharge toward the output node via the second inductor L2, and the first inductor L1 is bypassed from the equivalent resonant path.

[0071] Figure 3 This is a circuit diagram of another power stage 300 of a 4:1 resonant switching capacitor power converter according to an embodiment of the present disclosure. Figure 3This illustrates another configuration of the first inductor L1 in a 4:1 resonant switching capacitor power converter. Power stage 300 includes switches Q1 through Q10, the first inductor L1, the second inductor L2, flying capacitors C1 through C3, and the output capacitor Cout. The first inductor L1 is coupled between the input node receiving the input voltage Vin and the switch Q1. The second inductor L2 is coupled between the second switching node Vx2 and the output node providing the output voltage Vout.

[0072] During the first on-time of power stage 300, the first on-time current path extends from the input node through the first inductor L1, switch Q1, flying capacitor C1, switch Q5, flying capacitor C2, switch Q6, flying capacitor C3, switch Q7, the second switching node Vx2, and the second inductor L2 to the output node. Therefore, flying capacitors C1 to C3 are connected in series and coupled in series with the first inductor L1 and the second inductor L2 between the input and output nodes. The resonant path of power stage 300 during the first on-time includes the first inductor L1 and the second inductor L2.

[0073] During the second on-time of power stage 300, switches Q2, Q3, Q4, Q8, Q9, and Q10 can couple flying capacitors C1 to C3 in parallel. The parallel-connected flying capacitors C1 to C3 are coupled in series with the second inductor L2 between the output node and ground. The first inductor L1 is not included in the equivalent resonant path during the second on-time. Since both the first inductor L1 and the second inductor L2 are included in the series charging path during the first on-time, the first inductor L1 can be... Figure 3 The configuration shown is between the input node and switch Q1, or as follows: Figure 2 The configuration shown is between switch Q7 and the second switching node Vx2. The position of the first inductor L1 can be selected according to layout, package, or printed circuit board winding requirements, while maintaining the same resonant path relationship.

[0074] Figure 4A This is an equivalent circuit diagram of a switching capacitor power converter operating during a first conduction time according to an embodiment of the present disclosure. Figure 4A In the diagram, the series equivalent capacitance Ceq1 represents the equivalent capacitance of the flyaway capacitor connected in series during the first conduction time. The series equivalent capacitance Ceq1, the first inductor L1, and the second inductor L2 are connected in series between the input node receiving the input voltage Vin and the output node providing the output voltage Vout. Figure 4A The equivalent circuit corresponds to Figure 1 , Figure 2 and Figure 3 The series charging state.

[0075] exist Figure 4AIn the equivalent circuit, the first resonant frequency is related to the first inductor L1, the second inductor L2, and the series equivalent capacitance Ceq1. The first resonant period corresponding to the first resonant frequency can be used to determine the first conduction time. When two flying capacitors are connected in series, the series equivalent capacitance Ceq1 corresponds to the equivalent capacitance of the two flying capacitors. When three flying capacitors are connected in series, the series equivalent capacitance Ceq1 corresponds to the equivalent capacitance of the three flying capacitors. In some embodiments, the first conduction time can be set to approximately half of the first resonant period. In other embodiments, the first conduction time can be adjusted near the first resonant period based on the zero-current switching detection result, the switching status signal, the dead time setting, or another control parameter of the controller.

[0076] Figure 4B This is an equivalent circuit diagram of a switching capacitor power converter operating during the second on-time according to an embodiment of the present disclosure. Figure 4B In the diagram, the parallel equivalent capacitance Ceq2 represents the equivalent capacitance of the flying capacitor connected in parallel during the second conduction time. The parallel equivalent capacitance Ceq2 and the second inductor L2 form an equivalent resonant path between the output node providing the output voltage Vout and the ground terminal. The first inductor L1 is not included. Figure 4B In the equivalent resonance path. Figure 4B The equivalent circuit corresponds to Figure 1 , Figure 2 and Figure 3 The parallel discharge state.

[0077] exist Figure 4B In the equivalent circuit, the second resonant frequency is related to the second inductor L2 and the parallel equivalent capacitance Ceq2. The second resonant period corresponding to the second resonant frequency can be used to determine the second conduction time. In some embodiments, the first and second resonant periods can be substantially equal, so that the first and second conduction times can be coordinated. When the flying capacitors have substantially the same capacitance value, the inductance value of the first inductor L1 can be greater than the inductance value of the second inductor L2. For example, in a single-phase 3:1 resonant mode using two flying capacitors in a series charging path, the inductance value of the first inductor L1 can be about three times the inductance value of the second inductor L2. In a 4:1 resonant mode using three flying capacitors in a series charging path, the inductance value of the first inductor L1 can be about eight times the inductance value of the second inductor L2. The above numerical relationships are illustrative design conditions and do not limit the scope of this disclosure. The derivation details are explained below.

[0078] The relationship between the first inductor L1 and the second inductor L2 can be derived from the first resonant frequency and the second resonant frequency. Figure 4A The first resonant frequency of the equivalent circuit shown It can be represented as:

[0079]

[0080] in The series equivalent capacitance of the flying capacitor connected in series during the first conduction time. Figure 4B The second resonant frequency of the equivalent circuit shown It can be represented as:

[0081]

[0082] in This is the parallel equivalent capacitance of the flying capacitor connected in parallel during the second conduction time. When the first resonant period and the second resonant period are designed to be substantially equal, the first resonant frequency... and the second resonant frequency They can be substantially equal. Therefore, the following relationship can be obtained:

[0083]

[0084] Assuming that the flying capacitors have the same capacitance value In a 3:1 resonant mode using two flying capacitors, the two flying capacitors are connected in series during the first conduction time and in parallel during the second conduction time. Therefore, the series equivalent capacitance... And the parallel equivalent capacitance .Will and Substituting into the above equation, we get:

[0085]

[0086] Therefore, the inductance value of the first inductor L1 can be expressed as:

[0087]

[0088] In a 4:1 resonant mode using three flying capacitors, the three flying capacitors are connected in series during the first conduction time and in parallel during the second conduction time. Therefore, the series equivalent capacitance... And the parallel equivalent capacitance for .Will and Substituting into the above equation, we get:

[0089]

[0090] Therefore, the inductance value of the first inductor L1 can be expressed as:

[0091]

[0092] Therefore, when the first resonant frequency and the second resonant frequency When designed to be substantially equal, the inductance value of the first inductor L1 can be greater than the inductance value of the second inductor L2. In a 3:1 resonant mode, the inductance value of the first inductor L1 can be approximately three times the inductance value of the second inductor L2. In a 4:1 resonant mode, the inductance value of the first inductor L1 can be approximately eight times the inductance value of the second inductor L2.

[0093] Figure 5 This is a circuit diagram of a two-phase resonant switching capacitor power converter 400 according to an embodiment of the present disclosure. The two-phase resonant switching capacitor power converter 400 includes a power stage 410 and a controller 420. The power stage 410 includes a first phase switching capacitor circuit, a second phase switching capacitor circuit, a first inductor L1, a second inductor L2, and an output capacitor Cout. The first phase switching capacitor circuit includes switches Q1 to Q10 and flying capacitors C1 to C3. The second phase switching capacitor circuit includes switches Q11 to Q20 and flying capacitors C4 to C6.

[0094] The first-phase switching capacitor circuit and the second-phase switching capacitor circuit are connected in parallel between the input node and the shared resonant inductor path. The first inductor L1 and the second inductor L2 are shared by the first-phase switching capacitor circuit and the second-phase switching capacitor circuit. The controller 420 receives the input voltage Vin, the output voltage Vout, and the voltage of the switching node Vx. The switching node Vx can be either the first switching node Vx1 or the second switching node Vx2. The controller 420 generates switching signals S1 to S20 to control switches Q1 to Q20.

[0095] The controller 420 can operate the first-phase switching capacitor circuit and the second-phase switching capacitor circuit with phase shifting. For example, the first-phase switching capacitor circuit and the second-phase switching capacitor circuit can operate with a 180-degree phase shift. When the flying capacitors C1 to C3 of the first-phase switching capacitor circuit are connected in series, the flying capacitors C4 to C6 of the second-phase switching capacitor circuit can be connected in parallel. When the flying capacitors C4 to C6 of the second-phase switching capacitor circuit are connected in series, the flying capacitors C1 to C3 of the first-phase switching capacitor circuit can be connected in parallel. Therefore, one phase can perform series charging while the other phase performs parallel discharging.

[0096] exist Figure 5 In the 4:1 resonant mode, a phase with three series-connected flying capacitors uses a resonant path including both the first inductor L1 and the second inductor L2. A phase with three parallel-connected flying capacitors uses a resonant path including the second inductor L2. The two phases are used alternately (see reference). Figure 4A and Figure 4BThe equivalent resonant circuit described above. The two-phase resonant switching capacitor power converter 400 can be configured to different resonant modes. In the 4:1 resonant mode, three flying capacitors of one phase participate in series-parallel operation. In the 3:1 resonant mode, one flying capacitor of each phase is disabled, and the remaining two flying capacitors of each phase participate in operation. In the 2:1 resonant mode, two flying capacitors of each phase are disabled, and one remaining flying capacitor of each phase participates in operation.

[0097] Figure 6 This is a circuit diagram of another power stage 500 of a dual-phase resonant switching capacitor power converter according to an embodiment of the present disclosure. Figure 6 This illustrates another configuration where the first inductor L1 is located on the input side of a two-phase resonant switching capacitor power converter. The power stage 500 includes a first-phase switching capacitor circuit, a second-phase switching capacitor circuit, a first inductor L1, a second inductor L2, and an output capacitor Cout. The first inductor L1 is coupled between the input node receiving the input voltage Vin and the first-phase switching capacitor circuit and the second-phase switching capacitor circuit. The second inductor L2 is coupled between the second switching node Vx2 and the output node providing the output voltage Vout. The first-phase switching capacitor circuit and the second-phase switching capacitor circuit are coupled to the first inductor L1 and the second switching node Vx2 via corresponding switches.

[0098] During 4:1 resonant operation, when the flying capacitor bank of one phase is connected in series, the first inductor L1 and the second inductor L2 are included in the series charging path between the input node and the output node. When the flying capacitor bank of the other phase is connected in parallel, the second inductor L2 is included in the corresponding discharge path between the output node and the ground terminal. Therefore, power stage 500 maintains the reference... Figure 5 While performing the biphase resonant operation, an alternative configuration for the first inductor L1 is provided. The first inductor L1 can be configured on the input side, and the second inductor L2 can be maintained on the output side, so that the series charging path and the parallel discharging path retain the corresponding resonant components.

[0099] Figure 7A This is a circuit diagram of the first switching state of a two-phase resonant switching capacitor power converter 400 operating in a 4:1 resonant mode according to an embodiment of the present disclosure. In the first switching state, switches Q1, Q5, Q6, Q7, Q12, Q13, Q14, Q18, Q19, and Q20 are turned on, and switches Q2, Q3, Q4, Q8, Q9, Q10, Q11, Q15, Q16, and Q17 are turned off. The flying capacitors C1 to C3 of the first phase switching capacitor circuit are connected in series with each other and are coupled in series with the first inductor L1 and the second inductor L2 between the input node and the output node. The flying capacitors C4 to C6 of the second phase switching capacitor circuit are connected in parallel with each other and are coupled in series with the second inductor L2 between the output node and the ground terminal.

[0100] In the first switching state, the series charging current of the first phase switching capacitor circuit flows from the input node, through the series-connected flying capacitors C1 to C3, the first inductor L1, and the second inductor L2, towards the output node. The parallel discharging current of the second phase switching capacitor circuit flows from the ground terminal, through the parallel-connected flying capacitors C4 to C6 and the second inductor L2, towards the output node. Therefore, the first switching state causes the first phase switching capacitor circuit to use the resonant path associated with the first inductor L1 and the second inductor L2, and causes the second phase switching capacitor circuit to use the resonant path associated with the second inductor L2.

[0101] Figure 7B This is a circuit diagram of the second switching state of a two-phase resonant switching capacitor power converter 400 operating in a 4:1 resonant mode according to an embodiment of the present disclosure. In the second switching state, switches Q2, Q3, Q4, Q8, Q9, Q10, Q11, Q15, Q16, and Q17 are turned on, and switches Q1, Q5, Q6, Q7, Q12, Q13, Q14, Q18, Q19, and Q20 are turned off. The flying capacitors C4 to C6 of the second-phase switching capacitor circuit are connected in series with each other and are coupled in series with the first inductor L1 and the second inductor L2 between the input node and the output node. The flying capacitors C1 to C3 of the first-phase switching capacitor circuit are connected in parallel with each other and are coupled in series with the second inductor L2 between the output node and the ground terminal.

[0102] In the second switching state, the series charging current of the second phase switching capacitor circuit flows from the input node, through the series-connected flying capacitors C4 to C6, the first inductor L1, and the second inductor L2, towards the output node. The parallel discharging current of the first phase switching capacitor circuit flows from the ground terminal, through the parallel-connected flying capacitors C1 to C3 and the second inductor L2, towards the output node. Therefore, the second switching state causes the second phase switching capacitor circuit to use the resonant path associated with the first inductor L1 and the second inductor L2, and causes the first phase switching capacitor circuit to use the resonant path associated with the second inductor L2.

[0103] Figure 7A The first switching state shown and Figure 7B The second switching state shown is a complementary switching state of a two-phase 4:1 resonant mode. By alternating between the first and second switching states, the controller 420 alternately charges the flying capacitor of one phase in series and discharges the flying capacitor of the other phase in parallel. The phase shift operation allows the power stage 410 to maintain power transfer while distributing resonant current between the first-phase switching capacitor circuit and the second-phase switching capacitor circuit.

[0104] Figure 8This is a circuit diagram of the zero-current switching detection circuit 420c and the on-time generator 420b according to embodiments of the present disclosure. The controller 420 includes the zero-current switching detection circuit 420c and the on-time generator 420b. The zero-current switching detection circuit 420c receives the voltage of the switching node Vx. The switching node Vx can be a first switching node Vx1 or a second switching node Vx2. A resistor divider including resistors Rd1 and Rd2 generates a sensing voltage signal Svx based on the voltage of the switching node Vx.

[0105] Another resistor divider, comprising resistors R1, R2, and R3, generates a first reference voltage Vref1 and a second reference voltage Vref2 based on the output voltage Vout. The first reference voltage Vref1 and the second reference voltage Vref2 define a voltage window used to evaluate the sensed voltage signal Svx. A first comparator CP1 compares the sensed voltage signal Svx with the first reference voltage Vref1 to generate a first switching state signal Sst1. A second comparator CP2 compares the sensed voltage signal Svx with the second reference voltage Vref2 to generate a second switching state signal Sst2.

[0106] NOR gate 420a receives the first switching state signal Sst1 and the second switching state signal Sst2, and generates a third switching state signal Sst3. The first switching state signal Sst1 can represent an early switching state. The second switching state signal Sst2 can represent an late switching state. The third switching state signal Sst3 can represent a zero-current switching state. The state signal Sst is provided to the on-time generator 420b based on the first switching state signal Sst1, the second switching state signal Sst2, and the third switching state signal Sst3. The on-time generator 420b generates a switching signal based on the state signal Sst.

[0107] The switching node Vx can be selected from either the first switching node Vx1 or the second switching node Vx2, and the voltage of the selected switching node Vx can be used to detect whether the inductor current of the second inductor L2 has reached zero current level. By sensing the voltage of the switching node Vx, the controller 420 can determine whether the current switching sequence is too early, too late, or close to zero current switching conditions. The on-time generator 420b can adjust the first on-time and the second on-time in response to the status signal Sst. Therefore, the controller 420 can make the inductor current of the second inductor L2 reach zero current level during the dead time after the first on-time and the second on-time.

[0108] Figure 9This is a waveform diagram of the switching signals and waveforms of a biphase resonant switching capacitor power converter 400 operating in 4:1 resonant mode according to an embodiment of the present disclosure. The first set of switching signals includes S1, S5, S6, S7, S12, S13, S14, S18, S19, and S20. The second set of switching signals includes S2, S3, S4, S8, S9, S10, S11, S15, S16, and S17. The switching period Tsw extends from time t0 to time t4. During the period from time t0 to time t1, the first set of switching signals is activated, and the power stage 410 operates in 4:1 resonant mode. Figure 7A The first switching state is shown. During the period from time t1 to time t2, power stage 410 operates during the dead time period. During the period from time t2 to time t3, the second set of switching signals is activated, and power stage 410 operates during the dead time period. Figure 7B The second switching state is shown. During the period from time t3 to time t4, power stage 410 operates during another dead time period.

[0109] The waveform diagram also shows the flying capacitor current ic1 of flying capacitor C1, the flying capacitor voltage Vc1 of flying capacitor C1, the first inductor current iL1 of the first inductor L1, and the second inductor current iL2 of the second inductor L2. The flying capacitor current ic1 has a resonant current waveform. The flying capacitor voltage Vc1 has a voltage ripple dVcf. The first inductor current iL1 and the second inductor current iL2 reach or approach zero current levels during the dead time. The first conduction time Ton1 and the second conduction time Ton2 may be equal or unequal, and the controller 420 can adjust the first conduction time Ton1 and the second conduction time Ton2 based on the zero current switching detection result. The first conduction time Ton1 can be equal to... Figure 4A The equivalent circuit is related, and the second conduction time Ton2 can be related to Figure 4B The equivalent circuit is related.

[0110] Figure 10A This is a circuit diagram of the third switching state of a two-phase resonant switching capacitor power converter 400 operating in a 3:1 resonant mode according to an embodiment of the present disclosure. In the third switching state, switches Q1, Q4, Q5, Q6, Q12, Q13, Q18, and Q19 are turned on, and switches Q2, Q3, Q7, Q8, Q9, Q10, Q11, Q14, Q15, Q16, Q17, and Q20 are turned off. In the 3:1 resonant mode, one flying capacitor in each phase is disabled. In the third switching state, the flying capacitor C3 in the first phase switching capacitor circuit and the flying capacitor C6 in the second phase switching capacitor circuit are disabled. Switches Q7 and Q10 associated with flying capacitor C3 remain off, and switches Q17 and Q20 associated with flying capacitor C6 remain off.

[0111] The flying capacitors C1 and C2 of the first phase switching capacitor circuit are connected in series and coupled in series with the second inductor L2 between the input and output nodes. The flying capacitors C4 and C5 of the second phase switching capacitor circuit are connected in parallel and coupled in series with the second inductor L2 between the output node and ground. Figure 10A In the 3:1 resonant mode shown, the first inductor L1 is not included in the series charging path or parallel discharging path of the remaining flying capacitors. The charging path uses two series-connected flying capacitors instead of three series-connected flying capacitors. Due to the reduced number of series-connected flying capacitors, the voltage deviation accumulated across the series-connected flying capacitors is less than the voltage deviation accumulated in the 4:1 resonant mode.

[0112] Figure 10B This is a circuit diagram of the fourth switching state of a two-phase resonant switching capacitor power converter 400 operating in 3:1 resonant mode according to an embodiment of the present disclosure. In the fourth switching state, switches Q2, Q3, Q8, Q9, Q11, Q14, Q15, and Q16 are turned on, and switches Q1, Q4, Q5, Q6, Q7, Q10, Q12, Q13, Q17, Q18, Q19, and Q20 are turned off. The flying capacitors C4 and C5 of the second-phase switching capacitor circuit are connected in series and coupled in series with the second inductor L2 between the input and output nodes. The flying capacitors C1 and C2 of the first-phase switching capacitor circuit are connected in parallel and coupled in series with the second inductor L2 between the output node and ground.

[0113] By alternating between the third and fourth switching states, the controller 420 operates the biphase resonant switching capacitor power converter 400 in a 3:1 resonant mode. During the first 3:1 mode conduction time, the remaining flying capacitors C1 and C2 of the first phase switching capacitor circuit are connected in series, and the remaining flying capacitors C4 and C5 of the second phase switching capacitor circuit are connected in parallel. During the second 3:1 mode conduction time, the remaining flying capacitors C4 and C5 of the second phase switching capacitor circuit are connected in series, and the remaining flying capacitors C1 and C2 of the first phase switching capacitor circuit are connected in parallel. During both 3:1 mode conduction times, the remaining flying capacitor path is associated with the second inductor L2, not with the first inductor L1.

[0114] Figure 11 This is a waveform diagram of the switching signals and waveforms of a biphase resonant switching capacitor power converter 400 operating in 3:1 resonant mode according to an embodiment of the present disclosure. The first set of switching signals includes S1, S4, S5, S6, S12, S13, S18, and S19. The second set of switching signals includes S2, S3, S8, S9, S11, S14, S15, and S16. The switching period Tsw extends from time t0 to time t4. During the period from time t0 to time t1, the first set of switching signals is activated, and the power stage 410 operates in 3:1 resonant mode. Figure 10A The third switching state is shown. During the period from time t1 to time t2, power stage 410 operates during the dead time period. During the period from time t2 to time t3, the second set of switching signals is activated, and power stage 410 operates during the dead time period. Figure 10B The fourth switching state is shown. During the period from time t3 to time t4, power stage 410 operates during another dead time period.

[0115] The waveform diagram illustrates the flying capacitor currents ic1 (C1), ic4 (C4), and iL2 (second inductor). The flying capacitor currents ic1 and ic4 correspond to the first-phase switching capacitor circuit and the second-phase switching capacitor circuit, respectively. The second inductor current iL2 reaches or approaches zero current level during the dead time. Because the 3:1 resonant mode uses fewer series-connected flying capacitors than the 4:1 resonant mode, the cumulative voltage deviation during the switching state transition is smaller.

[0116] The 2:1 resonant mode can be understood using the same mode selection principle. In the 2:1 resonant mode, two flying capacitors in each phase are disabled, and only one remaining flying capacitor in each phase is operational. For example, in the first phase switching capacitor circuit, flying capacitors C2 and C3 can be disabled, and switches Q6, Q7, Q9, and Q10 associated with the disabled flying capacitors remain off. In the second phase switching capacitor circuit, flying capacitors C5 and C6 can be disabled, and switches Q16, Q17, Q19, and Q20 associated with the disabled flying capacitors remain off. Therefore, flying capacitor C1 in the first phase switching capacitor circuit and flying capacitor C4 in the second phase switching capacitor circuit remain operational. In the 2:1 resonant mode, the charging and discharging paths of the remaining flying capacitors in each phase are related to the second inductor L2, not the first inductor L1.

[0117] Since only one flying capacitor is used per phase in the 2:1 resonant mode, the voltage deviation caused by the series connection of multiple flying capacitors will not accumulate in the same way as in the 4:1 resonant mode, and the waveform behavior is not substantially affected by the absence of the first inductor L1 in the remaining flying capacitor path.

[0118] Figure 12 This is a simulated waveform diagram of a biphase resonant switching capacitor power converter 400 operating in 4:1 resonant mode and having a first inductor L1 and a second inductor L2, according to an embodiment of the present disclosure. The simulated waveform includes the output voltage VOUT, the first inductor current IL1 of the first inductor L1, the second inductor current IL2 of the second inductor L2, the flying capacitor current Ic1 of the flying capacitor C1, the flying capacitor current Ic4 of the flying capacitor C4, the flying capacitor voltage Vc1 of the flying capacitor C1, and the flying capacitor voltage Vc4 of the flying capacitor C4.

[0119] The first inductor current IL1 and the second inductor current IL2 have resonant current pulses. Since the three flying capacitors can be coupled in parallel and discharge through the second inductor L2 during the parallel discharge state, the second inductor current IL2 can be greater than the first inductor current IL1. The flying capacitor currents Ic1 and Ic4 also have resonant current waveforms corresponding to the interleaved operation of the first phase switching capacitor circuit and the second phase switching capacitor circuit.

[0120] In the 4:1 resonant mode, three flying capacitors can be connected in series during series charging operation. The voltage deviation of each flying capacitor can accumulate along the series connection path. The first inductor L1 participates in the 4:1 series charging path and shares a portion of the voltage difference generated during state transitions. The second inductor L2 participates in both the series charging path and the parallel discharging path. Therefore, the first inductor L1 and the second inductor L2 distribute the voltage difference along the resonant path. Figure 12 The flying capacitor currents Ic1 and Ic4 shown have a smoother resonant waveform than the waveform generated under the condition that the first inductor L1 is replaced by a short circuit.

[0121] Figure 13 This is a simulated waveform diagram of a biphase resonant switching capacitor power converter 400 operating in 4:1 resonant mode and without a first inductor L1, according to an embodiment of the present disclosure. The simulated waveform includes the output voltage VOUT, the second inductor current IL2 of the second inductor L2, the flying capacitor current Ic1 of the flying capacitor C1, the flying capacitor current Ic4 of the flying capacitor C4, the flying capacitor voltage Vc1 of the flying capacitor C1, and the flying capacitor voltage Vc4 of the flying capacitor C4. Figure 13 The comparison condition is illustrated when the first inductor L1 is replaced by a short circuit.

[0122] In the comparison conditions, when multiple flying capacitors are connected in series during a switching state transition, the voltage deviation of each flying capacitor can be accumulated. For example, if each of the three flying capacitors has a voltage deviation of approximately 0.5V, the accumulated voltage deviation of the three flying capacitors connected in series can be approximately 1.5V. If another capacitor path has a voltage deviation of approximately 0.5V, a voltage difference of approximately 1V can be generated between the capacitor paths during the switching state transition. When the first inductor L1 is replaced by a short circuit, the voltage difference is applied more directly to the flying capacitor paths. Therefore, the instantaneous current through the flying capacitors increases, and the flying capacitor currents Ic1 and Ic4 contain switching current surges.

[0123] Figure 13The comparison conditions explain why the first inductor L1 is significant in the 4:1 resonant mode. In the 4:1 resonant mode, the three flying capacitors of one phase can be connected in series, and the three flying capacitors of the other phase can be connected in parallel. When the switching state changes, a voltage difference can be generated between the two capacitor paths. With the first inductor L1, a portion of the voltage difference can be distributed across the first inductor L1, rather than being directly applied to the flying capacitor path. Without the first inductor L1, the voltage difference could drive a large instantaneous current in the flying capacitor path. In contrast, if... Figure 12 As shown, the first inductor L1 can share part of the voltage difference, and the flying capacitor current can have a smoother resonant waveform.

[0124] The above also explains why the waveform behavior in the 3:1 resonant mode is less affected when the first inductor L1 is not included in the remaining flying capacitor path. In the 3:1 resonant mode, only two flying capacitors are connected in series during the series charging operation. Therefore, the cumulative voltage deviation caused by the series-connected flying capacitors is smaller than that in the 4:1 resonant mode using three series-connected flying capacitors. In the 2:1 resonant mode, only one remaining flying capacitor participates in the operation per phase, so the voltage deviation caused by the series connection of multiple flying capacitors does not accumulate in the same way. Therefore, the waveform behavior in the 2:1 resonant mode is substantially unaffected by the absence of the first inductor L1 in the remaining flying capacitor path.

[0125] Figure 14 This is a flowchart of a method for operating a switching capacitor power converter 100 according to an embodiment of the present disclosure. The method includes steps S1401 to S1402. Any hardware or technical modifications fall within the scope of this disclosure. Steps S1401 to S1402 are described below.

[0126] Step S1401: During the first conduction time, the controller 20 controls multiple switches to couple the first inductor L1, the second inductor L2 and at least two flying capacitors in series between the input node and the output node.

[0127] Step S1402: During the second conduction time, the controller 20 controls multiple switches to connect at least two flying capacitors in parallel with each other and to couple them in series with the second inductor L2 between the output node and the ground terminal.

[0128] The details of steps S1401 to S1402 have been described in detail above, and will not be repeated here. By executing steps S1401 to S1402, the switching capacitor power converter 100 forms different resonant paths during different conduction times. During the first conduction time, the first inductor L1, the second inductor L2, and at least two flying capacitors are connected in series, so that the first inductor L1 participates in the resonant charging path. During the second conduction time, at least two flying capacitors are connected in parallel with each other and connected in series with the second inductor L2, so that the energy stored in the flying capacitors can be transferred through the second inductor L2. The different resonant paths allow the controller 20 to coordinate the first and second conduction times with the resonant characteristics of the power stage 10, thereby supporting resonant operation and zero-current switching.

[0129] In summary, the switching capacitor power converter and operating method disclosed herein provide resonant operation by using a first inductor, a second inductor, and flying capacitors configured in different resonant paths during different conduction times. During the first conduction time, the first inductor, the second inductor, and the flying capacitors can be connected in series between the input node and the output node. During the second conduction time, the flying capacitors can be connected in parallel with each other and connected in series with the second inductor between the output node and ground. The controller can adjust the conduction time based on zero-current switching detection, and the converter can support 4:1, 3:1, and 2:1 resonant modes. A two-phase embodiment further provides interleaved operation by using two groups of flying capacitors with a shared inductor. Therefore, the disclosed embodiments provide a flexible switching capacitor power conversion architecture suitable for high-density resonant power conversion.

[0130] The foregoing outlines the features of several embodiments, enabling those skilled in the art to fully understand the various aspects of the invention. Those skilled in the art should recognize that the invention provides a basis for designing or modifying other processes and structures to achieve substantially the same functionality and / or results as the embodiments described above. Furthermore, such equivalent configurations do not depart from the spirit and scope of the invention, and various changes, substitutions, and modifications can be made without departing from that spirit and scope.

Claims

1. A method of operating a switching capacitor power converter for switching power between an input node and an output node, the switching capacitor power converter comprising a controller, a plurality of switches, a first inductor, a second inductor, and at least two flying capacitors, the method comprising: The controller controls the switches during a first on-time to couple the first inductor, the second inductor, and the at least two flying capacitors in series between the input node and the output node; and The controller controls the switches during a second on-time to connect the at least two flying capacitors in parallel with each other and to couple them in series with the second inductor between the output node and a ground terminal.

2. The method of claim 1, further comprising: The controller adjusts the first on-time and the second on-time based on the zero-current switching detection result, so that the inductor current of the second inductor substantially reaches a zero-current level during the dead time after the first on-time and the second on-time.

3. The method of claim 2, wherein the zero-current switching detection result is generated by the controller sensing a voltage of a switching node, generating a sensing voltage signal based on the voltage of the switching node, and comparing the sensing voltage signal with a first reference voltage and a second reference voltage generated based on the output voltage of the output node, wherein the switching node is one of a first switching node and a second switching node of the switching capacitor power converter.

4. The method of claim 1, wherein the first conduction time is based on a first resonant period related to the series equivalent capacitance of the first inductor, the second inductor, and one of the at least two flying capacitors, and the second conduction time is based on a second resonant period related to the parallel equivalent capacitance of the second inductor and one of the at least two flying capacitors.

5. The method of claim 4, wherein the inductance value of one of the first inductors is greater than the inductance value of one of the second inductors, and the first resonant period and the second resonant period are substantially equal.

6. The method of claim 1, wherein the at least two flying capacitors comprise three flying capacitors, wherein control during the first on-time includes connecting the three flying capacitors in series between the input node and the output node, and wherein control during the second on-time includes connecting the three flying capacitors in parallel between the output node and the ground terminal.

7. The method of claim 6, wherein the at least two flying capacitors form a first flying capacitor group, wherein the switching capacitor power converter further includes a second flying capacitor group comprising three flying capacitors, and wherein the controller operates the first flying capacitor group and the second flying capacitor group with a phase shift, such that: During the first conduction time, the flying capacitors of the first flying capacitor group are connected in series with each other and are coupled in series with the first inductor and the second inductor between the input node and the output node; and the flying capacitors of the second flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal; and During the second conduction time, the flying capacitors of the second flying capacitor group are connected in series with each other and are coupled in series with the first inductor and the second inductor between the input node and the output node. The flying capacitors of the first flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal.

8. The method of claim 7, further comprising: By disabling one flying capacitor in the first flying capacitor group and one flying capacitor in the second flying capacitor group through the controller, and controlling the remaining flying capacitors in the first flying capacitor group and the remaining flying capacitors in the second flying capacitor group with the phase shift, the switching capacitor power converter is operated in a 3:1 resonant mode, such that: During a first 3:1 mode conduction time, the remaining flying capacitors of the first flying capacitor bank are connected in series with each other and coupled in series with the second inductor between the input node and the output node; and the remaining flying capacitors of the second flying capacitor bank are connected in parallel with each other and coupled in series with the second inductor between the output node and the ground terminal; and During a second 3:1 mode on-time, the remaining flying capacitors of the second flying capacitor group are connected in series with each other and are coupled in series with the second inductor between the input node and the output node, and the remaining flying capacitors of the first flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal.

9. The method of claim 7, further comprising: By disabling two flying capacitors in the first flying capacitor group and two flying capacitors in the second flying capacitor group using the controller, and controlling the remaining flying capacitors in one of the first and second flying capacitor groups using the phase shift, the switching capacitor power converter is operated in a 2:1 resonant mode, such that: During a first 2:1 mode on-time, the remaining flying capacitor of the first flying capacitor bank and the second inductor are connected in series between the input node and the output node, and the remaining flying capacitor of the second flying capacitor bank and the second inductor are connected in series between the output node and the ground terminal; and During a second 2:1 mode on-time, the remaining flying capacitor of the second flying capacitor group and the second inductor are connected in series between the input node and the output node, and the remaining flying capacitor of the first flying capacitor group and the second inductor are connected in series between the output node and the ground terminal.

10. The method of claim 1, wherein at least one of the first inductor and the second inductor comprises a conductive path of a printed circuit board, a conductive path of an integrated circuit, or a package wire.

11. A switching capacitor power converter, comprising: One input node; One output node; A power stage is coupled between the input node and the output node, and the power stage includes multiple switches, a first inductor, a second inductor, and at least two flying capacitors; and A controller, coupled to these switches, is used for: During a first on-time, the switches are controlled to couple the first inductor, the second inductor, and the at least two flying capacitors in series between the input node and the output node; and During a second on-time, the switches are controlled to connect the at least two flying capacitors in parallel with each other and to couple them in series with the second inductor between the output node and a ground terminal.

12. The switching capacitor power converter of claim 11, wherein the controller is further configured to adjust the first on-time and the second on-time based on a zero-current switching detection result, such that the inductor current of one of the second inductors substantially reaches a zero-current level during the dead time following the first on-time and the second on-time.

13. The switching capacitor power converter of claim 12, wherein the controller is used to generate the zero-current switching detection result by: The method involves sensing a voltage at one of the switching nodes, generating a sensing voltage signal based on the voltage at the switching node, and comparing the sensing voltage signal with a first reference voltage and a second reference voltage generated based on the output voltage at one of the output nodes, wherein the switching node is one of a first switching node and a second switching node of the switching capacitor power converter.

14. The switching capacitor power converter of claim 11, wherein the first on-time is based on a first resonant period related to the equivalent capacitance of the first inductor, the second inductor, and one of the at least two flying capacitors connected in series, and the second on-time is based on a second resonant period related to the equivalent capacitance of the second inductor and one of the at least two flying capacitors connected in parallel.

15. The switching capacitor power converter of claim 14, wherein the inductance value of one of the first inductors is greater than the inductance value of one of the second inductors, and the first resonant period and the second resonant period are substantially equal.

16. The switching capacitor power converter of claim 11, wherein the at least two flying capacitors comprise three flying capacitors, wherein the controller is configured to control the switches during the first on-time to couple the three flying capacitors in series between the input node and the output node, and wherein the controller is configured to control the switches during the second on-time to couple the three flying capacitors in parallel between the output node and the ground terminal.

17. The switching capacitor power converter of claim 16, wherein the at least two flying capacitors form a first flying capacitor bank, and the power stage further comprises: A second flying capacitor bank, comprising three flying capacitors, wherein the controller is configured to operate the first flying capacitor bank and the second flying capacitor bank with a phase shift, such that: During the first conduction time, the flying capacitors of the first flying capacitor group are connected in series with each other and are coupled in series with the first inductor and the second inductor between the input node and the output node; and the flying capacitors of the second flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal; and During the second conduction time, the flying capacitors of the second flying capacitor group are connected in series with each other and are coupled in series with the first inductor and the second inductor between the input node and the output node. The flying capacitors of the first flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal.

18. The switching capacitor power converter of claim 17, wherein the controller is further configured to disable one of the flying capacitors of the first flying capacitor group and one of the flying capacitors of the second flying capacitor group, and to control the plurality of remaining flying capacitors of the first flying capacitor group and the plurality of remaining flying capacitors of the second flying capacitor group with the phase shift, so as to operate the switching capacitor power converter in a 3:1 resonant mode, such that: During a first 3:1 mode conduction time, the remaining flying capacitors of the first flying capacitor bank are connected in series with each other and coupled in series with the second inductor between the input node and the output node; and the remaining flying capacitors of the second flying capacitor bank are connected in parallel with each other and coupled in series with the second inductor between the output node and the ground terminal; and During a second 3:1 mode on-time, the remaining flying capacitors of the second flying capacitor group are connected in series with each other and are coupled in series with the second inductor between the input node and the output node, and the remaining flying capacitors of the first flying capacitor group are connected in parallel with each other and are coupled in series with the second inductor between the output node and the ground terminal.

19. The switching capacitor power converter of claim 17, wherein the controller is further configured to disable two flying capacitors of the first flying capacitor group and two flying capacitors of the second flying capacitor group, and to control the remaining flying capacitor of one of the first flying capacitor groups and the remaining flying capacitor of one of the second flying capacitor groups with the phase shift, so as to operate the switching capacitor power converter in a 2:1 resonant mode, such that: During a first 2:1 mode on-time, the remaining flying capacitor of the first flying capacitor bank and the second inductor are connected in series between the input node and the output node, and the remaining flying capacitor of the second flying capacitor bank and the second inductor are connected in series between the output node and the ground terminal; and During a second 2:1 mode on-time, the remaining flying capacitor of the second flying capacitor group and the second inductor are connected in series between the input node and the output node, and the remaining flying capacitor of the first flying capacitor group and the second inductor are connected in series between the output node and the ground terminal.

20. The switching capacitor power converter of claim 11, wherein at least one of the first inductor and the second inductor comprises a conductive path of a printed circuit board, a conductive path of an integrated circuit, or a package wire.

Images