Single-inductor bipolar output power switching circuit and related control method

Abstract

The invention discloses a single-inductor bipolar output power switching circuit and a related control method. The power conversion circuit comprises an input end, two output ends, three nodes, a first switch coupled between the input end and the first node, a second switch coupled between the second node and a ground potential, a third switch coupled between the third node and the ground potential, and a fourth switch coupled between the third node and the first output end, a fifth switch coupled between the second node and the second output end, a path control element, an inductor coupled between the first node and the third node, a first capacitor coupled between the first output end and a ground potential, a second capacitor coupled between the second output end and the ground potential, and a control circuit. The path control element adjusts a voltage difference between the first and second nodes. The control circuit provides first to fifth control signals to selectively turn on or off the first to fifth switches, respectively.

Description

Technical Field

[0001] The present invention relates to a power conversion circuit and a related control method, and more particularly to a single-inductor bipolar-output power conversion circuit for improving conversion efficiency and a related control method. Background Art

[0002] Generally, when a back-end circuit requires a positive voltage and a negative voltage for a supply power, a power converter steps down an input voltage to generate a stepped-down positive voltage and a stepped-down negative voltage. For example, in mobile display applications, an active-matrix organic light-emitting diode (AMOLED) display panel and an audio amplifier commonly require power supplies with positive and negative polarities. Therefore, a single-inductor bipolar-output (SIBO) DC-DC voltage conversion circuit is often used, which has a single output inductor and multiple switches, and converts the input voltage into two output voltages with opposite polarities by providing different energy paths.

[0003] Therefore, how to improve the conversion efficiency of the SIBO voltage conversion circuit is an important issue. Summary of the Invention

[0004] The present invention provides a single-inductor bipolar-output power conversion circuit, which includes an input terminal for receiving an input voltage, a first output terminal for outputting a first output voltage, a second output terminal for outputting a second output voltage, first to third nodes, first to fifth switches, a path control element, an inductor, a first capacitor, a second capacitor, and a control circuit. The first end of the first switch is coupled to the input terminal, the second end of the first switch is coupled to the first node, and the control end of the first switch is used to receive a first control signal. The first end of the second switch is coupled to the second node, the second end of the second switch is coupled to a ground potential, and the control end of the second switch is used to receive a second control signal. The first end of the third switch is coupled to the third node, the second end of the third switch is coupled to the ground potential, and the control end of the third switch is used to receive a third control signal. The first end of the fourth switch is coupled to the third node, the second end of the fourth switch is coupled to the first output terminal, and the control end of the fourth switch is used to receive a fourth control signal. The first end of the fifth switch is coupled to the second node, the second end of the fifth switch is coupled to the second output terminal, and the control end of the fifth switch is used to receive a fifth control signal. The path control element is coupled between the first node and the second node to adjust the voltage difference between the first node and the second node. The inductor is coupled between the first node and the third node. The first end of the first capacitor is coupled to the first output terminal, and the second end of the first capacitor is coupled to the ground potential. The first end of the second capacitor is coupled to the second output terminal, and the second end of the second capacitor is coupled to the ground potential. The control circuit is used to provide the first control signal to the fifth control signal.

[0005] The present invention also provides a method for controlling a single-inductor bipolar-output power conversion circuit. The single-inductor bipolar-output power conversion circuit includes an input terminal for receiving an input voltage, a first output terminal for outputting a first output voltage, a second output terminal for outputting a second output voltage, first to third nodes, a first switch coupled between the input terminal and the first node, a second switch coupled between the second node and a ground potential, a third switch coupled between the third node and the ground potential, a fourth switch coupled between the third node and the first output terminal, a fifth switch coupled between the second node and the second output terminal, a first flying capacitor coupled between the first node and the second node, an inductor coupled between the first node and the third node, a first capacitor coupled between the first output terminal and the ground potential, and a second capacitor coupled between the second output terminal and the ground potential. The method includes conducting the first switch to the third switch and turning off the fourth switch and the fifth switch in a first operation phase, so that the input voltage charges the inductor and the first flying capacitor; conducting the first switch and the fourth switch and turning off the second switch, the third switch, and the fifth switch in a second operation phase, so that the stored energy in the inductor charges the first capacitor to establish the first output voltage at the first output terminal; and conducting the third switch and the fifth switch and turning off the first switch, the second switch, and the fourth switch in a third operation phase, so that the stored energy in the inductor and the first flying capacitor charges the second capacitor to establish the second output voltage at the second output terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to an embodiment of the present invention.

[0007] Figure 2 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to another embodiment of the present invention.

[0008] Figure 3 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to another embodiment of the present invention.

[0009] Figure 4 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to another embodiment of the present invention.

[0010] Figure 5 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to another embodiment of the present invention.

[0011] Figure 6 FIG. is a schematic diagram of a single-inductor bipolar-output power conversion circuit according to another embodiment of the present invention.

[0012]

Symbol Explanation

[0013] 10: Path control element

[0014] 20: Control circuit

[0015] 31, 32: Adjustable voltage source

[0016] 101 - 106: SIBO power conversion circuit

[0017] IN: Input terminal

[0018] OUT1: First output terminal

[0019] OUT2: Second output terminal

[0020] N1 - N3: Node

[0021] L: Inductor

[0022] SW0 - SW6: Switch

[0023] R1, R2: Resistor

[0024] C FLY1 , C FLY2 : Flying capacitor

[0025] C1, C2: Capacitor

[0026] V IN : Input voltage

[0027] V OUT1 : First output voltage

[0028] V OUT2 : Second output voltage

[0029] ΔV1: First compensation voltage

[0030] ΔV2: Second compensation voltage

[0031] VC1, VC2: Capacitor cross - voltage

[0032] I L : Inductor current

[0033] GND: Ground potential

[0034] S0 - S8: Control signal

[0035] P1, P2, P3, P11 - P14: Energy path Detailed implementation manner

[0036] Figures 1 to 6Schematic diagram of the SIBO power conversion circuits 101-106 in the embodiments of the present invention. Each of the SIBO power conversion circuits 101-106 includes an input terminal IN, a first output terminal OUT1, a second output terminal OUT2, nodes N1-N3, an inductor L, switches SW1-SW5, capacitors C1-C2, a path control element 10, and a control circuit 20. The SIBO power conversion circuits 101-106 can receive an input voltage V IN through the input terminal IN IN and perform power conversion on the input voltage V OUT1 to provide a first output voltage V OUT2 and a second output voltage V OUT1 at the first output terminal OUT1 and the second output terminal OUT2 respectively, where the first output voltage V OUT2 is a positive voltage and the second output voltage V

[0037] In the SIBO power conversion circuits 101-106, the first terminal of switch SW1 is coupled to the input terminal IN, the second terminal is coupled to node N1, and the control terminal is coupled to the control circuit 20 to receive a control signal S1, and can be selectively turned on or off according to the control signal S1, thereby controlling the signal transmission path between the input terminal IN and node N1. The first terminal of switch SW2 is coupled to node N2, the second terminal is coupled to a ground potential GND, and the control terminal is coupled to the control circuit 20 to receive a control signal S2, and can be selectively turned on or off according to the control signal S2, thereby controlling the signal transmission path between node N1 and the ground potential GND. The first terminal of switch SW3 is coupled to node N3, the second terminal is coupled to the ground potential GND, and the control terminal is coupled to the control circuit 20 to receive a control signal S3, and can be selectively turned on or off according to the control signal S3, thereby controlling the signal transmission path between node N3 and the ground potential GND. The first terminal of switch SW4 is coupled to node N3, the second terminal is coupled to the first output terminal OUT1, and the control terminal is coupled to the control circuit 20 to receive a control signal S4, and can be selectively turned on or off according to the control signal S4, thereby controlling the signal transmission path between node N3 and the first output terminal OUT1. The first terminal of switch SW5 is coupled to node N2, the second terminal is coupled to the second output terminal OUT2, and the control terminal is coupled to the control circuit 20 to receive a control signal S5, and can be selectively turned on or off according to the control signal S5, thereby controlling the signal transmission path between node N2 and the second output terminal OUT2. The inductor L is coupled between node N1 and node N2, and can generate a self-induced electromotive force in response to the pressure difference between node N1 and node N2, thereby adjusting the inductor current I Lvalue. The first end of capacitor C1 is coupled to the first output terminal OUT1, and the second end of capacitor C1 is coupled to the ground potential GND for storing the first output voltage V OUT1 energy. The first end of capacitor C2 is coupled to the first output terminal OUT1, and the second end of capacitor C2 is coupled to the ground potential GND for storing the second output voltage V OUT2 energy.

[0038] The first end of the path control element 10 is coupled to the node N1, and the second end is coupled to the node N2, and can adjust the voltage difference between the node N1 and the node N2. In Figures 1 to 5 the shown SIBO power conversion circuits 101-105, the path control element 10 is implemented by a flying capacitor C FLY1 wherein the first end of the flying capacitor C FLY1 is coupled to the node N1, and the second end is coupled to the node N2, and can adjust the voltage difference between the node N1 and the node N2 according to the state of each switch. In Figure 6 the shown SIBO power conversion circuit 106, the path control element 10 is implemented by a switch SW0, wherein the first end of the switch SW0 is coupled to the node N1, the second end of the switch SW0 is coupled to the node N2, and the control end of the switch SW0 is coupled to the control circuit 20 to receive a control signal S0, and can selectively couple the node N1 to the node N2 according to the control signal S0, thereby adjusting the voltage difference between the node N1 and the node N2.

[0039] In Figure 2 the shown embodiment, the SIBO power conversion circuit 102 further includes at least one resistor, which is connected in series with the path control element 10. Figure 2 An embodiment showing two resistors, wherein the resistor R1 is connected in series between the node N1 and the first end of the flying capacitor C FLY1 and the resistor R2 is connected in series between the node N2 and the second end of the flying capacitor C FLY1 However, the number of resistors connected in series with the path control element 10 does not limit the present invention.

[0040] In Figure 3 the shown embodiment, the SIBO power conversion circuit 103 further includes the flying capacitor C FLY2 and the switch SW6. The first end of the flying capacitor C FLY2 is coupled to the first end of the switch SW4, the second end of the flying capacitor C FLY2 is coupled to the node N3, and VC2 represents the voltage across the flying capacitor C FLY2 The first end of the switch SW6 is coupled to the input terminal IN, and the second end is coupled to the flying capacitor C FLY2between the first end of and the first end of switch SW4, and the control end is coupled to control circuit 20 to receive a control signal S6, and can be selectively turned on or off according to control signal S6, thereby controlling the signal transmission path between input terminal IN and the first end of switch SW4.

[0041] In Figure 4 In the illustrated embodiment, power conversion circuit 104 further includes an adjustable voltage source 31, coupled between the second end of switch SW2 and ground potential GND, and can adjust its voltage across according to a control signal S7 provided by control circuit 20, thereby providing a first compensation voltage ΔV1.

[0042] In Figure 5 In the illustrated embodiment, power conversion circuit 105 further includes a flying capacitor C FLY2 , switch SW6, and adjustable voltage sources 31 and 32. The first end of flying capacitor C FLY2 is coupled to the first end of switch SW4, the second end of flying capacitor C FLY2 is coupled to node N3, and VC2 represents the voltage across flying capacitor C FLY2 . The first end of switch SW6 is coupled between the first end of flying capacitor C FLY2 and the first end of switch SW4, the second end is coupled to adjustable voltage source 32, and the control end is coupled to control circuit 20 to receive a control signal S6, and can be selectively turned on or off according to control signal S6, thereby controlling the signal transmission path between adjustable voltage source 32 and the first end of flying capacitor C FLY2 . Adjustable voltage source 31 is coupled between the second end of switch SW2 and ground potential GND, and can adjust its voltage across according to a control signal S7 provided by control circuit 20, thereby providing a first compensation voltage ΔV1. Adjustable voltage source 32 is coupled between the second end of switch SW6 and ground potential GND, and can adjust its voltage across according to a control signal S8 provided by control circuit 20, thereby providing a second compensation voltage ΔV2.

[0043] In Figure 6 In the illustrated embodiment, path control element 10 of power conversion circuit 106 is implemented by a switch SW0. The first end of switch SW0 is coupled to node N1, and the second end is coupled to node N2, and can selectively couple node N1 to node N2 according to a control signal SW0 provided by control circuit 20, thereby adjusting the voltage difference between node N1 and node N2.

[0044] In the present invention, the control signal S1 periodically switches between a first enabling potential and a first disabling potential with a first duty cycle, the control signal S2 periodically switches between a second enabling potential and a second disabling potential with a second duty cycle, the control signal S3 periodically switches between a third enabling potential and a third disabling potential with a third duty cycle, the control signal S4 periodically switches between a fourth enabling potential and a fourth disabling potential with a fourth duty cycle, the control signal S5 periodically switches between a fifth enabling potential and a fifth disabling potential with a fifth duty cycle, the control signal S6 periodically switches between a sixth enabling potential and a sixth disabling potential with a sixth duty cycle, and the control signal S0 periodically switches between a seventh enabling potential and a seventh disabling potential with a seventh duty cycle. In the present invention, each control signal may have the same duty cycle, or each may have a different duty cycle. In the present invention, each control signal may have the same enabling potential and disabling potential, or each may have different enabling potentials and disabling potentials. In one embodiment, the control circuit 20 adjusts the duty cycle of each switch according to the input voltage V IN 、the first output voltage V OUT1 and the second output voltage V OUT1 .

[0045] In the present invention, the operation of the SIBO power conversion circuits 101-106 includes three operation phases. First, the SIBO power conversion circuit 101 will be described.

[0046] In the first operation phase of the SIBO power conversion circuit 101, the control circuit 20 outputs the control signals S1-S3 with enabling potentials to turn on the switches SW1-SW3, and outputs the control signals S4-S5 with disabling potentials to turn off the switches SW4 and SW5. At this time, the energy of the input voltage V IN will be transmitted to the ground potential GND through the switches SW1, the inductor L, and the switch SW3, thereby charging the inductor L, and its corresponding energy path is shown by the dotted arrow P11. On the other hand, the energy of the input voltage V IN will also be transmitted to the ground potential GND through the switches SW1, the flying capacitor C FLY1 and the switch SW2, thereby charging the flying capacitor C FLY1 , and its corresponding energy path is shown by the dotted arrow P12. At this time, the cross voltage VC1 value across the flying capacitor C FLY1 is V IN . Therefore, the first operation phase is the charging operation phase of the inductor L and the flying capacitor C FLY .

[0047] In the second operation stage of the SIBO power conversion circuit 101, the control circuit 20 outputs control signals S1 and S4 with an enabling potential to turn on switches SW1 and SW4, and outputs control signals S2, S3, and S5 with a disabling potential to turn off switches SW2, SW3, and SW5. At this time, the inductor current I L flows from the inductor L through switch SW4 and capacitor C1 to the ground potential GND, and its corresponding energy path is shown by the dashed arrow P2. That is to say, the stored energy in the inductor L charges capacitor C1 through the first end of capacitor C1, and then a first output voltage V OUT1 is established at the first output terminal OUT1. L Therefore, the second operation stage is the positive output excitation working stage of the power conversion circuit 101, and at this time the discharge slope of the inductor current I OUT1 is V

[0048] / L. FLY In the third operation stage of the SIBO power conversion circuit 101, the control circuit 20 outputs control signals S3 and S5 with an enabling potential to turn on switches SW3 and SW5, and outputs control signals S1, S2, and S4 with a disabling potential to turn off switches SW1, SW2, and SW4. At this time, the stored energy in the flying capacitor C L and the inductor L is transmitted to the ground potential GND through switch SW3, that is, it charges capacitor C2 through the second end of capacitor C2, and then a second output voltage VOUT2 is established at the second output terminal OUT2, and its corresponding energy path is shown by the dashed arrow P3. Therefore, the third operation stage is the negative output excitation working stage of the power conversion circuit 101, and at this time the discharge slope of the inductor current I OUT2 is (V IN +V

[0049] ) / L. Figure 2 In the embodiment shown in L , the operation of the SIBO power conversion circuit 102 is similar to that of the SIBO power conversion circuit 101, but the resistors R1 and R2 can provide a current limiting function, and thus can more precisely control the discharge slope of the inductor current I

[0050] In Figure 3 the embodiment shown, in the first operation stage of the SIBO power conversion circuit 103, the control circuit 20 outputs control signals S1 - S3 and S6 with an enabling potential to turn on switches SW1 - SW3 and SW6, and outputs control signals S4 - S5 with a disabling potential to turn off switches SW4 and SW5. Therefore, in addition to the previously described energy paths P11 and P12, the first end of the flying capacitor C FLY2 is coupled to the input voltage V IN through switch SW6, and the flying capacitor CFLY2 The second terminal of which is coupled to the ground potential GND via the switch SW3, where the flying capacitor C FLY2 The voltage across VC2 across both ends is V IN , and the corresponding energy path is shown by the dashed arrow P13.

[0051] In the second operating stage of the SIBO power conversion circuit 103, the control circuit 20 outputs control signals S1 and S4 with an enabling potential to turn on the switches SW1 and SW4, and outputs control signals S2, S3, S5, and S6 with a disabling potential to turn off the switches SW2, SW3, SW5, and SW6. At this time, the inductor current I L will flow from the inductor L through the flying capacitor C FLY2 , the switch SW4, and the capacitor C1 to the ground potential GND, thereby establishing a first output voltage V OUT1 at the first output terminal OUT1, and its corresponding energy path is shown by the dashed arrow P2. The voltage across VC2 across both ends of the flying capacitor C FLY2 can reduce the root mean square (RMS) current of the inductor L, that is, it can adjust the discharge slope of the inductor current I L in the second operating stage to (V IN -V OUT1 ) / L, thereby improving the power conversion efficiency in the second operating stage.

[0052] In the third operating stage of the SIBO power conversion circuit 103, the control circuit 20 outputs control signals S3 and S5 with an enabling potential to turn on the switches SW3 and SW5, and outputs control signals S1, S2, S4, and S6 with a disabling potential to turn off the switches SW1, SW2, SW4, and SW6. At this time, the stored energy of the flying capacitor C FLY and the inductor L will be transferred to the ground potential GND via the switch SW3, that is, it will charge the second terminal of the capacitor C2, thereby establishing a second output voltage V OUT2 at the second output terminal OUT2, and its corresponding energy path is shown by the dashed arrow P3. And the discharge slope of the inductor current I L in the third operating stage is also (V OUT2 +V IN ) / L.

[0053] In Figure 4In the illustrated embodiment, the operation of the SIBO power conversion circuit 104 is similar to that of the SIBO power conversion circuit 101, but the adjustable voltage source 31 can adjust its cross voltage according to the control signal S7 provided by the control circuit 20, and then provide a first compensation voltage ΔV1. In the first operation stage, when the switches SW1 and SW2 are turned on, the first compensation voltage ΔV1 provided by the adjustable voltage source 31 in the energy path P12 can adjust the cross voltage VC1 across the flying capacitor C FLY1 at both ends, that is, adjust the value of VC1 to (V IN -ΔV1). In this way, in the third operation stage, when the switches SW3 and SW5 are turned on, the discharge slope of the inductor current I L on the energy path P3 can be adjusted to (V OUT2 +V IN -ΔV1) / L.

[0054] In Figure 5 the illustrated embodiment, in the first operation stage of the SIBO power conversion circuit 105, the control circuit 20 outputs control signals S1 - S3 and S6 with enabling potentials to turn on the switches SW1 - SW3 and SW6, and outputs control signals S4 - S5 with disabling potentials to turn off the switches SW4 and SW5. Therefore, in addition to the previously described energy paths P11 and P12, the first end of the flying capacitor C FLY2 is coupled to the adjustable voltage source 32 via the switch SW6, and the second end of the flying capacitor C FLY2 is coupled to the ground potential GND via the switch SW3, where the corresponding energy path is shown by the dashed arrow P14. In the first operation stage of the SIBO power conversion circuit 105, the first compensation voltage ΔV1 provided by the adjustable voltage source 31 in the energy path P12 can adjust the cross voltage VC1 across the flying capacitor C FLY1 at both ends (VC1 = V IN -ΔV1), and the second compensation voltage ΔV2 provided by the adjustable voltage source 32 in the energy path P14 can adjust the cross voltage VC2 across the flying capacitor C FLY2 at both ends (VC2 = ΔV2).

[0055] In the second operation stage of the SIBO power conversion circuit 105, the control circuit 20 outputs control signals S1 and S4 with enabling potentials to turn on the switches SW1 and SW4, and outputs control signals S2, S3, S5 and S6 with disabling potentials to turn off the switches SW2, SW3, SW5 and SW6. At this time, the inductor current I L will flow from the inductor L through the flying capacitor C FLY2 , the switch SW4 and the capacitor C1 to the ground potential GND, and then establish a first output voltage V OUT1, the corresponding energy path is shown by the dashed arrow P2. The flying capacitor C FLY2 The voltage across both ends of the flying capacitor C, VC2, can reduce the root mean square current of the inductor L, that is, it can adjust the discharge slope of the inductor current I L in the second operating stage to (ΔV2 - V OUT1 ), and then improve the power conversion efficiency in the second operating stage.

[0056] In the third operating stage of the SIBO power conversion circuit 105, the control circuit 20 outputs control signals S3 and S5 with enabling potentials to turn on the switches SW3 and SW5, and outputs control signals S1, S2, S4, and S6 with disabling potentials to turn off the switches SW1, SW2, SW4, and SW6. At this time, the stored energy in the flying capacitor C FLY and the inductor L will be transferred to the ground potential GND through the switch SW3, that is, it will charge the second end of the capacitor C2, and then establish a second output voltage V OUT2 at the second output terminal OUT2. The corresponding energy path is shown by the dashed arrow P3, and the discharge slope of the inductor current I L in the third operating stage is (V OUT2 +V IN -ΔV1) / L.

[0057] In Figure 6 the illustrated embodiment, in the first operating stage of the SIBO power conversion circuit 106, the control circuit 20 outputs control signals S1 and S3 with enabling potentials to turn on the switches SW1 and SW3, and outputs control signals S0, S2, S4, and S5 with disabling potentials to turn off the switches SW0, SW2, SW4, and SW5. At this time, the energy of the input voltage V IN will be transferred to the ground potential GND through the switches SW1, the inductor L, and the switch SW3, and then charge the inductor L. The corresponding energy path is shown by the dashed arrow P1. Therefore, the first operating stage is the charging working stage of the inductor L.

[0058] In the second operating stage of the SIBO power conversion circuit 106, the control circuit 20 outputs control signals S0, S2, and S4 with enabling potentials to turn on the switches SW0, SW2, and SW4, and outputs control signals S1, S3, and S5 with disabling potentials to turn off the switches SW1, SW3, and SW5. At this time, the inductor current I L will flow from the inductor L through the switch SW4 and the capacitor C1 to the ground potential GND, and then establish a first output voltage V OUT1 at the first output terminal OUT1. The corresponding energy path is shown by the dashed arrow P2. Therefore, the second operating stage is the positive output excitation working stage of the power conversion circuit 106. At this time, the inductor current I LThe discharge slope of is V OUT1 / L.

[0059] In the third operation stage of the SIBO power conversion circuit 106, the control circuit 20 outputs control signals S0, S3, and S5 with enabling potentials to turn on switches SW0, SW3, and SW5, and outputs control signals S1, S2, and S4 with disabling potentials to turn off switches SW1, SW2, and SW4. At this time, the stored energy in the inductor L is transmitted to the ground potential GND via switch SW3, that is, the second terminal of the capacitor C2 is charged, and then a second output voltage V is established at the second output terminal OUT2 OUT2 , and its corresponding energy path is shown by the dashed arrow P3. At this time, the inductor current I L The discharge slope of is (V OUT2 +V IN ) / L.

[0060] The SIBO power conversion circuits 101-106 according to the embodiments of the present invention can be applied to a display device or an audio source amplifier, but are not limited thereto.

[0061] In the embodiments of the present invention, the switches SW0-SW6 can be metal-oxide-semiconductor field-effect transistors (MOSFETs), bipolar junction transistors (BJTs), or other elements with similar functions. For an N-type transistor, the enabling potential is a high potential, and the disabling potential is a low potential; for a P-type transistor, the enabling potential is a low potential, and the disabling potential is a high potential. However, the types of the switches SW0-SW6 do not limit the scope of the present invention.

[0062] In summary, the SIBO voltage conversion circuit of the present invention provides different energy paths through a single inductor and multiple switches to convert an input voltage into two output voltages with opposite polarities, and improves the conversion efficiency through a path control element.

[0063] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims

1. A single-inductor bipolar-output power conversion circuit, comprising: Input terminal (IN) for receiving an input voltage (V IN ); The first output terminal (OUT1) is used to output the first output voltage (V OUT1 ); The second output terminal (OUT2) for outputting a second output voltage (V OUT2 ); A first node (N1); A second node (N2); A third node (N3); A first switch (SW1), comprising: A first terminal coupled to the input terminal; The second terminal is coupled to the first node; And A control terminal for receiving a first control signal (S1); A second switch (SW2), comprising: A first terminal coupled to the second node; A second terminal coupled to the ground potential (GND); and A control terminal for receiving a second control signal (S2); A third switch (SW3), comprising: A first terminal coupled to the third node; A second terminal coupled to the ground potential; And A control terminal for receiving a third control signal (S3); A fourth switch (SW4), comprising: A first terminal coupled to the third node; A second terminal coupled to the first output terminal; And A control terminal for receiving a fourth control signal (S4); A fifth switch (SW5), comprising: A first terminal coupled to the second node; A second terminal coupled to the second output terminal; And A control terminal for receiving a fifth control signal (S5); A path control element (10) coupled between the first node and the second node for adjusting the voltage difference between the first node and the second node; An inductor (L) coupled between the first node and the third node; A first capacitor (C1), comprising: A first terminal coupled to the first output terminal; and A second terminal coupled to the ground potential; A second capacitor (C2), comprising: A first terminal coupled to the second output terminal; And A second terminal coupled to the ground potential; And A control circuit (20) for providing the first control signal to the fifth control signal.

2. The single-inductor bipolar-output power conversion circuit as described in claim 1, wherein the path control element includes a first flying capacitor (C FLY1 ), a first end of the first flying capacitor is coupled to the first node, and a second end of the first flying capacitor is coupled to the second node.

3. The single-inductor bipolar-output power conversion circuit according to claim 2, wherein the path control element further comprises at least one resistor (R1 / R2), and the at least one resistor is coupled between the first node and the first end of the first flying capacitor or between the second node and the second end of the first flying capacitor.

4. The single-inductor bipolar-output power conversion circuit according to claim 2, further comprising: A sixth switch (SW6), comprising: A first terminal coupled to the first terminal of the fourth switch; A second terminal coupled to the input terminal; and A control terminal for receiving a sixth control signal (S6); and Second flying capacitor (C FLY2 ), which includes: A first terminal coupled to the first terminal of the fourth switch; and A second terminal coupled to the third node, wherein the control circuit is further used to provide the sixth control signal.

5. The single-inductor bipolar-output power conversion circuit according to claim 2), further comprising: A first adjustable voltage source (31) coupled between the second terminal of the second switch and the ground potential for providing a first compensation voltage (ΔV1) according to a seventh control signal (S7), wherein the control circuit is further used to provide the seventh control signal.

6. The single-inductor bipolar-output power conversion circuit according to claim 2, further comprising: A sixth switch (SW6), comprising: A first terminal coupled to the first terminal of the fourth switch; Second terminal; And A control terminal for receiving a sixth control signal (S6); Second flying capacitor (C FLY2 ), which includes: a first terminal coupled to the first terminal of the fourth switch; and a second terminal coupled to the third node; a first adjustable voltage source (31) coupled between the second terminal of the second switch and the ground potential for providing a first compensation voltage (ΔV1) according to a seventh control signal (S7); and a second adjustable voltage source (32) coupled between the second terminal of the sixth switch and the ground potential for providing a second compensation voltage (ΔV2) according to an eighth control signal (S8), wherein the control circuit is further configured to provide the seventh control signal and the eighth control signal.

7. The single-inductor bipolar-output power conversion circuit according to claim 1, wherein: the control circuit is further configured to provide a ninth control signal (S0); and the path control element includes a seventh switch (SW0), which includes: a first terminal coupled to the first node; a second terminal coupled to the first node; and a control terminal for receiving the ninth control signal.

8. The single-inductor bipolar-output power conversion circuit according to claim 1, wherein: the first control signal periodically switches between a first enabling potential and a first disabling potential with a first duty cycle; the second control signal periodically switches between a second enabling potential and a second disabling potential with a second duty cycle; the third control signal periodically switches between a third enabling potential and a third disabling potential with a third duty cycle; the fourth control signal periodically switches between a fourth enabling potential and a fourth disabling potential with a fourth duty cycle; the fifth control signal periodically switches between a fifth enabling potential and a fifth disabling potential with a fifth duty cycle; and the control circuit adjusts the first duty cycle to the fifth duty cycle according to the input voltage, the first output voltage, and the second output voltage.

9. The single-inductor bipolar-output power conversion circuit according to claim 1, which outputs the first output voltage and the second output voltage to drive a display panel or an audio source amplifier.

10. The single-inductor bipolar-output power conversion circuit according to claim 1, wherein the first output voltage is a positive voltage and the second output voltage is a negative voltage.

11. A method for controlling a single-inductor bipolar-output power conversion circuit, the single-inductor bipolar-output power conversion circuit including an input terminal for receiving an input voltage, a first output terminal for outputting a first output voltage, a second output terminal for outputting a second output voltage, first to third nodes, a first switch coupled between the input terminal and the first node, a second switch coupled between the second node and the ground potential, a third switch coupled between the third node and the ground potential, a fourth switch coupled between the third node and the first output terminal, a fifth switch coupled between the second node and the second output terminal, a first flying capacitor coupled between the first node and the second node, an inductor coupled between the first node and the third node, a first capacitor coupled between the first output terminal and the ground potential, and a second capacitor coupled between the second output terminal and the ground potential, the method comprising: Turn on the first switch to the third switch and turn off the fourth switch and the fifth switch in the first operation phase, so that the input voltage charges the inductor and the first flying capacitor; Turn on the first switch and the fourth switch and turn off the second switch, the third switch and the fifth switch in the second operation phase, so that the stored energy in the inductor charges the first capacitor to establish the first output voltage at the first output terminal; And Turn on the third switch and the fifth switch and turn off the first switch, the second switch and the fourth switch in the third operation phase, so that the stored energy in the inductor and the first flying capacitor charges the second capacitor to establish the second output voltage at the second output terminal.

12. The method according to claim 11, further comprising: Providing at least one resistor between the first node and the first end of the first flying capacitor or between the second node and the second end of the first flying capacitor.

13. The method (embodiment of FIG. 4) according to claim 11, further comprising: Providing a first compensation voltage at the second node in the first operation phase, wherein the potential of the first compensation voltage is higher than the ground potential.

14. The method according to claim 11, wherein the single-inductor bipolar output power conversion circuit further comprises a sixth switch coupled between the input terminal and the first end of the fourth switch and a second flying capacitor coupled between the first end of the fourth switch and the third node, and the method further comprises: Turning on the sixth switch in the first operation phase, so that the input voltage charges the second flying capacitor; Turning off the sixth switch in the second operation phase, so that the stored energy in the second flying capacitor reduces the root mean square (RMS) current of the inductor; and Turning off the sixth switch in the third operation phase.

15. The method according to claim 11, wherein the single-inductor bipolar output power conversion circuit further comprises a second flying capacitor coupled between the first end of the fourth switch and the third node, and the method further comprises: Providing a second compensation voltage at the first end of the fourth switch in the first operation phase, wherein the potential of the second compensation voltage is higher than the ground potential.

16. The method according to claim 11, further comprising: Outputting a first control signal that periodically switches between a first enabling potential and a first disabling potential with a first duty cycle to selectively turn on or off the first switch; Outputting a second control signal that periodically switches between a second enabling potential and a second disabling potential with a second duty cycle to selectively turn on or off the second switch; Outputting a third control signal that periodically switches between a third enabling potential and a third disabling potential with a third duty cycle to selectively turn on or off the third switch; Outputting a fourth control signal that periodically switches between a fourth enabling potential and a fourth disabling potential with a fourth duty cycle to selectively turn on or off the fourth switch; And Outputting a fifth control signal that periodically switches between a fifth enabling potential and a fifth disabling potential with a fifth duty cycle to selectively turn on or off the fifth switch.

17. The method according to claim 16, further comprising: Adjusting the first duty cycle to the fifth duty cycle according to the input voltage, the first output voltage, and the second output voltage.

18. The method according to claim 16, further comprising: Outputting the first output voltage and the second output voltage to drive a display panel or an audio source amplifier.

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