A dc-dc converter and electronic device

Abstract

This invention relates to a DC-DC converter and an electronic device. The DC-DC converter includes: a conversion circuit including an inductor, a plurality of switching devices, a voltage input terminal, and at least one output branch; a step controller configured to control the switching of the plurality of switching devices based on the voltage output of the voltage output terminal of the at least one output branch, such that the conversion circuit adjusts the voltage output of the voltage output terminal of the at least one output branch to a target value based on the voltage input to the at least one voltage input terminal; at any given time, the inductor is used only for one output branch, and when the inductor is used to output voltage at the voltage output terminal of each output branch, the current of the inductor continuously rises from a valley to a peak value, and then falls from the peak value to a valley value. The step controller also controls the switching of the plurality of switching devices to make the valley values ​​of the current waveform change in a stepwise manner, all of which are greater than zero, thereby reducing the ripple of the inductor current and the ripple of the voltage output at the voltage output terminal.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more particularly to a DC-DC converter and electronic device. Background Technology

[0002] DC-DC converters can reduce the number of inductors, essentially allowing multiple DC-DC converters to share a single inductor. In existing technologies, the inductor current is typically controlled to vary between its peak value Ipk and zero, resulting in significant current ripple. For applications requiring high maximum load capacity, Ipk is designed to be very large, and the more output branches there are, the larger Ipk needs to be. A larger Ipk results in greater current ripple. For the same output capacitor value, this also leads to greater output voltage ripple. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned technical problems and provide a DC-DC converter and electronic device that makes the valley value of the current waveform in the inductor change in a stepwise manner and is always greater than zero, thereby reducing the ripple of the current in the inductor and the ripple of the voltage output at the voltage output terminal, and improving the performance of the circuit.

[0004] To achieve the above objectives, a first aspect of the present invention provides a DC-DC converter, comprising: a conversion circuit including an inductor, a plurality of switching devices, a voltage input terminal, and at least one output branch, each output branch including a voltage output terminal and an output capacitor having one end coupled to the voltage output terminal and the other end grounded; and a step controller configured to control the switching of the plurality of switching devices according to the voltage output of the voltage output terminal of the at least one output branch, such that the conversion circuit adjusts the voltage output of the voltage output terminal of the at least one output branch to a target value through the inductor based on the voltage input to the voltage input terminal; at any given time, the inductor is used only for one output branch, and when the inductor is used to output voltage at the voltage output terminal of each output branch, the current in the inductor continuously rises from a valley value to a peak value, and then falls from the peak value to a valley value, wherein the step controller further controls the switching of the plurality of switching devices to make the valley values ​​of the current waveform change in a step manner and all of them are greater than zero.

[0005] Optionally, the step controller is further configured to control the on and off of the plurality of switching devices such that when the inductor is used in each output branch, the peak value of the current waveform in the inductor changes in a step manner, and the trend of the step change of the peak value is consistent with the trend of the step change of the valley value.

[0006] Optionally, when the inductor is used to output voltage at the voltage output terminal of each output branch, the current in the inductor includes multiple successively increasing valley steps, each valley step having a corresponding valley value, and the valley value of the current waveform switches between at least two selected valley steps in the multiple valley steps; when the inductor is used to output voltage at the voltage output terminal of each output branch, the current in the inductor includes multiple successively increasing peak steps, each peak step having a corresponding peak value, and the peak value of the current waveform switches between at least two selected peak steps in the multiple peak steps; the step controller controls the on and off of the plurality of switching devices based on the comparison between the current in the inductor and the selected at least two valley steps and the selected at least two peak steps.

[0007] Optionally, the process of the current in the inductor rising from a valley to a peak and then falling back to a valley forms a pulse. The waveform of the current in the inductor changes periodically. Within one cycle, the waveform of the current in the inductor includes at least one larger pulse formed by a larger peak level among at least two selected peak levels and a larger valley level among at least two selected valley levels, and at least one smaller pulse formed by a smaller peak level among at least two selected peak levels and a smaller valley level among at least two selected valley levels.

[0008] Optionally, a set number of pulses is used as an adjustment period. When the voltage output at the voltage output terminal is lower than the lower limit of the target value, the number of smaller pulses in the set number of pulses in one adjustment period is reduced and the number of larger pulses is increased accordingly to increase the proportion of larger pulses in the set number of pulses. When the number of smaller pulses is reduced to zero, if the voltage output at the voltage output terminal is lower than the lower limit of the target value, wherein: at least two valley levels are reselected in the multi-level valley levels, and at least one of the reselected valley levels is greater than the larger valley level of the previously selected at least two valley levels, the waveform of the current switches between the reselected at least two valley levels; and / or, at least two peak levels are reselected in the multi-level valley levels, and at least one of the reselected peak levels is greater than the larger peak level of the previously selected at least two peak levels, the waveform of the current switches between the reselected at least two peak levels.

[0009] Optionally, a set number of pulses is used as an adjustment period. When the voltage output at the voltage output terminal is higher than the upper limit of the target value, the number of larger pulses in the set number of pulses in one adjustment period is reduced and the number of smaller pulses is increased accordingly to increase the proportion of smaller pulses in the set number of pulses. When the number of larger pulses is reduced to zero, if the voltage output at the voltage output terminal is still higher than the upper limit of the target value, wherein: at least two valley levels are reselected in the multi-level valley levels, and at least one of the reselected valley levels is less than the smaller valley level of the previously selected at least two valley levels, the waveform of the current switches between the reselected at least two valley levels; and / or, at least two peak levels are reselected in the multi-level valley levels, and at least one of the reselected peak levels is less than the smaller peak level of the previously selected at least two peak levels, the waveform of the current switches between the reselected at least two peak levels.

[0010] Optionally, when the valley of the current waveform switches between two valley levels and the peak value switches between two peak levels, the waveform of the current in the inductor changes from the larger valley level to the larger peak level by coupling the first connection terminal of the inductor to the voltage input terminal during a first time period; the waveform of the current in the inductor changes from the larger peak level to the larger valley level by grounding the first connection terminal of the inductor during a second time period; the waveform of the current in the inductor changes from the larger valley level to the smaller peak level by re-coupling the first connection terminal of the inductor to the voltage input terminal during a third time period; and the waveform of the current in the inductor changes from the smaller peak level to the smaller valley level by grounding the first connection terminal of the inductor again during a fourth time period.

[0011] Optionally, the plurality of switching devices includes a first switching device and a second switching device. The first switching device is coupled between the voltage input terminal and the first node. One end of the second switching device is coupled to the first node and the other end is grounded. The first connection terminal of the inductor is coupled to the first node. When the step controller controls the first switching device to close and controls the second switching device to open, the first connection terminal of the inductor is coupled to the voltage input terminal, and the current in the inductor rises from a valley value to a peak value. When the step controller controls the second switching device to close and controls the first switching device to open, the first connection terminal of the inductor is grounded, and the current in the inductor drops from a peak value to a valley value.

[0012] Optionally, the at least one output branch includes multiple output branches, each with a branch switch connected in series. The step controller is configured to close the branch switch on only one of the multiple output branches while opening the branch switches on the other output branches, so that the multiple output branches can time-division multiplex the inductor; or, the at least one output branch includes only one output branch, and the inductor is always used for the one output branch.

[0013] A second aspect of the present invention provides an electronic device comprising the DC-DC converter provided in the first aspect above.

[0014] In the above technical solution, the step controller is configured to control the conduction and disconnection of multiple switching devices based on the voltage output terminal of at least one output branch. This allows the conversion circuit to adjust the voltage output terminal of at least one output branch to the target value through an inductor, based on the voltage input terminal. At any given time, the inductor is used for only one output branch. When the inductor outputs voltage at the voltage output terminal of each output branch, the current in the inductor continuously rises from a valley to a peak value and then falls from the peak value back to a valley value. The step controller also controls the conduction and disconnection of multiple switching devices to make the valley value of the current waveform in the inductor change in a stepwise manner and all values ​​are greater than zero. This reduces the ripple of the current in the inductor and the ripple of the voltage output terminal, which helps to improve the performance of the circuit.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the circuit structure of a DC-DC converter;

[0018] Figure 2 For use Figure 1 The waveform of the current in the inductor during a DC-DC converter;

[0019] Figure 3 A schematic diagram of the circuit structure of a DC-DC converter provided in an embodiment of this application;

[0020] Figure 4 for Figure 3An exemplary waveform of the current in the inductor of a DC-DC converter;

[0021] Figure 5 A schematic diagram of the circuit structure of another DC-DC converter provided in an embodiment of this application;

[0022] Figure 6 for Figure 5 An exemplary waveform of the current in the inductor of a DC-DC converter;

[0023] Figure 7 for Figure 5 Another exemplary waveform diagram of the current in the inductor of a DC-DC converter;

[0024] Figure 8 This is a schematic diagram of the circuit structure of another DC-DC converter provided in the embodiments of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Figure 1 This is a schematic diagram of the circuit structure of a DC-DC converter. (Example) Figure 1 As shown, the circuit includes a discontinuous circuit control circuit, switches K1, K2, K3, and K4, inductor L1, capacitor C1, and capacitor C2. VIN is the input power supply. Switch K1 is coupled between the input power supply VIN and the first node SW1. One end of switch K2 is coupled to the first node SW1, and the other end is grounded. Switch K3 is coupled between the second node SW2 and the first voltage output terminal VO1. Switch K4 is coupled between the second node SW2 and the second voltage output terminal VO2. One end of capacitor C1 is coupled to the voltage output terminal VO1, and the other end is grounded. One end of capacitor C2 is coupled to the voltage output terminal VO2, and the other end is grounded. This DC-DC converter uses one inductor L1 to connect two output branches. The output terminal of the first output branch is the first voltage output terminal VO1, and the output terminal of the second output branch is the second voltage output terminal VO2, which can generate two output voltages. This is a single-inductor multi-output DC-DC converter, which is equivalent to multiple DC-DC converters sharing one inductor, thus saving the number of inductors.

[0027] Figure 2 For use Figure 1 The waveform of the current in the inductor during a DC-DC converter. Figure 2The dashed line represents zero current. During time period T1, switches K1 and K3 are on (other switches are off). During time period T1, the inductor current provides current to the first output branch. At this time, the inductor current rises with a slope of (VIN-VO1) / L, storing energy in inductor L1, where VIN is the input power supply voltage, VO1 is the voltage at the first voltage output terminal, and L is the inductance value of inductor L1. When the discontinuous control circuit detects that the inductor current has reached the first peak value Ipk1 (determined by the design) from zero, it controls the switch to the next time period (i.e., time period T2). During time period T2, switches K2 and K3 are on (other switches are off). During time period T2, the inductor current provides current to the first output branch. At this time, the inductor current drops from the peak value to zero with a slope of (-VO1) / L, releasing energy from inductor L1. When the discontinuous control circuit detects that the inductor current has reached zero, it controls the switch to the next time period. The system operates in two phases: Phase T3 and Phase T4. During Phase T3, switches K1 and K4 are on (other switches are off). The inductor current provides current to the second output branch. The inductor current rises with a slope of (VIN-VO2) / L, storing energy in inductor L1. Here, VIN is the input power supply voltage, and VO2 is the voltage at the second voltage output terminal. When the discontinuous control circuit detects that the inductor current has reached its second peak value Ipk2 (determined by the design), it switches to the next phase (P4). During Phase T4, switches K2 and K4 are on (other switches are off). The inductor current provides current to the second output branch. The inductor current decreases with a slope of (-VO2) / L, releasing energy from inductor L1. When the discontinuous control circuit detects that the inductor current has reached zero, it switches to the next phase (the next Phase T1). This allows for repeated cyclic control with a period from T1 to T4.

[0028] When the control periods of the two branches are equal, i.e., T1 + T2 = T3 + T4, where T1 is the time of period T1, T2 is the time of period T2, T3 is the time of period T3, and T4 is the time of period T4. With the above control method, when both outputs operate simultaneously, the maximum output current capability of each branch is approximately Ipk / 4, where Ipk is the peak current of one of the controlled branches. For example, for the first output branch, the inductor current peak is designed to be Ipk1, and the maximum output current value of the first output branch is Ipk1 / 4; for the second output branch, the inductor current peak is designed to be Ipk2, and the maximum output current value of the first output branch is Ipk2 / 4. Similarly, if designed with a single inductor and N outputs, when all N outputs operate simultaneously, the maximum output current capability of each branch is approximately IpkN / (2×n), where IpkN is the peak inductor current of the nth branch, and n is the number of output branches. For example, if there are 10 outputs, then n = 10. To meet the maximum load capacity requirement, Ipk is designed to be very large. For applications with very high maximum load capacity requirements, Ipk is designed to be extremely large, and the more output branches there are, the larger Ipk needs to be, resulting in greater current ripple.

[0029] Assuming the inductor current ripple is ΔI within a period T, according to the charge formula: ΔQ = ΔI·T, where ΔQ is the change in charge within time T, ΔI is the current ripple (i.e., the change in current) within time T, and T is the time period. According to the capacitance formula: ΔQ = ΔV·C, where ΔQ is the change in charge within time T, ΔV is the voltage ripple across the capacitor within time T (i.e., the change in capacitor voltage), and T is the time period. Solving these two formulas simultaneously yields: It is evident that the voltage ripple across the capacitor is directly proportional to the inductor current ripple ΔI. Therefore, the larger the current ripple, the greater the ripple will be for the same output capacitor value (i.e., ...). Figure 1 The capacitance value of C1 or C2 will also lead to a larger output voltage ripple.

[0030] Therefore, embodiments of this application provide a DC-DC converter and electronic device that reduce the ripple of the inductor current and the voltage output at the voltage output terminal, thereby improving the performance of the circuit.

[0031] Figure 3 This is a schematic diagram of the circuit structure of a DC-DC converter provided in an embodiment of this application. Figure 3 As shown, the DC-DC converter includes a conversion circuit and a stepped controller. The conversion circuit includes an inductor L1, multiple switching devices, a voltage input terminal VIN, and at least one output branch. Each output branch includes a voltage output terminal and an output capacitor with one end coupled to the voltage output terminal and the other end grounded. Figure 3The diagram shows a first voltage output terminal VO1 and an output capacitor C1. One end of the output capacitor C1 is coupled to the voltage output terminal VO1, and the other end is grounded. Multiple switching devices include a first switching device K1 (hereinafter referred to as "switch K1"), a second switching device K2 (hereinafter referred to as "switch K2"), and a third switching device K3 (hereinafter referred to as "switch K3"). Switch K1 is coupled to the voltage input terminal VIN and the first node SW1. One end of switch K2 is coupled to the first node SW1, and the other end is grounded. Switch K3 is coupled to the second node SW2 and the first voltage output terminal VO1. An inductor L1 is coupled between the first node SW1 and the second node SW2. The ladder controller is configured to control the on and off states of the multiple switching devices based on the voltage output from at least one output branch, such that the conversion circuit adjusts the voltage output from at least one output branch to a target value based on the voltage input from the voltage input terminal VIN via the inductor L1. At any given moment, when inductor L1 is used for only one output branch and outputs voltage at the voltage output terminal of each output branch, the current in inductor L1 continuously rises from the valley to the peak value and then falls from the peak value back to the valley value. The step controller also controls the conduction and disconnection of multiple switching devices to make the valley value of the current waveform change in a step manner and all of them are greater than zero.

[0032] Continue to refer to Figure 3 When the first voltage output terminal VO1 needs to output voltage, the step controller controls switch K3 to close. Then, the step controller controls switch K1 to close and switches K2 to open. The first connection terminal of inductor L1 is coupled to the voltage input terminal VIN. The current in inductor L1 continuously rises from the valley value to the peak value. Then, the step controller controls switch K2 to close and switches K1 to open. The first connection terminal of inductor L1 is grounded, and the current in inductor L1 continuously decreases from the peak value to the valley value.

[0033] At least one output branch may consist of only one output branch, and inductor L1 is always used for that single output branch, such as... Figure 3 As shown. It is understandable that two, three or more output branches can be set as needed, and the switches and capacitors on each output branch can be increased accordingly to realize an N-way output structure.

[0034] In the above technical solution, the step controller is configured to control the conduction and disconnection of multiple switching devices based on the voltage output terminal of at least one output branch. This allows the conversion circuit to adjust the voltage output terminal of at least one output branch to the target value through an inductor, based on the voltage input terminal. At any given time, the inductor is used for only one output branch. When the inductor outputs voltage at the voltage output terminal of each output branch, the current in the inductor continuously rises from a valley to a peak value and then falls from the peak value back to a valley value. The step controller also controls the conduction and disconnection of multiple switching devices to make the valley value of the current waveform in the inductor change in a stepwise manner and all values ​​are greater than zero. This reduces the ripple of the current in the inductor and the ripple of the voltage output terminal, which helps to improve the performance of the circuit.

[0035] To further reduce the ripple of the current in inductor L1, embodiments of this application can perform quantized step control not only on the valley value of the current in inductor L1, but also on the peak value of the current in inductor L1. Specifically, the step controller can also be configured to control the on and off of multiple switching devices, so that when inductor L1 is used in each output branch, the peak value of the current waveform in inductor L1 changes in a step, and the trend of the step change of the peak value is consistent with the trend of the step change of the valley value. That is, the peak value and valley value of the current in inductor L1 can be quantized and controlled in a step simultaneously. For example, when the valley value of the current decreases, the peak value of the current can be decreased accordingly; when the peak value of the current increases, the valley value of the current can be increased accordingly, so that the difference between the peak value and the valley value of the current is small, thereby reducing the current ripple.

[0036] Specifically, when inductor L1 is used to output voltage at the voltage output terminal of each output branch, the current in inductor L1 can include multiple successively increasing valley steps, each valley step having a corresponding valley value. The valley value of the current waveform can switch between at least two selected valley steps. When inductor L1 is used to output voltage at the voltage output terminal of each output branch, the current in inductor L1 can include multiple successively increasing peak steps, each peak step having a corresponding peak value. The peak value of the current waveform can switch between at least two selected peak steps. The step controller controls the on and off of multiple switching devices based on a comparison between the current in inductor L1 and at least two selected valley steps and at least two selected peak steps.

[0037] The process of the current in inductor L1 rising from a valley to a peak and then falling back to a valley forms a pulse. The waveform of the current in inductor L1 changes periodically. Within one cycle, the waveform of the current in inductor L1 includes at least one larger pulse formed by the larger peak level among at least two peak levels and the larger valley level among at least two valley levels, and at least one smaller pulse formed by the smaller peak level among at least two peak levels and the smaller valley level among at least two valley levels.

[0038] Figure 4 for Figure 3 An exemplary waveform of the current in the inductor of a DC-DC converter. (e.g.) Figure 4 As shown, the current waveform includes a larger peak value IpkH, a smaller peak value IpkL, a larger valley value IvH, and a smaller valley value IvL. Since the difference between the larger peak value IpkH and the smaller valley value IvL is large when the current in inductor L1 varies between these two values ​​within a time period, this results in large current ripple. Therefore, within a time period such as T1 and T3, the current in inductor L1 can vary between the larger peak value IpkH and the larger valley value IvH to form a larger pulse, thus reducing the difference between them and minimizing current ripple. Similarly, within another time period such as T2 and T4, the current in inductor L1 can vary between the smaller peak value IpkL and the smaller valley value IvL to form a smaller pulse, thus minimizing the difference between them and minimizing current ripple.

[0039] Continue to refer to Figure 3 and Figure 4 When the valley of the current waveform switches between two valley levels and the peak value switches between two peak levels, the waveform of the current in inductor L1 changes from the larger valley level IvH to the larger peak level IpkH by coupling the first connection terminal of inductor L1 to the voltage input terminal VIN during the first time period T1; the waveform of the current in inductor L1 changes from the larger peak level IpkH to the larger valley level IvH by grounding the first connection terminal of inductor L1 during the second time period T2; the waveform of the current in inductor L1 changes from the larger valley level IpkH to the smaller peak level IpkL by re-coupling the first connection terminal of inductor L1 to the voltage input terminal VIN during the third time period T3; and the waveform of the current in inductor L1 changes from the smaller peak level IpkL to the smaller valley level IvL by grounding the first connection terminal of inductor L1 during the fourth time period T4.

[0040] Figure 5 This is a schematic diagram of the circuit structure of another DC-DC converter provided in an embodiment of this application. Figure 3The difference in the circuit of the DC-DC converter shown is that, Figure 5 In the circuit of the DC-DC converter shown, inductor L1 connects two output branches. The output terminal of the first output branch is the first voltage output terminal VO1, and the output terminal of the second output branch is the second voltage output terminal VO2. A fourth switching device K4 (hereinafter referred to as "switch K4") is connected in series on the second output branch. The conversion circuit also includes an output capacitor C2, one end of which is coupled to the second voltage output terminal VO2, and the other end is grounded.

[0041] In other words, the second connection terminal of inductor L1 can be coupled to multiple output branches. The output terminal of each output branch is a voltage output terminal. Each output branch has a branch switch such as switch K3 and switch K4 connected in series. The ladder controller is configured to control the branch switch such as K3 (or K4) on one of the multiple output branches to close while controlling the branch switches such as K4 (or K3) on other output branches to open, so that multiple output branches can time-division multiplex inductor L1.

[0042] In addition, Figure 5 The control method of the intermediate-level controller and Figure 3 The control methods of intermediate-level controllers are also different, which will be discussed below. Figure 6 and Figure 7 A detailed introduction will follow.

[0043] Figure 6 for Figure 5 An exemplary waveform of the current in the inductor of a DC-DC converter. (e.g.) Figure 6As shown, the dashed line is still the zero current line. The current waveform of inductor L1 can be designed so that the valley value is higher than 0, and the current ripple of inductor L1 is designed to be small, allowing the current valley value of inductor L1 to switch between two adjacent current steps. During the T1 period, switches K1 and K3 are turned on (other switches are turned off). During the T1 period, the inductor current provides current to the first output branch (output terminal is VO1). At this time, the inductor current rises with a slope of (VIN-VO1) / L to store energy in inductor L1. When the step controller detects that the inductor current reaches IpkH, it controls the switch to enter the next period state (i.e., the T2 period). Here, IpkH is designed to be IvH+ΔI, where IpkH is the higher value of the current peak, IvH is the higher value of the current valley, and ΔI is the difference between the current peak and valley. During the T2 period, switches K2 and K3 are turned on (other switches are turned off). During the T2 period, the inductor current provides current to the first output branch (output terminal is VO1). The inductor L1 provides current to the output branch (output terminal VO1). At this time, the inductor current decreases with a slope of (-VO1) / L, releasing energy. When the step controller detects that the inductor current reaches IvH, it switches to the next time period (T3). During T3, switches K1 and K4 are turned on (other switches are off). The inductor current provides current to the second output branch (output terminal VO2). At this time, the inductor current increases with a slope of (VIN-VO2) / L, storing energy in inductor L1. When the step controller detects that the inductor current reaches IpkH, it switches to the next time period (T4). Here, IpkH is designed to be IvH + ΔI, where IpkH = IvH + ΔI. H represents the higher peak value of the current, IvH represents the higher valley value of the current, and ΔI represents the difference between the peak and valley values ​​of the current. During period T4, switches K2 and K4 are turned on (other switches are turned off). During period T4, the inductor current provides current to the second output branch (output terminal VO2). At this time, the inductor current decreases at a slope of (-VO2) / L, and inductor L1 releases energy. When the step controller detects that the inductor current reaches IvH, it controls the switch to enter the next period state (i.e., the next period T5). During period T5, switches K1 and K3 are turned on (other switches are turned off). During period T5, the inductor current provides current to the first output branch (output terminal VO1). At this time, the inductor current decreases at a slope of (VIN-VO1). As the slope of the current increases, energy is stored in inductor L1. When the step controller detects that the inductor current reaches IpkL, it switches to the next time period (i.e., time period T6). Here, IpkL is designed as IvL + ΔI, where IpkL is the lower value of the current peak, IvL is the lower value of the current valley, and ΔI is the difference between the current peak and valley. During time period T6, switches K2 and K3 are turned on (other switches are turned off). During time period T6, the inductor current provides current to the first output branch. At this time, the inductor current decreases at a slope of (-VO1) / L, and inductor L1 releases energy. When the step controller detects that the inductor current reaches IvL, it switches to the next time period (i.e., time period T7).During time period T7, switches K1 and K4 are turned on (other switches are turned off). The inductor current provides current to the second output branch (output terminal VO2) during time period T7. At this time, the inductor current rises with a slope of (VIN-VO2) / L, storing energy in inductor L1. When the step controller detects that the inductor current reaches IpkL, it controls the switch to the next time period (i.e., time period T8). IpkL is designed as IvL + ΔI, where IpkL is the lower peak value of the current, IvL is the lower valley value of the current, and ΔI is the difference between the peak and valley values ​​of the current. During time period T8, switches K2 and K4 are turned on (other switches are turned off). The inductor current provides current to the second output branch during time period T8. At this time, the inductor current decreases with a slope of (-VO2) / L, releasing energy from inductor L1. When the step controller detects that the inductor current reaches Iv2L, it controls the switch to the next time period (i.e., the next time period).

[0044] The current supplied to the first output branch during periods T1 and T2 can be considered as one pulse, and the current supplied to the first output branch during periods T5 and T6 can be considered as a second pulse. The current supplied to the second output branch during periods T3 and T4 can be considered as one pulse, and the current supplied to the first output branch during periods T7 and T8 can be considered as a second pulse.

[0045] Additionally, it should be noted that the IpkH of the first output branch and the IpkH of the second output branch can be the same or different; the IpkL of the first output branch and the IpkL of the second output branch can be the same or different; the IvH of the first output branch and the IvH of the second output branch can be the same or different; the IvL of the first output branch and the IvL of the second output branch can be the same or different; these values ​​can be selected as needed. Furthermore, for the formula "IpkH = IvH + ΔI", any two of the three values ​​"IpkH, IvH, ΔI" can be determined first during the design process; for the formula "IpkL = IvL + ΔI", any two of the three values ​​"IvL, IpkL, ΔI" can be determined first during the design process.

[0046] In this method, a set number of pulses can be used as an adjustment cycle. When the voltage output at the voltage output terminal is lower than the lower limit of the target value, the number of smaller pulses in the set number of pulses in one adjustment cycle is reduced and the number of larger pulses is increased accordingly, so as to increase the proportion of larger pulses in the set number of pulses.

[0047] When the number of smaller pulses decreases to zero, if the voltage output at the voltage output terminal is lower than the lower limit of the target value, at least two valley levels can be reselected from the multi-level valley levels, and at least one of the reselected valley levels is greater than the larger valley level of the previously selected at least two valley levels. The current waveform switches between the reselected at least two valley levels. Alternatively or further, at least two peak levels can be reselected from the multi-level valley levels, and at least one of the reselected peak levels is greater than the larger peak level of the previously selected at least two peak levels. The current waveform switches between the reselected at least two peak levels. Specifically, this can be done in, but is not limited to, the following two ways:

[0048] The first method

[0049] In a set number of pulses within an adjustment cycle, the number of larger pulses can be reduced and the number of previous-level pulses can be increased accordingly. The valley value of the previous-level pulse is the valley level above the larger of the two adjacent valley levels, so that the current waveform switches between the larger of the two adjacent valley levels and the valley level above the larger one. That is, one of the at least two reselected valley levels can be the larger of the at least two previously selected valley levels, and the other of the at least two reselected valley levels is the valley level above the larger of the at least two previously selected valley levels.

[0050] Specifically, in a step controller, several current valley levels Is1, Is2, Is3, ... IsM and several current peak levels Ip1, Ip2, Ip3, ... IpM can be set. The values ​​of the several current valley levels can be increased sequentially. The step controller selects two adjacent values ​​as the inductor current valley control. In one example, the step controller selects Is7 and Is8 as valley values ​​(i.e., setting IvL = Is7, IvH = Is8). If the step controller detects that one of the output voltages is lower than the target lower limit, it increases the pulse ratio with Is8 as the valley value. Taking 20 consecutive pulses as an example, the pulse with Is8 as the valley value can be any value between 0 / 20 and 20 / 20, that is, its ratio can be x / 20, where x varies from an integer between 0 and 20. If the step controller detects that the output voltage is below the target lower limit and the proportion of higher valley values ​​has increased to the maximum value, such as 20 / 20, the step controller will select a larger valley value step, such as Is8 and Is9, as the valley value to mix the two current valley values ​​of Is8 and Is9 for modulation.

[0051] In addition, the peak value of the previous pulse can also be switched to the previous peak value of the larger of the two adjacent peak values, so that the ripple of the previous pulse is smaller. That is, one of the at least two reselected peak values ​​can be the larger of the at least two previously selected peak values, and the other of the at least two reselected valley values ​​can be the previous peak value of the larger of the at least two previously selected peak values.

[0052] The second method

[0053] The two newly selected valley orders can both be greater than the two previously selected valley orders; the two newly selected peak orders can both be greater than the two previously selected peak orders. For example, the two previously selected valley orders could be Is7 and Is8, and the two newly selected valley orders could be Is9 and Is10; the two previously selected peak orders could be Ip7 and Ip8, and the two newly selected peak orders could be Ip9 and Ip10.

[0054] Alternatively, a set number of pulses can be used as an adjustment cycle. When the voltage output at the voltage output terminal is higher than the upper limit of the target value, the number of larger pulses in the set number of pulses in one adjustment cycle is reduced and the number of smaller pulses is increased accordingly, so as to increase the proportion of smaller pulses in the set number of pulses.

[0055] When the number of large pulses decreases to zero, if the voltage output at the voltage output terminal is still higher than the upper limit of the target value, at least two valley levels can be reselected from the multi-level valley levels, and at least one of the reselected valley levels is less than the smaller valley level of the previously selected at least two valley levels. The current waveform switches between the reselected at least two valley levels. Alternatively or further, at least two peak levels can be reselected from the multi-level valley levels, and at least one of the reselected peak levels is less than the smaller peak level of the previously selected at least two peak levels. The current waveform switches between the reselected at least two peak levels. Specifically, this can be done in, but is not limited to, the following two ways:

[0056] The first method

[0057] Within a set number of pulses in an adjustment cycle, the number of smaller pulses can be reduced and the number of next-level pulses can be increased accordingly. The valley value of the next-level pulse is the next-level valley value of the smaller of the two adjacent valley values, so that the waveform of the current switches between the next-level valley value of the smaller of the two adjacent valley values ​​and the smaller one. That is, one of the at least two reselected valley values ​​can be the smaller of the at least two previously selected valley values, and the other of the at least two reselected valley values ​​is the next-level valley value of the smaller of the at least two previously selected valley values.

[0058] Specifically, in one example, the step controller selects Is7 and Is8 as valley values ​​(i.e., IvL = Is7, IvH = Is8). If the step controller detects that one of the output voltages is higher than the upper limit of the target value, it reduces the pulse ratio with Is8 as the valley value. Taking 20 consecutive pulses as an example, the pulse with Is8 as the valley value can be any value between 0 / 20 and 20 / 20, that is, its ratio can be x / 20, where x varies from 0 to 20. When x decreases to 0, there are two possible methods: (1) The step controller will select a smaller valley step as the current valley value, such as Is6 and Is7 as valley values, to mix the two current valley values ​​Is6 and Is7 for modulation; (2) The current output of this output branch can be skipped. For example, when the output voltage of the first output branch is higher than the upper limit of the target value and x has decreased to 0, the current output of the first output branch can be skipped and the mode of only outputting current to the second output branch can be operated. That is, switches K1 and K4 are turned on for a period of time, switches K2 and K4 are turned on for another period of time, and then the process is repeated. Switch K3 does not participate in the turn-on.

[0059] In addition, the peak value of the next-level pulse can also be switched to the next-level peak value of the smaller of the two adjacent peak values, so that the ripple of the next-level pulse is smaller. That is, one of the reselected at least two peak values ​​can be the smaller of the previously selected at least two peak values, and the other of the reselected at least two peak values ​​is the next-level peak value of the smaller of the previously selected at least two peak values.

[0060] The second method

[0061] The two newly selected valley orders can both be smaller than the two previously selected valley orders; the two newly selected peak orders can both be smaller than the two previously selected peak orders. For example, the two previously selected valley orders could be Is7 and Is8, and the two newly selected valley orders could be Is4 and Is5; the two previously selected peak orders could be Ip7 and Ip8, and the two newly selected peak orders could be Ip4 and Ip5.

[0062] Figure 7 for Figure 5 Another exemplary waveform diagram of the current in the inductor of a DC-DC converter. (e.g.) Figure 7 As shown, the waveform of the inductor current includes three peak levels Ipk1, Ipk2, and Ipk3, and three valley levels Iv1, Iv2, and Iv3. The step controller can control... Figure 5The switching of multiple switching devices causes the inductor current waveform to have a large repetition period of T1 to T12. During the T1-T2 period, charge is supplied to the first output branch, and the peak value of the current waveform is Ipk3, and the valley value is Iv3; during the T3-T4 period, charge is supplied to the second output branch, and the peak value of the current waveform is Ipk3, and the valley value is Iv3; during the T5-T6 period, charge is supplied to the first output branch, and the peak value of the current waveform is Ipk2, and the valley value is Iv2; during the T7-T8 period, charge is supplied to the second output branch, and the peak value of the current waveform is Ipk2, and the valley value is Iv2; during the T9-T10 period, charge is supplied to the first output branch, and the peak value of the current waveform is Ipk1, and the valley value is Iv1; during the T11-T12 period, charge is supplied to the second output branch, and the peak value of the current waveform is Ipk1, and the valley value is Iv1.

[0063] Figure 8 This is a schematic diagram of the circuit structure of another DC-DC converter provided in an embodiment of this application. Figure 5 The difference in the circuit of the DC-DC converter shown is that, Figure 8 By adding switch K5 and output capacitor C3, three outputs are achieved. Switch K5 is coupled between the second node SW2 and the third voltage output terminal VO3. One end of capacitor C3 is coupled to the third voltage output terminal VO3, and the other end is grounded. The step controller can control the on and off of switch K5. Figure 8 The control method of the DC-DC converter in the middle can be referred to Figure 5 The control method of the DC-DC converter is shown.

[0064] In addition, this application also provides an electronic device that includes the aforementioned DC-DC converter.

[0065] In summary, in this embodiment, the step controller is configured to control the on and off of multiple switching devices based on the voltage output of at least one output branch. This allows the conversion circuit to adjust the voltage output of at least one output branch to a target value via inductor L1, based on the voltage input at the voltage input terminal. At any given time, the inductor is used only for one output branch, and when the inductor outputs voltage at the voltage output terminal of each output branch, the current in inductor L1 continuously rises from a valley to a peak value, and then falls from the peak value back to a valley value. Furthermore, by controlling the on and off of multiple switching devices, the step controller makes the valley values ​​of the current waveform in inductor L1 change in a stepwise manner, all of which are greater than zero. This reduces the ripple of the current in inductor L1 and the ripple of the voltage output at the voltage output terminal, thus improving the performance of the circuit.

[0066] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0067] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A DC-DC converter, characterized in that, include: A conversion circuit includes an inductor, multiple switching devices, a voltage input terminal, and at least one output branch. Each output branch includes a voltage output terminal and an output capacitor with one end coupled to the voltage output terminal and the other end grounded. When the inductor outputs a voltage at the voltage output terminal of each output branch, the current in the inductor includes a series of progressively increasing valley levels, each valley level having a corresponding valley value. The valley value of the current waveform switches between at least two selected valley levels in the series of valley levels. When the inductor is used to output voltage at the voltage output terminal of each output branch, the current in the inductor includes multiple peak steps that increase sequentially, each peak step having a corresponding peak value, and the peak value of the current waveform switches between at least two peak steps selected in the multiple peak steps. A step controller is configured to control the on and off of the plurality of switching devices based on the voltage output of the voltage output terminal of the at least one output branch, such that the conversion circuit adjusts the voltage output of the voltage output terminal of the at least one output branch to a target value through the inductor based on the voltage input at the voltage input terminal. The step controller controls the on and off of the plurality of switching devices by comparing the current in the inductor with at least two selected valley steps and at least two selected peak steps. The process of the current in the inductor rising from a valley to a peak and then falling back to a valley forms a pulse. The waveform of the inductor current changes periodically. Within one cycle, the waveform of the inductor current includes at least one larger pulse formed by the larger peak level and the larger valley level among at least two selected peak levels, and at least one smaller pulse formed by the smaller peak level and the smaller valley level among at least two selected peak levels. A set number of pulses is used as an adjustment cycle. When the voltage output at the voltage output terminal is lower than the lower limit of the target value, the number of smaller pulses in the set number of pulses in one adjustment cycle is reduced and the number of larger pulses is increased accordingly to increase the proportion of larger pulses in the set number of pulses. When the number of smaller pulses decreases to zero, if the voltage output at the voltage output terminal is lower than the lower limit of the target value, wherein: In the multi-level valley steps, at least two valley steps are reselected, and at least one of the reselected valley steps is greater than the larger valley step of the previously selected at least two valley steps; the waveform of the current switches between the reselected at least two valley steps; and / or, At least two peak levels are reselected in the multi-level peak levels, and at least one of the reselected peak levels is greater than the larger peak level of the previously selected at least two peak levels, and the waveform of the current switches between the reselected at least two peak levels. At any given time, the inductor is used only for one output branch, and when the inductor is used to output voltage at the voltage output terminal of each output branch, the current in the inductor continuously rises from a valley value to a peak value, and then falls from the peak value to a valley value. The step controller also controls the conduction and disconnection of the multiple switching devices to make the valley value of the current waveform change in a step manner and all of them are greater than zero.

2. The DC-DC converter according to claim 1, characterized in that, The step controller is further configured to control the on and off of the plurality of switching devices, such that when the inductor is used in each output branch, the peak value of the current waveform in the inductor changes in a step manner, and the trend of the step change of the peak value is consistent with the trend of the step change of the valley value.

3. The DC-DC converter according to claim 1, characterized in that, Using a set number of pulses as an adjustment cycle, when the voltage output at the voltage output terminal is higher than the upper limit of the target value, the number of larger pulses in the set number of pulses in one adjustment cycle is reduced and the number of smaller pulses is increased accordingly, so as to increase the proportion of smaller pulses in the set number of pulses; When the number of larger pulses decreases to zero, if the voltage output at the voltage output terminal is still higher than the upper limit of the target value, wherein: At least two valley levels are reselected in the multi-level valley levels, and at least one of the reselected valley levels is smaller than the smaller valley level of the previously selected at least two valley levels, and the waveform of the current switches between the reselected valley levels. And / or, At least two peak levels are reselected in the multi-level peak levels, and at least one of the reselected peak levels is less than the smaller peak level of the previously selected at least two peak levels, and the waveform of the current switches between the reselected at least two peak levels.

4. The DC-DC converter according to claim 1, characterized in that, When the valley of the current waveform switches between two valley levels and the peak value switches between two peak levels, By coupling the first connection terminal of the inductor to the voltage input terminal during the first time period, the waveform of the current in the inductor changes from the larger valley level of the two valley levels to the larger peak level of the two peak levels; by grounding the first connection terminal of the inductor during the second time period, the waveform of the current in the inductor changes from the larger peak level to the larger valley level. By reconnecting the first connection terminal of the inductor to the voltage input terminal during the third time period, the waveform of the current in the inductor changes from the larger valley level of the two valley levels to the smaller peak level of the two peak levels; by grounding the first connection terminal of the inductor again during the fourth time period, the waveform of the current in the inductor changes from the smaller peak level to the smaller valley level.

5. The DC-DC converter according to any one of claims 1-4, characterized in that, The plurality of switching devices includes a first switching device and a second switching device. The first switching device is coupled between the voltage input terminal and the first node. One end of the second switching device is coupled to the first node and the other end is grounded. The first connection terminal of the inductor is coupled to the first node. When the step controller controls the first switching device to close and controls the second switching device to open, the first connection terminal of the inductor is coupled to the voltage input terminal, and the current in the inductor rises from the valley value to the peak value; When the step controller controls the second switching device to close and controls the first switching device to open, the first connection terminal of the inductor is grounded, and the current in the inductor drops from the peak value to the valley value.

6. The DC-DC converter according to any one of claims 1-4, characterized in that: The at least one output branch includes multiple output branches, each with a branch switch connected in series. The ladder controller is configured to close the branch switch on only one of the multiple output branches while opening the branch switches on the other output branches, so that the multiple output branches time-division multiplex the inductor; or... The at least one output branch includes only one output branch, and the inductor is always used for the one output branch.

7. An electronic device, characterized in that, The electronic device includes a DC-DC converter as claimed in any one of claims 1 to 6.

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