Digital integral mode constant on-time control system and method for switching power supplies

Abstract

The application discloses a digital integral mode constant conduction time control system and method of a switching power supply, and the system comprises: a pulse signal output by a DIMCOT control module in a load change transient state is used to control a PWM waveform of a PWM generation module to change from a first level state to a second level state, a counter of a constant conduction time generation module is triggered to start counting according to the second level state, and when a count value reaches a preset value, a reset signal is generated, so that the PWM waveform of the PWM generation module changes from the second level state to the first level state, thereby obtaining a square wave signal with a preset duty cycle, and then the opening or closing of the switching power supply is controlled, and the constant conduction time of the switching power supply is realized. Thus, the switching period is changed in the load change transient state to quickly increase the PWM duty cycle, there is no inertia link in linear control, the system delay is reduced, and faster transient response, higher light load efficiency and more flexible control strategy are achieved.

Description

Technical Field

[0001] This invention relates to the field of switching power supply control technology, and in particular to a digital integral mode constant on-time control system and method for switching power supplies. Background Technology

[0002] A switching power supply is a main circuit that uses semiconductor power devices as switches to transform a power supply mode into another, and employs automatic control closed-loop stabilization and protection mechanisms during the transition. The main topologies of switching power supplies include buck converters, boost converters, flyback converters, and forward converters. In recent years, the increasing demand for dynamic power in central processing units (CPUs) and neural network processors has driven the development of DC-DC voltage regulator modules (VRMs) to provide clean, low-ripple, and high-efficiency voltages under various dynamically changing current loads.

[0003] Current-mode constant on-time control (CMCOT) is widely used in Buck converters due to its simple compensation network, fast transient response, and high light-load efficiency. CMCOT is a variable-frequency control method, offering higher light-load efficiency compared to fixed-frequency control, and it eliminates the need for the compensation network found in traditional voltage or current-mode control, resulting in simpler circuit design. However, CMCOT control has two main drawbacks. First, its transient response is limited when the load changes. During load boost transients, the increase in inductor current is affected by the on-time (T) of each cycle. ON ) and minimum shutdown time (T) OFF\MIN The limitation of ) results in a large undershoot in the output; and in the load buck transient, if T ON When the load changes initially, the decay of the inductor current will be delayed by a turn-on time (T). ON The fixed width of the inductor current ripple leads to significant output overshoot. Secondly, in multiphase architectures, this ripple-based CMCOT control cannot operate at the ripple elimination point where the inductor current ripple becomes zero. To address these issues, most systems introduce nonlinear control for optimization, but none are applicable to different steady-state and transient conditions. Reverse-charge constant on-time control (IQCOT) improves the transient performance of CMCOT by naturally increasing or decreasing the on-time during load transient changes. In symmetrical multiphase architectures, IQCOT control can also operate normally at the ripple elimination point. However, implementing IQCOT control places high demands on hardware circuitry, and the controller components are complex, making implementation difficult.

[0004] Switching power supplies can be categorized into analog control and digital control based on their control methods. Traditional analog control circuits, primarily composed of operational amplifiers, level comparators, and RC circuits, have long dominated the switching power supply market due to their low cost and extensive experience. However, with the increasing demands for power density and reliability in switching power supplies, digital power supply technology is rapidly developing. Due to the conversion delay of the analog-to-digital converter (ADC) in the control loop, the transient performance of digital control switching power supplies in traditional voltage and current modes is lower than that of analog control switching power supplies. However, their advantages of flexibility, controllability, high modularity, and high intelligence make digital control superior to traditional analog control in complex, high-performance system applications. Therefore, digital control switching power supplies are the inevitable trend in the future development of power management chips. Summary of the Invention

[0005] This invention provides a digital integral mode constant on-time control system and device for switching power supplies, which solves the problems in related technologies where control systems have high requirements for hardware circuits and the components used in the controller are complex, making implementation difficult.

[0006] A first aspect of the present invention provides a digital integral mode constant on-time control system for a switching power supply, comprising: a DIMCOT control module, a constant on-time generation module, and a PWM generation module;

[0007] The input terminal of the DIMCOT control module is connected to the output terminals of the voltage sampling module and the current sampling module, respectively. The output terminal of the DIMCOT control module is connected to the input terminal of the PWM generation module. It is used to amplify the difference between the reference voltage and the output feedback voltage of the voltage sampling module to obtain an error signal. The difference between the error signal and the inductor current signal of the current sampling module is integrated and inverted before being applied to the control signal. A pulse signal is output according to the sign bit of the control signal and the pulse signal is output to the PWM generation module so that when the pulse signal meets the preset condition, the square wave signal generated by the PWM generation module changes from the first level state to the second level state. The initial value of the control signal is a preset threshold.

[0008] The input terminal of the constant on-time generation module is connected to the output terminal of the PWM generation module, and the output terminal of the constant on-time generation module is connected to the input terminal of the PWM generation module. It is used to start counting when the square wave signal is in the second level state, stop counting when the count value reaches a preset value, generate a reset signal, and output the reset signal to the PWM generation module, so that the square wave signal of the PWM generation module changes from the second level state to the first level state.

[0009] The output terminal of the PWM generation module is connected to the input terminal of the drive module. It is used to generate the square wave signal according to the pulse signal and the reset signal, and output the square wave signal to the drive module so as to control the switching power supply to turn on or off, so that the switching power supply maintains a constant conduction time.

[0010] Optionally, in one embodiment of the present invention, the control signal decreases in reverse integral starting from the preset threshold at the beginning of each switching cycle. When the integral value has not decreased to 0, the sign bit of the control signal is low and the pulse signal is low; when the integral value decreases to less than or equal to 0, the sign bit of the control signal is high and the pulse signal is high.

[0011] Optionally, in one embodiment of the present invention, the preset condition is that the pulse signal is at a high level.

[0012] Optionally, in one embodiment of the present invention, when the PWM waveform of the PWM generation module is started on the rising edge, the square wave signal of the PWM generation module changes from a low level state to a high level state when the pulse signal meets the preset conditions.

[0013] Optionally, in one embodiment of the present invention, the constant on-time generation module includes:

[0014] A counter, the input of which is connected to the output of the PWM generation module, is used to count when the square wave signal is in the second level state;

[0015] A comparator, the input of which is connected to the output of the counter and the output of which is connected to the input of the PWM generation module, is used to compare the count value of the counter with the preset value, and output the reset signal when the count value is equal to the preset value.

[0016] Optionally, in one embodiment of the present invention, the constant conduction time generation module is further configured to clear the count value of the counter to zero after outputting the reset signal.

[0017] Optionally, in one embodiment of the present invention, both the voltage sampling module and the current sampling module acquire the output feedback voltage and inductor current signals of the load through an analog-to-digital converter and a sampling circuit.

[0018] Optionally, in one embodiment of the present invention, the constant on-time of the switching power supply is:

[0019]

[0020] Where N is a preset value and Fclk is the system clock.

[0021] A second aspect of the present invention provides a digital integral mode constant on-time control method for a switching power supply, used in the digital integral mode constant on-time control system for the switching power supply described in the above embodiments. The method includes the following steps:

[0022] Obtain the output feedback voltage and inductor current signals;

[0023] The difference between the reference voltage and the output feedback voltage is amplified to obtain an error signal. The difference between the error signal and the inductor current signal is integrated and inverted before being applied to the control signal. The initial value of the control signal is a preset threshold. A pulse signal is output according to the sign bit of the control signal.

[0024] When the pulse signal meets the preset conditions, the square wave signal is changed from the first level state to the second level state and counted. When the count value is a preset value, the square wave signal is changed from the second level state to the first level state, the square wave signal is output, and the switching power supply is controlled to turn on or off according to the square wave signal, so that the switching power supply maintains a constant conduction time.

[0025] The Digital Integration Mode Constant On-time (DIMCOT) time control system and method for switching power supplies according to embodiments of the present invention have the following beneficial effects:

[0026] (1) The DIMCOT control adopted takes the Buck converter as a typical application. Compared with the existing COT control scheme, it has a higher degree of intelligence and modularity. The parameters of the digital controller can be flexibly changed through programming, which has high versatility.

[0027] (2) The DIMCOT control scheme adopted uses a digital state machine to realize the control timing, and adopts optimized digital control logic to reduce the digital calculation delay and optimize the dynamic response speed of the system.

[0028] (3) The DIMCOT control scheme adopted is not only applicable to single-phase switching power supply controllers, but can also be applied to multi-phase power supply control, which has high flexibility.

[0029] (4) The DIMCOT control scheme is a variable frequency control strategy. Compared with fixed frequency digital control, PWM has higher resolution and avoids the occurrence of subharmonic oscillation.

[0030] (5) DIMCOT control is a pure digital control that can be implemented through FPGA, MCU, ASIC and other methods, and has strong compatibility.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 This is a schematic diagram of a digital integral mode constant on-time control system for a switching power supply according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the actual application structure of a digital integral mode constant on-time control system for a switching power supply according to an embodiment of the present invention;

[0035] Figure 3 This is a circuit structure diagram of a DIMCOT control module according to an embodiment of the present invention;

[0036] Figure 4 A waveform diagram of a DIMCOT control module provided according to an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the state machine of a DIMCOT control module according to an embodiment of the present invention;

[0038] Figure 6 This is a waveform diagram of a constant on-time generation module according to an embodiment of the present invention;

[0039] Figure 7 The above is a SIMPLIS simulation waveform diagram of the system according to an embodiment of the present invention in a single-phase Buck converter application.

[0040] Figure 8 This is a flowchart of a digital integral mode constant on-time control method for a switching power supply according to an embodiment of the present invention. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] Figure 1 This is a schematic diagram of a digital integral mode constant on-time control system for a switching power supply according to an embodiment of the present invention.

[0043] like Figure 1 As shown, the digital integral mode constant on-time control system of the switching power supply includes: a DIMCOT control module 100, a constant on-time generation module 200, and a PWM generation module 300.

[0044] The input terminals of the DIMCOT control module 100 are connected to the output terminals of the voltage sampling module and the current sampling module, respectively. The output terminal of the DIMCOT control module 100 is connected to the input terminal of the PWM generation module 300. It is used to amplify the difference between the reference voltage and the output feedback voltage of the voltage sampling module to obtain an error signal. The difference between the error signal and the inductor current signal of the current sampling module is integrated and inverted before being applied to the control signal. A pulse signal is output according to the sign bit of the control signal and the pulse signal is output to the PWM generation module so that when the pulse signal meets the preset conditions, the square wave signal generated by the PWM generation module changes from the first level state to the second level state. The initial value of the control signal is a preset threshold.

[0045] The input terminal of the constant on-time generation module 200 is connected to the output terminal of the PWM generation module 300, and the output terminal of the constant on-time generation module 200 is connected to the input terminal of the PWM generation module 300. It is used to start counting when the square wave signal is in the second level state, stop counting when the count value reaches the preset value, generate a reset signal, and output the reset signal to the PWM generation module, so that the square wave signal of the PWM generation module changes from the second level state to the first level state.

[0046] The output terminal of the PWM generation module 300 is connected to the input terminal of the drive module. It is used to generate a square wave signal based on the pulse signal and the reset signal, and output the square wave signal to the drive module so that the drive module can control the switching power supply to turn on or off, so that the switching power supply maintains a constant conduction time.

[0047] Specifically, the output of the DIMCOT control module is a pulse signal V. tr The input is the output feedback signal V sampled by the voltage sampling module and the current sampling module. fb and inductor current signal V iL First, the output feedback voltage V fb With reference voltage V ref The difference is amplified to obtain the error signal V. C Then, the error signal V C With inductor current signal V iL The difference is integrated and inverted before being applied to the control signal V.ramp The initial value is set to the preset threshold V. TH V is coming soon ramp The signal originates from the preset threshold V. TH Start subtracting V C With V iL The integral of the difference.

[0048] Optionally, in one embodiment of the present invention, the control signal is decremented by inverse integration starting from a preset threshold at the beginning of each switching cycle. When the integral value has not decreased to 0, the sign bit of the control signal is low and the pulse signal is low; when the integral value decreases to less than or equal to 0, the sign bit of the control signal is high and the pulse signal is high.

[0049] Specifically, based on the above embodiments, if the control signal V ramp When the sign bit changes to 1, it represents the error signal V. C With inductor current signal V iL The integral of the difference reaches the preset threshold V TH Therefore, by comparing the control signal V ramp The sign bit of the output pulse signal V tr Pulse signal V tr When the set level state is reached, the level state transition of the PWM waveform in the PWM generation module 300 can be controlled.

[0050] Pulse signal V tr When in a high-level state, the level transition of the PWM waveform in the PWM generation module 300 can be controlled. If the PWM waveform of the PWM generation module is started on a rising edge, when the pulse signal meets the preset conditions, the square wave signal of the PWM generation module changes from a low-level state to a high-level state.

[0051] Both the voltage sampling module and the current sampling module acquire the load's output feedback voltage and inductor current signals through an analog-to-digital converter and a sampling circuit.

[0052] The constant on-time generation module 200 can generate a reset signal to control the level transition of the PWM waveform in the PWM generation module 300. If the PWM waveform of the PWM generation module starts on the rising edge, the reset signal can control the falling edge of the PWM waveform. The constant on-time generation module 200 counts based on the square wave signal Q generated by the PWM generation module 300. When the count value reaches a preset value N, it outputs the reset signal. The reset signal will be transmitted to the PWM generation module 300 to change the level state of the square wave signal Q, thus achieving a constant and controllable on-time. The square wave signal Q, where Fclk is the system clock.

[0053] PWM generation module 300 generates pulse signals V from DIMCOT control module 100. tr The reset signal generated by the constant on-time generation module 200 is converted into a square wave signal Q with a corresponding duty cycle. This is then transmitted via pulse signal V. tr The rising edge triggers the output to a high level, while the rising edge of the reset signal causes the output to go low, thus generating a square wave signal Q.

[0054] like Figure 2 The diagram illustrates the system architecture of a DIMCOT control system applied in a Buck converter. It mainly includes a power stage module, a current sampling module, a voltage sampling module, a DIMCOT control module, a PWM generation module, a constant on-time generation module, and a drive module. The power stage module includes MOSFETs MOS1 and MOS2, and a filter inductor L. S Ideal filter capacitor C O The series equivalent resistance (ESR) is also considered. The inductor acts as an energy storage element, storing energy when MOS1 is on and MOS2 is off, and allowing current i to flow when MOS1 is off and MOS2 is on. L Energy is released in the direction of the signal. Capacitors can "absorb" ripple, smoothing the voltage waveform. Actual capacitors are not ideal components; due to the influence of dielectric material, packaging, operating frequency, and operating temperature, they will effectively have a series resistance (ESR). This ESR plays an indispensable role in the design of small-signal feedback control and output ripple suppression in switching power supplies. The current sampling module and voltage sampling module use an analog-to-digital converter (ADC) and external sampling circuitry to sample the output feedback voltage and inductor current signals, thereby obtaining the output feedback voltage V. fb and inductor current signal V iL This is passed to the DIMCOT control module. The DIMCOT control module performs internal calculations and generates V. tr Pulse signal. Passed through V tr The pulse signal and the reset signal generated by the constant conduction time generation module are used by the PWM generation module to output a square wave signal Q with a corresponding duty cycle. Finally, the drive module controls the on and off of the upper and lower transistors.

[0055] Figure 3 The circuitry of the DIMCOT control module is shown. Output feedback voltage V. fb With reference voltage V ref The output voltage error signal V is obtained by comparing and amplifying the signals. C Error signal V C With inductor current signal V iL Subtract them and integrate the difference. This invention will control the signal V... ramp The initial value of the signal is set to the threshold V.TH Then from V TH Start subtracting V C With V iL Integral the difference, and finally compare V. ramp The sign bit, if it is 1, represents V. C With V iL The integral of the difference reached the threshold V. TH This is achieved by comparing V. ramp The sign bit of the signal, the output pulse V tr The signal method saves power consumption and delay, simplifies digital control timing, reduces resource utilization, and enables the system to respond to power dynamic events more quickly.

[0056] Figure 4 The waveforms of the DIMCOT control module under different states are shown, including V. iL Signal, V C Signal, V ramp Signal and output pulse V tr Signal, among which, Figure 4 (a) represents the steady state. Figure 4 (b) represents the load boost transient. Figure 4 (c) represents the transient voltage drop. Using the threshold V... TH Subtract V iL Signal and V C Integrating the signal difference yields V. ramp Signal. When V ramp When the signal is reduced to 0, V TR Output a high-level pulse. During load boost transients, V... C The rapid rise caused V iL With V C The difference increases, V ramp The signal is reduced to 0 faster, i.e., the output V tr The signal duty cycle increases, thereby increasing the inductor current V. iL Conversely, under load-drop transients, V ramp Integration is slower, output V tr The signal duty cycle decreases, thereby reducing the inductor current V. iL .

[0057] Figure 5 The state machine in the DIMCOT control module is demonstrated. In this invention, a digital control algorithm is implemented by setting up a state machine with 7 cycles. In cycle S0, the reference signal V... ref With feedback voltage V fb The difference is amplified during the S1 period to obtain the error signal V. C S2 periodic calculation error signal V C With inductor current signal ViL The difference i ramp And amplified in the S3 period to obtain K iramp V is obtained by cumulatively subtracting the integrand over period S4. ramp If V ramp If the sign bit is 1, then V is generated in cycle S5. tr Pulse and V ramp Reset to V TH Otherwise, return to the S0 cycle.

[0058] Optionally, in one embodiment of the present invention, the constant conduction time generation module includes: a counter, the input terminal of which is connected to the output terminal of the PWM generation module, for counting when the square wave signal is in the second level state; and a comparator, the input terminal of which is connected to the output terminal of the counter and the output terminal of which is connected to the input terminal of the PWM generation module, for comparing the count value of the counter with a preset value, and outputting a reset signal when the count value is equal to the preset value.

[0059] Figure 6 The waveform diagram of the constant on-time generation module is shown. The constant on-time generation module consists of a counter and a comparator, with inputs being a square wave signal Q and the system clock F. clk The output is a reset signal. In the DIMCOT control module, when V... ramp When the signal is above the threshold, V tr When the output level is high, the output Q of the PWM module changes from low to high. At this time, the counter in the constant on-time generation module will change according to the system clock F. clk The counter starts counting from zero. When the count reaches a specific value N, a reset signal is output to reset the counter. The output reset signal serves as the input to the PWM module, turning the square wave signal Q low to achieve a constant on-time T. ON A square wave Q signal. Constant on-time T. ON With numerical value N and system frequency F clk The relationship is:

[0060] Figure 7 The simulation waveforms of DIMCOT control using Simplis are shown, illustrating the output voltage and current waveforms under steady-state and load-switching transient conditions. It can be seen that this DIMCOT control method can achieve a fast transient response.

[0061] The digital integral mode constant on-time control system for switching power supplies proposed in this invention is mainly applied to, but not limited to, Buck converters. It rapidly increases the PWM duty cycle by changing the switching period during load changes. It eliminates the inertial element in linear control, reducing system delay. The proposed DIMCOT control has faster transient response, higher efficiency under light loads, and a more flexible control strategy.

[0062] Next, with reference to the accompanying drawings, a digital integral mode constant on-time control method for switching power supplies according to an embodiment of the present invention is described.

[0063] Figure 8 This is a flowchart of a digital integral mode constant on-time control method for a switching power supply according to an embodiment of the present invention.

[0064] like Figure 8 As shown, the digital integral mode constant on-time control method for switching power supplies is used in the digital integral mode constant on-time control system of the switching power supply in the above embodiment. The method includes the following steps:

[0065] In step S101, the output feedback voltage and inductor current signals are acquired.

[0066] In step S102, the difference between the reference voltage and the output feedback voltage is amplified to obtain an error signal. The difference between the error signal and the inductor current signal is integrated and inverted before being applied to the control signal. The initial value of the control signal is a preset threshold, and a pulse signal is output according to the sign bit of the control signal.

[0067] In step S103, when the pulse signal meets the preset conditions, the square wave signal is changed from the first level state to the second level state and counted. When the count value is a preset value, the square wave signal is changed from the second level state to the first level state, the square wave signal is output, and the switching power supply is controlled to turn on or off according to the square wave signal, so that the switching power supply maintains a constant conduction time.

[0068] It should be noted that the foregoing explanation of the embodiment of the digital integral mode constant on-time control system for switching power supplies also applies to the digital integral mode constant on-time control method of the switching power supply in this embodiment, and will not be repeated here.

[0069] The digital integral mode constant on-time control method for switching power supplies proposed in this embodiment of the invention rapidly increases the PWM duty cycle by changing the switching period during load changes. It eliminates the inertial element in linear control, reducing system delay. The proposed DIMCOT control has faster transient response, higher efficiency under light load, and more flexible control strategy.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of the invention pertain.

Claims

1. A digital integral mode constant on-time control system for a switching power supply, characterized in that, include: DIMCOT control module, constant on-time generation module, and PWM generation module; The input terminal of the DIMCOT control module is connected to the output terminals of the voltage sampling module and the current sampling module, respectively. The output terminal of the DIMCOT control module is connected to the input terminal of the PWM generation module. It is used to amplify the difference between the reference voltage and the output feedback voltage of the voltage sampling module to obtain an error signal. The difference between the error signal and the inductor current signal of the current sampling module is integrated and inverted before being applied to the control signal. A pulse signal is output according to the sign bit of the control signal and the pulse signal is output to the PWM generation module so that when the pulse signal meets the preset condition, the square wave signal generated by the PWM generation module changes from the first level state to the second level state. The initial value of the control signal is a preset threshold. The input terminal of the constant on-time generation module is connected to the output terminal of the PWM generation module, and the output terminal of the constant on-time generation module is connected to the input terminal of the PWM generation module. It is used to start counting when the square wave signal is in the second level state, stop counting when the count value reaches a preset value, generate a reset signal, and output the reset signal to the PWM generation module, so that the square wave signal of the PWM generation module changes from the second level state to the first level state. The output terminal of the PWM generation module is connected to the input terminal of the drive module. It is used to generate the square wave signal according to the pulse signal and the reset signal, and output the square wave signal to the drive module so as to control the switching power supply to turn on or off, so that the switching power supply maintains a constant conduction time.

2. The system according to claim 1, characterized in that, At the beginning of each switching cycle, the control signal decrements in reverse by integrating from the preset threshold. When the integral value has not decreased to 0, the sign bit of the control signal is low and the pulse signal is low. When the integral value decreases to less than or equal to 0, the sign bit of the control signal is high and the pulse signal is high.

3. The system according to claim 2, characterized in that, The preset condition is that the pulse signal is at a high level.

4. The system according to claim 3, characterized in that, When the PWM waveform of the PWM generation module is started on the rising edge, the square wave signal of the PWM generation module changes from a low level to a high level when the pulse signal meets the preset conditions.

5. The system according to claim 1, characterized in that, The constant on-time generation module includes: A counter, the input of which is connected to the output of the PWM generation module, is used to count when the square wave signal is in the second level state; A comparator, the input of which is connected to the output of the counter and the output of which is connected to the input of the PWM generation module, is used to compare the count value of the counter with the preset value, and output the reset signal when the count value is equal to the preset value.

6. The system according to claim 5, characterized in that, The constant on-time generation module is also used to clear the counter value to zero after outputting the reset signal.

7. The system according to claim 1, characterized in that, Both the voltage sampling module and the current sampling module acquire the load's output feedback voltage and inductor current signals through an analog-to-digital converter and a sampling circuit.

8. The system according to any one of claims 1-7, characterized in that, The constant on-time of the switching power supply is: Where N is a preset value and Fclk is the system clock.

9. A digital integral mode constant on-time control method for a switching power supply, used in the digital integral mode constant on-time control system of the switching power supply according to any one of claims 1-8, characterized in that, Includes the following steps: Obtain the output feedback voltage and inductor current signals; The difference between the reference voltage and the output feedback voltage is amplified to obtain an error signal. The difference between the error signal and the inductor current signal is integrated and inverted before being applied to the control signal. The initial value of the control signal is a preset threshold. A pulse signal is output according to the sign bit of the control signal. When the pulse signal meets the preset conditions, the square wave signal is changed from the first level state to the second level state and counted. When the count value is a preset value, the square wave signal is changed from the second level state to the first level state, the square wave signal is output, and the switching power supply is controlled to turn on or off according to the square wave signal, so that the switching power supply maintains a constant conduction time.

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