Single-inductor multi-output switching converter and control method thereof

Abstract

The invention discloses a single-inductor multi-output switching converter which comprises a plurality of output switching tubes, the first power ends of the output switching tubes are connected with a power loop node of the switching converter, the second power ends of the output switching tubes are connected with an output node of the switching converter, and in the switching process of the output power of a plurality of output paths, the output power of the output paths is output. In a follow current state, the control end of the output switch tube is connected to the first power end of the output switch tube. According to the single-inductor multi-output control scheme, in the switching process of multiple output paths, in the follow current state, the control end of the output switch tube is connected to the first power end of the output switch tube, so that the on-off control of the switch tube is simple, a complex control circuit is not needed, the cost is low, the whole system is simple, and the adaptability is good.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a single-inductor multi-output switching converter and its control method. Background Technology

[0002] A single inductor multiple outputs (SIMO) switching converter is a switching converter that shares a single inductor with two or more output paths. It can provide different supply voltages through different output paths to meet the power requirements of different modules.

[0003] One implementation of the existing single-inductor multi-output switching converter (SIMO) is as follows: Figure 1 As shown, this is a buck-boost switching converter. Taking two output paths as an example, switches Q1 and Q2 act as control switches for the output paths. Switches Q1 and Q2 control the switching on and off according to the power supply requirements of the load. During the switching process of switches Q1 and Q2, a freewheeling current is required to prevent backflow between the two output paths. Current practices typically involve setting switches Q1 and Q2 as multiple switches connected in series / parallel, using the body diode of one of the switches for freewheeling to control the current of the two output paths. However, the multiple-switch approach leads to complex control and low system efficiency.

[0004] Therefore, it is necessary to provide improved technical solutions to overcome the above-mentioned technical problems existing in the prior art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a single-inductor multi-output switching converter and its control method, so as to solve the technical problems of complex control and low system efficiency in the prior art.

[0006] According to this application, a single-inductor multi-output switching converter is used to power multiple output paths, including multiple output switching transistors, each of which corresponds to one of the multiple output paths. The first power terminal of each of the multiple output switching transistors is connected to the power loop node of the switching converter, and the second power terminal is connected to the output node of the corresponding output path. During the switching of the output power of the multiple output paths, in the freewheeling state, the control terminal of the output switching transistor corresponding to the two output paths currently being switched is connected to its first power terminal.

[0007] Preferably, during power output in a certain output path, the control terminal of the corresponding output switch is connected to a drive voltage to keep it on. After the output path stops outputting power, the control terminal of the corresponding output switch is connected to a reference ground to keep it off.

[0008] Preferably, the output switch is a gallium nitride transistor.

[0009] Preferably, the output switch is two connected MOS transistors, wherein the control terminals of the two MOS transistors are connected together and the source terminals of the two MOS transistors are connected together, and the two drain terminals of the two MOS transistors serve as the first power terminal and the second power terminal of the output switch, respectively.

[0010] Preferably, in the freewheeling state, the control terminal of the output switch is connected to its first power terminal through a first connecting circuit, wherein the first connecting circuit is a first connecting switch or a first connecting resistor.

[0011] Preferably, when the first connecting circuit is a first connecting switch, the first connecting switch is two P-type MOS transistors connected in series. The sources of the two P-type MOS transistors are connected, one drain of the two P-type MOS transistors is connected to the first power terminal of the output switch, and the other drain is connected to the control terminal of the output switch. The control terminals of the two P-type MOS transistors are connected together and connected to the driving voltage through a first pull-up transistor and connected to the reference ground through a first pull-down transistor.

[0012] Preferably, when the first connecting circuit is a first connecting switch, the first connecting switch is a P-type MOS transistor. The source electrode of the P-type MOS transistor is connected to the first power terminal of the output switch, the drain electrode is connected to the control terminal of the output switch, the body electrode of the P-type MOS transistor is connected to the driving voltage, and the control terminal of the P-type MOS transistor is connected to the driving voltage through a first pull-up transistor and connected to the reference ground through a first pull-down transistor.

[0013] Preferably, it further includes a clamping switch, one power terminal of which is connected to the driving voltage, and the other power terminal of which is connected to the control terminal of the P-type MOS transistor via a diode, so as to clamp the control terminal voltage of the P-type MOS transistor.

[0014] Preferably, the system further includes a second connecting switch and a third connecting switch. The control terminal of the output switch is connected to the driving voltage through the second connecting switch. When the output path outputs power, the second connecting switch is turned on to enable the output switch to turn on. The control terminal of the output switch is connected to the reference ground through the third connecting switch. When the output path stops outputting power, the third connecting switch is turned on to enable the output switch to turn off.

[0015] Preferably, in freewheeling mode, the output switch is turned on and controlled according to the voltage at its two power terminals.

[0016] Secondly, a control method for a single-inductor, multi-output switching converter is provided to power multiple output paths. The switching converter includes multiple output switches, each corresponding to one of the multiple output paths. During power output from a particular output path, the control terminal of its corresponding output switch is connected to a driving voltage to keep it on. During power switching between multiple output paths, in freewheeling mode, the control terminals of the output switches corresponding to the two currently switching output paths are connected to their first power terminals. After a particular output path stops outputting power, the control terminal of its corresponding output switch is connected to ground to keep it off. The first power terminals of each of the multiple output switches are connected to the power loop node of the switching converter, and the second power terminals are connected to the output node of the corresponding output path.

[0017] Preferably, in freewheeling mode, the output switch is turned on and controlled according to the voltage at its two power terminals.

[0018] Preferably, the output switch is a gallium nitride transistor, or the output switch is two connected MOS transistors, wherein the control terminals of the two MOS transistors are connected together and the source terminals are connected together, and the two drain terminals of the two MOS transistors serve as the first power terminal and the second power terminal of the output switch, respectively.

[0019] Preferably, the control terminal of the output switch is connected to its first power terminal through a first connecting circuit; the control terminal of the output switch is connected to the driving voltage through a second connecting circuit; and the control terminal of the output switch is connected to the reference ground through a third connecting circuit.

[0020] Preferably, in the freewheeling state, the first connecting circuit is on, and the second and third connecting circuits are off; in the output power state, the first connecting circuit is on or off, the second connecting circuit is on, and the third connecting circuit is off; in the stopped output power state, the first connecting circuit is on or off, the second connecting circuit is off, and the third connecting circuit is on.

[0021] The single-inductor multi-output switching converter of this invention includes multiple output path switching transistors. The first power terminal of each output switching transistor is connected to the power loop node of the switching converter, and the second output power terminal is connected to the output node of the switching converter. During the switching of the output power of the multiple output paths, in freewheeling mode, the control terminal of each output switching transistor is connected to its first power terminal. Through the single-inductor multi-output control scheme of this application, during the switching of multiple output paths in freewheeling mode, the on / off control is performed based on the magnitude of the voltages at the two power terminals of the switching transistor. This simplifies the control of the switching transistors, eliminates the need for complex control circuits, and results in high system control efficiency, low cost, and a simple overall system with good adaptability. Attached Figure Description

[0022] Figure 1 A circuit block diagram of a single-inductor multi-output switching converter in the prior art;

[0023] Figure 2 This is a first circuit block diagram of a single-inductor multi-output switching converter according to the present invention;

[0024] Figure 3 This is a second circuit block diagram of a single-inductor multi-output switching converter according to the present invention;

[0025] Figure 4 Here is a detailed circuit diagram of a first embodiment of the first output path according to the present invention;

[0026] Figure 5 Here is a detailed circuit diagram of a second embodiment of the first output path according to the present invention;

[0027] Figure 6 The diagram shows the working waveforms according to the present invention. Detailed Implementation

[0028] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the present invention.

[0029] To provide the public with a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the invention, but those skilled in the art can fully understand the invention without these details.

[0030] The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0031] refer to Figure 2A first circuit block diagram of a single-inductor multi-output switching converter according to the present invention and Figure 4 Here is a detailed circuit diagram of a first embodiment of the first output path according to the present invention; as follows: Figure 2 As shown, this embodiment of the single-inductor multi-output switching converter takes a buck-boost switching converter as an example, and a two-output path as an example. The switching converter shown includes multiple output switches, and each of the multiple output switches corresponds one-to-one with the multiple output paths, such as... Figure 2 Q1 and Q2 are output switching transistors. The first power terminals of the plurality of output switching transistors are all connected to the power loop node of the switching converter, and the second power terminals are connected to the output node of the corresponding output path, such as... Figure 2 In the switching converter, multiple output paths are connected to the power loop node SW, such as the first output path, the second output path, etc. The left power terminals of the switching transistor Q1 in the first output path and the switching transistor Q2 in the second output path are both connected to the node SW of the switching converter, and the right power terminals are respectively connected to the output nodes of their respective paths, such as one end of the output capacitor.

[0032] like Figure 2As shown, each output path also includes a switch control circuit for controlling the on / off state of the output switch transistor. Taking the first output path as an example, the switch control circuit is connected to the control terminal Gate of the output switch transistor, multiple switch transistors, and the driving voltage for power supply. Specifically, the control terminal Gate of the output switch transistor is connected to its first power terminal, such as node SW, through a first connecting circuit, such as S1; the control terminal Gate of the output switch transistor is connected to the driving voltage, such as BST, through a second connecting circuit, such as S2; and the control terminal Gate of the output switch transistor is connected to reference ground GND through a third connecting circuit, such as S3. In this example, the output switch transistor is a gallium nitride transistor, which does not have a body diode. Preferably, the gallium nitride transistor can be a symmetrical gallium nitride transistor device. Based on the above output path structure, and according to the working requirements of multiple output paths, the switching state of the output switch is controlled as follows: If the current output path is in power output state, the first connecting circuit is turned on or off, the second connecting circuit is turned on, and the third connecting circuit is turned off. The control terminal Gate of the corresponding output switch is connected to the driving voltage to keep it on, thus outputting power. If the current output path is in a stopped power output state, the first connecting circuit is turned on or off, the second connecting circuit is turned off, and the third connecting circuit is turned on. The control terminal Gate of the corresponding output switch is connected to the reference ground to keep it off. If the current output path is in a power switching freewheeling state, such as when the first output path switches to the second output path to output power, the first connecting circuit is turned on, and the second and third connecting circuits are turned off. The control terminal Gate of the output switch corresponding to the two output paths currently undergoing power switching is connected to its first power terminal. That is, one power terminal of the output switch is connected to its control terminal. Thus, during the freewheeling phase, when the voltage difference across the output switch reaches a certain value, such as the output switch's on-threshold, the output switch is turned on. Figure 2 As shown, the voltage difference across the output switch is the difference between node SW and output terminal Vo1. In this way, during the power switching process between the two output paths, the current in the system can have a continuous flow path, and the current will not flow between the two output paths, thus preventing backflow between the output paths.

[0033] Continue to refer to Figure 4This is a circuit diagram of an implementation of the first output path according to the present invention. Other output paths have the same structure as the first output path. Taking the first output path as an example, the first output path includes an output switch and a switching control circuit that controls the output switch. Specifically, in this example, the first connecting circuit S1 is a first connecting switch, which is two P-type transistors M3 connected in series. The sources of the two P-type transistors are connected. One drain of the two P-type transistors is connected to the first power terminal of the output switch, such as node SW, and the other drain is connected to the control terminal Gate of the output switch. The control terminals of the two P-type transistors are connected together and connected to the driving voltage through a first pull-up transistor M2, and connected to the reference ground through a first pull-down transistor M4. Figure 4 As shown, when the first pull-down transistor M4 is turned on, the voltage drop at the control terminal of the P-type transistor M3 decreases, and the P-type transistor M3 is turned on. When the first pull-up transistor M2 is turned on, the voltage drop at the control terminal of the P-type transistor M3 increases, and the P-type transistor M3 is turned off. Thus, through the control of switching transistors M2 and M4, the P-type transistor M3 can be switched on and off to determine whether the output switching transistor Q1 is connected to node SW. (Continue to refer to...) Figure 4 The second connected circuit S2 includes a switch M1, and the control terminal of the output switch is connected to a driving voltage such as BST through the switch M1; the third connected circuit S3 includes a switch M0, and the control terminal of the output switch is connected to the reference ground GND through the switch M0. The switch M1 and the switch M0 are controlled to turn on and off according to the system's enable signal. For example, if the first output path needs to output power, the switch M1 receives an enable signal after the freewheeling phase ends. If the first output path needs to stop outputting power, the switch M1 receives a disable enable signal before the freewheeling phase.

[0034] Preferably, in this example, the first output circuit further includes a clamping switch M5. One power terminal of the clamping switch is connected to a driving voltage such as BST, and the other power terminal of the clamping switch is connected to the control terminal of the P-type transistor via a diode to clamp the control terminal voltage of the P-type transistor. The clamping switch clamps the gate-source voltage of the P-type transistor M3 to prevent overvoltage damage to the switch.

[0035] refer to Figure 6The waveforms shown illustrate the switching states under different operating conditions. In the t0-t1 stage, switches M0 and M2 are on, the gate is connected to ground, the S3 circuit is conducting, and the S1 and S2 paths are off. The output switch is on, and the output path stops supplying power to the load. In the t1-t2 stage, switches M3 and M4 are on, the S1 circuit is conducting, and the S2 and S3 paths are off. The two output paths switch power, with the gate connected to one of the power terminals (e.g., the left power terminal). The output switch switches on and off according to the voltage across it, and the output path can continue normally. In the t2-t3 stage, switches M1 and M2 are on, the S2 circuit is conducting, the S1 and S3 paths are off, the gate is connected to the drive voltage, the output switch is on, and the output path supplies power to the load. Through the on / off control of switches M0-M5, the output switches in each stage can be effectively controlled, ensuring both the supply of output power and smooth switching during power transitions. The overall system structure is simple and easy to control.

[0036] Here, the first connecting switch can also be implemented in other ways, such as a P-type transistor. The drain electrode of the P-type transistor is connected to the first power terminal of the output switch, the source electrode is connected to the control terminal of the output switch, the body electrode of the P-type transistor is connected to the driving voltage BST, and the control terminal of the P-type transistor is connected to the driving voltage through a first pull-up diode and to the reference ground through a first pull-down diode. If a P-type transistor is used, the body diode of the P-type transistor needs to have a high withstand voltage to withstand the driving voltage BST. The driving voltage in this application can be the same driving voltage or different driving voltages; the example uses the same driving voltage BST. The first connecting switch can also be other forms of switching structure, as long as it can achieve the function of this invention.

[0037] refer to Figure 3 This is a second circuit block diagram of a single-inductor multi-output switching converter according to the present invention. In this example, the switching converter is a flyback switching converter, and the output path is still two outputs. In this example, the output switching transistors are two connected field-effect transistors, wherein the control terminals of the two field-effect transistors are connected together and the source terminals are connected together, and the two drain terminals of the two field-effect transistors serve as the first power terminal and the second power terminal of the output switching transistor, respectively. Figure 3 As shown, the first power terminal of the output switching transistor is connected to the power loop node of the switching converter, such as the cathode node SW of the diode, and the second power terminal is connected to the output node, such as one end of the output capacitor. In this example, the first power terminals of multiple output switching transistors are connected to the power loop node of the corresponding channel.

[0038] refer to Figure 5The following is a detailed circuit diagram of a second embodiment of the first output path according to the present invention. In this embodiment, the first connecting circuit is a first connecting resistor. The control terminal of the output switch is connected to its first power terminal through the first connecting resistor. Since the connection is made through a resistor, no special control circuit is required, and the output switch Q1 can be easily connected to node SW.

[0039] In summary, the single-inductor multi-output switching converter connects the first power terminal of the output switching transistor to the power loop node of the switching converter, and the second output power terminal is connected to the output node of the switching converter. Through the single-inductor multi-output control scheme of this application, during the switching process of multiple output paths, in freewheeling mode, the on / off control is performed based on the magnitude of the voltages at the two power terminals of the switching transistor. This simplifies the control of the switching transistor, eliminates the need for complex control circuits, and results in high system control efficiency, low cost, and a simple overall system with good adaptability.

[0040] It should be noted that the specific implementations and corresponding illustrations provided are merely one way of describing the implementation method of the present invention, and are not intended to limit the specific structure of the implementation scheme of the present invention. Various changes or modifications can be made to these implementation schemes without departing from the principles and essence of the present invention, but all such changes and modifications fall within the protection scope of the present invention.

[0041] Although the embodiments are described and illustrated separately above, some common technologies are involved. Those skilled in the art can replace and integrate them between the embodiments. If there is any content not explicitly described in one embodiment, then another described embodiment can be referred to.

[0042] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A single-inductor multi-output switching converter for supplying power to multiple output paths, characterized in that, It includes multiple output switches, each corresponding one-to-one with a multiple output path. The first power terminals of the plurality of output switches are connected to the power loop node of the switching converter, and the second power terminals are connected to the output node of the corresponding output path. During the switching of output power of multiple output paths, in freewheeling mode, the control terminal of the output switch corresponding to the two output paths currently undergoing power switching is connected to its first power terminal.

2. The single-inductor multi-output switching converter according to claim 1, characterized in that, In a certain output path for power output, the control terminal of the corresponding output switch is connected to a drive voltage to keep it conducting. After the output path stops outputting power, the control terminal of its corresponding output switch is connected to the reference ground so that it remains off.

3. The single-inductor multi-output switching converter according to claim 1, characterized in that, The output switch is a gallium nitride transistor.

4. The single-inductor multi-output switching converter according to claim 1, characterized in that, The output switch consists of two connected MOS transistors, with their control terminals and source terminals connected together. The two drain terminals of the two MOS transistors serve as the first power terminal and the second power terminal of the output switch, respectively.

5. The single-inductor multi-output switching converter according to claim 1, characterized in that, In freewheeling mode, the control terminal of the output switch is connected to its first power terminal via a first connection circuit. Wherein, the first connected circuit is a first connected switch or a first connected resistor.

6. The single-inductor multi-output switching converter according to claim 5, characterized in that, When the first connected circuit is the first connected switching transistor The first connecting switch is two P-type MOS transistors connected in series, with the sources of the two P-type MOS transistors connected together. One drain of the two P-type MOS transistors is connected to the first power terminal of the output switch, and the other drain is connected to the control terminal of the output switch. The control terminals of the two P-type MOS transistors are connected together and connected to the driving voltage through the first pull-up transistor and to the reference ground through the first pull-down transistor.

7. The single-inductor multi-output switching converter according to claim 5, characterized in that, When the first connected circuit is the first connected switching transistor The first connected switching transistor is a P-type MOS transistor. The source electrode of the P-type MOS transistor is connected to the first power terminal of the output switching transistor, the drain electrode is connected to the control terminal of the output switching transistor, and the body electrode of the P-type MOS transistor is connected to the driving voltage. The control terminal of the P-type MOS transistor is connected to the driving voltage through a first pull-up transistor and to the reference ground through a first pull-down transistor.

8. The single-inductor multi-output switching converter according to claim 6 or 7, characterized in that, It also includes a clamping switch, one of the power terminals of which is connected to the drive voltage. The other power terminal of the clamping switch is connected to the control terminal of the P-type MOS transistor via a diode to clamp the control terminal voltage of the P-type MOS transistor.

9. The single-inductor multi-output switching converter according to claim 2, characterized in that, It also includes a second connecting switch and a third connecting switch. The control terminal of the output switch is connected to the driving voltage through a second connecting switch. When power is output through this output path, the second connecting switch is turned on to enable the output switch to turn on. The control terminal of the output switch is connected to the reference ground through a third connecting switch. When the output path stops outputting power, the third connecting switch is turned on to turn off the output switch.

10. The single-inductor multi-output switching converter according to claim 1, characterized in that, In freewheeling mode, the output switch is controlled to conduct based on the voltage at its two power terminals.

11. A control method for a single-inductor multi-output switching converter, used to supply power to multiple output paths, characterized in that, The switching converter includes multiple output switches, each corresponding one-to-one with a plurality of output paths. In a certain output path, the control terminal of the corresponding output switch is connected to the drive voltage to keep it conducting. During the switching of output power of multiple output paths, in freewheeling mode, the control terminal of the output switch corresponding to the two output paths currently switching power is connected to its first power terminal. After a certain output path stops outputting power, the control terminal of its corresponding output switch is connected to the reference ground so that it remains off. The first power terminals of the plurality of output switching transistors are all connected to the power loop node of the switching converter, and the second power terminals are connected to the output node of the corresponding output path.

12. The control method for a single-inductor multi-output switching converter according to claim 11, characterized in that, In freewheeling mode, the output switch is controlled to conduct based on the voltage at its two power terminals.

13. The control method for a single-inductor multi-output switching converter according to claim 11, characterized in that, The output switch is a gallium nitride transistor, or The output switch consists of two connected MOS transistors, with the control terminals and source terminals of the two MOS transistors connected together. The two drain terminals of the two MOS transistors serve as the first power terminal and the second power terminal of the output switch, respectively.

14. The control method for a single-inductor multi-output switching converter according to claim 11, characterized in that, The control terminal of the output switch is connected to its first power terminal through a first connecting circuit. The control terminal of the output switch is connected to the driving voltage through a second connection circuit; The control terminal of the output switch is connected to the reference ground via a third connection circuit.

15. The control method for a single-inductor multi-output switching converter according to claim 14, characterized in that, In the freewheeling state, the first connected circuit is on, while the second and third connected circuits are off. In the output power state, the first connected circuit is on or off, the second connected circuit is on, and the third connected circuit is off. When the power output is stopped, the first connected circuit is turned on or off, the second connected circuit is turned off, and the third connected circuit is turned on.

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