LDO circuit, LDO and power supply system
By setting up a noise optimization circuit in the LDO circuit, including differential mode and common mode filtering units, the problem of insufficient noise optimization capabilities in the existing LDO circuit in a high-noise environment is solved, effectively suppressing differential mode and common mode noise is achieved, and performance stability is improved.
Patent Information
- Application Number
- CN202421908624.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-07
- Publication Date
- 2025-05-30
- Estimated Expiration
- 2034-08-07
AI Technical Summary
When existing LDO circuits face high noise environments, their noise optimization capabilities are insufficient, which affects performance stability, especially in noise-sensitive application scenarios.
A noise optimization circuit is set up in front of the LDO main circuit, including a differential mode filter unit and a common mode filter unit. The filter circuit composed of capacitors is optimized to filter differential mode noise and common mode noise.
Effectively suppress differential and common mode noise in power supply signals, improve the noise optimization capability of LDO circuits, and improve performance stability.
Smart Images
Figure CN222926990U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power management, and particularly relates to an LDO circuit, an LDO and a power supply system. Background Technique
[0002] With the rapid popularization of consumer electronic devices and the continuous improvement of performance requirements, the LDO (Low Dropout Regulator) as a key power management component plays a crucial role in electronic devices such as mobile phones, computers, and tablets. The LDO occupies an important position in power management with its characteristics of low power consumption, high efficiency, and low noise. However, in the actual application environment, the power supply system will inevitably be interfered by various environmental noises, especially electromagnetic interference (EMI). These noises will seriously affect the performance stability of the LDO, especially in noise-sensitive application scenarios. With the continuous expansion and complexity of the LDO usage scenarios, higher challenges are posed to the noise suppression ability of the LDO circuit. Although the circuit design in the existing LDO power supply system already has a certain noise optimization ability, its performance appears inadequate when facing increasingly high noise optimization requirements.
[0003] Therefore, how to effectively improve the noise optimization ability in the LDO circuit is an urgent problem to be solved at present. Content of the Utility Model
[0004] The main purpose of the utility model is to propose an LDO circuit, aiming to solve the problem of how to effectively improve the noise optimization ability in the LDO circuit.
[0005] To achieve the above purpose, the LDO circuit proposed by the utility model includes:
[0006] The LDO main circuit includes a first input terminal, a second input terminal, an output terminal and a ground terminal. The first input terminal is used to receive a reference voltage. The second input terminal is connected to a power supply. The output terminal is connected to a load, and is used to process the input voltage input to its input terminal according to the reference voltage to obtain a constant output voltage, and output the output voltage through its output terminal.
[0007] The noise optimization circuit. The input terminal of the noise optimization circuit is connected to the input terminal of the LDO main circuit. The ground terminal of the noise optimization circuit is grounded. The noise optimization circuit is used to filter the differential-mode noise and common-mode noise connected to the input terminal of the LDO main circuit.
[0008] In an embodiment, the noise optimization circuit includes:
[0009] Differential-mode filtering unit, the input end of the differential-mode filtering unit is connected to the input end of the LDO main circuit, and the differential-mode filtering unit is used to filter differential-mode noise introduced at the input end of the LDO main circuit;
[0010] Common-mode filtering unit, the input end of the common-mode filtering unit is connected to the input end of the LDO main circuit, and the grounding end of the common-mode filtering unit is grounded, which is used to filter common-mode noise introduced at the input end of the LDO main circuit.
[0011] In one embodiment, the differential-mode filtering unit includes a first capacitor and a second capacitor. The first end of the first capacitor is interconnected with the first end of the second capacitor and the second input end of the LDO main circuit, and the second end of the first capacitor is connected to the second end of the second capacitor and the output end of the LDO main circuit.
[0012] In one embodiment, the common-mode filtering unit includes a third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor. The first end of the third capacitor is interconnected with the first end of the fourth capacitor and the second input end of the LDO main circuit. The second end of the third capacitor is interconnected and grounded with the first end of the fifth capacitor, the second end of the fourth capacitor, the first end of the sixth capacitor and the grounding end of the LDO main circuit. The second end of the fifth capacitor is interconnected with the second end of the sixth capacitor and the output end of the LDO main circuit.
[0013] In one embodiment, the third capacitor and the fifth capacitor have the same capacitance value, and the fourth capacitor and the sixth capacitor have the same capacitance value.
[0014] In one embodiment, the LDO circuit further includes:
[0015] Overcurrent protection module, the overcurrent protection module is serially arranged between the second input end of the LDO main circuit and the power supply, and the overcurrent protection module is used to disconnect the connection between the LDO main circuit and the power supply when the current in the LDO main circuit is greater than a preset current value.
[0016] In one embodiment, the LDO circuit further includes:
[0017] Overtemperature protection module, the overtemperature protection module is serially arranged between the second input end of the LDO main circuit and the power supply, and the overtemperature protection module further includes a temperature detection end, and the temperature detection end is connected to the heat source component of the LDO main circuit. The overtemperature protection module is used to disconnect the connection between the LDO main circuit and the power supply when it detects that the temperature of the heat source component is greater than a preset temperature value.
[0018] The present utility model also provides an LDO, characterized in that the LDO includes the LDO circuit as described above.
[0019] The present utility model also provides a power supply system, characterized in that the power supply system is an LDO power supply system, and the power supply system includes a power supply, a load, and the LDO as described above.
[0020] The technical solution of the present utility model adopts an LDO circuit, and a noise optimization circuit is arranged in front of the main body circuit of the LDO. When the power supply signal is transmitted, the noise optimization circuit optimizes and filters the differential-mode noise and / or common-mode noise therein, so that the differential-mode noise and / or common-mode noise in the power supply signal are effectively suppressed, thereby effectively improving the noise optimization ability in the LDO circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.
[0022] Figure 1 It is a schematic diagram of the module structure of an embodiment of the LDO circuit provided by the present utility model;
[0023] Figure 2 It is a schematic diagram of the module structure of an embodiment of the LDO circuit provided by the present utility model;
[0024] Figure 3 It is a schematic diagram of the circuit structure of an embodiment of the LDO circuit provided by the present utility model;
[0025] Figure 4 It is a schematic diagram of the module structure of an embodiment of the LDO circuit provided by the present utility model;
[0026] Figure 5 It is a schematic diagram of the module structure of an embodiment of the LDO circuit provided by the present utility model;
[0027] Figure 6 It is a schematic diagram of the noise optimization result of the simulation test of an embodiment of the LDO circuit provided by the present utility model;
[0028] Figure 7 It is a schematic diagram of the common-mode noise optimization result of the simulation test of an embodiment of the LDO circuit provided by the present utility model;
[0029] Figure 8Schematic diagram of the differential-mode noise optimization result of the simulation test of an embodiment of the LDO circuit provided by the present utility model;
[0030] Explanation of the reference numerals in the drawings:
[0031] 10. Noise optimization circuit; 11. Differential-mode filtering unit; C1. First capacitor; C2. Second capacitor; 12. Common-mode filtering unit; C3. Third capacitor; C4. Fourth capacitor; C5. Fifth capacitor; C6. Sixth capacitor; 20. LDO main circuit; 30. Overcurrent protection module; 40. Over-temperature protection module.
[0032] The realization, functional characteristics and advantages of the purpose of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments
[0033] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.
[0034] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.
[0035] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.
[0036] With the rapid popularization of consumer electronic devices and the continuous improvement of performance requirements, the LDO (Low Dropout Regulator) as a key power management component plays a crucial role in electronic devices such as mobile phones, computers, and tablets. With its characteristics of low power consumption, high efficiency, and low noise, the LDO occupies an important position in power management. However, in the actual application environment, the power supply system will inevitably be interfered by various environmental noises, especially electromagnetic interference (EMI). These noises will seriously affect the performance stability of the LDO, especially in noise-sensitive application scenarios. With the continuous expansion and complexity of the LDO usage scenarios, higher challenges are posed to the noise suppression ability of the LDO circuit. Although the circuit design in the existing LDO power supply system already has a certain noise optimization ability, when faced with increasingly high noise optimization requirements, its performance appears inadequate.
[0037] Therefore, how to effectively improve the noise optimization ability in the LDO circuit is an urgent problem to be solved currently.
[0038] Based on this, the present utility model proposes an LDO circuit.
[0039] Please refer to Figure 1 , in an embodiment of the present utility model, the LDO circuit includes:
[0040] The LDO main circuit 20 includes a first input terminal, a second input terminal, an output terminal, and a ground terminal. The first input terminal is used to receive a reference voltage. The second input terminal is connected to a power supply. The output terminal is connected to a load and is used to process the input voltage input to its input terminal according to the reference voltage to obtain a constant output voltage and output the output voltage through its output terminal.
[0041] The noise optimization circuit 10, the input terminal of the noise optimization circuit is connected to the input terminal of the LDO main circuit 20, the ground terminal of the noise optimization circuit 10 is grounded, and the noise optimization circuit 10 is used to filter the differential-mode noise and common-mode noise accessed at the input terminal of the LDO main circuit 20.
[0042] It should be noted that the LDO main circuit 20 includes a first input terminal and a second input terminal. The first input terminal is used to receive the reference voltage Vref, and the second input terminal is used to receive the input voltage Vin provided by the power supply. The LDO main circuit is used to process the input voltage Vin input to its second input terminal according to the reference voltage Vref input to its first input terminal to obtain a constant output voltage Vout, and output the constant output voltage Vout through its output terminal. The reference voltage Vref in this embodiment can be generated by an existing reference voltage generation module. In addition, the output voltage Vout output by the output terminal of the LDO main circuit is equal to the reference voltage Vref.
[0043] The noise optimization circuit 10 can be a filter circuit composed of multiple capacitors, which is used to filter out the noise interference in the power line and cut off the transmission path of electromagnetic interference. Compared with the noise optimization circuit in the existing LDO circuit, it has a stronger optimization effect on differential-mode noise and common-mode noise. Among them, differential-mode noise refers to the noise voltage difference between two power lines (such as positive and negative poles). This kind of noise is usually caused by internal signal changes in the circuit or external power fluctuations; common-mode noise refers to the common noise voltage between the power line (or signal line) and the ground wire. Common-mode noise may be caused by external factors such as electromagnetic radiation and ground loop, or may be generated inside the device.
[0044] The technical solution of the present invention adopts an LDO circuit, and a noise optimization circuit 10 is arranged in front of the LDO main circuit 20. When the power supply signal is transmitted, the noise optimization circuit 10 optimizes and filters the differential-mode noise and / or common-mode noise therein, so that the differential-mode noise and / or common-mode noise in the power supply signal are effectively suppressed, thereby effectively improving the noise optimization ability in the LDO circuit.
[0045] Please refer to Figure 2 , in an embodiment of the present invention, the noise optimization circuit 10 includes:
[0046] A differential-mode filtering unit 11, the input terminal of the differential-mode filtering unit 11 is connected to the input terminal of the LDO main circuit 20, and the differential-mode filtering unit 11 is used to filter the differential-mode noise connected to the input terminal of the LDO main circuit 20;
[0047] A common-mode filtering unit 12, the input terminal of the common-mode filtering unit 12 is connected to the input terminal of the LDO main circuit 20, and the grounding terminal of the common-mode filtering unit 12 is grounded, which is used to filter the common-mode noise connected to the input terminal of the LDO main circuit 20.
[0048] It should be noted that the differential-mode filtering unit 11 can be a circuit composed of multiple differential-mode capacitors, which is used to provide the filtering function for differential-mode noise in the power supply signal, and suppress the noise signal in a specific frequency range by selecting the corresponding capacitance value. When a differential-mode signal is generated between the first input terminal and the second input terminal, the differential-mode signal is transmitted through the main path of the circuit, while the high-frequency differential-mode noise is bypassed through the capacitors between the differential-mode filtering units 11, without generating a current flowing to the ground, thereby ensuring the integrity of signal transmission and reducing the interference of differential-mode noise.
[0049] The common-mode filtering unit 12 can be a circuit composed of multiple common-mode capacitors, which is used to provide the filtering function for common-mode noise in the power supply signal, and suppress the noise signal in a specific frequency range by selecting the corresponding capacitance value. When a common-mode interference signal appears, the voltage change caused by the common-mode interference signal makes the formed current flow to the ground through the capacitance coupling effect of the capacitors in the common-mode filtering unit 12, reducing the influence of the interference signal on the circuit and effectively optimizing the common-mode noise.
[0050] In this embodiment, by setting the differential-mode filtering unit 11 between the first input terminal and the second input terminal to optimize the incoming differential-mode noise signal, and setting the common-mode filtering unit 12 to optimize the incoming common-mode noise signal, the interference of differential-mode noise and common-mode noise to the electrical equipment (load) and the LDO main circuit 20 in the circuit is effectively reduced, and the noise optimization ability in the LDO circuit is effectively improved.
[0051] Please refer to Figure 3 , in an embodiment of the present invention, the differential-mode filtering unit 11 includes a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is interconnected with the first end of the second capacitor C2 and the second input terminal of the LDO main circuit 20, and the second end of the first capacitor C1 is connected to the second end of the second capacitor C2 and the output terminal of the LDO main circuit 20.
[0052] It should be noted that the first capacitor C1 and the second capacitor C2 are differential-mode filtering capacitors, and capacitors with appropriate specifications can be selected according to the circuit design. The differential-mode noise in the LDO circuit is a special type of noise, which exists in the form of high frequency between two electrodes. This noise can be bypassed through the capacitor between the two electrodes. By setting the first capacitor C1 and the second capacitor C2 between the first input terminal and the second input terminal, the differential-mode noise generated by the high-frequency pulse in the power supply signal is optimized and filtered through the first capacitor C1 and the second capacitor C2, reducing the interference of the differential-mode noise in the LDO circuit to the subsequent electrical equipment (load) and the LDO main circuit 20.
[0053] Please refer to Figure 3, in an embodiment of the present utility model, the common-mode filtering unit 12 includes a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6. The first end of the third capacitor C3 is interconnected with the first end of the fourth capacitor C4 and the second input terminal of the LDO main circuit 20. The second end of the third capacitor C3 is interconnected and grounded with the first end of the fifth capacitor C5, the second end of the fourth capacitor C4, the first end of the sixth capacitor C6, and the ground terminal of the LDO main circuit 20. The second end of the fifth capacitor C5 is interconnected with the second end of the sixth capacitor C6 and the output terminal of the LDO main circuit 20.
[0054] It should be noted that the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 are common-mode filtering capacitors, and capacitors with appropriate specifications can be selected according to the circuit design. The common-mode noise in the LDO circuit is the noise between the line and the ground, which refers to the noise that appears simultaneously between two signal lines and the ground wire (or reference point) during the signal transmission process. The voltage amplitudes generated by this noise on the two signal lines are equal and the phases are the same. By setting the paths of the third capacitor C3 and the fifth capacitor C5, and the paths of the fourth capacitor C4 and the sixth capacitor C6 between the first input terminal and the second input terminal, and connecting them to the LDO main circuit 20 and grounding respectively, the common-mode interference signal is guided to the ground, effectively reducing the interference of the common-mode noise in the LDO circuit on the subsequent electrical equipment (load) and the LDO main circuit 20.
[0055] In an embodiment of the present utility model, the capacitance values of the third capacitor C3 and the fifth capacitor C5 are the same, and the capacitance values of the fourth capacitor C4 and the sixth capacitor C6 are the same.
[0056] It should be noted that common-mode noise usually refers to the noise signal acting on two signal lines with the same phase and amplitude. If the capacitance values of the third capacitor C3 and the fifth capacitor C5 are the same, and the capacitance values of the fourth capacitor C4 and the sixth capacitor C6 are the same, it can ensure that the current distribution generated under the interference of common-mode noise is uniform, effectively filtering the common-mode noise, thereby effectively reducing the interference of the common-mode noise in the LDO circuit on the subsequent electrical equipment (load) and the LDO main circuit 20, and improving the optimization ability for common-mode noise.
[0057] Exemplarily, to help understand the technical concept or technical principle of the LDO circuit after combining this embodiment with the above embodiments, please refer to Figure 3 , Figure 3A schematic diagram of the circuit structure of an LDO circuit is provided as follows: The first capacitor is 0.1 μF, the second capacitor is 1 μF, the third capacitor is 22 nF, the fourth capacitor is 100 nF, the fifth capacitor is 22 nF, and the sixth capacitor is 100 nF. The capacitance values of the above capacitors can be selected after simulation based on Ansys. By simulating and testing the LDO circuit of this embodiment based on Ansys and with the help of tools such as Sware, the test results of its noise optimization ability can be obtained. For example, Figure 6 shows the intensity of the noise interference signal in the circuit of the optimized LDO circuit of this embodiment at different frequencies. It can be seen that the intensity of the optimized noise interference signal is significantly lower than that before optimization. Therefore, adopting the LDO circuit of this embodiment can effectively suppress the noise in the circuit; for example, Figure 7 shows the intensity of the common-mode noise interference signal in the circuit of the optimized LDO circuit of this embodiment at different frequencies. It can be seen that the intensity of the optimized common-mode noise interference signal is significantly lower than that before optimization. Therefore, adopting the LDO circuit of this embodiment can effectively suppress the common-mode noise in the circuit. For example, Figure 8 shows the intensity of the differential-mode noise interference signal in the circuit of the optimized LDO circuit of this embodiment at different frequencies. It can be seen that the intensity of the optimized differential-mode noise interference signal is significantly lower than that before optimization. Therefore, adopting the LDO circuit of this embodiment can effectively suppress the differential-mode noise in the circuit.
[0058] In summary, according to the simulation test results, it can be obtained that by adopting the LDO circuit of this embodiment, both the differential-mode noise and the common-mode noise are effectively controlled. The LDO circuit of this embodiment effectively improves the noise optimization ability of the LDO circuit by setting up the noise optimization circuit 10.
[0059] Please refer to Figure 4 , in an embodiment of the present invention, the LDO circuit further includes:
[0060] An overcurrent protection module 30, which is serially arranged between the second input terminal of the LDO main circuit 20 and the power supply. The overcurrent protection module 30 is used to disconnect the connection between the LDO main circuit 20 and the power supply when the current in the LDO main circuit 20 is greater than a preset current value.
[0061] It should be noted that the overcurrent protection module 30 can be a fuse, a thermal relay, an electromagnetic relay, or an overcurrent protection circuit. Combinations of a relay and a switching tube can be selected, etc. This embodiment does not limit this. The overcurrent protection module 30 can automatically cut off the circuit when the current exceeds a preset value to prevent damage to the switching power supply and subsequent electrical equipment (load). Taking the electromagnetic relay as an example, the electromagnetic relay controls the opening and closing of the contacts through the magnetic field generated by the current. When the current flowing through the overcurrent protection module 30 is greater than the preset current value, the magnetic field strength increases, causing the contacts of the electromagnetic relay to disconnect, thereby cutting off the connection between the power supply and the switching power supply module.
[0062] Please refer to Figure 5 , in an embodiment of the present invention, the LDO circuit further includes:
[0063] An overtemperature protection module 40, the overtemperature protection module 40 is serially arranged between the second input terminal of the LDO main circuit 20 and the power supply, and the overtemperature protection module 40 further includes a temperature detection terminal, the temperature detection terminal is connected to the heat source component of the LDO main circuit 20, and the overtemperature protection module 40 is used to disconnect the connection between the LDO main circuit 20 and the power supply when detecting that the temperature of the heat source component is greater than a preset temperature value.
[0064] It should be noted that the overtemperature protection module can be a circuit composed of a temperature sensor, a comparator, a trigger, and a switching tube. The temperature inside the heat source component of the LDO main circuit 20 is detected by the temperature sensor and converted into a voltage signal for output; the comparator compares the voltage signal output by the temperature sensor with a preset threshold voltage signal; if the voltage signal output by the temperature sensor exceeds the preset threshold voltage signal, the comparator outputs a high-level signal; the high-level signal triggers the trigger to output a signal to control the switching tube to cut off the connection between the LDO main circuit 20 and the power supply. In this way, when the temperature inside the heat source component of the LDO main circuit 20 exceeds the preset temperature value, the overtemperature protection module 40 will automatically cut off the power supply to protect the LDO main circuit 20 from damage.
[0065] The present invention also proposes an LDO, which includes the LDO circuit described in any one of the above embodiments. The specific structure of the LDO circuit refers to the above embodiments. Since this LDO adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.
[0066] The present utility model also provides a power supply system, which is an LDO power supply system. The power supply system includes a power supply, a load, and the LDO as described in the above embodiments. The specific structure of the LDO refers to the above embodiments. Since this power supply system adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.
[0067] The above is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present utility model.
Claims
1. An LDO circuit, characterized in that: include: The LDO main circuit includes a first input terminal, a second input terminal, an output terminal and a ground terminal, wherein the first input terminal is used to receive a reference voltage, the second input terminal is connected to a power supply, and the output terminal is connected to a load, and is used to process an input voltage input to the input terminal according to the reference voltage to obtain a constant output voltage, and output the output voltage through the output terminal; A noise optimization circuit, wherein the input end of the noise optimization circuit is connected to the input end of the LDO main circuit, the ground end of the noise optimization circuit is grounded, and the noise optimization circuit is used to filter the differential mode noise and common mode noise connected to the input end of the LDO main circuit.
2. The LDO circuit according to claim 1, wherein: The noise optimization circuit comprises: A differential mode filter unit, wherein the input end of the differential mode filter unit is connected to the input end of the LDO main circuit, and the differential mode filter unit is used to filter the differential mode noise connected to the input end of the LDO main circuit; A common mode filter unit, wherein the input end of the common mode filter unit is connected to the input end of the LDO main circuit, and the ground end of the common mode filter unit is grounded, and is used to filter the common mode noise connected to the input end of the LDO main circuit.
3. The LDO circuit according to claim 2, wherein: The differential mode filtering unit includes a first capacitor and a second capacitor, wherein the first end of the first capacitor is interconnected with the first end of the second capacitor and the second input end of the LDO main circuit, and the second end of the first capacitor is connected with the second end of the second capacitor and the output end of the LDO main circuit.
4. The LDO circuit according to claim 2, wherein: The common-mode filtering unit includes a third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor, a first end of the third capacitor is interconnected with a first end of the fourth capacitor and a second input end of the LDO main circuit, a second end of the third capacitor is interconnected with a first end of the fifth capacitor, a second end of the fourth capacitor, a first end of the sixth capacitor and a ground end of the LDO main circuit and is grounded, and a second end of the fifth capacitor is interconnected with a second end of the sixth capacitor and an output end of the LDO main circuit.
5. The LDO circuit according to claim 4, characterized in that: The third capacitor has the same capacitance value as the fifth capacitor, and the fourth capacitor has the same capacitance value as the sixth capacitor.
6. The LDO circuit according to claim 1, wherein: The LDO circuit further includes: An overcurrent protection module is provided in series between the second input terminal of the LDO main circuit and the power supply, and is used for disconnecting the LDO main circuit from the power supply when the current of the LDO main circuit is greater than a preset current value.
7. The LDO circuit according to claim 1, wherein: The LDO circuit further includes: An over-temperature protection module is provided in series between the second input terminal of the LDO main circuit and the power supply, and the over-temperature protection module also includes a temperature detection terminal, the temperature detection terminal is connected to the heat source component of the LDO main circuit, and the over-temperature protection module is used to disconnect the LDO main circuit from the power supply when it is detected that the temperature of the heat source component is greater than a preset temperature value.
8. An LDO, characterized in that: The LDO comprises the LDO circuit according to any one of claims 1 to 7.
9. A power supply system, characterized in that: The power supply system is an LDO power supply system, and the power supply system comprises a power supply, a load, and the LDO as claimed in claim 8.