Driving circuit, controller and switching power supply

Abstract

The invention provides a driving circuit, a controller and a switching power supply, and the driving circuit comprises a driver, a first power supply end of which receives a first voltage signal, a second power supply end of which is coupled with a current output end of a power tube to receive a second voltage signal, and an output end of which is coupled with a control end of the power tube; and the driving power supply circuit is used for switching a power supply path for providing the first voltage signal to the first power supply end along with the change of the second voltage signal at the switch node, and the driver realizes automatic switching of the driving current along with the switching of the power supply path. According to the invention, the driving current is automatically switched according to the rise of the second voltage signal at the switch node, the change rate of the driving current in the conduction process of the power tube can be reduced, the switching noise is reduced, the EMI performance is improved, and the ringing effect of the switch node is reduced.

Description

Technical Field

[0001] The present application relates to the field of switch drive technology, and in particular to a drive circuit, a controller and a switch power supply. Background Art

[0002] The switching power supply is mainly composed of a power stage circuit with a power tube and a controller with a drive circuit. The power stage circuit is used to realize the conversion from input voltage to output voltage, which usually includes a power tube and an inductor. The drive circuit in the controller can drive the power tube in the power stage circuit to turn on or off quickly to adjust the conversion efficiency of the power stage circuit. The current topological structures of the power stage circuit mainly include buck structure, boost structure, boost-buck structure and other structures.

[0003] However, in a switching power supply, when the power tube is turned on too quickly, the voltage rise and fall speeds at the current output terminal SW of the power tube in the power stage circuit will also be too fast. Due to the existence of parasitic inductance, this will cause excessive overshoot or undershoot at the current output terminal SW, thereby causing the risk of reduced life of the power stage circuit or even direct damage. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a driving circuit, a controller and a switching power supply, which aim to reduce the change rate of the driving current, reduce switching noise, improve EMI performance, and reduce ringing effects.

[0005] According to a first aspect of the present application, a driving circuit is provided, which is applied to a switching power supply, and the driving circuit includes:

[0006] A driver, wherein the input end receives a control signal, the first power supply end receives a first voltage signal, the second power supply end is coupled to the current output end of the power tube in the switching power supply at a switch node to receive a second voltage signal, and the output end is coupled to the control end of the power tube. During the power tube is turned on, the driver outputs a corresponding driving current to the control end of the power tube;

[0007] A driving power supply circuit is coupled to the first power supply end of the driver and the switch node. The driving power supply circuit is used to switch the power supply path for providing the first voltage signal to the first power supply end following the change of the second voltage signal at the switch node. The driver realizes automatic switching of the driving current following the switching of the power supply path.

[0008] Optionally, the driving power supply circuit includes an isolation device,

[0009] The power supply path includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal and a preset voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal.

[0010] The first end of the isolation device is connected to the preset voltage source, and the second end is connected to the first power supply end.

[0011] Optionally, the isolation device includes a first diode, and the driving power supply circuit realizes automatic switching of the power supply path in response to the conduction and cutoff conditions of the first diode within different voltage ranges of the second voltage signal.

[0012] Optionally, the switching of the power supply path corresponds to the switching of the equivalent resistance, and the power supply paths before and after the switching have different equivalent resistances.

[0013] Optionally, when the second voltage signal is within a first voltage range, a power supply path through which the driving power supply circuit provides the first voltage signal to the first power supply end is the first power supply path, and the driver outputs a first driving current to the control end of the power tube using an equivalent resistance of the first power supply path;

[0014] When the second voltage signal is within a second voltage range, the driving power supply circuit provides the first voltage signal to the first power supply end so as to supply power from the first power supply path and the second power supply path, and the driver outputs a second driving current to the control end of the power tube;

[0015] When the second voltage signal is within the third voltage range, the power supply path for providing the first voltage signal at the first power supply end of the driving power supply circuit is the second power supply path, and the driver outputs a third driving current to the control end of the power tube using the equivalent resistance of the second power supply path.

[0016] The equivalent resistance of the second power supply path is greater than the equivalent resistance of the first power supply path, the first drive current is greater than the second drive current, and the second drive current is greater than the third drive current.

[0017] Optionally, within the second voltage range, when the second voltage signal gradually increases, the power supply path for providing the first voltage signal is gradually switched from the first power supply path to the second power supply path.

[0018] Optionally, the driving power supply circuit includes a first diode coupled to a first power supply path, and the driving power supply circuit realizes automatic switching of the power supply path in response to the conduction and cutoff conditions of the first diode within different voltage ranges of the second voltage signal.

[0019] Optionally, the driving power supply circuit is configured such that the cathode potential of the first diode increases as the second voltage signal increases, and the first diode gradually switches from a forward conduction state to a reverse cutoff state after the second voltage signal increases to exceed the first voltage range;

[0020] During the forward conduction period of the first diode, the driving power supply circuit provides the first voltage signal to the first power supply end by using the first power supply path;

[0021] During the transition period from the forward conduction to the reverse cutoff of the first diode, the driving power supply circuit uses the first power supply path and the second power supply path to jointly provide the first voltage signal to the first power supply end;

[0022] After the first diode is reversely cut off, the driving power supply circuit uses the second power supply path to provide the first voltage signal to the first power supply end.

[0023] Optionally, the driving power supply circuit further includes:

[0024] An energy storage element, coupled to the second power supply path, wherein a second end of the energy storage element is coupled to the switch node so as to use the second voltage signal at the switch node as a reference potential;

[0025] a charging unit, coupled to the first end of the energy storage element, for charging the energy storage element,

[0026] Wherein, the driving power supply circuit configures the cathode potential of the first diode to increase with the increase of the second voltage signal based on the potential change of the first end of the energy storage element relative to the second voltage signal.

[0027] Optionally, the driving power supply circuit further includes:

[0028] A resistance unit is coupled between the first end of the energy storage element and the first power supply end, and the equivalent resistance of the second power supply path includes the effective resistance value of the resistance unit.

[0029] Optionally, during a period when the second voltage signal is less than a first threshold voltage, the second voltage signal is within the first voltage range;

[0030] During a period when the second voltage signal is greater than the first threshold voltage and less than a second threshold voltage, the second voltage signal is within the second voltage range;

[0031] While the second voltage signal is greater than the second threshold voltage and the difference between the input voltage of the switching power supply and the second voltage signal is greater than a preset threshold, the second voltage signal is within the third voltage range; or, while the second voltage signal is greater than the second threshold voltage and within a predetermined delay time before a rising edge of the control signal appears, the second voltage signal is within the third voltage range.

[0032] Optionally, when a rising edge appears in the control signal, the driver starts to output the first driving current to the control end of the power tube.

[0033] Optionally, the magnitude of the second driving current is negatively correlated with the magnitude of the second voltage signal.

[0034] Optionally, the preset voltage source includes:

[0035] a first voltage source, wherein a negative electrode of the first voltage source is coupled to a reference ground, and a positive electrode of the first voltage source is coupled to an anode of the first diode,

[0036] During the forward conduction period of the first diode, the driving power supply circuit uses the first voltage source and the first diode to provide the first voltage signal.

[0037] Optionally, the first threshold voltage is equal to zero, and the second threshold voltage is equal to the forward conduction voltage of the first diode.

[0038] Optionally, the preset voltage source includes:

[0039] a first voltage source, wherein a negative electrode of the first voltage source is coupled to a reference ground;

[0040] a second voltage source, wherein a negative electrode of the second voltage source is coupled to a positive electrode of the first voltage source, and a positive electrode of the second voltage source is coupled to an anode of the first diode,

[0041] Wherein, during the forward conduction period of the first diode, the driving power supply circuit uses the first voltage source, the second voltage source and the first diode to provide the first voltage signal.

[0042] Optionally, the first threshold voltage is equal to the output voltage of the second voltage source, and the second threshold voltage is equal to the sum of the output voltage of the second voltage source and the forward conduction voltage of the first diode.

[0043] Optionally, the charging unit includes:

[0044] the first voltage source;

[0045] A second diode, wherein an anode of the second diode is coupled to the positive electrode of the first voltage source, and a cathode of the second diode is coupled to the first end of the energy storage element.

[0046] Optionally, the charging unit includes:

[0047] a third voltage source, wherein a negative electrode of the third voltage source is coupled to a reference ground;

[0048] A second diode, wherein an anode of the second diode is coupled to the positive electrode of the third voltage source, and a cathode of the second diode is coupled to the first end of the energy storage element.

[0049] Optionally, the first threshold voltage is equal to the difference between the output voltages of the first voltage source and the third power supply voltage, and the second threshold voltage is equal to the sum of the difference between the output voltages of the first voltage source and the third power supply voltage and the forward conduction voltage of the first diode.

[0050] Optionally, the resistance unit includes:

[0051] A first resistor, wherein a first end of the first resistor is coupled to a first end of the energy storage element, and a second end of the first resistor is coupled to the first power supply end.

[0052] Optionally, the resistance unit further includes:

[0053] A first switch is coupled in parallel with the first resistor, and the first switch is turned on after the difference between the input voltage of the switching power supply and the second voltage signal is less than a preset threshold, or the first switch is turned on after a predetermined delay time after a rising edge of the control signal appears.

[0054] Optionally, the resistance unit comprises: a variable resistance device with adjustable effective resistance;

[0055] After the difference between the input voltage of the switching power supply and the second voltage signal is less than a preset threshold, or after a predetermined delay time of a rising edge of the control signal, the effective resistance of the variable resistance device is less than the effective resistance of the variable resistance device during the period when the second voltage signal is in the third voltage range.

[0056] Optionally, the resistance unit further includes:

[0057] A fourth voltage source is connected in series with the first switch and then coupled in parallel with the first resistor.

[0058] Optionally, the switching of the power supply path corresponds to the switching of the driving power supply voltage, and the power supply paths before and after the switching provide different driving power supply voltages, wherein the driving power supply voltage is the difference between the first voltage signal and the second voltage signal.

[0059] Optionally, the power supply path includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal and the first voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal.

[0060] The second power supply path includes a second voltage source or an energy storage element, and a voltage of the first voltage source is different from a voltage of the second voltage source or the energy storage element.

[0061] Optionally, the driver includes at least one stage of driving unit, and the first power supply end of the last stage of driving unit in the driver is coupled to the first power supply end of the driver to receive the first voltage signal.

[0062] According to a second aspect of the present application, a controller is provided, comprising: a driving circuit as described in any embodiment of the present application.

[0063] According to a third aspect of the present application, a switching power supply is provided, comprising: a controller as described in any embodiment of the present application.

[0064] The beneficial effects of this application include at least:

[0065] In the embodiment of the present application, a driving power supply circuit in a driving circuit is configured to automatically switch the power supply path following the change of the second voltage signal at the switch node to provide a first voltage signal to the first power supply end of the driver, so that in the process of the driver outputting the driving current according to the first voltage signal and the second voltage signal, the driver can automatically switch the driving current according to the rise of the second voltage signal at the switch node, thereby realizing multi-stage opening of the driving circuit, reducing the change rate of the driving current during the conduction process of the power tube, which is beneficial to reducing switching noise, and the circuit structure is simple and reliable.

[0066] In a further preferred scheme, the embodiment of the present application is arranged to drive the power tube with a larger driving current in the early stage of the power tube conduction (such as during the period when the second voltage signal is less than the second threshold voltage), which can improve the switching speed of the power tube and reduce the switching loss; and in the later stage of the power tube conduction (such as during the period when the second voltage signal is greater than the second threshold voltage, and the difference with the input voltage of the switching power supply is greater than the preset threshold), the driving current is limited by the resistance unit, thereby limiting the voltage change rate at the switch node with a smaller driving current, effectively reducing the ringing of the voltage at the switch node, and helping to improve the EMI performance of the system.

[0067] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1A circuit diagram of a switching power supply provided according to a first embodiment of the present application is shown;

[0069] Figure 2 A circuit diagram of a switching power supply provided according to a second embodiment of the present application is shown;

[0070] Figure 3 A circuit diagram of a switching power supply provided according to a third embodiment of the present application is shown;

[0071] Figure 4 A circuit diagram of a switching power supply provided according to a fourth embodiment of the present application is shown;

[0072] Figure 5 A circuit diagram of a switching power supply provided according to a fifth embodiment of the present application is shown;

[0073] Figure 6 A circuit diagram of a switching power supply provided according to a sixth embodiment of the present application is shown;

[0074] Figure 7 A schematic diagram showing some operating waveforms of a switching power supply according to some embodiments of the present application is shown. DETAILED DESCRIPTION

[0075] In order to facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0076] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0077] In the description of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments. "And / or" in this article is a description of the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. "Coupled" is a description of the connection relationship between the associated objects. For example, A is coupled to B, which can represent a direct connection between A and B, or an indirect connection between A and B through other devices / units / modules. "Multiple" refers to two or more than two. In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present application, the words "first", "second" and the like are used to distinguish the same items or similar items with substantially the same functions and effects. Those skilled in the art can understand that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first", "second" and the like do not limit them to be necessarily different.

[0078] In addition, the same figure marks in the figures represent the same or similar structures, and thus their repeated description will be omitted. That is, the various parts in this specification are described in a combination of parallel and progressive manners, and each part focuses on the differences from other parts. The same or similar parts between the various parts can be referenced to each other.

[0079] The control end driving schemes of the main power tube of the switching power supply in the related art include the following:

[0080] Solution 1: The main power tube uses a single drive power supply and is driven by a hard switch control method. However, in this solution, when the main power tube is turned on, the change rate of the control end drive current of the main power tube is relatively fast. Based on the oscillation of the parasitic inductance and parasitic capacitance in the main power tube, on the one hand, it is easy to cause the voltage spike at the switch node of the switching power supply to be too high, requiring a power tube with a higher voltage resistance; on the other hand, it is easy to cause the switching noise of the power tube to be too large, affecting the EMI performance of the system.

[0081] Solution 2: Reduce the switching speed, such as connecting a drive resistor in series at the power supply of the drive circuit to reduce the rate of change of the drive current. However, the degree of reduction in the switching speed in this solution is fixed, which can easily lead to a significant increase in switching losses.

[0082] Solution 3: Use a multi-stage drive mode to detect the switch node voltage at different stages and select the corresponding drive current to output, so as to reduce the change rate of the drive current. However, this solution is complex to design, difficult to implement, and has a high design cost.

[0083] Solution 4: Limit the change rate of the drive current by limiting the peak current. However, this solution is not effective in reducing the voltage ringing of the switch node.

[0084] Figures 1 to 6 The circuit diagrams of the switching power supplies provided in different embodiments of the present application are respectively shown. It should be noted that: Figures 1 to 6 Only a buck-type switching power supply topology is shown as an example. The driving scheme of the present application can also be applied to other non-isolated (such as boost, boost-buck) or isolated (such as forward, flyback, full-bridge or push-pull topologies, etc.) switching power supply topologies.

[0085] exist Figures 1 to 6 In each of the examples shown, the switching power supply includes: a power tube Q1 , a rectifier tube Q2 , an inductor L, an output capacitor Co and a controller 100 .

[0086] The power tube Q1 is coupled between the application terminal of the voltage input terminal Vin and the switch node SW. Exemplarily, the power tube Q1 can be selected as an NMOS transistor, in which case the drain of the power tube Q1 is coupled to the voltage input terminal of the switching power supply, and the current output terminal of the power tube Q1 is coupled to the switch node SW.

[0087] The rectifier tube Q2 is, for example, a diode, wherein the cathode of the rectifier tube Q2 is coupled to the switch node SW, and the anode of the rectifier tube Q2 is coupled to a reference ground providing a reference potential.

[0088] A first terminal of the inductor L is coupled to the switch node SW, a second terminal of the inductor L is coupled to a first terminal of the output capacitor Co, and a second terminal of the output capacitor Co is coupled to the reference ground. The switching power supply generates an output voltage Vout at the first terminal of the output capacitor Co.

[0089] The control circuit 100 includes a control signal generating circuit 110 and a driving circuit.

[0090] The control signal generating circuit 110 generates a control signal (PWM signal) for driving the power tube Q1. The specific structure and working principle of the control signal generating circuit 110 can be understood by referring to the existing technical solutions, and will not be described in detail in this article.

[0091] The driving circuit is coupled between the output terminal of the control signal generating circuit 110 and the control terminal of the power tube Q1, and is used to improve the driving capability of the PWM signal output by the control signal generating circuit 110. The driving circuit can apply the first voltage signal VDD to the control terminal of the power tube Q1 so as to put the power tube Q1 into a conducting state, and the driving circuit can also apply the second voltage signal (i.e., the node voltage of the switch node SW) Vsw to the control terminal of the power tube Q1 so as to put the power tube Q1 into a shut-off state.

[0092] Furthermore, the driving circuit includes: a driver 120 and a driving power supply circuit 130. The input end of the driver 120 receives a control signal (such as a PWM signal), the first power supply end of the driver 120 receives a first voltage signal VDD, the second power supply end of the driver 120 is coupled to the switch node SW to receive the second voltage signal Vsw, and the output end of the driver 120 is coupled to the control end of the power tube Q1. When the power tube Q1 is turned on, the driver 120 outputs a corresponding driving current Ig to the control end of the power tube Q1.

[0093] The driver 120 includes at least one driving unit. In some examples, the driver 120 includes, for example, a plurality of cascaded inverters and a buffer 123, wherein the plurality of inverters correspond to a plurality of preceding driving units, and the buffer 123 corresponds to the last driving unit. In this embodiment, two cascaded inverters 121 and 122 are used as an example for explanation. The driving capability of the inverter increases step by step with the progression of the cascade, that is, the driving capability of the inverter 122 is greater than the driving capability of the inverter 121, and at the same time, the driving capability of the buffer 123 is the strongest, so that the buffer 123 has sufficient driving capability to switch the control terminal potential of the power tube Q1 between high and low.

[0094] refer to Figure 1 In this embodiment, the input end of the inverter 121 corresponds to the input end of the driver 120, the first power supply end of the buffer 123 corresponds to the first power supply end of the driver 120, the second power supply end of the buffer 123 corresponds to the second power supply end of the driver 120, and the output end of the buffer 123 corresponds to the output end of the driver 120.

[0095] The driving power supply circuit 130 is coupled to the first power supply terminal of the driver 120 and the switching node SW. The driving power supply circuit 130 is used to automatically switch the power supply path that provides the first voltage signal VDD to the first power supply terminal of the driver 120 following the change of the second voltage signal Vsw at the switching node. The driver 120 can realize automatic switching of the driving current Ig following the automatic switching of the power supply path.

[0096] Optionally, in some embodiments of the present application, the switching of the power supply path is accompanied by or corresponds to the switching of the equivalent resistance, and the power supply paths before and after the switching have different equivalent resistances.

[0097] The structure and working principle of the driving circuits in these embodiments are further described below in conjunction with the accompanying drawings.

[0098] Embodiment 1

[0099] Figure 1 Shown is a circuit diagram of a switching power supply provided in the first embodiment of the present application.

[0100] like Figure 1 As shown, in this embodiment, the power supply path includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal of the driver 120 and the preset voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal of the driver 120. The driving power supply circuit 130 includes an isolation device, a first end of the isolation device is connected to the preset voltage source, and a second end is connected to the first power supply terminal of the driver 120, wherein the driving power supply circuit 130 realizes automatic switching of the power supply path in response to the on and off conditions of the isolation device within different voltage ranges of the second voltage signal Vsw.

[0101] In some preferred examples, the aforementioned isolation device includes a first diode D1, and the driving power supply circuit 130 realizes automatic switching of the power supply path in response to the conduction and cutoff conditions of the first diode D1 within different voltage ranges of the second voltage signal Vsw.

[0102] When the second voltage signal Vsw is within the first voltage range (for example, during the period when the second voltage signal Vsw is less than the first threshold voltage), the power supply path for the driving power supply circuit 130 to provide the first voltage signal VDD to the first power supply terminal of the driver 120 is the first power supply path, and the driver 120 uses the equivalent resistance of the first power supply path to output the first driving current (recorded as Ig1) to the control terminal of the power tube Q1. Further, when the PWM signal has a rising edge, the driver 120 starts to output the first driving current Ig1 to the control terminal of the power tube Q1, so that the power tube Q1 can quickly enter the first conduction stage (such as the Miller platform conduction stage).

[0103] As the second voltage signal Vsw rises, when the second voltage signal Vsw is within the second voltage range (for example, during the period when the second voltage signal Vsw is greater than the first threshold voltage and less than the second threshold voltage), the driving power supply circuit 130 provides the first voltage signal VDD to the first power supply end of the driver 120 to supply power from the first power supply path and the second power supply path. At this time, the driver 120 outputs a second driving current (referred to as Ig2) to the control end of the power tube Q1; further, as the second voltage signal Vsw gradually increases, the driving power supply circuit 130 provides the first voltage signal VDD. The power supply path is switched from the first power supply path to the second power supply path step by step;

[0104] When the second voltage signal Vsw is within a third voltage range (for example, when the second voltage signal Vsw is greater than the second threshold voltage, and the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is greater than a preset threshold; or, when the second voltage signal Vsw is greater than the second threshold voltage, and within a predetermined delay time when a rising edge of the control signal PWM appears), the power supply path of the driving power supply circuit 130 that provides the first voltage signal VDD to the first power supply end of the driver 120 is completely switched to the second power supply path. At this time, the driver 120 uses the equivalent resistance of the second power supply path to output a third driving current (denoted as Ig3) to the control end of the power tube Q1.

[0105] In this embodiment, the equivalent resistance of the second power supply path is greater than the equivalent resistance of the first power supply path, the first drive current Ig1 is greater than the second drive current Ig2, and the second drive current Ig2 is greater than the third drive current Ig3. Figure 7 As shown. In this way, during the conduction process of the power tube Q1, a larger driving current can be used to provide the switching speed of the power tube Q1 to reduce the switching loss, and then a smaller driving current can be used to limit the voltage change rate (i.e., dv / dt) of the second voltage signal Vsw at the switch node SW, thereby solving the ringing problem of the voltage at the switch node SW and improving the EMI performance of the system.

[0106] In some preferred examples, the magnitude of the second driving current Ig2 is negatively correlated with the magnitude of the second voltage signal Vsw, so that a smooth transition can be achieved when the driving current is switched.

[0107] Exemplarily, the cathode potential of the first diode D1 configured in the driving power supply circuit 130 (i.e., the potential of the node A) increases with the increase of the second voltage signal Vsw, and the first diode D1 gradually switches from the forward conduction state to the reverse cut-off state after the second voltage signal Vsw increases to exceed the first voltage range. During the forward conduction period of the first diode D1, the driving power supply circuit 130 uses the first power supply path to provide the first voltage signal VDD to the first power supply terminal of the driver 120. During the transition period from the forward conduction to the reverse cut-off period of the first diode D1, the driving power supply circuit 130 uses the first power supply path and the second power supply path to jointly provide the first voltage signal VDD to the first power supply terminal of the driver 120. After the first diode D1 is reversely cut off, the driving power supply circuit 130 uses the second power supply path to provide the first voltage signal VDD to the first power supply terminal of the driver 120.

[0108] Furthermore, the driving power supply circuit 130 further includes: an energy storage element coupled to the second power supply path, and a charging unit coupled to the first end of the energy storage element. The second end of the energy storage element is coupled to the switch node SW to use the second voltage signal VSW at the switch node SW as a reference potential; the charging unit is used to charge the energy storage element. The driving power supply circuit 130 configures the cathode potential of the first diode D1 to increase with the increase of the second voltage signal Vsw based on the potential change of the first end of the energy storage element relative to the second voltage signal Vsw.

[0109] Furthermore, the driving power supply circuit 130 further includes: a resistance unit coupled between the first end of the energy storage element and the first power supply end, and the equivalent resistance of the second power supply path includes the effective resistance value of the resistance unit.

[0110] When implementing it, Figure 1 As shown, the energy storage element is, for example, a startup capacitor Cboot. The resistor unit is, for example, a first resistor R. The charging unit includes, for example, a first voltage source V1 and a second diode D2. Figure 1 In the example shown, the preset voltage source includes a first voltage source V1, a cathode of the first voltage source V1 is coupled to a reference ground (or other reference node with a fixed potential), a positive electrode of the first voltage source V1 is coupled to an anode of a first diode D1, a cathode of the first diode D1 (i.e., node A) is coupled to a first power supply terminal of the driver 120, an anode of the second diode D2 is coupled to the positive electrode of the first voltage source V1, a cathode of the second diode D2 is coupled to a first end of a startup capacitor Cboot (i.e., node B), a second end of the startup capacitor Cboot is coupled to a switch node SW, a first end of a first resistor R is coupled to a first end of the startup capacitor Cboot, and a second end of the first resistor R is coupled to a first power supply terminal of the driver 120.

[0111] When the second voltage signal Vsw is within the first voltage range, the first diode D1 is forward-conducted, and the driving power supply circuit 130 uses the first voltage source V1 and the first diode D1 to provide the first voltage signal VDD. When the second voltage signal Vsw is within the second voltage range, the forward conduction degree of the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the driving power supply circuit 130 uses the first voltage source V1, the first diode D, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD, which is specifically manifested in that the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the first voltage source V1 and the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the startup capacitor Cboot and the first resistor R gradually increases as the second voltage signal Vsw increases. When the second voltage signal Vsw is within the third voltage range, the first diode D1 is reversely cut off, and the driving power supply circuit 130 uses the startup capacitor Cboot and the first resistor R to provide the first voltage signal VDD.

[0112] In this embodiment, the first threshold voltage is, for example, equal to zero, and the second threshold voltage is equal to the forward conduction voltage (denoted as Vd1) of the first diode D1, that is, after the second voltage signal Vsw is greater than the forward conduction voltage Vd1 of the first diode D1, the second voltage signal Vsw enters the third voltage range.

[0113] In some examples, the first power supply end of the last-stage driving unit in the driver 120 (such as the buffer 123) is coupled to the first power supply end of the driver 120 (i.e., node A), and receives the first voltage signal VDD to obtain the power supply voltage. The first power supply ends of the other-stage driving units in the driver 120 except the last-stage driving unit obtain the power supply voltage from other nodes of the circuit (such as node B).

[0114] refer to Figure 7 In this embodiment, the working principle of the driving circuit is as follows:

[0115] At time t1, the PWM signal received by the driver 120 switches from a low level to a high level, that is, a rising edge appears in the PWM signal. In the time period t1-t2, the first voltage signal VDD is provided by the first voltage source V1 and the first diode D1, and the ideal voltage of the second voltage signal Vsw at the switch node SW in the switching power supply is zero, and then VDD-Vsw=V1-Vd1, at this time, the drive current Ig output by the driver 120 is the first drive current Ig1, and Ig1=(V1-Vd1-Vgs) / (Rg+R1), Rg is the equivalent resistance between the first power supply terminal and the output terminal of the driver 120, and R1 represents the equivalent resistance of the first power supply path. Since R1 is approximately zero, the first drive current Ig1 can also be expressed as Ig1=(V1-Vd1-Vgs) / Rg. The first drive current Ig1 can control the power tube Q1 to quickly enter the first conduction stage based on the Miller effect.

[0116] At time t2, the power tube Q1 enters the Miller platform conduction stage, and the second voltage signal Vsw starts to rise from the first threshold voltage. In the time period t2-t3, the first diode D1 is in a transition state between the forward conduction state and the reverse cutoff state, and the forward conduction degree of the first diode D1 gradually decreases. The first voltage signal VDD is provided by the first voltage source V1, the first diode D1, the startup capacitor Cboot and the first resistor R. As the second voltage signal Vsw increases, the difference between the first voltage signal VDD and the second voltage signal Vsw gradually decreases, and then in the time period t2-t3, the second drive current Ig2 output by the driver 120 gradually decreases as the second voltage signal Vsw increases, and its magnitude is negatively correlated with the magnitude of the second voltage signal Vsw.

[0117] At time t3, the second voltage signal Vsw rises to a value greater than the second threshold voltage (i.e., the forward conduction voltage Vd1 of the first diode D1), and the first diode D1 enters a reverse cutoff state. At this time, the potential of the first end of the startup capacitor Cboot (i.e., the potential of node B) is greater than the cathode potential of the first diode D1 (i.e., the potential of node A), so that the first voltage signal VDD is provided by the startup capacitor Cboot and the first resistor R. At this time, the drive current Ig output by the driver 120 is the third drive current Ig3, and Ig3 = (Vcboot-Vgs) / (Rg+R2), Vcboot represents the voltage on the startup capacitor Cboot, and R2 represents the equivalent resistance of the second power supply path. Since Vcboot is approximately equal to V1-Vd2, and R2 is approximately equal to the resistance value of the first resistor R, the third drive current Ig3 can also be expressed as Ig3 = (V1-Vd2-Vgs) / (Rg+R1), and Vd2 represents the forward conduction voltage of the second diode D2. That is to say, after time t3, the third driving current Ig3 output by the driver 120 is independent of the magnitude of the second voltage signal Vsw at the switch node SW. At this time, the driving circuit can limit the driving current Ig through the resistor R, thereby limiting the voltage change rate at the switch node SW, thereby reducing the voltage ringing at the switch node SW.

[0118] It should be noted that, in this embodiment, the forward conduction voltages of the first diode D1 and the second diode D2 are equal, that is, Vd1=Vd2, are used as an example for description, but in other embodiments of the present application, the forward conduction voltages of the first diode D1 and the second diode D2 may not be equal. In addition, the second threshold voltage in the embodiment of the present application actually refers to the voltage of the switch node SW corresponding to when the first diode D1 is completely turned off.

[0119] As can be seen from the above, the driving circuit disclosed in this embodiment adopts a dual driving power supply (including a first voltage signal VDD and a second voltage signal Vsw), and in the conduction process of the power tube Q1, the power supply path of the other driving power supply (i.e., the first voltage signal VDD) can be automatically adjusted according to the voltage change of one of the driving power supplies (i.e., the second voltage signal Vsw), including driving the power tube with a larger driving current in the early stage of the power tube conduction (such as in the time period t1-t3), thereby improving the switching speed of the power tube and reducing the switching loss; and in the later stage of the power tube conduction (such as after time t3), the first voltage signal VDD is passed through the startup capacitor Cboot and the first resistor R, so that it is convenient to limit the voltage change rate of the switch node SW through the resistor R, so as to achieve the purpose of reducing the voltage ringing at the switch node SW. In other words, the driving circuit disclosed in this embodiment can automatically switch the driving current Ig output to the control end of the power tube Q1 according to the voltage change at the switch node SW, and the multi-stage opening of the driving circuit can be automatically realized without the need to perform the detection and comparison of the switch node voltage in the whole process, and the circuit structure is simple, and the difficulty of implementation and design cost are low.

[0120] Embodiment 2

[0121] The structure of the switching power supply disclosed in this embodiment is as follows Figure 2 shown.

[0122] Specifically, the switching power supply disclosed in this embodiment is based on the same structure as the above-mentioned embodiment 1, and the similarities are not repeated here.

[0123] The difference is that: in this embodiment, the driving circuit further includes a voltage detection unit 131, and the resistance unit in the driving power supply circuit 130 further includes a first switch S1. The first switch S1 is coupled in parallel with the first resistor R, and the voltage detection unit 131 is used to detect the second voltage signal Vsw, and control the first switch S1 to turn on after detecting that the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than a preset threshold.

[0124] Of course, in other implementations of the embodiments of the present application, the resistance unit including the first switch S1 and the first resistor R can also be replaced by a variable resistance device with an adjustable effective resistance. In this case, the variable resistance device is set to have an effective resistance value after the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than a preset threshold value that is less than the effective resistance value of the variable resistance device when the second voltage signal Vsw is in the third voltage range.

[0125] refer to Figure 7Compared with the first embodiment, the driving circuit disclosed in this embodiment is also used to turn on the first switch S1 at time t4, that is, when the second voltage signal Vsw is close to the input voltage Vin (such as when the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than the preset threshold), and the driving power supply circuit 130 uses the power supply path formed by the startup capacitor Cboot and the first switch S1 to provide the first voltage signal VDD to the driver 120, so that the power tube Q1 can quickly enter the normal opening stage. It can be understood that after time t4, the driving current Ig output by the driver 120 is (V1-Vd2-Vgs) / (Rg+Rs1 / / R), where Vd2 represents the forward conduction voltage of the second diode D2, Rs1 represents the on-resistance of the first switch, the symbol " / " represents the division operation, and "Rs1 / / R" represents the parallel resistance value of the resistor Rs1 and the resistor R.

[0126] It can be understood that the present embodiment further adds a turn-on phase of the driving circuit, which can quickly realize the normal turn-on of the power tube Q1 on the basis of reducing the voltage ringing of the switch node SW, thereby further reducing the switching loss.

[0127] Embodiment 3

[0128] The structure of the switching power supply disclosed in this embodiment is as follows Figure 3 shown.

[0129] Specifically, the switching power supply disclosed in this embodiment is based on the same structure as the above-mentioned embodiment 1 or embodiment 2, and the similarities are not repeated here.

[0130] The difference is that: in this embodiment, the preset voltage source includes a first voltage source V1 and a second voltage source V2.

[0131] exist Figure 3 In the example shown, the driving power supply circuit 130 specifically includes: a first voltage source V1, a second voltage source V2, a first diode D1, a second diode D2, a startup capacitor Cboot and a first resistor R. The cathode of the first voltage source V1 is coupled to the reference ground, the anode of the first voltage source V1 is coupled to the cathode of the second voltage source V2, the anode of the second voltage source V2 is coupled to the anode of the first diode D1, the cathode of the first diode D1 is coupled to the first power supply terminal of the driver 120, the anode of the second diode D2 is coupled to the anode of the first voltage source V1, the cathode of the second diode D2 is coupled to the first end of the startup capacitor Cboot, the second end of the startup capacitor Cboot is coupled to the switch node SW, the first end of the first resistor R is coupled to the first end of the startup capacitor Cboot, and the second end of the first resistor R is coupled to the first power supply terminal of the driver 120.

[0132] Among them, when the second voltage signal Vsw is within the first voltage range, the first diode D1 is forward-conducted, and the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2 and the first diode D1 to provide the first voltage signal VDD. When the second voltage signal Vsw is within the second voltage range, the forward conduction degree of the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2, the first diode D, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD, which is specifically manifested in that the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the first voltage source V1, the second voltage source V2 and the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the startup capacitor Cboot and the first resistor R gradually increases as the second voltage signal Vsw increases. When the second voltage signal Vsw is within the third voltage range, the first diode D1 is reversely cut off, and the driving power supply circuit 130 uses the startup capacitor Cboot and the first resistor R to provide the first voltage signal VDD.

[0133] Further, when the driving power supply circuit 130 further includes a first switch S1 coupled in parallel with the first resistor R, when the second voltage signal Vsw exceeds the third voltage range, that is, when the second voltage signal Vsw is close to the input voltage Vin (such as when the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than a preset threshold), the first switch S1 is turned on, and at this time, the driving power supply circuit 130 uses the startup capacitor Cboot and the first switch S1 to provide the first voltage signal VDD. Among them, the opening control principle of the first switch S1 can be understood with reference to the above-mentioned embodiment 2, and will not be repeated here.

[0134] In this embodiment, the first threshold voltage is, for example, equal to the output voltage of the second voltage source V2, and the second threshold voltage is equal to the sum of the output voltage of the second voltage source V2 and the forward conduction voltage of the first diode D1, that is, V2+Vd1.

[0135] In this embodiment, the working principle of the driving circuit can be understood by referring to the working principle of the driving circuit described in the above-mentioned embodiment 1 and embodiment 2, and will not be repeated here. The difference is that in this embodiment, the moment t2 corresponds to the moment when the second voltage signal Vsw rises to a value greater than the first threshold voltage (i.e., V2), and the moment t3 corresponds to the moment when the second voltage signal Vsw rises to a value greater than the second threshold voltage (i.e., V2+Vd1). That is to say, in this embodiment, by adding the second voltage source V2 between the first voltage source V1 and the first diode D1, the driving circuit can be controlled to adjust the driving current Ig only when the second voltage signal Vsw rises to a value close to the output voltage of the second voltage source V2, and then the first resistor R intervenes to adjust the driving current Ig, thereby realizing flexible control of the timing of adjusting the driving current through the first resistor R, and having a wider range of applications. Among them, it is assumed that the output voltage of the second voltage source V2 is much greater than the forward conduction voltage Vd1 of the first diode.

[0136] Embodiment 4

[0137] The structure of the switching power supply disclosed in this embodiment is as follows Figure 4 shown.

[0138] Specifically, the switching power supply disclosed in this embodiment is based on the same structure as the above-mentioned embodiment 1, embodiment 2 or embodiment 3, and the similarities are not repeated here.

[0139] The difference is that: in this embodiment, the charging unit includes, for example, a third voltage source V3 and a second diode D2.

[0140] exist Figure 4 In the example shown, the driving power supply circuit 130 specifically includes: a first voltage source V1, a third voltage source V3, a first diode D1, a second diode D2, a startup capacitor Cboot and a first resistor R. The cathode of the first voltage source V1 is coupled to the reference ground, the anode of the first voltage source V1 is coupled to the anode of the first diode D1, the cathode of the first diode D1 is coupled to the first power supply terminal of the driver 120, the cathode of the third voltage source V3 is coupled to the reference ground, the anode of the third voltage source V3 is coupled to the anode of the second diode D2, the cathode of the second diode D2 is coupled to the first end of the startup capacitor Cboot, the second end of the startup capacitor Cboot is coupled to the switch node SW, the first end of the first resistor R is coupled to the first end of the startup capacitor Cboot, and the second end of the first resistor R is coupled to the first power supply terminal of the driver 120.

[0141] Among them, when the second voltage signal Vsw is within the first voltage range, the first diode D1 is forward-conducted, and the driving power supply circuit 130 uses the first voltage source V1 and the first diode D1 to provide the first voltage signal VDD (for the case where a second voltage source V2 is also provided on the first power supply path, the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2 and the first diode D1 to provide the first voltage signal VDD). When the second voltage signal Vsw is within the second voltage range, the forward conduction degree of the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the driving power supply circuit 130 uses the first voltage source V1, the first diode D, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD (for the case where the second voltage source V2 is also provided on the first power supply path, the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2, the first diode D1, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD), which is specifically manifested in that the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the first voltage source V1 and the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the startup capacitor Cboot and the first resistor R gradually increases as the second voltage signal Vsw increases. When the second voltage signal Vsw is within the third voltage range, the first diode D1 is reversely cut off, and the driving power supply circuit 130 uses the startup capacitor Cboot and the first resistor R to provide the first voltage signal VDD.

[0142] Further, when the driving power supply circuit 130 further includes a first switch S1 coupled in parallel with the first resistor R, when the second voltage signal Vsw exceeds the third voltage range, that is, when the second voltage signal Vsw is close to the input voltage Vin (such as when the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than a preset threshold), the first switch S1 is turned on, and at this time, the driving power supply circuit 130 uses the startup capacitor Cboot and the first switch S1 to provide the first voltage signal VDD. Among them, the opening control principle of the first switch S1 can be understood with reference to the above-mentioned embodiment 2, and will not be repeated here.

[0143] In this embodiment, the first threshold voltage is equal to the difference between the output voltages of the first voltage source V1 and the third power supply voltage V3, that is, V1-V3, and the second threshold voltage is equal to the sum of the difference between the output voltages of the first voltage source V1 and the third power supply voltage V3 and the forward conduction voltage of the first diode D1, that is, V1-V3+Vd1.

[0144] In this embodiment, the working principle of the driving circuit can be understood by referring to the working principle of the driving circuit described in the above-mentioned embodiment 1, embodiment 2 and embodiment 3, and will not be repeated here. The difference is that: in this embodiment, the moment t2 corresponds to the moment when the second voltage signal Vsw rises to a value greater than the first threshold voltage (i.e., V1-V2), and the moment t3 corresponds to the moment when the second voltage signal Vsw rises to a value greater than the second threshold voltage (i.e., V1-V2+Vd1). That is to say, in this embodiment, by adding a third voltage source V3, and setting the first voltage source V1 and the third voltage source V3 to be coupled to the first diode D1 and the second diode D2 respectively, the driving circuit can be controlled to adjust the driving current Ig only when the second voltage signal Vsw rises to a value close to V1-V3+Vd1 through the first resistor R, so that the timing of adjusting the driving current through the first resistor R can be flexibly controlled through another implementation method, which has a wider range of application and a larger range of options.

[0145] Embodiment 5

[0146] The structure of the switching power supply disclosed in this embodiment is as follows Figure 5 shown.

[0147] Specifically, the switching power supply disclosed in this embodiment is based on the same structure as the above-mentioned embodiment 2, embodiment 3 or embodiment 4, and the similarities are not repeated here.

[0148] The difference is that: in this embodiment, the resistance unit further includes a fourth voltage source V4.

[0149] exist Figure 5 In the example shown, the driving power supply circuit 130 specifically includes: a first voltage source V1, a third voltage source V3, a fourth voltage source V4, a first diode D1, a second diode D2, a startup capacitor Cboot, a first switch S1 and a first resistor R. The cathode of the first voltage source V1 is coupled to the reference ground, the anode of the first voltage source V1 is coupled to the anode of the first diode D1, the cathode of the first diode D1 is coupled to the first power supply terminal of the driver 120, the cathode of the third voltage source V3 is coupled to the reference ground, the anode of the third voltage source V3 is coupled to the anode of the second diode D2, the cathode of the second diode D2 is coupled to the first end of the startup capacitor Cboot, the second end of the startup capacitor Cboot is coupled to the switch node SW, the first end of the first resistor R is coupled to the first end of the startup capacitor Cboot, the second end of the first resistor R is coupled to the first power supply terminal of the driver 120, and the fourth voltage source V4 and the first switch S1 are connected in series and then coupled in parallel with the first resistor R.

[0150] Among them, when the second voltage signal Vsw is within the first voltage range, the first diode D1 is forward-conducted, and the driving power supply circuit 130 uses the first voltage source V1 and the first diode D1 to provide the first voltage signal VDD (for the case where a second voltage source V2 is also provided on the first power supply path, the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2 and the first diode D1 to provide the first voltage signal VDD). When the second voltage signal Vsw is within the second voltage range, the forward conduction degree of the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the driving power supply circuit 130 uses the first voltage source V1, the first diode D, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD (for the case where a second voltage source V2 is also provided on the first power supply path, the driving power supply circuit 130 uses the first voltage source V1, the second voltage source V2, the first diode D1, the startup capacitor Cboot and the first resistor R to jointly provide the first voltage signal VDD). Specifically, the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the first voltage source V1 and the first diode D1 gradually decreases as the second voltage signal Vsw increases, and the proportion of the first voltage signal VDD provided by the driving power supply circuit 130 using the startup capacitor Cboot and the first resistor R gradually increases as the second voltage signal Vsw increases. When the second voltage signal Vsw is within the third voltage range, the first diode D1 is reversely cut off, and the driving power supply circuit 130 uses the startup capacitor Cboot and the first resistor R to provide the first voltage signal VDD; when the second voltage signal Vsw exceeds the third voltage range, that is, when the second voltage signal Vsw is close to the input voltage Vin (such as when the difference between the input voltage Vin of the switching power supply and the second voltage signal Vsw is less than the preset threshold), the first switch S1 is turned on, and at this time, the driving power supply circuit 130 uses the startup capacitor Cboot, the fourth voltage source V4 and the first switch S1 to provide the first voltage signal VDD. Among them, the opening control principle of the first switch S1 can be understood with reference to the above-mentioned embodiment 2, and will not be repeated here.

[0151] In this embodiment, the first threshold voltage is equal to the difference between the output voltages of the first voltage source V1 and the third power supply voltage V3, that is, V1-V3, and the second threshold voltage is equal to the sum of the difference between the output voltages of the first voltage source V1 and the third power supply voltage V3 and the forward conduction voltage of the first diode D1, that is, V1-V3+Vd1.

[0152] In this embodiment, the working principle of the driving circuit can be understood by referring to the working principle of the driving circuit described in the aforementioned Embodiment 2, Embodiment 3 and Embodiment 4, and will not be described in detail here.

[0153] It can be understood that, in this embodiment, after the second voltage signal Vsw exceeds the third voltage range, a higher first power supply voltage VDD can be provided to the first power supply terminal of the driver 120 , thereby achieving a larger driving current.

[0154] Embodiment 6

[0155] The structure of the switching power supply disclosed in this embodiment is as follows Figure 6 shown.

[0156] Specifically, the switching power supply disclosed in this embodiment is based on the same structure as any one of the above-mentioned embodiments 2 to 4, and the similarities are not repeated here.

[0157] The difference is that in this embodiment, a delay circuit 131 is used to replace the voltage detection unit 131. Figure 6 In the example shown, the input end of the delay circuit 131 receives a PWM signal, and the output end is coupled to the control end of the first switch S1. The delay circuit 131 is used to control the first switch S1 to turn on after a predetermined delay time after a rising edge of the PWM signal appears.

[0158] The driving circuit disclosed in this embodiment is equivalent to the opening control of the first switch S1 implemented by adopting a fixed delay scheme. Compared with the above-mentioned embodiment 2, this embodiment does not need to perform voltage sampling of the switch node SW during the opening process of the power tube Q1, and the circuit structure and control scheme are simpler.

[0159] Of course, for the embodiment using a variable resistor device with adjustable effective resistance as the resistance unit, the variable resistor device is correspondingly set to have an effective resistance value after a predetermined delay time of the rising edge of the PWM signal that is smaller than the effective resistance value of the variable resistor device during the period when the second voltage signal Vsw is in the third voltage range.

[0160] In addition, in some other embodiments of the present application, the driving power supply circuit 130 can be set to switch the power supply path for providing the first voltage signal VDD to the first power supply end of the driver 120 corresponding to the switching of the driving power supply voltage, for example, the power supply path before and after the switching provides different driving power supply voltages, wherein the driving power supply voltage is the difference between the first voltage signal VDD and the second voltage signal Vsw.

[0161] In these embodiments, the power supply path for the driving power supply circuit 130 to provide the first voltage signal VDD to the first power supply terminal of the driver 120 includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal of the driver 120 and the first voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal of the driver 120. In these embodiments, a first isolation device (such as a first diode) located between the first power supply terminal and the first voltage source can also be provided in the first power supply path, so that the driving power supply circuit 130 realizes automatic switching of the power supply path in response to the on and off conditions of the first isolation device within different voltage ranges of the second voltage signal Vsw.

[0162] In these embodiments, when the second voltage signal Vsw is within the first voltage range, the driving power supply circuit 130 uses the first power supply path to provide the first voltage signal VDD to the first power supply end of the driver 120, so that the driver 120 has a first driving power supply voltage; when the second voltage signal Vsw is within the second voltage range, the driving power supply circuit 130 uses the second power supply path to provide the first voltage signal to the first power supply end of the driver 120, so that the driver 120 has a second driving power supply voltage, and controls the power tube Q1 to operate in the amplification area; the first driving power supply voltage is greater than the second driving power supply voltage.

[0163] In a specific implementation, the second power supply path includes, for example, a second voltage source, and the voltage of the first voltage source is different from the voltage of the second voltage source. Furthermore, the second power supply path also includes, for example, a second isolation device (such as a second diode) located between the first power supply and the second voltage source of the driver 120 to achieve a more stable and reliable power supply path switching effect. Of course, in other embodiments, the second voltage source on the second power supply path can also be replaced by a first energy storage element, such as a first capacitor. On this basis, the drive power supply circuit 130 also includes a charging unit for charging the first energy storage element, and the charging unit can be implemented, for example, by setting an additional second voltage source.

[0164] In a further preferred example, the power supply path for the driving power supply circuit 130 to provide the first voltage signal VDD to the first power supply terminal of the driver 120 also includes a third power supply path between the first power supply terminal and the second power supply terminal of the driver 120. At this time, when the second voltage signal Vsw is within the third voltage range, the driving power supply circuit 130 uses the third power supply path to provide the first voltage signal VDD to the first power supply terminal of the driver 120, so that the driver 120 has the third driving power supply voltage, and controls the power tube Q1 to work in the saturation region.

[0165] In specific implementation, optionally, the third power supply path includes, for example, a third voltage source and a first switch, and by controlling the on and off of the first switch, the driving power supply circuit 130 provides the first voltage signal VDD to the first power supply terminal of the driver 120 using the third power supply path after the absolute value of the difference between the second voltage signal Vsw and the input voltage Vin of the switching power supply is less than the first preset voltage, or after the control signal PWM has a rising edge of the first predetermined delay time. Of course, in other embodiments, the third voltage source on the third power supply path can also be replaced by a second energy storage element, such as a second capacitor. On this basis, the driving power supply circuit 130 also includes a charging unit for charging the second energy storage element, and the charging unit can be implemented, for example, using the first voltage source, or by setting an additional third voltage source.

[0166] In summary, in the driving circuit disclosed in each embodiment of the present application, the driver adopts a dual driving power supply to output the driving current, and the driving current output by the driver can be automatically switched by utilizing the rise of the second voltage signal at the switching node SW. During the entire turning-on process of the power tube Q1, it is only necessary to detect whether the second voltage signal at the switching node SW is close to the system input voltage Vin (in some embodiments, there is even no need to detect and compare the second voltage signal at the switching node SW), so as to realize multi-stage turning-on control of the driving circuit, which can not only avoid the problems of excessive voltage spikes at the switching node SW and excessive switching noise, but also reduce the rate of change of the driving current during the turning-on process of the power tube, realize different speed reductions of the driving current at different stages, effectively reduce the switching loss, and make the circuit structure simpler and more reliable.

[0167] In some preferred embodiments, the driving circuit scheme disclosed in the present application can drive the power tube with a larger driving current in the early stage of the power tube conduction, so as to increase the switching speed of the power tube and reduce the switching loss; and in the later stage of the power tube conduction, the driving current is limited by the resistance unit, so as to limit the voltage change rate at the switching node SW with a smaller driving current, which can effectively reduce the ringing of the voltage at the switching node SW and help improve the EMI performance of the system.

[0168] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present application, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present application.

Claims

1. A driving circuit, applied to a switching power supply, comprising: A driver, wherein the input end receives a control signal, the first power supply end receives a first voltage signal, the second power supply end is coupled to the current output end of the power tube in the switching power supply at a switch node to receive a second voltage signal, and the output end is coupled to the control end of the power tube. During the power tube is turned on, the driver outputs a corresponding driving current to the control end of the power tube; A driving power supply circuit is coupled to the first power supply end of the driver and the switch node. The driving power supply circuit is used to switch the power supply path for providing the first voltage signal to the first power supply end following the change of the second voltage signal at the switch node. The driver realizes automatic switching of the driving current following the switching of the power supply path.

2. The driving circuit according to claim 1, wherein: The driving power supply circuit includes an isolation device, The power supply path includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal and a preset voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal. The first end of the isolation device is connected to the preset voltage source, and the second end is connected to the first power supply end.

3. The driving circuit according to claim 2, wherein: The isolation device includes a first diode, and the driving power supply circuit realizes automatic switching of the power supply path in response to the conduction and cutoff conditions of the first diode within different voltage ranges of the second voltage signal.

4. The driving circuit according to claim 3, wherein: The switching of the power supply path corresponds to the switching of the equivalent resistance, and the power supply paths before and after the switching have different equivalent resistances.

5. The driving circuit according to claim 4, wherein: When the second voltage signal is within the first voltage range, the power supply path through which the driving power supply circuit provides the first voltage signal to the first power supply end is the first power supply path, and the driver outputs a first driving current to the control end of the power tube using the equivalent resistance of the first power supply path; When the second voltage signal is within a second voltage range, the driving power supply circuit provides the first voltage signal to the first power supply end so as to supply power from the first power supply path and the second power supply path, and the driver outputs a second driving current to the control end of the power tube; When the second voltage signal is within the third voltage range, the power supply path through which the driving power supply circuit provides the first voltage signal to the first power supply end is the second power supply path, and the driver outputs a third driving current to the control end of the power tube using the equivalent resistance of the second power supply path. The equivalent resistance of the second power supply path is greater than the equivalent resistance of the first power supply path, the first drive current is greater than the second drive current, and the second drive current is greater than the third drive current. 6 . The driving circuit according to claim 5 , wherein within the second voltage range, when the second voltage signal gradually increases, the power supply path for providing the first voltage signal is gradually switched from the first power supply path to the second power supply path.

7. The driving circuit according to claim 3, wherein: The driving power supply circuit also includes: An energy storage element, coupled to the second power supply path, wherein a second end of the energy storage element is coupled to the switch node so as to use the second voltage signal at the switch node as a reference potential; a charging unit, coupled to the first end of the energy storage element, for charging the energy storage element, Wherein, the driving power supply circuit configures the cathode potential of the first diode to increase with the increase of the second voltage signal based on the potential change of the first end of the energy storage element relative to the second voltage signal.

8. The driving circuit according to claim 7, wherein: The driving power supply circuit also includes: A resistance unit is coupled between the first end of the energy storage element and the first power supply end, and the equivalent resistance of the second power supply path includes the effective resistance value of the resistance unit.

9. The driving circuit according to claim 7, wherein: During a period when the second voltage signal is less than the first threshold voltage, the second voltage signal is within the first voltage range; During a period when the second voltage signal is greater than the first threshold voltage and less than a second threshold voltage, the second voltage signal is within the second voltage range; While the second voltage signal is greater than the second threshold voltage and the difference between the input voltage of the switching power supply and the second voltage signal is greater than a preset threshold, the second voltage signal is within the third voltage range; or, while the second voltage signal is greater than the second threshold voltage and within a predetermined delay time before a rising edge of the control signal appears, the second voltage signal is within the third voltage range.

10. The driving circuit according to claim 5, wherein: When a rising edge appears on the control signal, the driver starts to output the first driving current to the control end of the power tube.

11. The driving circuit according to claim 5, wherein: The magnitude of the second driving current is negatively correlated with the magnitude of the second voltage signal.

12. The driving circuit according to claim 9, wherein: The preset voltage source comprises: a first voltage source, wherein a negative electrode of the first voltage source is coupled to a reference ground, and a positive electrode of the first voltage source is coupled to an anode of the first diode, During the forward conduction period of the first diode, the driving power supply circuit uses the first voltage source and the first diode to provide the first voltage signal.

13. The driving circuit according to claim 12, wherein: The first threshold voltage is equal to zero, and the second threshold voltage is equal to the forward conduction voltage of the first diode.

14. The driving circuit according to claim 9, wherein: The preset voltage source comprises: a first voltage source, wherein a negative electrode of the first voltage source is coupled to a reference ground; a second voltage source, wherein a negative electrode of the second voltage source is coupled to a positive electrode of the first voltage source, and a positive electrode of the second voltage source is coupled to an anode of the first diode, Wherein, during the forward conduction period of the first diode, the driving power supply circuit uses the first voltage source, the second voltage source and the first diode to provide the first voltage signal.

15. The driving circuit according to claim 14, wherein: The first threshold voltage is equal to the output voltage of the second voltage source, and the second threshold voltage is equal to the sum of the output voltage of the second voltage source and the forward conduction voltage of the first diode.

16. The driving circuit according to claim 12 or 14, wherein: The charging unit comprises: the first voltage source; A second diode, wherein an anode of the second diode is coupled to the positive electrode of the first voltage source, and a cathode of the second diode is coupled to the first end of the energy storage element.

17. The driving circuit according to claim 12 or 14, wherein: The charging unit comprises: a third voltage source, wherein a negative electrode of the third voltage source is coupled to a reference ground; A second diode, wherein an anode of the second diode is coupled to the positive electrode of the third voltage source, and a cathode of the second diode is coupled to the first end of the energy storage element.

18. The driving circuit according to claim 17, wherein: The first threshold voltage is equal to the difference between the output voltages of the first voltage source and the third power supply voltage, and the second threshold voltage is equal to the sum of the difference between the output voltages of the first voltage source and the third power supply voltage and the forward conduction voltage of the first diode.

19. The driving circuit according to claim 8, wherein: The resistance unit comprises: A first resistor, wherein a first end of the first resistor is coupled to a first end of the energy storage element, and a second end of the first resistor is coupled to the first power supply end.

20. The driving circuit according to claim 19, wherein: The resistance unit further includes: A first switch is coupled in parallel with the first resistor, and the first switch is turned on after the difference between the input voltage of the switching power supply and the second voltage signal is less than a preset threshold, or the first switch is turned on after a predetermined delay time after a rising edge of the control signal appears.

21. The driving circuit according to claim 8, wherein: The resistance unit comprises: a variable resistance device with adjustable effective resistance; After the difference between the input voltage of the switching power supply and the second voltage signal is less than a preset threshold, or after a predetermined delay time of a rising edge of the control signal, the effective resistance of the variable resistance device is less than the effective resistance of the variable resistance device during the period when the second voltage signal is in the third voltage range.

22. The driving circuit according to claim 20, wherein: The resistance unit further includes: A fourth voltage source is connected in series with the first switch and then coupled in parallel with the first resistor.

23. The driving circuit according to claim 1, wherein: The switching of the power supply path corresponds to the switching of the driving power supply voltage, and the power supply paths before and after the switching provide different driving power supply voltages, wherein the driving power supply voltage is the difference between the first voltage signal and the second voltage signal.

24. The driving circuit according to claim 23, wherein: The power supply path includes a first power supply path and a second power supply path, the first power supply path is located between the first power supply terminal and the first voltage source, and the second power supply path is located between the first power supply terminal and the second power supply terminal. The second power supply path includes a second voltage source or an energy storage element, and a voltage of the first voltage source is different from a voltage of the second voltage source or the energy storage element.

25. The driving circuit according to claim 1, wherein: The driver comprises at least one stage of driving unit, and the first power supply end of the last stage of driving unit in the driver is coupled to the first power supply end of the driver to receive the first voltage signal.

26. A controller comprising: A drive circuit as claimed in any one of claims 1 to 25.

27. A switching power supply comprising: A controller as claimed in claim 26.

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