Switching power supply starting method and system

Abstract

The application provides a switching power supply starting method and system. The method comprises the following steps: monitoring the starting time of a switching power supply controller; judging whether the starting time exceeds a first preset time; when the starting time does not exceed the first preset time, adjusting the bandwidth of an integrator to a first bandwidth threshold; and when the starting time exceeds the first preset time, adjusting the bandwidth of the integrator to a second bandwidth threshold, wherein the second bandwidth threshold is smaller than the first bandwidth threshold. Thus, in the cold starting process, the bandwidth is increased, the loop is established quickly, and the auxiliary winding supplies power to the controller as soon as possible. In the hot starting process of the switching power supply, the bandwidth of the integrator in the controller is reduced, the loop establishment speed is reduced, and the problem of output current overshoot in the high-voltage hot starting process is avoided.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more specifically to a switching power supply startup method and system. Background Technology

[0002] Flyback power supply circuits are widely used in low-power power supplies and various power adapters due to their simple circuit structure and low cost. However, for current flyback power supply circuits, during cold starts, especially with low input voltages, the following issues arise: firstly, the low bus voltage results in a small current supplying the controller; secondly, at the beginning of system operation, the energy obtained by the secondary winding is primarily used to charge the electrolytic capacitors, leading to a slow rise in output voltage. Therefore, for a considerable period, the auxiliary winding cannot supply power to the controller because it cannot obtain energy. The controller's power consumption after operation is far greater than the energy supplied by the bus voltage through the resistor. Thus, the controller's power supply voltage gradually decreases. When the controller's power supply voltage drops to the undervoltage protection threshold, it triggers the power-down protection, causing startup failure. Typically, multiple startup processes are required before the system reaches normal operating conditions. For LED lighting, this results in excessively long startup times.

[0003] To address this issue, a common approach is to accelerate loop establishment. However, this approach has a drawback: for hot starts, the output current can overshoot. Generally, due to the large size of the output electrolytic capacitor, after a previous power outage, the capacitor stores a significant amount of charge, causing the output voltage to take a long time to drop to 0V. If power is restored quickly after a power outage, the output voltage remains high, even maintaining its original value. In this case, if the startup still follows the accelerated cold start approach, it will lead to output current overshoot, affecting load lifespan. Summary of the Invention

[0004] Based on this, the technical problem to be solved by the present invention is to overcome the defect of current overshoot during hot start of the flyback power supply circuit in the prior art, thereby providing a switching power supply startup method and system.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, a method for starting up a switching power supply is provided, wherein the switching power supply has a built-in integrator, the method comprising: monitoring the startup time of the switching power supply controller; determining whether the startup time exceeds a first preset time; when the startup time does not exceed the first preset time, adjusting the bandwidth of the integrator to a first bandwidth threshold; when the startup time exceeds the first preset time, adjusting the bandwidth of the integrator to a second bandwidth threshold, wherein the second bandwidth threshold is less than the first bandwidth threshold.

[0007] Optionally, after adjusting the bandwidth of the integrator to a first bandwidth threshold, the power supply startup method further includes: monitoring the output voltage of the power supply; determining whether the output voltage exceeds a preset voltage threshold; and maintaining the bandwidth of the integrator at the first bandwidth threshold when the output voltage does not exceed the preset voltage threshold.

[0008] Optionally, the power supply startup method further includes: when the output voltage exceeds the preset voltage threshold, adjusting the bandwidth of the integrator to a third bandwidth threshold, wherein the third bandwidth threshold is greater than the second bandwidth threshold and the third bandwidth threshold is less than the first bandwidth threshold.

[0009] Optionally, the power supply startup method further includes: determining whether the duration for which the output voltage exceeds the preset voltage threshold exceeds a second preset duration; when the duration for which the output voltage exceeds the preset voltage threshold does not exceed the second preset duration, maintaining the bandwidth of the integrator at a first bandwidth threshold, wherein the second preset duration is less than the first preset duration.

[0010] Optionally, the power supply startup method further includes: when the duration for which the output voltage exceeds the preset voltage threshold exceeds a second preset duration, adjusting the bandwidth of the integrator to a third bandwidth threshold, wherein the third bandwidth threshold is greater than the second bandwidth threshold and the third bandwidth threshold is less than the first bandwidth threshold.

[0011] Optionally, the power supply startup method further includes: adjusting the bandwidth of the integrator by controlling the number of digital integration units connected in the integrator.

[0012] Optionally, the integrator includes: a voltage-to-current conversion circuit, a clock circuit, an integration loop, and an analog-to-digital converter (ADC). The first input terminal of the voltage-to-current conversion circuit receives the output voltage of the switching power supply, and the second input terminal receives a preset voltage threshold. The output terminal of the voltage-to-current conversion circuit is connected to the input terminal of the clock circuit. The voltage-to-current conversion circuit converts the difference between the output voltage and the preset voltage threshold into a current signal and sends the current signal to the clock circuit. The output terminal of the clock circuit is connected to the control terminal of the integration loop. The clock circuit converts the current signal into a clock signal and controls the number of digital integration units connected in the integration loop according to the clock signal, thereby adjusting the bandwidth of the integrator. The output terminal of the integration loop is connected to the output terminal of the ADC. The integration loop sends the bandwidth to the ADC. The ADC converts the bandwidth into a digital signal.

[0013] Optionally, the integration loop includes: a plurality of digital integration units connected in series, each digital integration unit being provided with a bypass switch, the bypass switch being used to control the digital integration unit to enter or exit the integration loop.

[0014] Optionally, the digital integration unit is a frequency divider circuit.

[0015] In a second aspect, embodiments of the present invention provide a switching power supply startup system, applying the switching power supply startup method described in the first aspect of the present invention, comprising: a monitoring module for monitoring the startup time of the switching power supply controller; a judgment module for judging whether the startup time exceeds a first preset time; a first adjustment module for adjusting the bandwidth of the integrator to a first bandwidth threshold when the startup time does not exceed the first preset time; and a second adjustment module for adjusting the bandwidth of the integrator to a second bandwidth threshold when the startup time exceeds the first preset time, wherein the second bandwidth threshold is less than the first bandwidth threshold.

[0016] The technical solution of this invention has the following advantages:

[0017] The switching power supply startup method provided by this invention involves the controller adjusting the integrator bandwidth based on the relationship between the startup time of the switching power supply and a first preset time. This increases the bandwidth during cold starts, accelerating loop establishment so that the auxiliary winding can supply power to the controller as quickly as possible. During hot starts, the bandwidth of the integrator inside the controller is reduced, decreasing the loop establishment speed and preventing output current overshoot during high-voltage hot starts. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a circuit diagram of a switching power supply in an embodiment of the present invention;

[0020] Figure 2 This is a flowchart illustrating a specific example of the switching power supply startup method in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the integrator principle in an embodiment of the present invention;

[0022] Figure 4 This is a timing diagram for controlling NMOS transistor M2 in an embodiment of the present invention;

[0023] Figure 5 This is a block diagram illustrating the principle of the switching power supply startup system in an embodiment of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Flyback power supply circuits are widely used in low-power power supplies and various power adapters due to their simple circuit structure and low cost. However, for applications such as... Figure 1The flyback power supply circuit shown exhibits several challenges during cold starts, particularly with low input voltages. Firstly, the low bus voltage results in a small current supplying the controller. Secondly, initially, the secondary winding primarily charges the electrolytic capacitor C5, causing a slow rise in output voltage. Therefore, for an extended period, the auxiliary winding cannot supply power to the controller due to insufficient energy. The controller's power consumption after startup far exceeds the energy supplied by the bus voltage through resistor R5. Consequently, the controller's power supply voltage gradually decreases. When the controller's power supply voltage drops below the undervoltage protection threshold, it triggers power-down protection, leading to startup failure. Typically, multiple startup attempts are required before the system reaches normal operating conditions. For LED lighting, this results in excessively long startup times.

[0029] To address this issue, a common approach is to accelerate loop establishment. This involves setting the bandwidth of the controller's internal integrator to a larger value to increase the output voltage rise rate, allowing the auxiliary winding to power the controller more quickly. However, this approach has a drawback: for hot starts, the rapid loop establishment can cause output current overshoot. Generally, because the output electrolytic capacitor C5 is large, after a previous power outage, the large amount of charge stored in C5 causes the output voltage to take a long time to drop to 0V. If power is restored quickly after a power outage, the output voltage remains high, even maintaining its original value. In this case, if the startup still follows the cold start approach to accelerate loop establishment, it will lead to output current overshoot, affecting load lifespan.

[0030] Therefore, to solve the above problems, embodiments of the present invention provide a switching power supply startup method. The switching power supply has a built-in integrator. For example... Figure 2 As shown, the power supply startup method includes the following steps:

[0031] Step S10: Monitor the startup time of the switching power supply controller.

[0032] In one specific embodiment, as follows Figure 1 The following explanation uses a primary-side feedback flyback switching power supply as an example. The switching power supply controller integrates an integrator. The integrator... Figure 2 Not shown in the diagram. When the switching power supply starts up, the internal timer of the controller begins counting, recording the startup time of the switching power supply controller. Once the switching power supply has finished starting up, the startup completion flag POR = 1, and the controller begins operation.

[0033] Step S20: Determine whether the startup time exceeds the first preset time.

[0034] In one specific embodiment, a first preset time Ltime is pre-set within the controller. This first preset time Ltime is the startup acceleration time. The switching power supply accelerates startup within the first preset time Ltime. The controller records the startup time of the switching power supply. The controller compares the startup time of the switching power supply with the first preset time Ltime to determine whether the startup time exceeds the first preset time. Based on the determination result, the controller adjusts the bandwidth of the subsequent integrator to avoid overshooting of the output current. In this embodiment of the invention, the first preset time is set according to actual needs.

[0035] Step S30: When the startup time does not exceed the first preset time, adjust the bandwidth of the integrator to the first bandwidth threshold.

[0036] In one specific embodiment, within a first preset time Ltime, the controller processes the system according to a cold start procedure. During the cold start process, in order to successfully start the switching power supply at a low voltage (e.g., 90V), the controller adjusts the integrator's bandwidth to a first bandwidth threshold. The first bandwidth threshold can be set according to actual needs; for example, it can be 16 times the normal bandwidth of the integrator, i.e., increasing the integrator's bandwidth by 16 times. By accelerating loop establishment during the cold start process, the rise rate of the output voltage Vo is increased, so that the auxiliary winding can supply power to the controller as quickly as possible.

[0037] Step S40: When the startup time exceeds the first preset time, adjust the bandwidth of the integrator to the second bandwidth threshold, where the second bandwidth threshold is less than the first bandwidth threshold.

[0038] In one specific embodiment, when the startup time exceeds a first preset time Ltime, the controller adjusts the integrator's bandwidth to a second bandwidth threshold, that is, returns the integrator's bandwidth to a normal value. By returning the integrator's bandwidth to a normal value, the controller stabilizes the output voltage, preventing the switching power supply from continuing to process as a cold start after startup, which would increase the probability of output current overshoot.

[0039] The switching power supply startup method provided by this invention involves the controller adjusting the integrator bandwidth based on the relationship between the startup time of the switching power supply and a first preset time. This increases the bandwidth during cold starts, accelerating loop establishment so that the auxiliary winding can supply power to the controller as quickly as possible. During hot starts, the bandwidth of the integrator inside the controller is reduced, decreasing the loop establishment speed and preventing output current overshoot during high-voltage hot starts.

[0040] In one embodiment, after adjusting the bandwidth of the integrator to a first bandwidth threshold, the power supply startup method further includes the following steps:

[0041] Step S11: Monitor the output voltage of the switching power supply.

[0042] Step S12: Determine whether the output voltage exceeds the preset voltage threshold.

[0043] Step S13: When the output voltage does not exceed the preset voltage threshold, maintain the bandwidth of the integrator at the first bandwidth threshold.

[0044] Step S14: When the output voltage exceeds the preset voltage threshold, adjust the bandwidth of the integrator to the third bandwidth threshold. The third bandwidth threshold is greater than the second bandwidth threshold and less than the first bandwidth threshold.

[0045] In one specific embodiment, when the startup time does not exceed a first preset time Ltime, the controller detects the output voltage Vo through the auxiliary winding. The controller determines whether the output voltage Vo exceeds a preset voltage threshold Vth. When the output voltage Vo does not exceed the preset voltage threshold Vth, the integrator remains at the first bandwidth threshold for the first preset time Ltime, i.e., the integrator bandwidth is increased by 16 times. In the initial startup phase, by increasing the integrator bandwidth by 16 times, the controller can accelerate loop establishment so that the auxiliary winding can supply power to the controller as quickly as possible. When the output voltage Vo exceeds the preset voltage threshold Vth, the controller considers the output voltage to have been established. At this time, to avoid overshoot in the output current, the controller adjusts the bandwidth from the first bandwidth threshold to the third bandwidth threshold. The third bandwidth threshold can be set according to actual needs; for example, the third bandwidth threshold can be 4 times the normal bandwidth of the integrator. That is, the integrator bandwidth is changed from increasing by 16 times to increasing by 4 times. In this embodiment of the invention, the preset voltage threshold is set according to actual needs.

[0046] In one embodiment, the power supply startup method further includes the following steps:

[0047] Step S21: Determine whether the duration for which the output voltage exceeds the preset voltage threshold exceeds the second preset duration.

[0048] Step S22: When the duration for which the output voltage exceeds the preset voltage threshold does not exceed the second preset duration, the bandwidth of the integrator is maintained at the first bandwidth threshold, and the second preset duration is less than the first preset duration.

[0049] Step S23: When the duration for which the output voltage exceeds the preset voltage threshold exceeds the second preset duration, the bandwidth of the integrator is adjusted to the third bandwidth threshold, which is greater than the second bandwidth threshold and less than the first bandwidth threshold.

[0050] In one specific embodiment, when the startup time does not exceed a first preset time Ltime, the controller detects the output voltage Vo through the auxiliary winding. The controller determines whether the duration for which the output voltage Vo exceeds a preset voltage threshold Vth exceeds a second preset time. When the duration for which the output voltage Vo exceeds the preset voltage threshold Vth does not exceed the second preset time, the controller is determined to be in a cold start state. Since the output voltage Vo does not exceed the preset voltage threshold Vth in the initial stage of a cold start, the bandwidth of the integrator is adjusted to the first bandwidth threshold, that is, the bandwidth of the integrator is increased by 16 times, so that the auxiliary winding can supply power to the controller as soon as possible. In this embodiment of the invention, the second preset time is set according to actual needs.

[0051] Furthermore, if the output voltage Vo exceeds the preset voltage threshold Vth for a duration exceeding a second preset duration, the controller is determined to be experiencing a hot start. For a hot start, the output voltage Vo of the switching power supply is equal to or close to the normal operating value. When the switching power supply is initially operating with the 16-fold increased bandwidth scheme used during a cold start, the controller can detect that the output voltage Vo exceeds the preset voltage threshold Vth. Therefore, the bandwidth is reduced from 16 times to 4 times to avoid output current overshoot during a hot start. By reducing the bandwidth of the controller's internal integrator during a hot start, the loop establishment speed is reduced, and the rise rate of the output voltage Vo is delayed, thus avoiding the output current overshoot problem during a high-voltage hot start.

[0052] In one embodiment, the power supply startup method further includes: adjusting the bandwidth of the integrator by controlling the number of digital integration units connected in the integrator.

[0053] In one specific embodiment, as follows Figure 3 Taking the integrator shown as an example, the integrator includes: a voltage-to-current conversion circuit 1, a clock circuit 2, an integration loop 3, and an analog-to-digital converter 4. The first input terminal of the voltage-to-current conversion circuit 1 receives the output voltage of the switching power supply, and the second input terminal receives a preset voltage threshold. The output terminal of the voltage-to-current conversion circuit 1 is connected to the input terminal of the clock circuit 2. The voltage-to-current conversion circuit 1 converts the difference between the output voltage and the preset voltage threshold into a current signal and sends the current signal to the clock circuit 2. The output terminal of the clock circuit 2 is connected to the control terminal of the integration loop 3. The clock circuit 2 converts the current signal into a clock signal and controls the number of digital integration units connected in the integration loop 3 according to the clock signal, thus adjusting the bandwidth of the integrator. The output terminal of the integration loop 3 is connected to the output terminal of the analog-to-digital converter 4. The integration loop 3 sends the bandwidth to the analog-to-digital converter 4, and the analog-to-digital converter 4 converts the bandwidth into a digital signal. The integration loop 3 includes multiple digital integration units connected in series. Each digital integration unit is equipped with a bypass switch, which controls the connection or disconnection of the digital integration unit from the integration loop 3.

[0054] In this embodiment of the invention, the primary-side feedback voltage is obtained through... Figure 1 The NMOS transistor M2 and resistor R1 are input to the controller CS terminal. The primary-side feedback voltage input to the controller CS terminal serves as the feedback voltage signal Vfb of the voltage-to-current conversion circuit 1 in the integrator. The voltage-to-current conversion circuit 1 converts the feedback voltage signal Vfb into a current signal I by subtracting the reference voltage Vref from the reference voltage. The voltage-to-current conversion circuit 1 sends the current signal to the clock circuit 2. The clock circuit 2 converts the current signal I into a clock signal CLK. The clock circuit 2 inputs the clock signal CLK into the integration loop 3. The integration loop 3 controls the bypass switch corresponding to each digital integration unit according to the clock signal CLK to control the number of digital integration units connected in the integrator, thereby adjusting the bandwidth of the integrator. The bandwidth output by the integration unit is then converted into a digital signal Vcomp by the analog-to-digital converter 4. The digital signal Vcomp is then compared with the reference voltage Vref. Figure 4 The intersection point is obtained by comparing the sawtooth waves shown. The controller determines the operating time of the RS latch based on the intersection point to generate the corresponding PWM waveform. The PWM waveform generated by the RS latch controls the NMOS transistor M2 through the driver.

[0055] According to such Figure 4 The waveform diagram shown illustrates that the conduction time of the NMOS transistor M2 is closely related to the digital signal Vcomp. Specifically, taking... Figure 4 The two digital signals Vcomp1 and Vcomp2 are illustrated below. When the digital signal Vcomp is Vcomp1, at time t1, Vcomp1 intersects with the vertical wave of the sawtooth wave, and the controller generates a PWM waveform to drive NMOS transistor M2 to turn on. At time t3, Vcomp1 intersects with the ramp wave of the sawtooth wave, and the controller generates a PWM waveform to drive NMOS transistor M2 to turn off. When the digital signal Vcomp is Vcomp2, at time t1, Vcomp2 intersects with the vertical wave of the sawtooth wave, and the controller generates a PWM waveform to drive NMOS transistor M2 to turn on. At time t2, Vcomp2 intersects with the ramp wave of the sawtooth wave, and the controller generates a PWM waveform to drive NMOS transistor M2 to turn off. It can be seen from the conduction time of NMOS transistor M2 that the larger the value of Vcomp, the longer the conduction time of NMOS transistor M2.

[0056] Furthermore, based on the relationship between the number of bits in a digital integration unit and bandwidth, it is known that the more bits a digital integration unit has, the smaller the digital signal Vcomp, i.e., the smaller the bandwidth. Specifically, during startup, the bandwidth needs to be increased to allow Vcomp to rise rapidly. The solution adopted is to shorten some digital integration units. For example, each additional bit of a digital integration unit reduces the bandwidth by a factor of 2. Each reduction of a digital integration unit increases the bandwidth by a factor of 2. Therefore, during cold startup, if the bandwidth of the integrator needs to be increased by 16 times, 4 digital integration units need to be shortened. When the startup time exceeds the first preset time Ltime, the number of bits in the digital integration unit needs to be restored to the initial number. In this embodiment of the invention, the digital integration unit is a frequency divider circuit.

[0057] This invention also provides a switching power supply startup system, which applies the above-described switching power supply startup method, such as... Figure 5 As shown, it includes:

[0058] Monitoring module 10 is used to monitor the startup time of the switching power supply controller. For details, please refer to the relevant description of step S10 in the above embodiments, which will not be repeated here.

[0059] The judgment module 20 is used to determine whether the startup time exceeds a first preset time. For details, please refer to the relevant description of step S20 in the above embodiments, which will not be repeated here.

[0060] The first adjustment module 30 is used to adjust the bandwidth of the integrator to a first bandwidth threshold when the startup time does not exceed a first preset time. For details, please refer to the relevant description of step S30 in the above embodiments, which will not be repeated here.

[0061] The second adjustment module 40 is used to adjust the bandwidth of the integrator to a second bandwidth threshold when the startup time exceeds a first preset time. The second bandwidth threshold is less than the first bandwidth threshold. For details, please refer to the relevant description of step S40 in the above embodiments, which will not be repeated here.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for starting a switching power supply, characterized in that, The switching power supply has a built-in integrator, and the switching power supply startup method includes: Monitor the startup time of the switching power supply controller; Determine whether the startup time exceeds a first preset time; When the startup time does not exceed the first preset time, the bandwidth of the integrator is adjusted to the first bandwidth threshold. When the startup time exceeds the first preset time, the bandwidth of the integrator is adjusted to a second bandwidth threshold, where the second bandwidth threshold is less than the first bandwidth threshold. The integrator includes: a voltage-to-current conversion circuit, a clock circuit, an integration loop, and an analog-to-digital converter, wherein, The first input terminal of the voltage-to-current conversion circuit receives the output voltage of the switching power supply, the second input terminal of the voltage-to-current conversion circuit receives a preset voltage threshold, the output terminal of the voltage-to-current conversion circuit is connected to the input terminal of the clock circuit, and the voltage-to-current conversion circuit is used to convert the difference between the output voltage and the preset voltage threshold into a current signal and send the current signal to the clock circuit. The output terminal of the clock circuit is connected to the control terminal of the integration circuit. The clock circuit is used to convert the current signal into a clock signal and control the number of digital integration units connected in the integration circuit according to the clock signal to adjust the bandwidth of the integrator. The output terminal of the integration circuit is connected to the output terminal of the analog-to-digital converter. The integration circuit is used to send the bandwidth to the analog-to-digital converter. The analog-to-digital converter is used to convert the bandwidth into a digital signal.

2. The switching power supply startup method according to claim 1, characterized in that, After adjusting the integrator's bandwidth to a first bandwidth threshold, the power supply startup method further includes: Monitor the output voltage of the switching power supply; Determine whether the output voltage exceeds a preset voltage threshold; When the output voltage does not exceed the preset voltage threshold, the bandwidth of the integrator is maintained at the first bandwidth threshold.

3. The switching power supply startup method according to claim 2, characterized in that, Also includes: When the output voltage exceeds the preset voltage threshold, the bandwidth of the integrator is adjusted to a third bandwidth threshold, which is greater than the second bandwidth threshold and less than the first bandwidth threshold.

4. The switching power supply startup method according to claim 2, characterized in that, Also includes: Determine whether the duration for which the output voltage exceeds the preset voltage threshold exceeds a second preset time; When the duration for which the output voltage exceeds the preset voltage threshold does not exceed the second preset time, the bandwidth of the integrator is maintained at the first bandwidth threshold, where the second preset time is less than the first preset time.

5. The switching power supply startup method according to claim 3, characterized in that, Also includes: When the duration for which the output voltage exceeds the preset voltage threshold exceeds the second preset time, the bandwidth of the integrator is adjusted to a third bandwidth threshold, which is greater than the second bandwidth threshold and less than the first bandwidth threshold.

6. The switching power supply startup method according to claim 1, characterized in that, Also includes: The bandwidth of the integrator is adjusted by controlling the number of digital integration units connected to it.

7. The switching power supply startup method according to claim 1, characterized in that, The integration loop includes: multiple digital integration units connected in series, each digital integration unit being provided with a bypass switch, the bypass switch being used to control the digital integration unit to enter or exit the integration loop.

8. The power supply startup method according to claim 7, characterized in that, The digital integration unit is a frequency divider circuit.

9. A switching power supply startup system, characterized in that, The switching power supply startup method according to any one of claims 1-8 includes: A monitoring module is used to monitor the startup time of the switching power supply controller; The judgment module is used to determine whether the startup time exceeds a first preset time; The first adjustment module is used to adjust the bandwidth of the integrator to a first bandwidth threshold when the startup time does not exceed the first preset time. The second adjustment module is used to adjust the bandwidth of the integrator to a second bandwidth threshold when the startup time exceeds the first preset time, wherein the second bandwidth threshold is less than the first bandwidth threshold.

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