Low dropout regulator circuit

Abstract

The application provides a low-dropout regulating circuit, and relates to the technical field of circuits.The circuit comprises a level shifting circuit, an error amplifier, a first switch unit, a low-pass filter circuit and a reference voltage generating circuit; one end of the level shifting circuit receives a first voltage and is connected with a power supply end of the error amplifier, and the other end is connected with a preset input power supply; a bias end of the first switch unit is connected with an output end of the error amplifier, one end of the first switch unit is connected with the preset input power supply, and the other end is connected with an output of the low-dropout regulating circuit; one end of the reference voltage generating circuit is connected with a first power supply, the other end is connected with a negative input end of the error amplifier, and the other end of the first switch unit is also connected with a positive input end of the error amplifier; and one end of the reference voltage generating circuit is connected with the negative input end of the error amplifier through the low-pass filter circuit.Compared with the prior art, the noise processing function is general, and the problem of relatively large noise may exist.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and more specifically, to a low-dropout regulation circuit. Background Technology

[0002] Low-noise low-dropout regulators (LDOs) are widely used in various electronic devices, especially those requiring high precision, low noise, and low power consumption; for example, battery-powered systems, image processing systems, embedded systems, communication systems, and industrial control scenarios.

[0003] In existing LDO technology, the core components are a differential amplifier and a feedback resistor network. The differential amplifier compares the input voltage with a reference voltage and adjusts the output voltage through the feedback resistor network. The design of the feedback resistor network is crucial for achieving low noise, as it controls the amplifier's gain and reduces errors.

[0004] However, the noise reduction function of LDOs in the current technology is generally limited, and there may be problems with high noise levels, which will affect the subsequent processing results. For example, in some image processing circuit applications, if the device noise is high, it will lead to a deterioration in image quality. Summary of the Invention

[0005] The purpose of this application is to provide a low differential pressure regulation circuit to address the shortcomings of the prior art, thereby solving the problem that the noise reduction function of the prior art is generally poor and may result in excessive noise.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, one embodiment of this application provides a low-dropout regulation circuit, the low-dropout regulation circuit comprising: a level shifting circuit, an error amplifier, a first switching unit, a low-pass filter circuit, and a reference voltage generation circuit; wherein:

[0008] One end of the level shifting circuit is used to receive the first input voltage and is connected to the power supply terminal of the error amplifier; the other end of the level shifting circuit is connected to a preset input power supply; wherein, the first voltage is higher than the second voltage of the preset input power supply.

[0009] The bias terminal of the first switching unit is connected to the output terminal of the error amplifier, one end of the first switching unit is connected to the preset input power supply, and the other end of the first switching unit is connected to the output of the low dropout regulation circuit.

[0010] One end of the reference voltage generating circuit is connected to the first power supply, and the other end is connected to the negative input terminal of the error amplifier. The other end of the first switching unit is also connected to the positive input terminal of the error amplifier.

[0011] One end of the reference voltage generating circuit is connected to the negative input terminal of the error amplifier through the low-pass filter circuit; the low-pass filter circuit is used to filter out noise in the low-dropout regulation circuit.

[0012] Optionally, the level shifting circuit includes: a current source and a second switching unit, wherein one end of the current source is connected to the first voltage, and the other end of the current source is connected to one end of the second switching unit; the other end of the second switching unit is grounded, and the bias terminal of the second switching unit is connected to the preset input power supply.

[0013] Optionally, the second switching unit is a second PMOS transistor; one end of the current source is connected to the first voltage, and the other end of the current source is connected to the drain of the second PMOS transistor; the source of the second PMOS transistor is grounded, and the gate of the second PMOS transistor is connected to the preset input power supply.

[0014] Optionally, the first switching unit is a first PMOS transistor; the drain of the first PMOS transistor is connected to the preset input power supply, the gate of the first PMOS transistor is connected to the output terminal of the error amplifier, and the source of the first PMOS transistor is connected to the output of the low dropout regulation circuit.

[0015] Optionally, the reference voltage generation circuit includes: an operational amplifier, a first resistor, and a second resistor, wherein:

[0016] The positive input terminal of the operational amplifier is connected to the first power supply, the negative input terminal of the operational amplifier is connected between the first resistor and the second resistor, the output terminal of the operational amplifier is connected to the first resistor, and the first resistor is grounded through the second resistor.

[0017] Optionally, the low-pass filter circuit includes a third resistor and a first capacitor, wherein one end of the third resistor is connected to the output terminal of the reference voltage generation circuit, and the other end is grounded through the first capacitor.

[0018] The value of the third resistor is greater than 100 kiloohms, and the value of the first capacitor is greater than 0.1 picofarads.

[0019] Optionally, the low-dropout regulation circuit further includes a charge pump circuit, one end of which is connected to the preset input power supply and the other end of which is connected to the level shifting circuit; the charge pump circuit is used to generate the first voltage.

[0020] Optionally, the low-dropout regulation circuit further includes: a second power supply connected to the level shifting circuit; the second power supply is used to generate the first voltage.

[0021] Optionally, the low-dropout regulation circuit further includes a second capacitor, one end of which is connected to the output of the low-dropout regulation circuit, and the other end of which is grounded.

[0022] The beneficial effects of this application are as follows: by using the low-dropout regulation circuit provided in this application, the power supply voltage is increased by setting the level shifting circuit, and since the first voltage connected to the level shifting circuit is higher than the second voltage of the preset input power supply, the problem of the power supply voltage being too low is solved. In addition, the filter circuit in this application is set in the low-dropout regulation, so that the device noise introduced by the first switching unit and the level shifting circuit in the low-dropout regulation circuit is removed, thereby reducing the noise in the low-dropout regulation circuit. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a low differential pressure regulation circuit structure provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of a low differential pressure regulation circuit structure provided in another embodiment of this application;

[0026] Figure 3 This is a schematic diagram of a low differential pressure regulation circuit structure provided in another embodiment of this application;

[0027] Figure 4 This is a schematic diagram of a low differential pressure regulation circuit structure provided in an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of a low differential pressure regulation circuit structure provided in another embodiment of this application.

[0029] Attachment Number:

[0030] 100 - Low dropout regulation circuit; 110 - Level shifting circuit; 111 - Current source; 112 - Second switching unit; 120 - Error amplifier; 130 - First switching unit; 140 - Low-pass filter circuit; 141 - Third resistor; 142 - First capacitor; 150 - Reference voltage generation circuit; 151 - Operational amplifier; 152 - First resistor; 153 - Second resistor; 160 - Charge pump circuit; 170 - Second capacitor. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0032] The components of the embodiments of this application described and illustrated in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] Low-noise low-dropout regulators (LDOs) are widely used in various electronic devices, especially those requiring high precision, low noise, and low power consumption; for example, battery-powered systems, image processing systems, embedded systems, communication systems, and industrial control applications. The lower noise of LDOs can lead to higher performance. For instance, in image processing, the relatively high noise of the components in a low-dropout regulator can degrade image quality. Therefore, minimizing the noise of the components in a low-dropout regulator is a pressing issue.

[0034] To address the aforementioned issues, this application provides a novel low-dropout regulation circuit with a novel circuit connection method, which reduces the noise of various components in the low-dropout regulation circuit, thereby improving the overall circuit performance of the low-dropout regulation circuit.

[0035] The following explanation, in conjunction with several specific application examples, illustrates a low differential pressure regulation circuit provided in the embodiments of this application. Figure 1 This is a schematic diagram of a low-dropout regulation circuit provided in one embodiment of this application, as shown below. Figure 1As shown, the low differential voltage regulation circuit 100 includes: a level shifting circuit 110, an error amplifier 120, a first switching unit 130, a low-pass filter circuit 140, and a reference voltage generation circuit 150; wherein:

[0036] One end of the level shifting circuit 110 is used to receive the input first voltage VINH and is connected to the power supply terminal of the error amplifier 120. The other end of the level shifting circuit 110 is connected to a preset input power supply. The first voltage VINH is higher than the second voltage VIN of the preset input power supply. The first voltage VINH is pulled up by the level shifting circuit 110 to generate a VDD voltage to power the error amplifier 120. Since the first voltage VINH in this application is higher than the second voltage VIN of the preset input power supply, the VDD voltage generated after the first voltage VINH is pulled up by the level shifting circuit 110 is also higher than VIN. That is, setting the level shifting circuit 110 in the low dropout regulation circuit 100 can improve the compatibility and performance of the circuit and help the low dropout regulation circuit 100 achieve more efficient signal transmission and processing.

[0037] The bias terminal of the first switching unit 130 is connected to the output terminal of the error amplifier 120. One end of the first switching unit 130 is connected to the preset input power supply VIN, and the other end of the first switching unit 130 is connected to the output VO of the low differential pressure regulation circuit.

[0038] One end of the reference voltage generation circuit 150 is connected to the first power supply BG, and the other end is connected to the negative input terminal of the error amplifier 120. The other end of the first switching unit 130 is also connected to the positive input terminal of the error amplifier 120. To further reduce noise, in the embodiments of this application, the reference voltage generation circuit 150 can be set so that the output voltage VR1 is equal to the output voltage VO of the low-voltage reference circuit.

[0039] In the embodiments of this application, the reference voltage generation circuit 150 in the low-dropout regulation circuit 100 serves to provide a stable reference voltage VR1 for the error amplifier 120, thereby ensuring the stability and performance of the low-dropout regulation circuit 100. The reference voltage is a crucial reference standard for the error amplifier 120 in comparing and amplifying differential signals. If the reference voltage is unstable, it will cause distortion in the output of the error amplifier 120, thus affecting the stability and performance of the entire circuit. In other words, the setting of the reference voltage generation circuit 150 ensures the stability of the output of the error amplifier 120, thereby guaranteeing the stability and performance of the entire circuit.

[0040] Therefore, the reference voltage generation circuit in a low-dropout regulation circuit needs to be designed to be very precise and stable to ensure the error amplifier functions properly. In practice, the reference voltage generation circuit is typically constructed using stable voltage sources and resistors to ensure the generation of a stable reference voltage.

[0041] One end of the reference voltage generation circuit 150 is connected to the negative input terminal of the error amplifier 120 through the low-pass filter circuit 140; the low-pass filter circuit 140 is used to filter out noise in the low-dropout regulation circuit, so as to reduce the circuit noise in the low-dropout regulation circuit.

[0042] Specifically, in the low-dropout regulation circuit 100, the low-pass filter circuit 140 primarily filters out high-frequency noise or interference to achieve signal smoothing and noise reduction. Specifically, the low-pass filter circuit 140 allows low-frequency signals to pass through while blocking or reducing the passage of high-frequency signals; thus, the low-pass filter circuit 140 can effectively remove high-frequency noise or interference from the signal, improving the signal-to-noise ratio and thereby improving the performance and stability of the low-dropout regulation circuit 100. Furthermore, in the low-dropout regulation circuit 100, the low-pass filter circuit 140 works in conjunction with other circuits such as the error amplifier 120 to achieve stable voltage output. The function of the low-pass filter circuit 140 is to reduce high-frequency noise or interference at the output of the error amplifier 120 to ensure stable voltage output.

[0043] In one embodiment of this application, the first switching unit 130 may be, for example, a first PMOS transistor; the drain of the first PMOS transistor is connected to a preset input power supply, the gate of the first PMOS transistor is connected to the output terminal of the error amplifier 120, and the source of the first PMOS transistor is connected to the output VO of the low dropout regulation circuit.

[0044] The low-dropout regulation circuit provided in this application improves the power supply voltage by setting up a level shifting circuit. Since the first voltage connected to the level shifting circuit is higher than the second voltage of the preset input power supply, the problem of the power supply voltage being too low is solved. In addition, the application also sets up a filter circuit in the low-dropout regulation, so that the device noise introduced by the first switching unit and the level shifting circuit in the low-dropout regulation circuit is removed, thereby reducing the noise in the low-dropout regulation circuit.

[0045] Optionally, based on the above embodiments, this application embodiment may also provide a low differential pressure regulation circuit, which will be illustrated below with reference to the accompanying drawings. Figure 2 A schematic flowchart of a low-dropout regulation circuit provided in another embodiment of this application is shown below. Figure 2As shown, the reference voltage generation circuit 150 includes: an operational amplifier 151, a first resistor 152, and a second resistor 153, wherein: the positive input terminal of the operational amplifier 151 is connected to the first power supply BG, the negative input terminal of the operational amplifier 151 is connected between the first resistor 152 and the second resistor 153, the output terminal of the operational amplifier 151 is connected to the first resistor 152, and the first resistor 152 is grounded through the second resistor 153.

[0046] Optionally, based on the above embodiments, this application embodiment may also provide a low differential pressure regulation circuit, which will be illustrated below with reference to the accompanying drawings. Figure 3 A schematic flowchart of a low-dropout regulation circuit provided in another embodiment of this application is shown below. Figure 3 As shown, the level shifting circuit 110 includes: a current source 111 and a second switching unit 112, wherein one end of the current source 111 is connected to a first voltage BG, and the other end of the current source 111 is connected to one end of the second switching unit 112; the other end of the second switching unit 112 is grounded, and the bias terminal of the second switching unit 112 is connected to a preset input power supply VIN.

[0047] In the embodiments of this application, the second switching unit 112 may be, for example, a second PMOS transistor; one end of the current source is connected to the first voltage VINH, and the other end of the current source 111 is connected to the drain of the second switching unit 112; the source of the second switching unit 112 is grounded, and the gate of the second switching unit 112 is connected to the preset input power supply VIN.

[0048] In the embodiments of this application, since the source voltage of the second switching unit 112 changes with the gate voltage of the second switching unit 112, and the gate voltage of the second switching unit 112 is equal to the voltage of the preset input power supply VIN, this setting means that when the voltage of the preset input voltage VIN undergoes a transient change, the power supply voltage VDD of the error amplifier 120 will also change with the preset input voltage VIN.

[0049] Because a MOSFET's source voltage follows its gate voltage, changes in the source-gate voltage affect the drain-source current. When the source-gate voltage increases, the drain-source current also increases; conversely, when the source-gate voltage decreases, the drain-source current decreases.

[0050] Therefore, in the embodiments of this application, when the voltage of the preset input voltage VIN undergoes a transient change, the output voltage of the error amplifier 120 (the output voltage of the error amplifier 120 is the gate input voltage of the first switching unit 130) will also change with the change of the preset input voltage VIN to ensure a certain proportional relationship. This setting makes the current change of the drain current of the first switching unit 130 relatively small, thereby achieving a higher power supply voltage suppression ratio.

[0051] Optionally, based on the above embodiments, this application embodiment may also provide a low differential pressure regulation circuit, which will be illustrated below with reference to the accompanying drawings. Figure 4 A schematic flowchart of a low-dropout regulation circuit provided in another embodiment of this application is shown below. Figure 4 As shown, the low-pass filter circuit 140 includes a third resistor 141 and a first capacitor 142, wherein one end of the third resistor 141 is connected to the output terminal of the reference voltage generation circuit 150, and the other end is grounded through the first capacitor 142.

[0052] In the embodiments of this application, the larger the values ​​of the third resistor 141 and the first capacitor 142, the more noise can be filtered out. Therefore, in the embodiments of this application, the values ​​of the third resistor 141 and the first capacitor 142 are generally designed to be relatively large.

[0053] In other words, the larger the product of the third resistor 141 and the first capacitor 142, the more voltage noise caused by device noise can be filtered out, thus achieving a low-noise effect. For example, in some possible embodiments, the value of the third resistor 141 can be any value greater than 100 kiloohms, and the value of the first capacitor 142 can be any value greater than 0.1 picofarads. It should be understood that the above embodiments are only illustrative examples, and the specific range and value of the third resistor 141 and the first capacitor 142 can be flexibly adjusted according to user needs, and are not limited to those given in the above embodiments.

[0054] Optionally, based on the above embodiments, this application embodiment may also provide a low differential pressure regulation circuit, which will be illustrated below with reference to the accompanying drawings. Figure 5 A schematic flowchart of a low-dropout regulation circuit provided in another embodiment of this application is shown below. Figure 5 As shown, the low differential pressure regulation circuit also includes a charge pump circuit 160, one end of which is connected to a preset input power supply VIN, and the other end is connected to a level shifting circuit 110; the charge pump circuit 160 is used to generate a first voltage VINH.

[0055] In the embodiments of this application, the charge pump circuit 160 uses the preset input power supply voltage VIN as the input voltage and generates a voltage CPO higher than VIN to power the level shifting circuit 110.

[0056] The output voltage CPO of the charge pump circuit 160 is at least |vthp| higher than the preset input power supply voltage VIN, where Vthp is the threshold voltage of the second switch unit 112.

[0057] In the embodiments of this application, when the input voltage of the low-dropout regulation circuit 100 is not high enough, the power supply voltage can be increased by setting a charge pump circuit 160 in the low-dropout regulation circuit 100, thereby reducing the device noise generated by components such as the first switching unit 130, the second switching unit 112 and the current source 111 in the level shifting circuit 110 in the low-dropout regulation circuit 100.

[0058] In some other possible embodiments, the low-dropout regulation circuit 100 further includes: a second power supply connected to the level shifting circuit 110; the second power supply is used to generate a first voltage VINH; that is, this application can directly connect the level shifting circuit 110 to the second power supply, so that the second power supply supplies power to the level shifting circuit 110, which in turn supplies power to the error amplifier 120 by generating a VDD voltage through the level shifting circuit 110.

[0059] In the low dropout regulation circuit 100, the common-mode input range of the error amplifier 120 refers to the range of common-mode input voltages within which the error amplifier 120 can operate normally. This range is determined by the circuit design and the parameters of each component in the circuit to ensure that the error amplifier 120 can correctly amplify the differential-mode signal and output a stable voltage. When the input common-mode voltage exceeds the common-mode input range of the error amplifier 120, the error amplifier 120 may fail to operate normally, resulting in output voltage distortion or instability. Therefore, when designing the low dropout regulation circuit 100, the common-mode input range of the error amplifier 120 needs to be carefully considered to ensure the stability and performance of the circuit.

[0060] To limit the common-mode input range, several measures can be taken, such as using a bias circuit to limit the common-mode voltage of the input signal within a suitable range, or adjusting the input and output impedances of the error amplifier by selecting appropriate components such as resistors and capacitors. These measures ensure that the error amplifier 120 operates within its normal operating range, thereby improving the performance and stability of the low-dropout regulation circuit 100.

[0061] In the embodiments of this application, the method to ensure that the error amplifier 120 operates within its normal operating range can be, for example, by setting the voltage VDD higher than the voltage value of VIN, specifically by a higher voltage value of |vthp|, where Vthp is the threshold voltage of the second switching unit 112. Since the threshold voltage of the second switching unit 112 is generally negative, the absolute value of the threshold voltage of the second switching unit 112 is taken as |vthp|, and the voltage VDD is set / adjusted to be higher than the voltage value of VIN by |vthp|. Through the above circuit configuration, it can be ensured that the input voltage VR2 at the negative input terminal of the error amplifier 120 is lower than the voltage value of VDD-|Vthp|, thereby satisfying the common-mode input range of the error amplifier 120, that is, ensuring the normal operation of the error amplifier 120, so as to ensure the performance and stability of the entire circuit.

[0062] Continue as Figure 1 and Figure 5 As shown in the embodiments of this application, the low-dropout regulation circuit 100 further includes a second capacitor 170, one end of which is connected to the output VO of the low-dropout regulation circuit, and the other end of which is grounded.

[0063] In the embodiments of this application, such as Figure 1 The provided circuit structure, by using a higher first voltage VINH as the power supply voltage for the level shifting circuit 110, allows the error amplifier 120 to meet the common-mode input range. Furthermore, the voltage VR2 input to the negative input terminal of the error amplifier 120 is the voltage filtered by the low-pass filter circuit 140. Since the values ​​of the first capacitor 142 and the third resistor 141 in the low-pass filter circuit 140 are both set relatively large, the noise generated by the level shifting circuit 110 and the second switching unit 112 can be removed, thereby reducing the noise in the low-dropout regulation circuit 100. Moreover, in this embodiment, even with only one preset input power supply, the following method can be used... Figure 3 The circuit structure shown processes the preset input power supply voltage through the charge pump circuit and then inputs it to the level shifting circuit. This can also improve the power supply of the error amplifier circuit and make the power supply voltage of the error amplifier circuit greater than the second voltage of the preset input power supply.

[0064] The low-dropout regulation circuit provided in this application uses a level shifting circuit to boost the power supply voltage. In some possible implementations, the first voltage can be generated by connecting a second power supply to the level shifting circuit. The first voltage generated by the second power supply needs to be greater than the second voltage of the preset input power supply. Alternatively, in scenarios where only a preset input power supply is available, a charge pump circuit can be added to generate a first voltage higher than the second voltage to power the level shifting circuit. Since the first voltage connected to the level shifting circuit is higher than the second voltage of the preset input power supply, the problem of insufficient power supply voltage is solved. Furthermore, the application also includes a filter circuit in the low-dropout regulation circuit to remove device noise introduced by the first switching unit and the level shifting circuit, thereby reducing noise in the low-dropout regulation circuit.

[0065] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0066] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0067] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in a combination of hardware and software functional units.

[0068] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A low-dropout regulation circuit, characterized in that, The low-dropout regulation circuit includes: a level shifting circuit, an error amplifier, a first switching unit, a low-pass filter circuit, and a reference voltage generation circuit; wherein: One end of the level shifting circuit is used to receive the first input voltage and is connected to the power supply terminal of the error amplifier; the other end of the level shifting circuit is connected to a preset input power supply; wherein, the first voltage is higher than the second voltage of the preset input power supply. The bias terminal of the first switching unit is connected to the output terminal of the error amplifier, one end of the first switching unit is connected to the preset input power supply, and the other end of the first switching unit is connected to the output of the low dropout regulation circuit. One end of the reference voltage generating circuit is connected to the first power supply, and the other end is connected to the negative input terminal of the error amplifier. The other end of the first switching unit is also connected to the positive input terminal of the error amplifier. One end of the reference voltage generation circuit is connected to the negative input terminal of the error amplifier through the low-pass filter circuit; the low-pass filter circuit is used to filter out noise in the low-dropout regulation circuit. The level shifting circuit includes: a current source and a second switching unit, wherein one end of the current source is connected to the first voltage, and the other end of the current source is connected to one end of the second switching unit; the other end of the second switching unit is grounded, and the bias terminal of the second switching unit is connected to the preset input power supply; The second switching unit is a second PMOS transistor; one end of the current source is connected to the first voltage, and the other end of the current source is connected to the drain of the second PMOS transistor; the source of the second PMOS transistor is grounded, and the gate of the second PMOS transistor is connected to the preset input power supply; The first switching unit is a first PMOS transistor; the drain of the first PMOS transistor is connected to the preset input power supply, the gate of the first PMOS transistor is connected to the output terminal of the error amplifier, and the source of the first PMOS transistor is connected to the output of the low dropout regulation circuit.

2. The circuit as described in claim 1, characterized in that, The reference voltage generation circuit includes: an operational amplifier, a first resistor, and a second resistor, wherein: The positive input terminal of the operational amplifier is connected to the first power supply, the negative input terminal of the operational amplifier is connected between the first resistor and the second resistor, the output terminal of the operational amplifier is connected to the first resistor, and the first resistor is grounded through the second resistor.

3. The circuit as described in claim 1, characterized in that, The low-pass filter circuit includes a third resistor and a first capacitor, wherein one end of the third resistor is connected to the output terminal of the reference voltage generation circuit, and the other end is grounded through the first capacitor.

4. The circuit as described in claim 3, characterized in that, The value of the third resistor is greater than 100 kiloohms, and the value of the first capacitor is greater than 0.1 picofarads.

5. The circuit as described in claim 1, characterized in that, The low-dropout regulation circuit further includes a charge pump circuit, one end of which is connected to the preset input power supply and the other end of which is connected to the level shifting circuit; the charge pump circuit is used to generate the first voltage.

6. The circuit as described in claim 1, characterized in that, The low-dropout regulation circuit further includes a second power supply connected to the level shifting circuit; the second power supply is used to generate the first voltage.

7. The circuit as described in claim 1, characterized in that, The low-dropout regulation circuit further includes a second capacitor, one end of which is connected to the output of the low-dropout regulation circuit, and the other end of which is grounded.

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