Power supply circuit and switching power supply

Abstract

The application discloses a power supply circuit and a switching power supply. The switching power supply comprises multiple voltage conversion channels, and the power supply circuit comprises multiple first power supply modules and at least one second power supply module. Each first power supply module is used for providing a first driving power supply voltage for a corresponding voltage conversion channel according to a reference power supply voltage of the corresponding channel and a first capacitor in the first power supply module. Each second power supply module is connected with two voltage conversion channels in the multiple voltage conversion channels. The second power supply module obtains a power supply voltage based on a first voltage conversion channel, and provides a second driving power supply voltage for a second voltage conversion channel according to the power supply voltage. The application can provide additional charge supplement for a high-side driver under a large duty cycle condition, and is beneficial to maintaining the normal work of the circuit under the large duty cycle condition, so that the duty cycle of the circuit can support continuous conversion.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power conversion, in particular to a power supply circuit and a switching power supply. BACKGROUND

[0002] In many electronic products of the present age, integrated chip (IC) is often used in combination with other components. However, the core voltage (Vcore) inside the integrated chip and the input voltage (Vin) are not exactly the same. In particular, in today's fast progress of chip manufacturing process, many integrated chips tend to use lower core voltage. Therefore, a boost / buck converter is needed to provide various DC voltages for the internal core circuit and the input / output circuit of the chip.

[0003] Figure 1a The implementation circuit of a conventional boost converter (BOOST circuit) is shown, Figure 1b The implementation circuit of a conventional buck converter (BUCK circuit) is shown. As can be seen, both the BOOST circuit and the BUCK circuit are mainly realized by controlling the conduction and turn-off of two N-type transistors (Q1 and Q2) to achieve voltage conversion. Taking the buck converter as an example, the controller 11 sends a pulse signal to the gate of the two switching tubes (Q1 and Q2) to control the duty cycle of the switching tube, thereby controlling the induced voltage on the power inductor L in the buck converter, and achieving voltage conversion. In addition, in the process of voltage reduction, in order to obtain better electrical performance, an NMOS transistor is usually used as a high-side switch. However, when the high-side NMOS transistor is turned on, a higher potential than the input voltage Vin is needed as the power supply for the upper gate driver 12, such as Figure 1a and 1b As shown, a bootstrap capacitor C1 is usually used to provide power supply for the upper gate driver 12.

[0004] In the application of multi-channel power management chips, multiple switching power supplies, i.e. voltage conversion circuits, are integrated in one integrated chip 10. Taking a dual-channel buck converter as an example, as shown in Figure 2As shown, the first and second buck conversion circuits in the chip 10 each include a respective bootstrap circuit to provide a driving power source for the upper transistor driver (12, 14). However, in some application scenarios, such as when the output voltage and the input voltage are close to each other, the duty cycle of the buck conversion circuit gradually increases until the upper transistor (i.e., the first switch transistor) Q1 is always on. In the case of a large duty cycle, the lower transistor (i.e., the second switch transistor) Q2 is turned on for a very short time or not at all, so the corresponding bootstrap capacitor (C1) does not have enough time to charge, resulting in insufficient driving voltage for the upper transistor Q1, which cannot work normally.

[0005] Therefore, it is necessary to provide an improved technical solution to overcome the above technical problems in the prior art. SUMMARY

[0006] To solve the above technical problems, the present application provides a power supply circuit and a switching power supply, which can provide additional charge to the high-side driver under the condition of a large duty cycle, thereby facilitating the normal operation of the circuit under the condition of a large duty cycle, so that the duty cycle of the circuit can support continuous conversion.

[0007] According to a first aspect of the present disclosure, a power supply circuit is provided, which is applied in a switching power supply, wherein the switching power supply includes a plurality of voltage conversion channels, and the power supply circuit includes a plurality of first power supply modules and at least one second power supply module,

[0008] The plurality of first power supply modules are connected one by one with the plurality of voltage conversion channels, and each first power supply module is configured to provide a first driving power voltage for the corresponding voltage conversion channel according to a reference power voltage of the corresponding channel and a first capacitor in the first power supply module;

[0009] Each second power supply module is connected with two voltage conversion channels in the plurality of voltage conversion channels, and the second power supply module obtains a power supply voltage based on a first voltage conversion channel in the two voltage conversion channels, and provides a second driving power voltage for a second voltage conversion channel in the two voltage conversion channels according to the power supply voltage;

[0010] Each voltage conversion channel in the plurality of voltage conversion channels can convert an input voltage according to a corresponding driving power voltage to provide a plurality of corresponding output voltages.

[0011] Optionally, when the switching duty cycle of the second voltage conversion channel in the two voltage conversion channels reaches a preset threshold, the power supply voltage provides the second driving power voltage for the second voltage conversion channel in the two voltage conversion channels.

[0012] Optionally, a duty cycle of the switch of the first voltage conversion channel is less than a duty cycle of the switch of the second voltage conversion channel, and the second power supply module provides a second driving power voltage to the second voltage conversion channel.

[0013] Optionally, each of the plurality of voltage conversion channels comprises a first switch tube and a second switch tube connected with an intermediate node of the corresponding voltage conversion channel, the second switch tube is connected with a reference ground, and the first switch tube and the second switch tube are coupled to an energy storage element in the corresponding voltage conversion channel through the intermediate node.

[0014] When the intermediate nodes of the two voltage conversion channels are both high, the second power supply module provides a second driving power voltage to the second voltage conversion channel.

[0015] Optionally, the second switch tube in the first voltage conversion channel has a conduction time period in each switching cycle, and the conduction time of the second switch tube in each switching cycle is greater than a preset threshold.

[0016] Optionally, each of the at least one second power supply module comprises a gating unit and a gate drive circuit.

[0017] The gating unit is used to control whether to provide the power supply voltage to the second voltage conversion channel.

[0018] The gate drive circuit controls the on-off state of the gating unit according to the level of the intermediate nodes of the two voltage conversion channels.

[0019] Optionally, when the intermediate nodes of the two voltage conversion channels are both high, the gating unit is turned on.

[0020] Optionally, the gating unit comprises a third switch tube, a fourth switch tube and a first resistor.

[0021] The third switch tube and the fourth switch tube are connected in series between the output end of the power supply voltage and the corresponding second voltage conversion channel, and the control ends of the third switch tube and the fourth switch tube are connected with the output end of the gate drive circuit.

[0022] The parasitic diode of the third switch tube and the parasitic diode of the fourth switch tube are reversely connected in series.

[0023] A first end of the first resistor is connected with the control end of the third switch tube, and a second end of the first resistor is connected with a common connection node of the third switch tube and the fourth switch tube.

[0024] Optionally, the gating unit comprises a fifth switch tube and a first diode.

[0025] The fifth switch tube and the first diode are connected in series between the output end of the power supply voltage and the corresponding second voltage conversion channel.

[0026] The control end of the fifth switch tube is connected with the output end of the gate drive circuit.

[0027] The first diode and the parasitic diode of the fifth switch tube are reversely connected in series.

[0028] Optionally, the first end of the first capacitor in the first power supply module is coupled with a reference power supply voltage of the corresponding channel, and the second end of the first capacitor is coupled with an intermediate node of the corresponding channel, and the voltage of the first capacitor is taken as an output voltage of the first power supply module.

[0029] Optionally, the second power supply module comprises a second capacitor,

[0030] The first end of the second capacitor is connected to the reference power supply voltage of the second voltage conversion channel through a second diode,

[0031] The second end of the second capacitor is connected with an intermediate node of the first voltage conversion channel.

[0032] The voltage of the first end of the second capacitor is taken as a power supply voltage of the second power supply module.

[0033] Optionally, the reference power supply voltage corresponding to the first voltage conversion channel is less than the reference power supply voltage corresponding to the second voltage conversion channel.

[0034] Optionally, the reference power supply voltage corresponding to the first voltage conversion channel is equal to the reference power supply voltage corresponding to the second voltage conversion channel,

[0035] The first end of the first capacitor in the first power supply module is connected with the second power supply module,

[0036] When the intermediate nodes of the two voltage conversion channels are both high, the voltage of the first end of the first capacitor is taken as the power supply voltage of the second power supply module.

[0037] According to the second aspect of the present disclosure, a switching power supply is provided, comprising a plurality of voltage conversion channels and a power supply circuit as described above,

[0038] The plurality of voltage conversion channels comprise a controller and a plurality of drivers, and the plurality of drivers receive switching control signals output by the controller to drive the switching state of the switch tubes in the plurality of voltage conversion channels.

[0039] The power supply circuit provides a driving power supply voltage for the plurality of drivers.

[0040] Optionally, each voltage conversion channel of the plurality of voltage conversion channels comprises a first switch tube and a second switch tube connected with an intermediate node of the corresponding voltage conversion channel, and a first driver driving the first switch tube and a second driver driving the second switch tube;

[0041] The second power supply module in the power supply circuit provides a second driving power voltage for the first driver in the corresponding voltage conversion channel of the power supply.

[0042] Optionally, the controller, the plurality of drivers and the switch tubes in the plurality of voltage conversion channels are integrated in an integrated circuit chip,

[0043] The first capacitor in the first power supply module and the second capacitor in the second power supply module are arranged outside the integrated circuit chip, and the other parts are integrated in the integrated circuit chip.

[0044] The present application has at least the following beneficial effects:

[0045] The embodiment of the present application adds at least one second power supply module in the power supply circuit, which can provide additional driving compensation for at least one upper tube driver (i.e. high side driver or first driver) in the switching power supply, so that when the switching duty cycle of at least one voltage conversion channel needs to be greater than a preset duty cycle threshold, the high side switch driver in the corresponding voltage conversion channel can provide sufficient conduction driving voltage for the corresponding first switch tube, i.e. the upper tube driver can provide additional charge compensation under large duty cycle condition, which is beneficial to keep the normal work of the circuit, so that the duty cycle of the circuit can support continuous conversion, and is also beneficial to realize the constant of the switching frequency of the circuit under the control of the duty cycle greater than the preset threshold.

[0046] It should be noted that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1a A circuit structure schematic diagram of a conventional boost conversion circuit (BOOST circuit) is shown;

[0048] Figure 1b A circuit structure schematic diagram of a conventional buck conversion circuit (BUCK circuit) is shown;

[0049] Figure 2 A circuit structure schematic diagram of an existing dual-path switching power supply is shown;

[0050] Figure 3 A structure schematic diagram of a switching power supply provided according to the first embodiment of the present application is shown;

[0051] Figure 4A schematic diagram of the structure of a switching power supply provided according to a second embodiment of the present invention is shown;

[0052] Figure 5 A schematic diagram of the structure of a switching power supply provided according to a third embodiment of the present invention is shown. Detailed Implementation

[0053] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in various forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0054] like Figure 3 and Figure 4 As shown, the switching power supply provided in this embodiment of the invention includes: multiple voltage conversion channels and a power supply circuit connected to the multiple voltage conversion channels.

[0055] The multiple voltage conversion channels include a controller 21 and multiple drivers, each of which is connected to the controller 21 to receive switching control signals output by the controller 21, thereby driving the switching state of the switching transistors in the corresponding voltage conversion channels. The power supply circuit is used to provide drive power voltage to the multiple drivers.

[0056] Each voltage conversion channel includes a first switch (defined as a high-side switch) and a second switch (defined as a low-side switch, i.e., the source / drain of the second switch is connected to ground) connected to the intermediate node (denoted as SW) of the corresponding voltage conversion channel, a first driver for driving the first switch, a second driver for driving the second switch, a power inductor, and an output capacitor. Both the first and second switches are coupled to an energy storage element, such as a power inductor, in the corresponding voltage conversion channel through the intermediate node SW. Based on the corresponding output capacitor and other conventional components, they together constitute the voltage conversion channel. Each voltage conversion channel can convert the input voltage Vin to provide a corresponding output voltage. It should be noted that the voltage conversion process of the input voltage Vin in each voltage conversion channel of the switching power supply in this embodiment is independent. Different voltage conversion channels can simultaneously or time-divisionally provide output voltages with different voltage values.

[0057] It is understood that, based on the different connection methods between the first switching transistor, the second switching transistor, the power inductor, and the output capacitor in each voltage conversion channel, the corresponding voltage conversion channel can be connected into any one of a boost conversion structure, a buck conversion structure, a buck-boost conversion structure, or other voltage conversion structures. This invention does not limit this. Meanwhile, the connection structures for boost and buck circuits can be found in [reference needed]. Figure 1a andFigure 1b To understand.

[0058] Further, the power supply circuit includes a plurality of first power supply modules and at least one second power supply module. The plurality of voltage conversion channels, the plurality of first power supply modules and the plurality of first capacitors are in one-to-one correspondence with each other.

[0059] Each first power supply module includes a first capacitor, and each second power supply module can be separately provided with a second capacitor or share a first capacitor with a specific first power supply module. The voltage of the plurality of capacitors can be used as the driving power voltage of the corresponding power supply module to support the conduction of the first switch tube and the second switch tube in each voltage conversion channel.

[0060] Each of the plurality of first power supply modules is configured to provide a first driving power voltage for the corresponding voltage conversion channel based on the reference power supply voltage of the corresponding voltage conversion channel and the first capacitor in the power supply module. Each of the at least one second power supply module is connected to at least two voltage conversion channels (e.g., including a first voltage conversion channel and a second voltage conversion channel) in the plurality of voltage conversion channels, and the second power supply module obtains a power supply voltage based on the first voltage conversion channel in the at least two voltage conversion channels, and provides a second driving power voltage for the second voltage conversion channel in the at least two voltage conversion channels according to the power supply voltage. In particular, when the switching duty cycle of the second voltage conversion channel in the two voltage conversion channels reaches a preset threshold (e.g., reaches 90% or more), the power supply voltage provides a second driving power voltage for the second voltage conversion channel in the at least two voltage conversion channels. When the switching duty cycle of the second voltage conversion channel is large, the corresponding first power supply module cannot provide sufficient driving voltage to the second driver, and the power supply voltage of the second power supply module supplements the charge, and the two can provide sufficient driving voltage to the second driver.

[0061] Meanwhile, each of the plurality of voltage conversion channels can convert the input voltage according to the corresponding driving power voltage to provide a plurality of output voltages. It can be understood that the first voltage conversion channel corresponds to the voltage conversion channel that does not require the second power supply module to provide an additional second driving power voltage, and the second voltage conversion channel corresponds to the voltage conversion channel that requires the second power supply module to provide an additional second driving power voltage.

[0062] In this embodiment, the first switch and the second switch in each voltage conversion channel are NMOS transistors, and the first driver in each voltage conversion channel can realize on-off control of the first switch by receiving a corresponding driving power voltage and a first switch control signal output by the controller 21, and the second driver in each voltage conversion channel can realize on-off control of the second switch by receiving a reference power voltage of the corresponding voltage conversion channel and a second switch control signal output by the controller 21. Specifically, the input end of the first driver is connected to the controller 21 to receive the first switch control signal, the output end of the first driver is connected to the control end of the first switch, the first supply end of the first driver is connected to the corresponding first supply module to receive the first driving power voltage, and the second supply end of the first driver is connected to the intermediate node SW of the corresponding voltage conversion channel. The input end of the second driver is connected to the controller 21 to receive the second switch control signal, the output end of the second driver is connected to the control end of the second switch, the first supply end of the second driver is connected to the reference power supply of the corresponding voltage conversion channel to receive the corresponding reference power voltage, and the second supply end of the second driver is connected to the reference ground. In addition, the first supply end of the first driver in some voltage conversion channels of the plurality of voltage conversion channels is also connected to the corresponding second supply module to receive the second driving power voltage. That is, the second supply module in the power supply circuit is used to provide the second driving power voltage for the first driver in the voltage conversion channel that needs the additional second driving power voltage.

[0063] The first end of the first capacitor of each first supply module is coupled (for example, through a corresponding diode) to the reference power voltage of the corresponding voltage conversion channel, and the second end of the first capacitor is coupled to the intermediate node SW of the corresponding voltage conversion channel, so that the voltage at the first end of the first capacitor can serve as the output voltage of the first supply module, that is, the first driving power voltage. In the corresponding voltage conversion channel, when the second switch is turned on and the first switch is turned off, the intermediate node SW of the voltage conversion channel is at a low level, and the corresponding reference power voltage charges the first capacitor through the corresponding diode; when the first switch is turned on and the second switch is turned off, the intermediate node SW of the voltage conversion channel is at a high level, and the first capacitor is discharged to provide the first driving power voltage for the first driver of the voltage conversion channel. Here, the level of the intermediate node is determined according to the high-side switch or the low-side switch, when the high-side switch is turned on, the level of the intermediate node approaches the input voltage, corresponding to a high level, and when the low-side switch is turned on, the level of the intermediate node approaches the voltage of the reference ground, corresponding to a low level. When the high-side switch is turned on, the first driving power voltage is greater than the intermediate node voltage, that is, the input voltage, so that the high-side NMOS transistor can be normally driven.

[0064] Each second power supply module includes a gating unit 27 and a gate drive circuit 26. The gating unit 27 is configured to control whether to provide the power supply voltage obtained by the corresponding second power supply module to the second voltage conversion channel. The input end of the gate drive circuit 26 is connected to the intermediate node (SW1, SW2) of the corresponding first voltage conversion channel and second voltage conversion channel, respectively. The output end of the gate drive circuit 26 is connected to the control end of the gating unit 27. The gate drive circuit 26 is configured to control the on-off state of the gating unit 27 according to the level of the intermediate node (SW1, SW2) of the corresponding two voltage conversion channels. Here, the input end of the gate drive circuit 26 can also receive the switching control signal of the first voltage conversion channel and the second voltage conversion channel, which can correspond to the level of the intermediate node (SW1, SW2) of the two voltage conversion channels, so as to obtain the information of the level of the intermediate node (SW1, SW2) according to the switching control signal.

[0065] In some examples of the present application, as shown in Figure 3 and Figure 4 The capacitor connected to the second power supply module is a second capacitor separately arranged in the second power supply module. The first end of the second capacitor is connected to the reference power supply voltage corresponding to the second voltage conversion channel through the second diode, and the second end is connected to the intermediate node SW1 of the corresponding first voltage conversion channel. The first end of the second capacitor is also connected to the input end of the gating unit 27. At this time, the voltage of the first end of the second capacitor is used as the power supply voltage of the second power supply module. In the present embodiment, the two voltage conversion channels connected to the second power supply module correspond to different reference power supply voltages, wherein the reference power supply voltage VCC2 corresponding to the first voltage conversion channel is smaller than the reference power supply voltage VCC1 corresponding to the second voltage conversion channel. In this way, more flexible control of each voltage conversion channel can be achieved, which can adapt to different power switches and different first capacitor values corresponding to different channels, and save costs.

[0066] In some examples of the present application, as shown in Figure 5As shown, the capacitor connected with the second power supply module is a first capacitor in the first voltage conversion channel. At this time, the first end of the first capacitor is connected with the input end of the gating unit 27 in addition to being connected with the first voltage conversion channel. At this time, when the intermediate nodes (SW1, SW2) of the two voltage conversion channels are both high level, the voltage at the first end of the first capacitor serves as the power supply voltage of the second power supply module. In this embodiment, the two voltage conversion channels connected with the second power supply module correspond to the same reference power supply voltage VCC, that is, the reference power supply voltage corresponding to the first voltage conversion channel is equal to the reference power supply voltage corresponding to the second voltage conversion channel. At this time, the capacitance of the first power supply module needs to be large enough to meet the charge demand in the second voltage conversion channel. In this way, the demand for capacitors can be reduced, which is conducive to reducing the circuit size and reducing the cost.

[0067] It should be noted that, based on the connection relationship of each second power supply module in the switching power supply, the duty cycle of the switch of the first voltage conversion channel connected with the second power supply module in the switching power supply should be less than the duty cycle of the switch of the second voltage conversion channel connected with the second power supply module, so that the second power supply module can provide the second drive power supply voltage to the corresponding second voltage conversion channel based on the first voltage conversion channel connected therewith. When the intermediate nodes of the two voltage conversion channels connected with the second power supply module are both high level (that is, the first switch tubes in the two voltage conversion channels are both turned on), the second power supply module provides the second drive power supply voltage to the corresponding second voltage conversion channel.

[0068] Specifically, when the intermediate node SW1 of the first voltage conversion channel corresponding to the second power supply module is low level, the corresponding reference power supply voltage charges the capacitor connected with the second power supply module; when the intermediate node SW1 of the first voltage conversion channel corresponding to the second power supply module is high level, the capacitor connected with the second power supply module is discharged, and after the corresponding gating unit 27 is turned on, the power supply voltage is provided to the second voltage conversion channel to provide the second drive power supply voltage to the first power supply end of the first driver in the second voltage conversion channel. The second drive power supply voltage is greater than the reference power supply voltage corresponding to the second voltage conversion channel, and when the intermediate nodes SW1 and SW2 of the first voltage conversion channel and the second voltage conversion channel are both high level, the gating unit 27 outputs the effective third switch control signal to the gating unit 27 to control the gating unit 27 to be in the turned-on state.

[0069] When the voltage on the first capacitor is insufficient to provide the first driver in the corresponding voltage conversion channel with a normal first driving power voltage for normally driving the first switch tube to turn on (for example, when the duty cycle of the corresponding second voltage conversion channel is greater than a preset threshold, so that the on duration of the second switch tube is too small), the voltage at the first end of the capacitor connected to the second voltage conversion channel can provide additional charge compensation for the first driver in the corresponding second voltage conversion channel, ensuring the normal operation of the voltage conversion channel. In the switching power supply, at least one voltage conversion channel can work normally under a specific operating environment (for example, under an operating environment with a duty cycle greater than a preset threshold). For example, the duty cycle of the voltage conversion channel in the switching power supply supports continuous change, and the maximum duty cycle can be close to or even reach 100%. At the same time, the switching frequency of the voltage conversion channel under large duty cycle control can be constant, that is, it is not affected by the minimum on time of the second switch tube, which is beneficial to improve the application range of the switching power supply.

[0070] In the first embodiment of the present application, as shown in Figure 3 or Figure 5 The gating unit 27 in the second power supply module includes a third switch tube Q3, a fourth switch tube Q4 and a first resistor R1. The third switch tube Q3 and the fourth switch tube Q4 are connected in series between the cathode of the second diode and the first power supply end of the first driver in the corresponding second voltage conversion channel, and the parasitic diode of the third switch tube Q3 and the parasitic diode of the fourth switch tube Q4 are connected in reverse series. The control ends of the third switch tube Q3 and the fourth switch tube Q4 are connected with the output end of the gate drive circuit 26. The first end of the first resistor R1 is connected with the control end of the third switch tube Q3, and the second end of the first resistor R1 is connected with the common connection node of the third switch tube Q3 and the fourth switch tube Q4.

[0071] In the second embodiment of the present application, as shown in Figure 4 The gating unit 27 in the second power supply module includes a fifth switch tube Q5 and a first diode D4. The fifth switch tube Q5 and the first diode D4 are connected in series between the output end of the power supply voltage and the first power supply end of the first driver in the corresponding second voltage conversion channel, and the first diode D4 and the parasitic diode of the fifth switch tube Q5 are connected in reverse series. The control end of the fifth switch tube Q5 is connected with the output end of the gate drive circuit 26. Optionally, the anode of the first diode D4 is connected with the output end of the power supply voltage, or the anode of the first diode D4 is connected with the output end of the power supply voltage through the fifth switch tube Q5.

[0072] Based on the above description, in the present application, the gate drive circuit 26 can control the on-off state of the gating unit 27 according to the level state (i.e. high or low) of the intermediate nodes (SW1, SW2) of the two voltage conversion channels (e.g. the first voltage conversion channel and the second voltage conversion channel) corresponding to the second power supply module, i.e. the switching state of the first switch tube in the two voltage conversion channels, for example, when the first switch tube in the two voltage conversion channels is both turned on, i.e. when the intermediate node SW1 of the first voltage conversion channel and the intermediate node SW2 of the second voltage conversion channel are both at a high level, an effective third switch control signal is output to control the gating unit 27 to be in a conductive state, so that the power supply voltage can be transmitted to the first power supply end of the first driver in the second voltage conversion channel, so that the first driver can have sufficient driving capability to maintain the conductive state of the first switch tube. At the same time, based on the circuit structure of the gating unit 27 in the present application, the bidirectional cutoff between the first capacitor in the first power supply module corresponding to the second voltage conversion channel and the capacitor connected with the second power supply module can be realized when the gate drive circuit 26 outputs an ineffective third switch control signal, so that the charge transfer between the first capacitor and the capacitor connected with the second power supply module will not occur based on the parasitic diode of the switch tube in the gating unit 27, which is beneficial to ensure the normal operation of the circuit.

[0073] In some possible embodiments of the present application, the controller 21 in the plurality of voltage conversion channels, the plurality of drivers, and the switch tube in each voltage conversion channel are integrated in the same integrated circuit chip 20, and the power inductance and the output capacitor in each voltage conversion channel are arranged outside the integrated circuit chip 20. At the same time, except that the first capacitor in each first power supply module and the capacitor connected with each second power supply module are arranged outside the integrated circuit chip 20, the other parts of the power supply circuit are integrated in the integrated circuit chip 20. In this way, it is beneficial to improve the integration of the switching power supply while ensuring the miniaturization of the integrated circuit chip 20.

[0074] Exemplarily, taking a switching power supply containing two step-down conversion circuits as an example, as shown in Figure 3 、 Figure 4 and Figure 5 , the switching power supply includes two voltage conversion channels (a first voltage conversion channel and a second voltage conversion channel), two first power supply modules and one second power supply module.

[0075] The first switch tube in the first voltage conversion channel is switch tube Q11, the second switch tube in the first voltage conversion channel is switch tube Q12, the first driver in the first voltage conversion channel is driver 22, and the second driver in the first voltage conversion channel is driver 23. Further, the first power supply end of driver 22 in the first voltage conversion channel is coupled to a corresponding first power supply module to receive a first driving power supply voltage. Switch tube Q11 and switch tube Q12 in the first voltage conversion channel are coupled to first power inductor L1 and first output capacitor Co1 through a middle node SW1, and can convert the input voltage Vin to output a first output voltage Vo1.

[0076] The first switch tube in the second voltage conversion channel is switch tube Q21, the second switch tube in the second voltage conversion channel is switch tube Q22, the first driver in the second voltage conversion channel is driver 24, and the second driver in the second voltage conversion channel is driver 25. Further, the first power supply end of driver 24 in the second voltage conversion channel is connected to a corresponding first power supply module and a second power supply module, respectively, to receive a first driving power supply voltage and a second driving power supply voltage. Switch tube Q21 and switch tube Q22 in the second voltage conversion channel are coupled to second power inductor L2 and second output capacitor Co2 through a middle node SW2, and can convert the input voltage Vin to output a second output voltage Vo2.

[0077] Further, in some examples of the present application, when the first voltage conversion channel and the second voltage conversion channel correspond to different reference power supply voltages, the reference Figure 3 and Figure 4 At this time, the working process of the switching power supply is as follows:

[0078] When switch tube Q11 in the first voltage conversion channel is off and switch tube Q12 is on, the middle node SW1 is low, at this time, the reference power supply voltage VCC2 charges capacitor C1 through diode D1, and the reference power supply voltage VCC1 charges capacitor C3 through diode D3;

[0079] When switch tube Q11 in the first voltage conversion channel is on and switch tube Q12 is off, the middle node SW1 is high, at this time, capacitor C1 discharges to provide the first driving power supply voltage for driver 22, and maintain the on state of switch tube Q11;

[0080] When the duty cycle of the second voltage conversion channel is less than a preset threshold (e.g. 90%) and the switch Q21 in the second voltage conversion channel is on while the switch Q22 is off, the intermediate node SW2 is at a high level, at this time, the capacitor C2 discharges and provides a first driving power voltage for the driver 24 together with the voltage of the capacitor C3 in the second power supply module, maintaining the on state of the switch Q21;

[0081] When the duty cycle of the second voltage conversion channel is greater than the preset threshold (e.g. 90%) and the switch Q21 in the second voltage conversion channel is off while the switch Q22 is on, the intermediate node SW2 is at a low level for too short a time or the intermediate node SW2 is always at a high level, at this time, the reference power voltage VCC1 cannot fully charge the capacitor C2; in this case, when the switch Q21 in the second voltage conversion channel is on while the switch Q22 is off, the intermediate node SW1 and the intermediate node SW2 are both at a high level, the gate drive circuit 26 controls the gating unit 27 to be on, at this time, the capacitor C3 discharges and can supplement the insufficient charge of the capacitor C2, together providing a second driving power voltage for the driver 24, ensuring the on state of the switch Q21 in the entire switching cycle.

[0082] Further, as shown in Figure 3 and Figure 4 The integrated circuit chip 20 in the switching power supply at least includes: a first input pin for receiving an input voltage Vin; a second input pin for receiving a feedback signal FB1 corresponding to a first output voltage Vo1; a third input pin for receiving a feedback signal FB2 corresponding to a second output voltage Vo2; a first output pin connected with the intermediate node SW1 of the first voltage conversion channel, the first power inductor L1 in the first voltage conversion channel being connected with the integrated circuit chip 20 through the first output pin; a second output pin connected with the intermediate node SW2 of the second voltage conversion channel, the second power inductor L2 in the second voltage conversion channel being connected with the integrated circuit chip 20 through the second output pin; a first power supply pin BST1 connected with the first power supply end of the driver 22 in the first voltage conversion channel and the cathode of the diode D1, respectively, the capacitor C1 in the corresponding first power supply module of the first voltage conversion channel being connected with the integrated circuit chip 20 through the first power supply pin BST1; a second power supply pin BST2 connected with the first power supply end of the driver 24 in the second voltage conversion channel and the cathode of the diode D2, respectively, the capacitor C2 in the corresponding first power supply module of the second voltage conversion channel being connected with the integrated circuit chip 20 through the second power supply pin BST2; a third power supply pin CP connected with the gating unit 27 in the second power supply module and the cathode of the diode D3, respectively, the capacitor C3 in the second power supply module being connected with the integrated circuit chip 20 through the third power supply pin CP; and a ground pin GND.

[0083] In some other examples of the present application, when the first voltage conversion channel and the second voltage conversion channel correspond to the same reference supply voltage VCC, the reference Figure 5 In this case, the operation of the switching power supply is as follows:

[0084] When the switch Q11 in the first voltage conversion channel is off and the switch Q12 is on, the intermediate node SW1 is low, and in this case the reference supply voltage VCC charges the capacitor C1 through the diode D1;

[0085] When the duty cycle of the second voltage conversion channel is less than a preset threshold (e.g. 90%), the switch Q21 in the second voltage conversion channel is off and the switch Q22 is on, the intermediate node SW2 is low, and in this case the reference supply voltage VCC fully charges the capacitor C2 through the diode D2;

[0086] When the duty cycle of the second voltage conversion channel is less than a preset threshold (e.g. 90%), the switch Q21 in the second voltage conversion channel is on and the switch Q22 is off, the intermediate node SW2 is high, and in this case the capacitor C2 discharges and together with the capacitor C1 provides the first driving supply voltage for the driver 24, maintaining the on state of the switch Q21;

[0087] When the duty cycle of the second voltage conversion channel is greater than a preset threshold (e.g. 90%), the switch Q21 in the second voltage conversion channel is off and the switch Q22 is on, the intermediate node SW2 is low for too short a time or the intermediate node SW2 is always high, and in this case the reference supply voltage VCC cannot fully charge the capacitor C2; in this case, when the intermediate node SW1 and the intermediate node SW2 are both high, the gate drive circuit 26 controls the gating unit 27 to be on, and in this case the capacitor C1 and the capacitor C2 discharge together, and the capacitor C1 can supplement the insufficient charge of the capacitor C2, ensuring the on state of the switch Q21 throughout the switching period.

[0088] Further, as Figure 5As shown, the integrated circuit chip 20 in the switching power supply at least includes: a first input pin for receiving an input voltage Vin; a second input pin for receiving a feedback signal FB1 corresponding to a first output voltage Vo1; a third input pin for receiving a feedback signal FB2 corresponding to a second output voltage Vo2; a first output pin connected with a middle node SW1 of a first voltage conversion channel, a first power inductor L1 in the first voltage conversion channel being connected with the integrated circuit chip 20 through the first output pin; a second output pin connected with a middle node SW2 of a second voltage conversion channel, a second power inductor L2 in the second voltage conversion channel being connected with the integrated circuit chip 20 through the second output pin; a first power supply pin BST1 connected with a first power supply end of a driver 22 in the first voltage conversion channel, a cathode of a diode D1 and a gating unit 27 respectively, a capacitor C1 in a first power supply module corresponding to the first voltage conversion channel being connected with the integrated circuit chip 20 through the first power supply pin BST1; a second power supply pin BST2 connected with a first power supply end of a driver 24 in the second voltage conversion channel and a cathode of a diode D2 respectively, a capacitor C2 in a first power supply module corresponding to the second voltage conversion channel being connected with the integrated circuit chip 20 through the second power supply pin BST2; and a ground pin GND.

[0089] Based on the above description, in the embodiment of the present application, the duty cycle of the first voltage conversion channel is configured to be less than a preset threshold (i.e. the second switch in the first voltage conversion channel exists a conduction period in each switching cycle, and the conduction time of the second switch in each switching cycle is greater than the preset threshold), so that in each switching cycle, the capacitors connected with the middle node SW1 of the first voltage conversion channel can have sufficient charging time, thereby making the second voltage conversion channel in the switching power supply be able to operate normally even in the case that the duty cycle is greater than the preset threshold, and the duty cycle of the second voltage conversion channel supports continuous change, the maximum duty cycle can be close to or even reach 100%, which is beneficial to improve the application range of the switching power supply.

[0090] Finally, it should be noted that: obviously, the above embodiments are only examples for clearly illustrating the present application, and are not limitations on the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A power supply circuit applied in a switching power supply, wherein, The switch power supply comprises a plurality of voltage conversion channels, the power supply circuit comprises a plurality of first power supply modules and at least one second power supply module, The plurality of first power supply modules are connected with the plurality of voltage conversion channels one by one, and each first power supply module is used for providing a first driving power supply voltage for a corresponding voltage conversion channel according to a reference power supply voltage of the corresponding channel and a first capacitor in the first power supply module. Each second power supply module is connected with two voltage conversion channels in the plurality of voltage conversion channels, the second power supply module obtains a power supply voltage based on a first voltage conversion channel in the two voltage conversion channels, and provides a second driving power supply voltage for a second voltage conversion channel in the two voltage conversion channels according to the power supply voltage. Each voltage conversion channel in the plurality of voltage conversion channels can convert an input voltage according to a corresponding driving power supply voltage to provide a plurality of corresponding output voltages.

2. The power supply circuit of claim 1, wherein, When the duty cycle of the switch of the second voltage conversion channel in the two voltage conversion channels reaches a preset threshold, the power supply voltage provides the second driving power supply voltage for the second voltage conversion channel in the two voltage conversion channels.

3. The power supply circuit of claim 2, wherein, The duty cycle of the switch of the first voltage conversion channel is less than the duty cycle of the switch of the second voltage conversion channel, and the second power supply module provides the second driving power supply voltage for the second voltage conversion channel.

4. The power supply circuit of claim 1, wherein, Each voltage conversion channel in the plurality of voltage conversion channels comprises a first switch tube and a second switch tube connected with an intermediate node of the corresponding voltage conversion channel, one end of the second switch tube is connected with a reference ground, and the first switch tube and the second switch tube are coupled to an energy storage element in the corresponding voltage conversion channel through the intermediate node, When the intermediate nodes of the two voltage conversion channels are both high, the second power supply module provides the second driving power supply voltage for the second voltage conversion channel.

5. The power supply circuit of claim 4, wherein, The second switch tube in the first voltage conversion channel has a conduction time period in each switching cycle, and the conduction time of the second switch tube in each switching cycle is greater than a preset threshold.

6. The power supply circuit of claim 4, wherein, Each second power supply module in the at least one second power supply module comprises a gate drive circuit and a gating unit. The gating unit is used to control whether the power supply voltage is provided to the second voltage conversion channel. The gate drive circuit controls the on-off state of the gating unit according to the level of the intermediate nodes of the two voltage conversion channels.

7. The power supply circuit of claim 6, wherein, When the intermediate nodes of the two voltage conversion channels are both high, the gating unit is turned on.

8. The power supply circuit of claim 6, wherein, The gating unit comprises a third switch tube, a fourth switch tube and a first resistor. The third switch tube and the fourth switch tube are connected in series between the output end of the power supply voltage and the corresponding second voltage conversion channel, and the control ends of the third switch tube and the fourth switch tube are connected with the output end of the gate drive circuit. The parasitic diode of the third switch tube and the parasitic diode of the fourth switch tube are reversely connected in series. A first end of the first resistor is connected to a control end of the third switch tube, and a second end of the first resistor is connected to a common connection node of the third switch tube and the fourth switch tube.

9. The power supply circuit of claim 6, wherein, The gating unit comprises a fifth switch tube and a first diode. The fifth switch tube and the first diode are connected in series between the output end of the supply voltage and the corresponding second voltage conversion channel. A control end of the fifth switch tube is connected to an output end of the gate drive circuit. The first diode and a parasitic diode of the fifth switch tube are connected in reverse series.

10. The power supply circuit of claim 4, wherein, A first end of a first capacitor in the first supply module is coupled to a reference power supply voltage of the corresponding channel, and a second end of the first capacitor is coupled to an intermediate node of the corresponding channel, and a voltage of the first capacitor serves as an output voltage of the first supply module.

11. The power supply circuit of claim 4, wherein, The second supply module comprises a second capacitor, A first end of the second capacitor is connected to a reference power supply voltage of the second voltage conversion channel through a second diode, A second end of the second capacitor is connected to an intermediate node of the first voltage conversion channel. A voltage of the first end of the second capacitor serves as a supply voltage of the second supply module.

12. The power supply circuit of claim 11, wherein, The reference power supply voltage corresponding to the first voltage conversion channel is less than the reference power supply voltage corresponding to the second voltage conversion channel.

13. The power supply circuit of claim 4, wherein, The reference power supply voltage corresponding to the first voltage conversion channel is equal to the reference power supply voltage corresponding to the second voltage conversion channel, The first end of the first capacitor corresponding to the first voltage conversion channel in the first supply module is connected to the second supply module, When the intermediate nodes of the two voltage conversion channels are both high, the voltage of the first end of the first capacitor serves as the supply voltage of the second supply module.

14. A switched mode power supply comprising a plurality of voltage conversion channels, wherein, The switching power supply further comprises the supply circuit according to any one of claims 1-13, The plurality of voltage conversion channels comprises a controller and a plurality of drivers, the plurality of drivers receiving switching control signals output by the controller to drive switching states of switch tubes in the plurality of voltage conversion channels. The supply circuit provides driving supply voltages for the plurality of drivers.

15. The switching power supply of claim 14, wherein, Each voltage conversion channel of the plurality of voltage conversion channels comprises a first switch tube and a second switch tube connected to an intermediate node of the corresponding voltage conversion channel, one end of the second switch tube is connected to a reference ground, and a first driver driving the first switch tube and a second driver driving the second switch tube. The second supply module in the supply circuit provides a second driving supply voltage for the first driver in the voltage conversion channel corresponding to the supply.

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