DC-dc converter

Abstract

The application relates to the technical field of power conversion circuits, and discloses a DC-DC converter which comprises an inductor, a plurality of branch switches and a charge pump module, wherein each branch switch is connected between the inductor and a corresponding voltage output end, the control end of each branch switch receives a corresponding switch control signal, each branch switch is turned on when the corresponding switch control signal is high, and is turned off when the corresponding switch control signal is low; the charge pump module comprises a switch combination and an energy storage capacitor, when one switch control signal is switched from high to low, the charge at the control end of the branch switch corresponding to the switch control signal is stored into the energy storage capacitor through the switch combination, and when one switch control signal is switched from low to high, the charge in the energy storage capacitor is delivered to the control end of the branch switch corresponding to the switch control signal through the switch combination. The application solves the problem of large switch loss when a gating switch is switched in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power conversion circuit, in particular to a DC-DC converter. BACKGROUND

[0002] As an important voltage conversion module, DC-DC converter can convert a given voltage signal into a user required result, and is widely used in various types of power management chips. Generally, for a specific output voltage, a separate inductor is needed. Since the area of high inductance inductor is generally large, the integration is poor, and the cost is also relatively high, which is not suitable for the current era of increasing integration.

[0003] Single inductor multiple output (SIMO) DC-DC converter has the function of obtaining multiple outputs by using a single inductor, reduces the number of components and the overall size, and provides efficient power distribution, greatly reducing the use cost of DC-DC converter, and is increasingly widely used in various scenarios today.

[0004] However, since a common inductor is used, the size of the corresponding shunt switch needs to be selected to be large to accurately adjust each output channel to ensure stability and reduce the output voltage regulation rate in high load scenarios. The larger size of the shunt switch will increase the switching loss due to its larger gate parasitic parameters. Therefore, an important step to improve the efficiency of SIMO type DCDC is to reduce the switching loss of the shunt switch during switching operation. SUMMARY

[0005] Therefore, the present application provides a DC-DC converter to solve the problem of large switching loss of the shunt switch during switching operation in the prior art.

[0006] In a first aspect, the present application provides a DC-DC converter, comprising: an inductor, a plurality of branch switches and a charge pump module, wherein,

[0007] Each branch switch is connected between the inductor and a corresponding voltage output terminal, and the control end of each branch switch receives a corresponding switch control signal. Each branch switch is turned on when the corresponding switch control signal is high, and is turned off when the corresponding switch control signal is low.

[0008] The charge pump module comprises a switch combination and an energy storage capacitor, when a switch control signal is switched from high level to low level, the charge of the control end of the branch switch corresponding to the switch control signal is stored into the energy storage capacitor through the switch combination, when a switch control signal is switched from low level to high level, the charge in the energy storage capacitor is delivered to the control end of the branch switch corresponding to the switch control signal through the switch combination.

[0009] In the conventional design, the charge of the control end of the branch switch is usually discharged to the ground after each switching, while in the present application, the charge is temporarily stored, and when the next branch switch is turned on, the temporarily stored charge is released to the control end of the next branch switch, thereby increasing the voltage of the control end of the next branch switch, reducing the on-resistance of the branch switch, reducing the on-loss, and at the same time, recycling the control end charge and reducing the switching loss.

[0010] In an alternative embodiment, each branch switch is an NMOS transistor, and the gate of the NMOS transistor is the control end of the branch switch.

[0011] Only one of the plurality of branch switches is on at the same time, and the other branch switches are off, and each branch switch is turned on in a regular order.

[0012] After a branch switch is switched from on to off, a dead time is waited, and then the next branch switch is switched from off to on, and during the dead time, all branch switches are off.

[0013] In an alternative embodiment, the DC-DC converter further comprises a first power transistor and a second power transistor.

[0014] The first power transistor connects or disconnects the input voltage and the switch node according to the first driving signal of the gate thereof, and the second power transistor connects or disconnects the ground and the switch node according to the second driving signal of the gate thereof.

[0015] The inductor is connected between the switch node and the branch switch.

[0016] When the first driving signal is low, the first power transistor connects the input voltage and the switch node, and when the first driving signal is high, the first power transistor disconnects the input voltage and the switch node.

[0017] When the second driving signal is high, the second power transistor connects the ground and the switch node, and when the second driving signal is low, the second power transistor disconnects the ground and the switch node.

[0018] The second power transistor is turned off when the first power transistor is turned on, and the first power transistor is turned off when the second power transistor is turned on.

[0019] In an alternative embodiment, the switch combination includes a first switch combination, a second switch combination and a third switch combination, wherein,

[0020] The first switch combination selectively connects the first connection end of the energy storage capacitor to the power supply end or the ground end;

[0021] The second switch combination selectively connects the second connection end of the energy storage capacitor to the control end of any branch switch;

[0022] The third switch combination selectively connects the second connection end of the energy storage capacitor to the control end of all branch switches.

[0023] In an alternative embodiment, when one switch control signal jumps from high level to low level and all switch control signals are low level, the first switch combination connects the first connection end of the energy storage capacitor to the ground end, and the third switch combination connects the second connection end of the energy storage capacitor to the control end of all branch switches, so that the charge of the control end of the branch switch corresponding to the one switch control signal is stored into the energy storage capacitor through the third switch combination;

[0024] When one switch control signal switches from low level to high level, the first switch combination connects the first connection end of the energy storage capacitor to the power supply end, and the second switch combination connects the second connection end of the energy storage capacitor to the control end of the branch switch corresponding to the switch control signal, so that the charge in the energy storage capacitor is delivered to the control end of the corresponding branch switch through the second switch combination.

[0025] In an alternative embodiment, the first switch combination includes a first switch unit and a second switch unit, the first switch unit is connected between the first connection end of the energy storage capacitor and the ground end, and the second switch unit is connected between the first connection end of the energy storage capacitor and the power supply end;

[0026] The second switch combination includes a plurality of third switch units, each third switch unit is connected between the second connection end of the energy storage capacitor and the control end of a corresponding branch switch;

[0027] The third switch combination includes a plurality of fourth switch units, each fourth switch unit is connected between the second connection end of the energy storage capacitor and the control end of a corresponding branch switch.

[0028] In an alternative embodiment, when one of the switch control signals is switched from high to low and all the switch control signals are low, the first switch unit is turned on, the second switch unit is turned off, all the fourth switch units are turned on, and all the third switch units are turned off, so that the first connection end of the energy storage capacitor is connected to the ground end, and the charge of the control end of the branch switch corresponding to the one of the switch control signals is stored in the energy storage capacitor through the fourth switch unit.

[0029] When one of the switch control signals is switched from low to high, the first switch unit is turned off, the second switch unit is turned on, so that the first connection end of the energy storage capacitor is connected to the power supply end, the third switch unit corresponding to the one of the switch control signals is turned on, and the other third switch units are turned off, and the fourth switch units are turned off, so that the second connection end of the energy storage capacitor is connected to the control end of the corresponding branch switch through the corresponding third switch unit, and the charge of the second connection end of the energy storage capacitor is transmitted to the control end of the corresponding branch switch through the corresponding third switch unit.

[0030] In an alternative embodiment, the first switch unit is an NMOS transistor, the drain and source of the NMOS transistor are used as the connection end of the first switch unit, and the gate of the NMOS transistor is used as the control end of the first switch unit.

[0031] The second switch unit is a PMOS transistor.

[0032] The third switch unit is a PMOS transistor.

[0033] The fourth switch unit is a PMOS transistor.

[0034] The drain and source of the PMOS transistor are used as the connection end of the second switch unit, the third switch unit, and the fourth switch unit, and the gate of the PMOS transistor is used as the control end of the second switch unit, the third switch unit, and the fourth switch unit.

[0035] In an alternative embodiment, the first switch combination and the third switch combination further comprise a third logic control circuit.

[0036] The third logic control circuit comprises an OR gate.

[0037] Each of the switch control signals is input into the OR gate, and the output end of the OR gate is connected to the gate of each of the fourth switch units.

[0038] The first switch combination further comprises a first logic control circuit.

[0039] The first logic control circuit comprises the OR gate in the third logic control circuit and a first inverter, that is, the OR gate is shared by the third logic control circuit and the first logic control circuit.

[0040] The output of the OR gate is connected to the gates of the first and second switching units via the first inverter.

[0041] In one alternative embodiment, the second switch combination further includes a second logic control circuit;

[0042] The second logic control circuit includes multiple second inverters, each second inverter corresponds to a third switching unit, and each switching control signal is connected to the gate of the third switching unit through a corresponding second inverter.

[0043] Each switch control signal is connected to the control terminal of the corresponding branch switch. Attached Figure Description

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a structural diagram of a DC-DC converter based on related technologies;

[0046] Figure 2 This is another DC-DC converter structure diagram related to the technology;

[0047] Figure 3 This is a voltage waveform diagram of a branch switch in a DC-DC converter, which is related to the technology.

[0048] Figure 4 This is a structural diagram of a first embodiment of a DC-DC converter according to an embodiment of the present invention;

[0049] Figure 5 This is a structural diagram of a second embodiment of a DC-DC converter according to an embodiment of the present invention;

[0050] Figure 6 This is a structural diagram of a third embodiment of a DC-DC converter according to an embodiment of the present invention;

[0051] Figure 7 This is a detailed structural diagram of a fourth embodiment of a DC-DC converter according to an embodiment of the present invention;

[0052] Figure 8 This is a structural diagram of a fourth embodiment of a DC-DC converter according to another embodiment of the present invention;

[0053] Figure 9 is a voltage waveform diagram of each node of a DC-DC converter according to an embodiment of the present application. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0055] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0056] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In the present application, the words such as "connection", "connection", "connection", "connection", "coupling" and the like represent electrical connection, unless otherwise specified, which means direct or indirect electrical connection. The direct electrical connection means the direct connection between two or more objects without any inserted object, and the indirect electrical connection means the connection between two or more objects with one or more objects (such as resistors, capacitors, inductors, switches, filters and other electrical elements or electrical units) inserted.

[0057] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0058] As an important voltage conversion module, a direct current-direct current (DC-DC) converter can convert a given voltage signal into a required result, and is widely used in various power management chips. Generally, for a specific output voltage, a separate inductor is needed. However, due to the large area and poor integration of the high inductance inductor, the cost is also relatively high, which is not suitable for the current era of increasing integration.

[0059] Reference Figure 1 and Figure 2 A single inductor multiple output (SIMO) DC-DC converter has the function of obtaining multiple outputs by using a single inductor, reduces the number of components and the overall size, provides efficient power distribution, greatly reduces the use cost of the DC-DC converter, and is increasingly widely used in various scenes.

[0060] However, due to the use of a single inductor, the size of the corresponding branch selection switch needs to be large to accurately adjust each output channel to ensure stability and reduce the output voltage adjustment rate in a high load scenario. Due to the larger gate parasitic parameters of the larger selection switch, the switching loss is also increased. Therefore, an important step to improve the efficiency of the SIMO type DCDC is to reduce the switching loss of the selection switch during switching operation. Reference Figure 1 , the gate voltage is VDD when the high level is VDD, and the low level is GND. GATE is a gate pulse signal, VOUT1, VOUT2,... VOUTn is the output voltage of the DCDC converter, and reference Figure 2 , Figure 2 is a typical circuit topology of a conventional SIMO type DCDC converter. The PULSE signal is a gate pulse signal, BUF1 and BUF2 are forward driving modules, S1, S2,... Sn are branch selection switch pulses. Normally, the switching of PM1 and NM1 controlled by the PULSE signal changes the charging or discharging mode of the inductor L1, thereby adjusting the output voltage required by the load. The switching of S1, S2,... Sn specifies a certain path connected to the inductor to complete the charging and discharging operation of the path. That is, in the prior art, the gate voltage of each branch switch is low, resulting in large switching loss. Figure 3 is a gate voltage waveform diagram of each branch switch in the related art.

[0061] To this end, the embodiment provides a DC-DC converter, as shown in Figure 4 , the DC-DC converter comprises an inductor L1, a plurality of branch switches and a charge pump module 10, wherein

[0062] Each branch switch N1-1 to N1-n is connected between the inductor L1 and a corresponding voltage output terminal Vout1-Voutn, and the control terminal of each branch switch receives a corresponding switch control signal S1-Sn. Each branch switch is turned on when its corresponding switch control signal is high, and is turned off when its corresponding switch control signal is low. For example, when the switch control signal S1 is high, the corresponding branch switch N1-1 is turned on, when the switch control signal S1 is low, the corresponding branch switch N1-1 is turned off, when the switch control signal S2 is high, the corresponding branch switch N1-2 is turned on, when the switch control signal S2 is low, the corresponding branch switch N1-2 is turned off, and so on.

[0063] The charge pump module 10 includes a switch combination M and an energy storage capacitor C1. When a switch control signal is switched from high to low, the charge at the control terminal of the branch switch corresponding to the switch control signal is stored in the energy storage capacitor C1 through the switch combination M, and when a switch control signal is switched from low to high, the charge in the energy storage capacitor C1 is transmitted to the control terminal of the branch switch corresponding to the switch control signal through the switch combination M.

[0064] Specifically, as shown in Figure 4 Each branch switch is N1-1, N1-2,..., N1-n, respectively. The switch combination M is connected to the control terminal of each branch switch.

[0065] Optionally, the switch combination includes a plurality of switches, and by cooperating the plurality of switches to turn on and off, the charge at the control terminal of the corresponding branch switch is stored in the energy storage capacitor C1 when a switch control signal is switched from high to low, and the charge of the energy storage capacitor C1 is transmitted to the control terminal of the corresponding branch switch when a switch control signal is switched from low to high.

[0066] It should be noted that the branch switch can also be referred to as a gating switch. When the overall SIMO type DCDC system completes the power-on operation and the output is stable, the branch switch starts to enter the working state and is opened one by one. The control end charge of the branch switch is multiplexed, and the charge pump technology is used to improve the gate voltage of the gating switch unit in the subsequent path, thereby improving the voltage of each gating switch gate when it is turned on. Compared with the traditional DC-DC converter, the gate voltage of the branch switch is often limited by the power supply voltage, which limits the ability to further reduce the on-resistance. By using the charge pump technology, the control end voltage of the branch switch is raised to a level higher than the power supply voltage, so that each branch switch can be turned on more fully. Therefore, not only the on-resistance loss is reduced, but also the current transmission efficiency of the system is improved. In addition, the higher control end driving voltage improves the performance of the voltage converter under heavy load conditions, which helps to maintain a lower on-resistance and higher efficiency, especially when handling large current applications, the efficiency is higher.

[0067] The DC-DC converter of the embodiment, when one switch control signal such as S1 is switched from high level to low level, the branch switch N1-1 is turned off, at this time the charge of the control end of the branch switch N1-1 is stored to the energy storage capacitor C1 through the switch combination M; when one switch control signal such as S2 is switched from low level to high level, the branch switch N1-2 is turned on, at this time the charge of the energy storage capacitor C1 is transmitted to the control end of the turned-on branch switch N1-2 through the switch combination M, so that the voltage of the control end of N1-2 is improved by the charge stored in the energy storage capacitor C1 compared with the original voltage (such as the power supply voltage), thereby improving the voltage of the control end of any branch switch when it is turned on. In this way, the control end charge of the branch switch is recycled, and therefore the switching loss is greatly reduced.

[0068] In some optional embodiments, as shown in Figure 5 Each branch switch is an NMOS transistor, the gate of the NMOS transistor is the control end of the branch switch, and the source and drain are the connection ends;

[0069] Only one of the plurality of branch switches is turned on at the same time, and the other branch switches are turned off, and each branch switch is turned on in a regular order;

[0070] After one branch switch is switched from on to off, in order to prevent mutual interference between the output paths, a dead time is needed between the switching logic of each path, and then the next branch switch is switched from off to on. During the dead time, all branch switches are turned off.

[0071] Specifically, referring to Figure 5The plurality of branch switches N1-1, N1-2,..., N1-n can be NMOS transistors respectively. The source and the drain of the NMOS transistor are two connection terminals of the branch switch respectively, and the gate of the NMOS transistor is a control terminal of the branch switch. Specifically, the drains of the NMOS transistors N1-1, N1-2,..., N1-n are connected to the inductor L1, the sources of the NMOS transistors N1-1, N1-2,..., N1-n are connected to the ground through the second capacitor C2 and the first resistor R1 respectively, and the sources of the NMOS transistors N1-1, N1-2,..., N1-n are connected to the voltage output terminals Vout1-Voutn respectively.

[0072] The rule sequence can be a preset sequence, and the preset sequence can be N1-1, N1-2, N1-3,..., N1-n in turn and circulate, and only one branch switch is turned on at the same time. After one branch switch is turned off, another branch switch is turned on, and a dead time is waited for, and in the dead time, all the branch switches are turned off.

[0073] For example, referring to Figure 5 S1, S2,..., Sn are switch control signals of the control terminals of N1-1, N1-2,..., N1-n respectively. One branch switch is connected to the inductor L1 by switch switching of S1, S2,..., Sn. If a state is that N1-1 is turned on first, then N1-1 is turned off and N1-2 is turned on, finally N1-2 is turned off and N1-3 is turned on, and by analogy, N1-n-1 is turned off and N1-n is turned on. When N1-1-1 of S1 is turned off from being turned on, the voltage of the gate is rapidly pulled down from high, and at this time, there is a short S1, S2,..., Sn off state (i.e. dead state).

[0074] In some optional embodiments, as shown in Figure 5 The DC-DC converter further comprises a first power transistor Q1 and a second power transistor Q2;

[0075] The first power transistor Q1 and a second driving signal according to the gate thereof communicate or disconnect the input voltage VDD and the switch node LX, and the second power transistor Q2 communicates or disconnects the ground and the switch node LX according to the second driving signal according to the gate thereof;

[0076] The inductor L1 is connected between the switch node LX and the branch switch;

[0077] When the first driving signal is low, the first power transistor Q1 communicates the input voltage and the switch node LX, and when the first driving signal is high, the first power transistor Q1 disconnects the input voltage and the switch node LX.

[0078] When the second driving signal is high, the second power transistor Q2 connects the ground terminal and the switching node LX, and when the second driving signal is low, the second power transistor Q2 disconnects the ground terminal and the switching node LX;

[0079] When the first power transistor Q1 is on, the second power transistor Q2 is off, and at this time, the inductor L1 is charged; when the second power transistor Q2 is on, the first power transistor Q1 is off, and at this time, the inductor L1 is discharged.

[0080] Specifically, as shown in Figure 5 , the gate of the first power transistor Q1 is connected with the output terminal of BUF2, the gate of the second power transistor Q2 is connected with the output terminal of BUF1, the source of the first power transistor Q1 is connected with the power terminal VDD, the drain of the first power transistor Q1 is connected with the switching node LX, the drain of the second power transistor Q2 is connected with the switching node LX, and the source of the second power transistor Q2 is connected with the ground terminal GND. The first power transistor Q1 is a PMOS transistor, the second power transistor Q2 is an NMOS transistor, the PULSE signal is a pulse control signal, and BUF1 and BUF2 are forward driving modules. The pulse control signal is respectively passed through BUF1 and BUF2 to obtain the first driving signal and the second driving signal. Under normal circumstances, the pulse control signal controls the switching of the first power transistor Q1 and the second power transistor Q2 to change the charging or discharging mode of the inductor L1, and by cooperating with the conduction or turn-off of the branch switch, the required voltage can be provided for different voltage output terminals Vout1-Voutn at different times.

[0081] Exemplarily, referring to Figure 5 , if N1-1 is turned off after being turned on, the switch combination M stores the charge of the gate of N1-1 to the energy storage capacitor C1 during the dead zone state. After the dead zone state, when N1-2 is turned on, the switch combination M transmits the charge stored in the energy storage capacitor C1 to the gate of N1-2, so that the voltage of the gate of N1-2 can be increased to be higher than the power voltage VDD, and the charge of the gate of N1-1 is recycled. Subsequently, the charge of the gate of N1-2 can be temporarily stored by the energy storage capacitor C1 and then provided to the gate of N1-3, and then the charge of the gate of N1-3 can be temporarily stored by the energy storage capacitor C1 and then provided to the gate of N1-4, and so on.

[0082] In some optional embodiments, as shown in Figure 6 , the switch combination M includes a first switch combination M1, a second switch combination M2, and a third switch combination M3, wherein,

[0083] The first switch combination M1 selectively connects the first connection end of the energy storage capacitor C1 to the power supply end VDD or the ground end GND;

[0084] The second switch combination M2 selectively connects the second connection end of the energy storage capacitor C1 to the control end of any one branch switch;

[0085] The third switch combination M3 selectively connects the second connection end of the energy storage capacitor C1 to the control end of all branch switches.

[0086] Specifically, referring to Figure 6 , the first end of the first switch combination M1 is connected to the first connection end of the energy storage capacitor C1, the two second ends of the first switch combination M1 are connected to the power supply end VDD and the ground end GND respectively, the first switch combination M1, the second switch combination M2 and the third switch combination M3 receive switch control signals S1, S2,..., Sn, and selectively connect the connection ends of the energy storage capacitor C1 based on the switch control signals S1, S2,..., Sn. The first end of the second switch combination M2 is connected to the second connection end of the energy storage capacitor C1, and the multiple second ends of the second switch combination M2 are connected to the control end of each branch switch respectively; the first end of the third switch combination M3 is connected to the second connection end of the energy storage capacitor C1, and the multiple second ends of the third switch combination M3 are connected to the control end of each branch switch respectively.

[0087] In some optional embodiments, as Figure 6 shown, when one switch control signal jumps from high level to low level and all switch control signals are low level, the first switch combination M1 connects the first connection end of the energy storage capacitor C1 to the ground end GND, and the third switch combination M3 connects the second connection end of the energy storage capacitor C1 to the control end of all branch switches, so as to store the charge of the control end of the branch switch corresponding to the one switch control signal into the energy storage capacitor C1 through the third switch combination M3;

[0088] When one switch control signal switches from low level to high level, the first switch combination M1 connects the first connection end of the energy storage capacitor C1 to the power supply end VDD, and the second switch combination M2 connects the second connection end of the energy storage capacitor C1 to the control end of the branch switch corresponding to the switch control signal, so as to deliver the charge in the energy storage capacitor C1 to the control end of the corresponding branch switch through the second switch combination M2.

[0089] Exemplarily, referring to Figure 6If the switch control signal S1 jumps from high level to low level, N1-1 is turned on and then turned off, the first switch combination M1 connects the first connection end of the energy storage capacitor C1 to the ground end GND, the third switch combination M3 stores the charge of the control end of N1-1 to the energy storage capacitor C1, after the dead zone state, when the switch control signal S2 jumps from low level to high level, N1-2 is turned on, the first switch combination M1 connects the power supply end VDD and the first connection end of the energy storage capacitor C1, the second switch combination M2 sends the charge stored in the energy storage capacitor C1 to the control end of N1-2, and so on.

[0090] In some optional embodiments, as shown in Figure 7 The first switch combination M1 includes a first switch unit 11 and a second switch unit 12, the first switch unit 11 is connected between the first connection end of the energy storage capacitor C1 and the ground end GND, and the second switch unit 12 is connected between the first connection end of the energy storage capacitor C1 and the power supply end VDD.

[0091] Specifically, the first switch unit 11 and the second switch unit 12 are turned on and off based on the switch control signals of all branch switches, one of the first switch unit 11 and the second switch unit 12 is turned on and the other is turned off. The first switch combination M1 is connected with S1, S2,..., Sn respectively, and the first switch combination M1 further includes a first control logic, when all branch switches are turned off, the first control logic can control the first switch unit 11 to be turned on and the second switch unit 12 to be turned off, and when any branch switch is turned on, the first control logic can control the first switch unit 11 to be turned off and the second switch unit 12 to be turned on.

[0092] The second switch combination M2 includes a plurality of third switch units 13-1 to 13-n, each third switch unit is connected between the second connection end of the energy storage capacitor C1 and the control end of a corresponding branch switch.

[0093] Specifically, each third switch unit is turned on and off according to the switch control signal S1-Sn of the branch switch corresponding to the third switch unit, so as to transmit the charge stored in the energy storage capacitor C1 to the control end of the corresponding branch switch. The second switch combination M2 is connected with S1, S2,..., Sn respectively, and the second switch combination M2 includes a second control logic, when any branch switch is turned on, the second control logic can turn on the third switch unit corresponding to the branch switch and turn off the remaining third switch units.

[0094] The third switch combination M3 includes a plurality of fourth switch units 14-1 to 14-n, each fourth switch unit is connected between the second connection end of the energy storage capacitor C1 and the control end of a corresponding branch switch.

[0095] Specifically, each fourth switch unit is turned on and off according to all the switch control signals, so as to transmit the voltage of the control end of the branch switch to the energy storage capacitor C1 for storage. The third switch combination M3 is connected with S1, S2,..., Sn respectively, and the third switch combination M3 further comprises a third control logic. When all the branch switches are turned off, the third control logic can turn on all the fourth switch units, otherwise, the third control logic turns off all the fourth switch units.

[0096] In some optional embodiments, as shown in Figure 7 When one switch control signal is switched from high level to low level and all the switch control signals are low level, i.e. in the dead zone state, the first switch unit 11 is turned on, the second switch unit 12 is turned off, the plurality of fourth switch units are turned on, and the plurality of third switch units are turned off. At this time, the first connection end of the energy storage capacitor C1 is connected to the ground end GND, so as to store the charge of the control end of the branch switch corresponding to the one switch control signal to the energy storage capacitor C1 through the fourth switch unit.

[0097] When one switch control signal is switched from low level to high level, the first switch unit 11 is turned off, and the second switch unit 12 is turned on, so as to connect the first connection end of the energy storage capacitor C1 to the power supply end VDD. The third switch unit corresponding to the switch control signal is turned on, and the rest of the third switch units are turned off. The plurality of fourth switch units are turned off. The second connection end of the energy storage capacitor C1 is connected to the control end of the corresponding branch switch through the corresponding third switch unit, so as to transmit the charge of the second connection end of the energy storage capacitor to the control end of the corresponding branch switch through the corresponding third switch unit.

[0098] Specifically, referring to Figure 7 The plurality of fourth switch units are 14-1, 14-2,..., 14-n respectively. The plurality of third switch units are 13-1, 13-2,..., 13-n respectively.

[0099] Exemplarily, referring to Figure 7 ​If the switch control signal S1 is switched from high level to low level and all switch control signals are low level, i.e. in the dead zone state, the branch switch N1-1 is turned on and then turned off, the first switch unit 11 is turned on, the second switch unit 12 is turned off, the plurality of fourth switch units are turned on, and the plurality of third switch units are turned off. At this time, the first connection end of the energy storage capacitor C1 is connected to the ground end GND, so that the charge of the control end of the branch switch N1-1 corresponding to the one switch control signal S1 is stored in the energy storage capacitor C1 through the fourth switch unit. After the dead zone state, when one switch control signal S2 is switched from low level to high level, the first switch unit 11 is turned off, the second switch unit 12 is turned on, and the first connection end of the energy storage capacitor C1 is connected to the power supply end VDD. The third switch unit 13-2 corresponding to the switch control signal S2 is turned on, and the rest of the third switch units are turned off. The plurality of fourth switch units are turned off, and the second connection end of the energy storage capacitor C1 is connected to the control end of the corresponding branch switch N1-2 through the corresponding third switch unit 13-2. In this way, the charge of the second connection end of the energy storage capacitor C1 is transmitted to the control end of the corresponding branch switch N1-2 through the corresponding third switch unit 13-2. The same is true for the other switch control signals.

[0100] In some optional embodiments, as shown in Figure 8 The first switch unit 11 is an NMOS transistor, the drain and source of the NMOS transistor are used as the connection end of the first switch unit, and the gate of the NMOS transistor is used as the control end of the first switch unit.

[0101] The second switch unit 12 is a PMOS transistor.

[0102] The third switch unit is a PMOS transistor.

[0103] The fourth switch unit is a PMOS transistor.

[0104] The drain and source of the PMOS transistor are used as the connection end of the second switch unit, the third switch unit and the fourth switch unit, and the gate of the PMOS transistor is used as the control end of the second switch unit, the third switch unit and the fourth switch unit.

[0105] Specifically, the first switch unit 11 is an NMOS transistor N2, which is turned on at a high level and turned off at a low level. The second switch unit 12 is a PMOS transistor P1, which is turned on at a low level and turned off at a high level. The plurality of third switch units are PMOS transistors P2-1, P2-2, …, P2-n respectively. The plurality of fourth switch units are PMOS transistors P3-1, P3-2, …, P3-n respectively. The PMOS transistors P2-1, P2-2, …, P2-n, P3-1, P3-2, …, P3-n are turned on at a low level and turned off at a high level.

[0106] It should be noted that the drain of each PMOS transistor P2-1, P2-2, …, P2-n is connected to the gate of the corresponding branch switch, and the source of the PMOS transistor P2-1, P2-2, …, P2-n is connected to the second connection end (i.e. the upper plate) of the energy storage capacitor C1. The source of each PMOS transistor P3-1, P3-2, …, P3-n is connected to the gate of the corresponding branch switch, and the drain of the PMOS transistor P3-1, P3-2, …, P3-n is connected to the second connection end (i.e. the upper plate) of the energy storage capacitor C1. The drain of P1 is connected to the first connection end (i.e. the lower plate) of the energy storage capacitor C1, and the source of P1 is connected to the power supply end VDD. The source of N2 is connected to the ground end GND, and the drain of N2 is connected to the first connection end (i.e. the lower plate) of the energy storage capacitor C1.

[0107] In some alternative embodiments, as shown in Figure 7 and 8 The third switch combination M3 further includes a third logic control circuit;

[0108] The third logic control circuit includes an OR gate OR1;

[0109] Each switch control signal S1-Sn is input to the OR gate OR1, and the output end of the OR gate OR1 is connected to the gate of each fourth switch unit;

[0110] The first switch combination M1 further includes a first logic control circuit;

[0111] The first logic control circuit includes the OR gate in the third logic control circuit and a first inverter NOT, i.e. the OR gate is shared by the third logic control circuit and the first logic control circuit;

[0112] The output end of the OR gate OR1 is connected to the gates of the first switch unit and the second switch unit through the first inverter NOT.

[0113] Specifically, the OR gate OR1 has multiple inputs, each of the switch control signals is input to the OR gate OR1. If all the switch control signals are low, i.e. in the dead zone, a low signal is output, and at this time, the multiple fourth switch units are all disconnected. If at least one of the switch control signals is high, a high signal is output, and at this time, the multiple fourth switch units are all disconnected.

[0114] Further, when the input of the first inverter NOT is high, a low signal is output, and when the input of the first inverter NOT is low, a high signal is output.

[0115] It should be noted that when the branch switch N1-1 is switched from on to off and all the switch control signals S1-Sn are low, the OR gate OR1 outputs a low signal, the low signal is output as a high signal through the first inverter NOT, the high signal makes N2 on and P1 off. Thus, the first connection end (i.e. the lower plate) of the energy storage capacitor C1 is connected to the ground GND. At the same time, the OR gate OR1 outputs a low signal, which makes P3-1, P3-2,..., P3-n all on, and the charge of the gate of the branch switch N1-1 is stored in the energy storage capacitor C1 through P3-1.

[0116] It should be noted that if any of the switch control signals is high, such as the switch control signal S2 being high, the branch switch N1-2 is on, and the OR gate OR1 outputs a high signal, the high signal is output as a low signal through the first inverter NOT, and the low signal makes P1 on and N2 off. Thus, the power supply end VDD is connected to the first connection end (i.e. the lower plate) of the energy storage capacitor C1. At the same time, the OR gate OR1 outputs a high signal, which makes P3-1, P3-2,..., P3-n all off. At the same time, the switch control signal S2 makes the corresponding P2-2 on, and the second connection end of the energy storage capacitor C1 is connected to the control end of the corresponding branch switch N1-2 through the corresponding P2-2, so that the charge of the second connection end of the energy storage capacitor C1 is transmitted to the control end of the corresponding branch switch N1-2 through the corresponding P2-2.

[0117] In some optional embodiments, as shown in Figure 7 and 8 The second switch combination M2 further includes a second logic control circuit.

[0118] The second logic control circuit includes multiple second inverters, each of which corresponds to a third switch unit, and each of the switch control signals is connected to the gate of the corresponding third switch unit through a corresponding inverter.

[0119] Each of the switch control signals is connected to the control end of the corresponding branch switch.

[0120] Specifically, the plurality of second inverters are INV1, INV2,..., INVn respectively, the input end of INV1 receives the switch control signal S1, and the output end of INV1 is connected with the gate of P2-1.

[0121] It should be noted that when S1 changes from low level to high level, the high level changes to low level through the corresponding INV1 of the switch control signal, and the low level makes the corresponding P2-1 open, at this time, the second connection end (i.e. the upper plate) of the energy storage capacitor C1 is connected with the corresponding branch switch N1-1, so that the charge in the energy storage capacitor C1 is transmitted to the branch switch N1-1 through the corresponding P2-1.

[0122] It should be noted that when the S2 switch control signal changes from high level to low level, the charge at the gate of N2-2 is transmitted to the energy storage capacitor C1 through the corresponding P3-2.

[0123] Exemplarily, referring to Figure 8 , if S1 changes from high level to low level, N1-1 is turned off after being turned on, at this time, it is in a dead zone state, or the output of the OR gate OR1 is low level, P3-1 to P3-n are all turned on, after the first inverter NOT, N2 is turned on, P3-1 stores the charge at the gate of N1-1 to the energy storage capacitor C1, after the dead zone state, if S2 changes from low level to high level, P1 connects the power supply end VDD with the energy storage capacitor C1, at the same time, P2-2 is turned on, P2-2 sends the charge stored in the energy storage capacitor C1 to the control end of N1-2, and so on.

[0124] In summary, referring to Figure 9 , OR1 is the output waveform of the OR gate OR1, and C1 is the potential difference between the two plates of the energy storage capacitor C1. Through the discharging and charging process of the energy storage capacitor C1, the on-voltage of each branch switch is VDD+ΔV, and the specific effect is different due to the size difference of each path selection switch, so that the voltage at the control end of any branch switch when turned on is improved, and then the on-resistance of the branch switch is reduced, so the on-loss is reduced and the current transmission efficiency of the system is improved. That is, the present application stores the charge when the gate charge is pulled low at the last off time, and reuses it when the branch switch is pulled high, which greatly reduces the switching loss compared with the traditional structure.

[0125] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A DC-DC converter, characterized by, The DC-DC converter comprises: an inductor, a plurality of branch switches and a charge pump module, wherein each branch switch is connected between the inductor and a corresponding voltage output terminal, and a control terminal of each branch switch receives a corresponding switch control signal, each branch switch is turned on when the corresponding switch control signal is high, and is turned off when the corresponding switch control signal is low; the charge pump module comprises a switch combination and an energy storage capacitor, when one switch control signal is switched from high to low, the charge at the control terminal of the branch switch corresponding to the switch control signal is stored into the energy storage capacitor through the switch combination, and when one switch control signal is switched from low to high, the charge in the energy storage capacitor is delivered to the control terminal of the branch switch corresponding to the switch control signal through the switch combination; only one of the plurality of branch switches is turned on at the same time, and the other branch switches are turned off, and each branch switch is turned on in a regular order; after one branch switch is switched from on to off, the next branch switch is switched from off to on, and all the branch switches are turned off during the dead time; the DC-DC converter further comprises a first power transistor and a second power transistor; the first power transistor connects or disconnects the input voltage and a switch node according to a first driving signal at the gate of the first power transistor, and the second power transistor connects or disconnects the ground and the switch node according to a second driving signal at the gate of the second power transistor; the inductor is connected between the switch node and the branch switches; the second power transistor is turned off when the first power transistor is turned on, and the first power transistor is turned off when the second power transistor is turned on.

2. The DC-DC converter according to claim 1, wherein each branch switch is an NMOS transistor, and the gate of the NMOS transistor is the control terminal of the branch switch.

3. The DC-DC converter according to claim 1, wherein the first power transistor connects the input voltage and the switch node when the first driving signal is low, and disconnects the input voltage and the switch node when the first driving signal is high; and the second power transistor connects the ground and the switch node when the second driving signal is high, and disconnects the ground and the switch node when the second driving signal is low.

4. The DC-DC converter according to claim 1, wherein the switch combination comprises a first switch combination, a second switch combination and a third switch combination, wherein the first switch combination selectively connects a first connection terminal of the energy storage capacitor to a power supply terminal or a ground terminal; the second switch combination selectively connects a second connection terminal of the energy storage capacitor to the control terminal of any one of the branch switches; and the third switch combination selectively connects the second connection terminal of the energy storage capacitor to the control terminals of all the branch switches.

5. The DC-DC converter according to claim 4, wherein When one of the switch control signals jumps from high level to low level and all the switch control signals are low level, the first switch combination connects the first connection end of the energy storage capacitor to the ground end, and the third switch combination connects the second connection end of the energy storage capacitor to the control end of all the branch switches, so that the charge of the control end of the branch switch corresponding to the one switch control signal is stored into the energy storage capacitor through the third switch combination; When one of the switch control signals jumps from low level to high level, the first switch combination connects the first connection end of the energy storage capacitor to the power supply end, and the second switch combination connects the second connection end of the energy storage capacitor to the control end of the branch switch corresponding to the switch control signal, so that the charge in the energy storage capacitor is delivered to the control end of the corresponding branch switch through the second switch combination.

6. The DC-DC converter of claim 5, wherein the first switch combination comprises a first switch unit and a second switch unit, the first switch unit is connected between the first connection end of the energy storage capacitor and the ground end, and the second switch unit is connected between the first connection end of the energy storage capacitor and the power supply end; the second switch combination comprises a plurality of third switch units, each third switch unit is connected between the second connection end of the energy storage capacitor and the control end of a corresponding branch switch; the third switch combination comprises a plurality of fourth switch units, each fourth switch unit is connected between the second connection end of the energy storage capacitor and the control end of a corresponding branch switch.

7. The DC-DC converter of claim 6, wherein when one of the switch control signals jumps from high level to low level and all the switch control signals are low level, the first switch unit is turned on, the second switch unit is turned off, a plurality of fourth switch units are turned on, and a plurality of third switch units are turned off, so that the first connection end of the energy storage capacitor is connected to the ground end, and the charge of the control end of the branch switch corresponding to the one switch control signal is stored into the energy storage capacitor through the fourth switch unit; when one of the switch control signals jumps from low level to high level, the first switch unit is turned off, the second switch unit is turned on, so that the first connection end of the energy storage capacitor is connected to the power supply end, the third switch unit corresponding to the switch control signal is turned on, the remaining third switch units are turned off, a plurality of fourth switches are turned off, the second connection end of the energy storage capacitor is connected to the control end of the corresponding branch switch through the corresponding third switch unit, so that the charge of the second connection end of the energy storage capacitor is delivered to the control end of the corresponding branch switch through the corresponding third switch unit.

8. The DC-DC converter of claim 7, wherein the first switch unit is an NMOS transistor, the drain and source of the NMOS transistor are used as the connection end of the first switch unit, and the gate of the NMOS transistor is used as the control end of the first switch unit; the second switch unit is a PMOS transistor; the third switch unit is a PMOS transistor; the fourth switch unit is a PMOS transistor. The drain and the source of the PMOS transistor are connected ends of the second, third and fourth switch units, and the gate of the PMOS transistor is a control end of the second, third and fourth switch units.

9. The DC-DC converter of claim 8, wherein, The third switch combination further comprises a third logic control circuit; The third logic control circuit comprises an OR gate; Each switch control signal is input into the OR gate, and the output end of the OR gate is connected to the gate of each fourth switch unit; The first switch combination further comprises a first logic control circuit; The first logic control circuit comprises the OR gate in the third logic control circuit and a first inverter, that is, the third logic control circuit and the first logic control circuit share the OR gate; The output end of the OR gate is connected to the gates of the first and second switch units through the first inverter.

10. The DC-DC converter of claim 9, wherein, The second switch combination further comprises a second logic control circuit; The second logic control circuit comprises a plurality of second inverters, each second inverter corresponding to a third switch unit, and each switch control signal is connected to the gate of the third switch unit through a corresponding second inverter; Each switch control signal is connected to the control end of the corresponding branch switch.

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