A control circuit, control method, and device

Abstract

The embodiment of the application discloses a control circuit, a control method and equipment. When the error voltage is less than the first reference voltage, the control circuit controls the charge-discharge module to enter the PSM mode, so that the hysteresis control of the ripple voltage is realized under the condition that the load is light. Moreover, the feedback voltage and the third reference voltage are obtained, the working mode of the charge-discharge module is adjusted according to the feedback voltage and the third reference voltage, and then the output voltage is adjusted, so that the control of the switching frequency is realized. The control of the output voltage in the PSM mode is realized through the comparator in the control circuit, so that the constant current is avoided to be used to pull down the output voltage, thereby the power consumption is reduced and the conversion efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of control technology, specifically to a control circuit, control method, and device. Background Technology

[0002] A DC-DC (Direct Current to Direct Current) converter is a voltage converter that effectively outputs a fixed voltage after transforming the input voltage. DC-DC converters are widely used in products such as mobile phones, headphones, and portable media players.

[0003] Currently, under light load conditions, the output voltage of a DC-DC converter entering PSM (Pulse Skip Modulation) mode decreases slowly, requiring a large quiescent current to maintain the frequency. This results in high quiescent power consumption and high power consumption under light load conditions. Therefore, reducing the power consumption and improving the conversion efficiency of DC-DC converters under light load conditions is a technical problem that needs to be solved. Summary of the Invention

[0004] In view of this, embodiments of this application provide a control circuit, control method, and device that can reduce the power consumption of a DC-DC converter and improve conversion efficiency under light load conditions.

[0005] To address the above problems, the technical solutions provided in this application are as follows:

[0006] In a first aspect, this application provides a control circuit, which includes a first output resistor, a second output resistor, an error amplifier, and a first comparator. One end of the first output resistor is grounded, and the other end is connected to one end of the second output resistor and the negative input terminal of the error amplifier. The other end of the second output resistor is input to the output voltage second comparator. The positive input terminal of the error amplifier is input to the second reference voltage. The output terminal of the error amplifier is connected to the negative input terminal of the first comparator. The positive input terminal of the first comparator is input to the first reference voltage. The output terminal of the first comparator is connected to a charge / discharge module, which is used to control the output voltage of the voltage output terminal.

[0007] The error amplifier is used to calculate the difference between the second reference voltage and the feedback voltage input to the negative input terminal of the error amplifier, and output the error voltage.

[0008] The first comparator is used to send first mode switching information to the charging and discharging module when the error voltage is less than the first reference voltage. The first mode switching information is used to instruct the charging and discharging module to enter the pulse skip modulation (PSM) mode.

[0009] In one possible implementation, the control circuit further includes a second comparator, the positive input terminal of which is connected to the connection terminal of the first output resistor and the second output resistor, the negative input terminal of which receives a third reference voltage, and the output terminal of which is connected to the charging and discharging module.

[0010] The second comparator is used to send a discharge signal to the charging and discharging module when the feedback voltage input to the positive input terminal of the second comparator is greater than the third reference voltage. The discharge signal is used to instruct the charging and discharging module to control the output voltage to no longer rise.

[0011] The second comparator is further configured to send a first charging signal to the charging / discharging module when the charging conditions are met, the first charging signal being used to instruct the charging / discharging module to control the output voltage to rise.

[0012] In one possible implementation, the second comparator is specifically used to send a first charging signal to the charging / discharging module when the feedback voltage is less than the hysteresis voltage of the third reference voltage, wherein the hysteresis voltage of the third reference voltage is determined based on the ripple voltage of the output voltage.

[0013] In one possible implementation, the control circuit further includes a timer, the output of the second comparator is connected to the input of the timer, and the output of the timer is connected to the charge / discharge module;

[0014] The timer is used to start timing after receiving the discharge signal, and when the timer reaches the discharge duration, it sends a second charging signal to the charging and discharging module, so that the charging and discharging module controls the power transistor to alternately turn on and off after receiving the second charging signal, thereby increasing the output voltage.

[0015] In one possible implementation, the timer is further configured to end the current timing when the first charging signal is received.

[0016] In one possible implementation, the first comparator is further configured to output second mode switching information when the error voltage is greater than or equal to the first reference voltage, the second mode switching information being used to instruct the charging and discharging module to enter pulse width modulation (PWM) mode.

[0017] Secondly, this application provides a control method applied to a control module of a control circuit. The control circuit includes a first output resistor, a second output resistor, and a control module. The first output resistor and the second output resistor are connected in series. The other end of the first output resistor is grounded, and the other end of the second output resistor is connected to an output voltage. The control module is connected to the series terminal of the first output resistor and the second output resistor, and the control module is connected to a charging and discharging module.

[0018] The control module acquires the feedback voltage and the second reference voltage, calculates the difference between the feedback voltage and the second reference voltage, and obtains the error voltage. The feedback voltage is the voltage at the series terminal of the first output resistor and the second output resistor.

[0019] The control module acquires a first reference voltage. When the error voltage is less than the first reference voltage, it sends a first mode switching information to the charging and discharging module. The first mode switching information is used to instruct the charging and discharging module to enter PSM mode.

[0020] In one possible implementation, the control module acquires a feedback voltage and a third reference voltage. When the feedback voltage is greater than the third reference voltage, it sends a discharge signal to the charging and discharging module so that the charging and discharging module, upon receiving the discharge signal, controls the power transistor to turn off, thereby preventing the output voltage from rising further.

[0021] When the charging conditions are met, the control module sends a charging signal to the charging and discharging module, so that after receiving the charging signal, the charging and discharging module controls the power transistor to turn on and off alternately, thereby increasing the output voltage.

[0022] In one possible implementation, the charging condition is one or more of the following: the time for which the power transistor is turned off is greater than or equal to the discharge duration, and the feedback voltage is less than the hysteresis voltage of the third reference voltage, wherein the hysteresis voltage of the third reference voltage is determined based on the ripple voltage of the output voltage.

[0023] In one possible implementation, the method further includes:

[0024] When the error voltage is greater than or equal to the first reference voltage, a second mode switching information is output, which is used to instruct the charging and discharging module to enter PWM mode.

[0025] Thirdly, this application provides an apparatus that includes the control circuit described in any of the above embodiments.

[0026] Therefore, the embodiments of this application have the following beneficial effects:

[0027] This application provides a control circuit, control method, and device. When the error voltage is less than a first reference voltage, the control circuit controls the charging / discharging module to enter PSM mode, achieving hysteresis control of the ripple voltage under light load conditions. Furthermore, by acquiring a feedback voltage and a third reference voltage, the operating mode of the charging / discharging module is adjusted based on these voltages, thereby adjusting the output voltage and controlling the switching frequency. Using a comparator in the control circuit to control the output voltage in PSM mode avoids the need for a constant current to pull down the output voltage, thus reducing power consumption and improving conversion efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a pull-down circuit for controlling the output voltage in the prior art;

[0029] Figure 2 This is a schematic diagram of a control circuit provided in an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of another control circuit provided in an embodiment of this application;

[0031] Figure 4 This application provides a schematic diagram illustrating the output voltage variation under PSM mode.

[0032] Figure 5 This is a schematic diagram illustrating the change in output voltage under another PSM mode provided in an embodiment of this application;

[0033] Figure 6 This is a schematic diagram of another control circuit provided in an embodiment of this application;

[0034] Figure 7 This application provides a schematic diagram illustrating the output voltage variation under PSM mode.

[0035] Figure 8 This is a flowchart illustrating the control method provided in an embodiment of this application. Detailed Implementation

[0036] To facilitate understanding and explanation of the technical solutions provided in the embodiments of this application, the background technology of this application will be described first.

[0037] After studying the charge / discharge cycle of a traditional DC-DC converter in PSM mode control, it was found that the current method of using a constant current to pull down the output voltage reduces the output voltage to a normal range. (See also...) Figure 1As shown in the figure, this is a schematic diagram of a pull-down circuit for controlling the output voltage in the prior art. After the DC-DC converter enters PSM mode, it starts timing when it detects that the output voltage is greater than the normal ripple voltage. When the maximum allowable time is reached, the control switch closes, causing the pull-down circuit to start working. A fixed current is used to pull down the output voltage vout, causing the output voltage to drop to the normal range. Using a pull-down circuit to control the output voltage consumes a large current under light load, increasing power consumption and reducing conversion efficiency.

[0038] Based on this, embodiments of this application provide a control circuit, control method, and device. The control circuit controls the charging / discharging module to enter PSM mode when the error voltage is less than a first reference voltage, achieving hysteresis control of the ripple voltage under light load conditions. Furthermore, by acquiring the feedback voltage and a third reference voltage, the operating mode of the charging / discharging module is adjusted according to these voltages, thereby adjusting the output voltage and controlling the switching frequency. Using a comparator in the control circuit to control the output voltage in PSM mode avoids the need for a constant current to pull down the output voltage, thus reducing power consumption and improving conversion efficiency.

[0039] To facilitate understanding of the technical solutions provided in the embodiments of this application, a control circuit provided in the embodiments of this application will be described below with reference to the accompanying drawings.

[0040] The control circuit provided in this application embodiment can be applied to DC / DC converters.

[0041] See Figure 2 As shown in the figure, this is a schematic diagram of a control circuit provided in an embodiment of this application. The control circuit 200 includes a first output resistor 201, a second output resistor 202, an error amplifier 203, and a first comparator 205. The first terminal of the first output resistor is grounded, and the second terminal of the first output resistor is connected to the first terminal of the second output resistor. The second terminal of the second output resistor is connected to a voltage output terminal. The second terminal of the first output resistor is connected to the negative input terminal of the error amplifier. A second reference voltage is input to the positive input terminal of the error amplifier. The output terminal of the error amplifier is connected to the negative input terminal of the first comparator. A first reference voltage is input to the positive input terminal of the first comparator. The output terminal of the first comparator is connected to a charge / discharge module. The charge / discharge module is used to control the output voltage.

[0042] An error amplifier is used to calculate the difference between the second reference voltage and the feedback voltage input to the negative input terminal of the error amplifier, and outputs an error voltage.

[0043] The first comparator is used to control the switching of the charging and discharging module's operating mode. The charging and discharging module has PSM mode and PWM (Pulse Width Modulation) mode. PWM mode is the operating mode of the charging and discharging module when the output voltage is within the normal output range. When the load becomes lighter, it is necessary to control the output voltage ripple, and the charging and discharging module enters PSM mode.

[0044] The first comparator compares the error voltage with the first reference voltage. When the error voltage is less than the first reference voltage, the first comparator sends a first mode switching message to the charge / discharge module. The first mode switching message instructs the charge / discharge module to enter PSM mode.

[0045] In one possible implementation, the first comparator outputs either 0 or 1 based on the relationship between the input error voltage and the first reference voltage. Specifically, the first mode switching information can be 1.

[0046] Furthermore, the first comparator is also used to output second mode switching information when the error voltage is greater than or equal to the first reference voltage. This second mode switching information instructs the charging / discharging module to enter PWM mode. Correspondingly, for example, when the first mode switching information is 1, the second mode switching information can be 0.

[0047] In one possible implementation, the control circuit also includes a second comparator, see [link to relevant documentation]. Figure 3 As shown, the positive input terminal of the second comparator 204 is connected to the first output resistor and the second output resistor, the negative input terminal of the second comparator receives the third reference voltage, and the output terminal of the second comparator is connected to the charge / discharge module. After the charge / discharge module enters PSM mode, the ripple of the output voltage needs to be controlled. The second comparator is used to control the switching of the charge / discharge mode in PSM mode, thereby adjusting the output voltage.

[0048] See Figure 4 As shown in the figure, this is a schematic diagram of the output voltage change in PSM mode according to an embodiment of this application. The time period from 0 to t1 is the discharge process, and the time period from t1 to t2 is the charging process. The control process of the second comparator on the output voltage is described below.

[0049] The second comparator compares the feedback voltage with the third reference voltage. When the feedback voltage is greater than the third reference voltage, the second comparator sends a discharge signal to the charge / discharge module. The discharge signal instructs the charge / discharge module to stop the output voltage from rising, i.e., the discharge process. Specifically, the charge / discharge module includes a power transistor, and the switching state of the power transistor directly affects the output voltage. The charge / discharge module can control the power transistor to turn off based on the discharge signal, so that the output voltage stops rising. It should be noted that the output voltage stopping rising specifically includes two cases: the output voltage remaining stable and decreasing. The third reference voltage can be determined based on the ripple voltage of the output voltage. Specifically, the third reference voltage can be a voltage divider across the first output resistor based on the upper limit threshold of the ripple voltage of the output voltage. The second comparator also sends a first charging signal to the charge / discharge module when the charging conditions are met. The first charging signal instructs the charge / discharge module to control the output voltage to rise, i.e., the charging process. Specifically, the charge / discharge module can control the power transistor to alternately turn on and off based on the first charging signal. When the power transistor is on, the output voltage rises slowly; when the power transistor is off, the output voltage stabilizes. By controlling the power transistor to alternately turn on and off, the output voltage can be controlled to rise slowly, thus achieving control over the output voltage.

[0050] The charging and discharging processes constitute one control cycle of the PSM mode. By controlling the output voltage in each control cycle of the PSM mode, it is possible to adjust the output voltage under light load conditions, thereby improving the converter's conversion efficiency under light load and controlling the output voltage ripple.

[0051] In one possible implementation, the switching charging state can be determined based on the relationship between the magnitude of the hysteresis voltage of the feedback voltage and the third reference voltage.

[0052] Specifically, the second comparator sends a first charging signal to the charging / discharging module when the feedback voltage is less than the hysteresis voltage of the third reference voltage. The hysteresis voltage of the third reference voltage can be determined based on the ripple voltage of the output voltage. In one possible implementation, the hysteresis voltage of the third reference voltage can be determined based on the lower threshold of the ripple voltage of the output voltage. Specifically, the hysteresis voltage of the third reference voltage can be a voltage division of the lower threshold of the ripple voltage of the output voltage across the first output resistor. In another possible implementation, the hysteresis voltage of the third reference voltage can be calculated using the third reference voltage and a preset hysteresis voltage. First, the preset hysteresis voltage is determined based on the difference between the upper and lower thresholds of the ripple voltage of the output voltage. Then, the hysteresis voltage of the third reference voltage is obtained by subtracting the preset hysteresis voltage from the third reference voltage.

[0053] See Figure 5As shown in the figure, this figure is a schematic diagram of the output voltage change in another PSM mode provided in an embodiment of this application.

[0054] The second comparator compares the feedback voltage with the hysteresis voltage of the third reference voltage to control the charging and discharging module. This allows the output voltage to stop decreasing when the ripple voltage reaches the lower threshold in PSM mode, thus controlling the output voltage.

[0055] In some cases, a charge and discharge cycle in PSM mode may take a long time, resulting in a reduced switching frequency.

[0056] Based on this, embodiments of this application also provide a control circuit, which, in addition to the aforementioned devices, further includes a timer. See also... Figure 6 As shown in the figure, this is a schematic diagram of another control circuit provided in an embodiment of this application. The input terminal of the timer 206 is connected to the output terminal of the second comparator, and the output terminal of the timer is connected to the charging / discharging module.

[0057] The timer is used to time the discharge process and ends the discharge process when the timer reaches the discharge duration.

[0058] Specifically, the timer starts timing upon receiving a discharge signal. When the discharge duration is reached, a second charging signal is sent to the charge / discharge module. The discharge duration can be preset, determined based on the charging duration and a preset maximum cycle length. The second charging signal instructs the charge / discharge module to control the output voltage increase, i.e., the charging process. Specifically, the charge / discharge module can control the power transistors to alternately turn on and off based on the second charging signal. When the power transistors are on, the output voltage rises slowly; when they are off, the output voltage stabilizes. By controlling the power transistors to alternately turn on and off, the output voltage can be controlled to rise slowly, thus achieving output voltage control.

[0059] See Figure 7 As shown in the figure, this figure is a schematic diagram of the output voltage change in a PSM mode provided by an embodiment of this application.

[0060] Specifically, if the feedback voltage is greater than or equal to the hysteresis voltage of the third reference voltage during the discharge duration, then upon reaching the discharge duration (t1 to t3), the timer sends a second charging signal to the charging / discharging module, causing the module to end the discharge mode and enter the charging mode.

[0061] Based on the above, it can be seen that by timing the discharge process with a timer, the discharge duration can be ensured to be not too long, thus limiting the switching frequency.

[0062] Furthermore, in some possible implementations, the feedback voltage is a hysteresis voltage that is less than the third reference voltage during the discharge duration. The second comparator sends a first charging signal to the charge / discharge module, and the charge / discharge module ends the discharge process and begins the charging process based on the first charging signal. Correspondingly, when the control circuit has a timer, the second comparator can send the first charging signal to the charge / discharge module through the timer. The timer ends its current timing upon receiving the first charging signal.

[0063] Based on the control circuit provided in the above method embodiments, this application also provides a control method applied to the control circuit. The control method will be described below with reference to the accompanying drawings.

[0064] See Figure 8 As shown, this figure is a schematic flowchart of the control method provided in an embodiment of this application. The control method is applied to a control module of a control circuit. The control circuit includes a first output resistor, a second output resistor, and a control module. The first output resistor and the second output resistor are connected in series. The other end of the first output resistor is grounded, and the other end of the second output resistor receives the output voltage. The control module is connected to the series terminal of the first and second output resistors and is also connected to a charging / discharging module. Figure 8 As shown, the control method includes:

[0065] S801: The control module acquires the feedback voltage and the second reference voltage, calculates the difference between the feedback voltage and the second reference voltage, and obtains the error voltage. The feedback voltage is the voltage at the series terminal of the first output resistor and the second output resistor.

[0066] S802: The control module acquires a first reference voltage. When the error voltage is less than the first reference voltage, it sends a first mode switching information to the charging and discharging module. The first mode switching information is used to instruct the charging and discharging module to enter PSM mode.

[0067] For the specific implementation of S801-S802 in this embodiment, please refer to the above description of the control circuit, which will not be repeated here.

[0068] In one possible implementation, the control module acquires a feedback voltage and a third reference voltage. When the feedback voltage is greater than the third reference voltage, it sends a discharge signal to the charging and discharging module so that the charging and discharging module, upon receiving the discharge signal, controls the power transistor to turn off, thereby preventing the output voltage from rising further.

[0069] When charging conditions are met, the control module sends a charging signal to the charging / discharging module. Upon receiving the charging signal, the charging / discharging module controls the power transistor to alternately turn on and off, causing the output voltage to rise. In one possible implementation, the charging condition is one or more of the following: the power transistor being off for a duration greater than or equal to the discharge duration, and the feedback voltage being less than a hysteresis voltage of the third reference voltage. The hysteresis voltage of the third reference voltage is determined based on the ripple voltage of the output voltage.

[0070] In one possible implementation, the method further includes:

[0071] When the error voltage is greater than or equal to the first reference voltage, the control module outputs second mode switching information, which is used to instruct the charging and discharging module to enter PWM mode.

[0072] Based on the control circuit provided in the above method embodiments, this application also provides a device that includes the control circuit described in any of the above embodiments.

[0073] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0074] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0075] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control circuit, characterized in that, The control circuit includes a first output resistor, a second output resistor, an error amplifier, and a first comparator. One end of the first output resistor is grounded, and the other end is connected to one end of the second output resistor and the negative input terminal of the error amplifier. The other end of the second output resistor receives the output voltage. The positive input terminal of the error amplifier receives the second reference voltage. The output terminal of the error amplifier is connected to the negative input terminal of the first comparator. The positive input terminal of the first comparator receives the first reference voltage. The output terminal of the first comparator is connected to a charge / discharge module, which controls the output voltage of the voltage output terminal. The error amplifier is used to calculate the difference between the second reference voltage and the feedback voltage input to the negative input terminal of the error amplifier, and output the error voltage. The first comparator is configured to send first mode switching information to the charge / discharge module when the error voltage is less than the first reference voltage. The first mode switching information is used to instruct the charge / discharge module to enter pulse skip modulation (PSM) mode. The control circuit further includes a second comparator, the positive input terminal of which is connected to the first output resistor and the second output resistor, the negative input terminal of which receives a third reference voltage, and the output terminal of which is connected to the charging and discharging module. The second comparator is used to send a discharge signal to the charging and discharging module when the feedback voltage input to the positive input terminal of the second comparator is greater than the third reference voltage. The discharge signal is used to instruct the charging and discharging module to control the output voltage to no longer rise. It is also used to send a first charging signal to the charging and discharging module when the charging conditions are met. The first charging signal is used to instruct the charging and discharging module to control the output voltage to rise.

2. The control circuit according to claim 1, characterized in that, The second comparator is specifically used to send a first charging signal to the charging and discharging module when the feedback voltage is less than the hysteresis voltage of the third reference voltage, wherein the hysteresis voltage of the third reference voltage is determined based on the ripple voltage of the output voltage.

3. The control circuit according to claim 1, characterized in that, The control circuit also includes a timer, the output of the second comparator is connected to the input of the timer, and the output of the timer is connected to the charging and discharging module; The timer is used to start timing after receiving the discharge signal, and when the timer reaches the discharge duration, it sends a second charging signal to the charging and discharging module, so that the charging and discharging module controls the power transistor to alternately turn on and off after receiving the second charging signal, thereby increasing the output voltage.

4. The control circuit according to claim 3, characterized in that, The timer is also used to end the current timing when the first charging signal is received.

5. The control circuit according to claim 1, characterized in that, The first comparator is further configured to output second mode switching information when the error voltage is greater than or equal to the first reference voltage. The second mode switching information is used to instruct the charging and discharging module to enter pulse width modulation (PWM) mode.

6. A control method, characterized in that, The method is applied to the control module of the control circuit, which includes a first output resistor, a second output resistor, and a control module. The first output resistor and the second output resistor are connected in series. The other end of the first output resistor is grounded, and the other end of the second output resistor is connected to the output voltage. The control module is connected to the series terminal of the first output resistor and the second output resistor, and the control module is connected to the charging and discharging module. The control module acquires the feedback voltage and the second reference voltage, calculates the difference between the feedback voltage and the second reference voltage, and obtains the error voltage. The feedback voltage is the voltage at the series terminal of the first output resistor and the second output resistor. The control module acquires a first reference voltage. When the error voltage is less than the first reference voltage, it sends a first mode switching information to the charging and discharging module. The first mode switching information is used to instruct the charging and discharging module to enter PSM mode. The method further includes: the control module acquiring a feedback voltage and a third reference voltage; when the feedback voltage is greater than the third reference voltage, sending a discharge signal to the charging and discharging module, so that the charging and discharging module, upon receiving the discharge signal, controls the power transistor to turn off, so that the output voltage no longer rises; when the charging conditions are met, the control module sending a charging signal to the charging and discharging module, so that the charging and discharging module, upon receiving the charging signal, controls the power transistor to alternately turn on and off, so that the output voltage rises.

7. The method according to claim 6, characterized in that, The charging condition is one or more of the following: the time for which the power transistor is turned off is greater than or equal to the discharge duration, and the feedback voltage is less than the hysteresis voltage of the third reference voltage. The hysteresis voltage of the third reference voltage is determined based on the ripple voltage of the output voltage.

8. The method according to claim 6, characterized in that, The method further includes: When the error voltage is greater than or equal to the first reference voltage, the control module outputs second mode switching information, which is used to instruct the charging and discharging module to enter PWM mode.

9. A device, characterized in that, The device includes the control circuit according to any one of claims 1-5.

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