CN116093882A

CN116093882A - Current limiting circuit, current limiting method and electronic equipment

Info

Publication number: CN116093882A
Application number: CN202211091807.1A
Authority: CN
Inventors: 刘生辉; 潘启辉; 肖想民; 樊胡兵; 卢良飞; 覃志华; 谢绍伟
Original assignee: Hytera Communications Corp Ltd
Current assignee: Hytera Communications Corp Ltd
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2023-05-09

Abstract

The application discloses a current limiting circuit, a current limiting method and electronic equipment, wherein the circuit comprises an input end connected with a power supply; the output end of the load is connected; the first switch is connected between the current detection unit and the follow current unit; the follow current unit is connected between the output end and the first switch; the current detection unit is connected between the input end and the first switch to detect the supply current of the power supply to the load; when the current detection unit detects that the supply current does not exceed the current detection threshold, the current detection unit controls the first switch to be in an on state, so that the power supply source supplies power to the load and charges the follow current unit; otherwise, the current detection unit controls the first switch to be in an off state, so that the power supply stops supplying power to the load, and the follow current unit supplies power to the load. Through the mode, the power supply circuit can be subjected to rapid overcurrent protection, the power of a load is automatically reduced, the load is not powered off, and abnormal interruption of the power supply can be prevented from supplying power to the load.

Description

Current limiting circuit, current limiting method and electronic equipment

Technical Field

The present disclosure relates to the field of current protection technologies, and in particular, to a current limiting circuit, a current limiting method, and an electronic device.

Background

Under the state of impedance mismatch, the current demand of the radio frequency emission system on the power supply is extremely large, and the duration of one pulse is tens of milliseconds; however, when the impedance returns to normal, the power supply current requirements of the rf transmission system are reduced by a factor. When designing the power supply of the radio frequency emission system, the overcurrent protection threshold value is set according to the maximum normal working requirement.

The current limiting protection circuit is characterized in that a current detection unit is added on a power supply path, signals detected by the current detection unit are sent to a chip end, and the grid electrode of the radio frequency amplifier is controlled through the chip so as to control the magnitude of power supply current. The scheme has the advantages that the time from the detection of the signal by the current detection unit to the control of the magnitude of the power supply current is long, and the overcurrent protection function cannot be realized in a short time (10 us).

Disclosure of Invention

The technical problem that this application mainly solves is to provide a current-limiting circuit, current-limiting method and electronic equipment, can carry out quick overcurrent protection to power supply circuit to make the sustainable work of load, prevent the load damage.

In order to solve the technical problem, a first aspect of the present application provides a current limiting circuit, which includes an input terminal for connecting to a power supply; the output end is used for connecting a load; the first switch is connected between the current detection unit and the follow current power supply; the follow current unit is connected between the output end and the first switch; the current detection unit is connected between the input end and the first switch to detect the supply current of the power supply to the load; when the current detection unit detects that the supply current does not exceed the current detection threshold, the current detection unit controls the first switch to be in an on state, so that the power supply source supplies power to the load and charges the follow current unit; when the current detection unit detects that the supplied current exceeds the current detection threshold, the current detection unit controls the first switch to be in an off state, so that the power supply source stops supplying power to the load, and the follow current unit supplies power to the load.

To solve the above technical problem, a second aspect of the present application provides a current limiting method, which includes: detecting whether the supply current input by the input end of the current limiting circuit exceeds a current detection threshold value; when the supplied current does not exceed the current detection threshold, a first switch between the input end and the output end of the current limiting circuit is controlled to be in an on state, so that the output end of the current limiting circuit supplies power to a load and charges a follow current unit; when the supply current exceeds the current detection threshold, the first switch is controlled to be in an off state, so that the power supply connected with the input end of the current limiting circuit stops supplying power to the load, and the follow current unit supplies power to the load.

To solve the above technical problem, a third aspect of the present application provides an electronic device, which includes the current limiting circuit provided in the first aspect.

The beneficial effects of this application are: unlike the prior art, the present application provides a current limiting circuit, which includes an input terminal, an output terminal, a first switch, a freewheel unit and a current detection unit. The input end is connected with a power supply, and the output end is connected with a load; the first switch is connected between the follow current unit and the current detection unit and is used for controlling the input end to supply power to the load; the follow current unit is connected between the output end and the first switch and is used for supplying power to the load after the first switch is disconnected; the current detection unit is connected between the input end and the first switch to detect the supply current of the load supplied by the power supply, judge whether the supply current exceeds a current detection threshold value, and control the on and off of the first switch so as to carry out overcurrent protection on the power supply circuit. Compared with the prior art, the first switch is controlled by the current detection unit, so that the first switch can be quickly turned off after the load is abnormal. Further, after the first switch is disconnected, the freewheeling unit can be used for supplying power to the load, so that the load can continuously work, and the load is prevented from being damaged due to abnormal power interruption of the power supply.

Drawings

FIG. 1 is a schematic diagram of an embodiment of a current limiting circuit provided herein;

FIG. 2 is a schematic diagram of the structure of the voltage acquisition and control unit provided by the present application;

FIG. 3 is a schematic diagram of another embodiment of a current limiting circuit provided herein;

FIG. 4 is a schematic diagram of a first current limiting result of the current limiting circuit;

FIG. 5 is a schematic diagram of a second current limiting result of the current limiting circuit;

fig. 6 is a schematic flow chart of an embodiment of a current limiting method provided in the present application.

Detailed Description

The following description of the embodiments of the present application, taken in conjunction with the accompanying drawings, will clearly and fully describe the embodiments of the present application, and it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

It should be noted that, in the embodiments of the present application, there is a description of "first", "second", etc., which are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a current limiting circuit provided in the present application.

In this embodiment, the current limiting circuit includes an input terminal 10, an output terminal 20, a first switch Q1, a freewheel unit 30, and a current detection unit 40. The input end 10 is used for connecting a power supply; the output terminal 20 is used for connecting a load; the first switch Q1 is connected between the freewheel unit 30 and the current detection unit 40, and the first switch Q1 may be a MOS transistor, which includes a gate, a source, and a drain; freewheel unit 30 is connected between output 20 and first switch Q1; the current detecting unit 40 is connected between the input terminal 10 and the first switch Q1 to detect a supply current of the power supply to the load. When the current detection unit 40 detects that the supply current does not exceed the current detection threshold, it controls the first switch Q1 to be in an on state, so that the supply power supplies power to the load and charges the freewheel unit 30; when the current detection unit 40 detects that the supply current exceeds the current detection threshold, it controls the first switch Q1 to be in an off state so that the supply power stops supplying power to the load, and the load is supplied with power through the freewheel unit 30.

The current detection threshold may be set according to the requirements of the load. For example, when the current provided by the power supply is 2A and the load needs to supply 1A during normal operation, if the load fails and the required supply current increases to 2A, the current detection threshold may be set between 1 and 2A, so that when the current detection unit 40 detects that the supply current provided by the power supply exceeds the current detection threshold, the first switch Q1 is controlled to be turned off, and the freewheel unit 30 supplies power to the load in time.

In this embodiment, the current detecting unit controls the first switch, so that the first switch can be quickly turned off after the load is abnormal. Further, after the first switch is disconnected, the freewheeling unit can be used for supplying power to the load, so that the load can continuously work, and the load is prevented from being damaged due to abnormal power interruption of the power supply.

With continued reference to fig. 1, the current detecting unit 40 includes a first resistor R1 and a voltage acquisition and control unit 401. The first resistor R1 is disposed on a power supply circuit formed by the input terminal 10, the first switch Q1 and the output terminal 20; the voltage acquisition and control unit 401 is connected to two ends of the first resistor R1 to detect a voltage difference between the two ends of the first resistor R1, and sends a control signal to control the first switch Q1 to be turned on or turned off based on the voltage difference between the two ends of the first resistor R1 and a preset voltage detection threshold corresponding to the current detection threshold. In a specific embodiment, a first end (i.e., a voltage collecting end a in fig. 1) of the first resistor R1 is connected to the input end 10, a second end (i.e., a voltage collecting end B in fig. 1) of the first resistor R1 is connected to the first switch Q1, and a user determines whether the supply current supplied to the load exceeds the current detection threshold by determining a comparison result between a voltage difference across the first resistor R1 and a preset voltage detection threshold. If the voltage difference between two ends of the first resistor R1 is higher than a preset voltage detection threshold value, the first switch Q1 is controlled to be disconnected; if the voltage difference across the first resistor R1 is lower than the preset voltage detection threshold, the first switch Q1 is controlled to be turned on. Wherein the preset voltage detection threshold may be set based on the current detection threshold.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a voltage acquisition and control unit provided in the present application. In the present embodiment, the voltage acquisition and control unit 401 includes a differential amplifier 4011, a voltage dividing circuit 4012, and a comparator 4013. The first input end (e.g., pin 8 in fig. 2) and the second input end (e.g., pin 7 in fig. 2) of the differential amplifier 4011 are respectively connected to the first end and the second end of the first resistor R1, so as to receive the voltages at two ends of the first resistor R1, further obtain the voltage difference at two ends of the first resistor R1, and amplify the voltage difference at two ends of the first resistor R1.

The voltage dividing circuit 4012 is connected to an output terminal (e.g., a2 pin in fig. 2) of the differential amplifier 4011, so as to divide the voltage difference across the amplified first resistor R1 to generate a divided voltage. Further, the voltage dividing circuit 4012 may include a second resistor R4 and a third resistor R6, the second resistor R4 and the third resistor R6 being connected in series between an output terminal of the differential amplifier 4011 and the ground voltage, and a first node a between the second resistor R4 and the third resistor R6 being an output terminal of the voltage dividing circuit 4012 to output the divided voltage.

The comparator 4013 has a first input terminal receiving a preset voltage detection threshold value, and a second input terminal (e.g., 3 pin in fig. 2) receiving the divided voltage output from the voltage dividing circuit 4012, for comparing the preset voltage detection threshold value with the divided voltage, thereby generating a corresponding control signal including an operating voltage representing a logic high level and a logic low level. Specifically, the comparator 4013 may compare the received divided voltage with a preset voltage detection threshold, in an embodiment, the divided voltage above the preset voltage detection threshold may not be converted, and the received original value of the divided voltage above the preset voltage detection threshold is output, where the original value of the divided voltage is the working voltage representing a logic high level; the voltage lower than the preset voltage detection threshold value can be converted, the ground voltage is output, and the ground voltage is the working voltage representing the logic low level. In another embodiment, the divided voltage higher than the preset voltage detection threshold may be converted, and the working voltage of the comparator is output, where the working voltage of the comparator is the working voltage representing the logic high level, and in this embodiment, the working voltage of the comparator may be 3.3V; and converting the voltage lower than the preset voltage detection threshold value, outputting a ground voltage, wherein the ground voltage is the working voltage representing the logic low level. It will be appreciated that the first input of the comparator 4013 receives a preset voltage detection threshold value, which may be set according to the user's needs.

In a specific embodiment, the voltage acquisition and control unit 401 may employ a high-side shunt monitor (such as INA200, INA201 or INA 202) with a voltage output and integrated comparator 4013, and if the voltage acquisition and control unit 401 is INA200, the differential amplifier 4011 included therein may amplify the voltage difference across R1 by 20 times, and may provide a voltage reference of 0.6V threshold (i.e. a preset voltage detection threshold). Assuming that the current flowing through the first resistor R1 is I, the voltage difference at two ends of the first resistor R1 is IR1, the amplified voltage difference obtained by amplifying the voltage difference by 20 times is 20IR1, the divided voltage obtained by the voltage dividing circuit 4012 is 20IR1 x r6/(r4+r6), the comparison of 20IR1 x r6/(r4+r6) and 0.6V is performed by the comparator 4013, if 20IR1 x r6/(r4+r6) is greater than 0.6V, the operating voltage representing the logic high level is output, and if 20IR1 x r6/(r4+r6) is less than 0.6V, the operating voltage representing the logic low level is output.

With continued reference to fig. 1, in an embodiment, the freewheel unit 30 may include a first inductor L1 and a first capacitor C1, where the first capacitor C1 is connected between a second node B and a ground voltage, the second node B is a connection point between the first inductor L1 and the output terminal 20, and the first inductor L1 is connected between the first switch Q1 and the output terminal 20. Further, the freewheel unit 30 may further include a diode D1, an anode of the diode D1 is connected to a ground voltage, and a cathode of the diode D1 is connected to a third node C, where the third node C is a connection point between the first inductor L1 and the first switch Q1. When the first switch Q1 is turned off, power is supplied to the load through the freewheel unit 30. In this embodiment, the diode D1 may be a zener diode D1, and is reversely connected in the circuit, when the current is too large, the reversely connected diode D1 may be broken down, so that the broken-down diode D1 is used for quick discharging, and the damage to the load at the rear end is prevented. In another embodiment, the freewheel unit 30 may include a first inductor L1, a first capacitor C1 and a MOS transistor.

Referring to fig. 3, fig. 3 is a schematic structural diagram of another embodiment of the current limiting circuit provided in the present application.

The current limiting circuit may further include a conversion circuit 50, and the conversion circuit 50 connects the current detection unit 40 and the first switch Q1 to convert a control signal output from the current detection unit 40 into a control signal matched with the first switch Q1 to control on and off of the first switch Q1. In an embodiment, the converting circuit 50 includes a plurality of resistors and switches, the control signal output by the current detecting unit 40 is a high voltage indicating a logic high level, the control signal of the first switch Q1 may be a low voltage indicating a logic low level, and the control signal output by the current detecting unit 40 may be converted into a control signal matching the first switch Q1 by the converting circuit.

Specifically, the conversion circuit 50 may include a first conversion circuit 501 and a second conversion circuit 502. The first conversion circuit 501 includes a second switch Q3 and a fourth resistor R3, where the second switch Q3 and the fourth resistor R3 are connected in series between a fourth node D and a ground voltage, the fourth node D is a connection point between the first switch Q1 and the first resistor R1, a control end of the second switch Q3 is connected to an output end of the voltage acquisition and control unit 401, and a connection point between the second switch Q3 and the fourth resistor R3 is used as an output node of the first conversion circuit 501 to convert a control signal output by the voltage acquisition and control unit 401 into a first control signal. That is, the control signal output from the voltage acquisition and control unit 401 may output the first control signal after passing through the second switch Q3 and the fourth resistor R3. The first control signal is different from the control signal output by the voltage acquisition and control unit 401, for example, the control signal output by the voltage acquisition and control unit 401 is a high voltage indicating a logic high level, and the first control signal may be a low voltage indicating a logic low level.

In an embodiment, the second switch Q3 is an N-MOS transistor, and the received level is turned on when the received level is higher than a certain value, and turned off when the received level is lower than a certain value. If the output terminal of the voltage acquisition and control unit 401 outputs a low voltage representing a logic low level, the second switch Q3 is turned off, and the high voltage of R3 will cause the output node of the first conversion circuit 501 to output a high voltage representing a logic high level, so that the low voltage representing a logic low level output by the voltage acquisition and control unit 401 can be converted into a high voltage representing a logic high level, and at this time, the corresponding first control signal is the high voltage representing a logic high level.

Further, the converting circuit 50 may further include a sixth resistor R5, and the output terminal of the voltage acquisition and control unit 401 is connected to the first voltage through the sixth resistor R5, where the first voltage may be an output voltage of other power sources. The sixth resistor is used to determine the high voltage representing the logic high level received by the second switch Q3. If the output end of the voltage collecting and controlling unit 401 outputs a logic high level, after being pulled up through the sixth resistor R5, a high voltage representing the logic high level is output, and the second switch Q3 is turned on immediately after receiving the high voltage representing the logic high level, so that the output node of the first converting circuit 501 outputs a ground voltage, the ground voltage represents the high voltage of the logic high level, which can be identified as the logic low level, and in this way, the conversion of the logic high level output by the voltage collecting and controlling unit 401 into the logic low level can be achieved, and at this time, the corresponding first control signal is the ground voltage representing the logic low level.

The second conversion circuit 502 includes a fifth resistor R2, a third switch Q2, and a fourth switch Q4, where the fifth resistor R2, the third switch Q2, and the fourth switch Q4 are connected in series between the fourth node D and the ground voltage, and control ends of the third switch Q2 and the fourth switch Q4 are respectively connected to an output node of the first conversion circuit 501 to receive a first control signal, a connection point between the third switch Q2 and the fourth switch Q4 is used as an output node of the second conversion circuit 502 to convert the first control signal output by the first conversion circuit 501 into a second control signal, and a control end of the first switch Q1 receives the second control signal to be in an on or off state based on control of the second control signal.

In one embodiment, the fourth switch Q4 is an N-MOS transistor; the third switch Q2 is a P-MOS tube, the level received by the P-MOS tube is conducted when the level is lower than a certain value, and the level is cut off when the level is higher than a certain value; the first control signal is a high voltage representing a logic high level. The third switch Q2 is turned on after receiving the first control signal, so that the output node (i.e., the connection point between the third switch Q2 and the fourth switch Q4) of the second conversion circuit 502 outputs the ground voltage, and the ground voltage can be identified as a logic low level. The output node of the second conversion circuit 502 is connected to the gate of the first switch Q1 (i.e., pin 4 of the first switch Q1 in fig. 3), so that a voltage difference exists between the source of the first switch Q1 (i.e., pins 1-3 of the first switch Q1 in fig. 3) and the gate, and the first switch Q1 is turned on.

In another embodiment, the first control signal is a ground voltage representing a logic low level, and the fourth switch Q4 is an N-MOS transistor; the third switch Q2 is a P-MOS tube, and one end of the fifth resistor R2 is connected with the source electrode of the first switch Q1. The third switch Q2 is turned on after receiving the first control signal, the fourth switch Q4 is turned off after receiving the first control signal, the output node of the second conversion circuit 502 (i.e. the connection point between the third switch Q2 and the fourth switch Q4) outputs a high voltage representing a logic high level through the high voltage of the fifth resistor R2, and since one end of the fifth resistor R2 is connected to the source of the first switch Q1, the output node of the second conversion circuit 502 is connected to the gate of the first switch Q1, so that the gate and the source of the first switch Q1 are connected, and the first switch Q1 is turned off.

Referring to fig. 3-5 in combination, fig. 4 is a schematic diagram of a first current limiting result of the current limiting circuit; fig. 5 is a schematic diagram of a second current limiting result of the current limiting circuit.

In a specific embodiment, the current limiting circuit provided in the present application is connected to a load, and the first resistor R1 is 50mΩ, the second resistor R4 is 1kΩ, and the third resistor R6 is 0.423kΩ, where the current limiting value I (i.e. the current detection threshold) is calculated by the above formula 20ir1×r6/(r4+r6) =0.6v. As shown in fig. 4, the monitoring software monitors the change of the supply current of the power supply to the load in the circuit, and when the load is normal, the change of the supply current is the first line segment in fig. 4; when the load fails, the change of the supply current corresponds to a second line segment in the graph, and the second line segment gradually increases to show that the supply current gradually increases; when the supply current increases to 2.05A, the first switch Q1 is turned off, the load is supplied with power from the flywheel power source, and at this time, the change of the supply current is a third line segment in the figure, and the supply current value decreases to 1.25A.

Further, as shown in fig. 5, the sixth line segment in fig. 5 is a waveform of the first switch Q1, the seventh line segment is an operational amplifier output waveform, and the response time of the overcurrent circuit in this embodiment is 940ns, where the response time is a time from when the current detection unit 40 detects that the supply current exceeds the current detection threshold to when the first switch Q1 is turned off.

From the above results, the current limiting circuit provided by the present application can rapidly turn off the power supply after the load is abnormal, and adopts the freewheel unit 30 to supply power, so as to avoid damaging the load.

Referring to fig. 1 and fig. 4 in combination, in an embodiment, after the current detection unit 40 detects that the supply current of the power supply to the load exceeds the current detection threshold for the first time, the first switch Q1 is controlled to be turned off. Since the supply current supplied to the load by the power supply falls to zero after the first switch Q1 is turned off, the current detection unit 40 can detect that the supply current supplied to the load is lower than the current detection threshold value in a very short time after the first switch Q1 is turned off, and then control the first switch Q1 to be turned on. If the load is still in an abnormal state at this time, the supplied current is detected to exceed the current detection threshold again, and the first switch Q1 is controlled to be turned off again. Therefore, in the period from the abnormal load occurrence to the normal load restoration, the first switch Q1 is always in the continuously closed and open state, as shown in fig. 4, the fourth line segment in fig. 4 is a waveform of the switch on state, and the fifth area indicates that the switch is in the continuously open and open state.

Referring to fig. 6, fig. 6 is a flow chart illustrating an embodiment of a current limiting method provided in the present application, where the current limiting method is applied to any one of the embodiments of the current limiting circuit, and the current limiting method includes:

s610: detecting whether the supply current input by the input end of the current limiting circuit exceeds a current detection threshold.

S620: when the supplied current does not exceed the current detection threshold, a first switch between the input end and the output end of the current limiting circuit is controlled to be in an on state, so that the output end of the current limiting circuit supplies power to the load and charges the follow current unit.

S630: when the supplied current exceeds the current detection threshold, the first switch is controlled to be in an off state, so that a power supply connected with the input end of the current limiting circuit stops supplying power to the load, and the follow current unit supplies power to the load.

Specifically, the current detection unit is used for detecting whether the supply current input by the input end of the current limiting circuit exceeds a current detection threshold, wherein the current detection unit comprises a first resistor and a high-side shunt monitor with a voltage output and an integrated comparator, the current detection threshold is set according to the current required by normal operation of a load, the current detection threshold can be set between the current provided by a power supply and the current required by normal operation of the load, for example, the current provided by the power supply is 2A, the current required by normal operation of the load is 1A, and the current detection threshold can be set to any value between 1 and 2A.

The high-side shunt monitor in the current detection unit can output different control signals according to whether the supply current input by the input end of the current limiting circuit exceeds a current detection threshold value, and further, the current detection unit can further comprise a conversion circuit, and the control signals output by the high-side shunt monitor are converted into control signals of the first switch through the conversion circuit so as to control the first switch to be turned on and turned off. When the first switch is in an on state, the output end of the current limiting circuit supplies power to the load and charges the follow current unit; when the first switch is in an off state, the freewheel unit supplies power to the load.

The present application also provides an electronic device, which may include the current limiting circuit in any of the above embodiments.

The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the patent application, and all equivalent structures or equivalent processes using the descriptions and the contents of the present application or other related technical fields are included in the scope of the patent application.

Claims

1. A current limiting circuit, comprising:

the input end is used for connecting a power supply;

the output end is used for connecting a load;

the first switch is connected between the current detection unit and the follow current unit; the follow current unit is connected between the output end and the first switch; the current detection unit is connected between the input end and the first switch to detect the supply current of the power supply to the load;

when the current detection unit detects that the supply current does not exceed a current detection threshold, the current detection unit controls the first switch to be in an on state so that the power supply source supplies power to the load and charges the follow current unit; when the current detection unit detects that the supply current exceeds the current detection threshold, the current detection unit controls the first switch to be in an off state so that the power supply stops supplying power to the load, and the follow current unit supplies power to the load.

2. The current limiting circuit of claim 1, wherein the current detection unit comprises:

the first resistor is arranged on a power supply loop formed by the input end, the first switch and the output end;

and the voltage acquisition and control unit is connected with two ends of the first resistor to detect the voltage difference between the two ends of the first resistor, and sends out a control signal to control the first switch to be opened or disconnected based on the voltage difference between the two ends of the first resistor and a preset voltage detection threshold corresponding to the current detection threshold.

3. The current limiting circuit of claim 2, wherein the voltage acquisition and control unit comprises:

the differential amplifier is used for receiving the voltage difference between the two ends of the first resistor and amplifying the voltage difference between the two ends of the first resistor;

the voltage dividing circuit is connected with the output end of the differential amplifier so as to divide the amplified voltage difference between the two ends of the first resistor to generate divided voltage;

and the first input end of the comparator receives the preset voltage detection threshold value, and the second input end of the comparator receives the divided voltage output by the voltage dividing circuit so as to compare the preset voltage detection threshold value with the divided voltage, thereby generating the corresponding control signal.

4. A current limiting circuit according to claim 3, wherein the voltage dividing circuit comprises a second resistor and a third resistor, wherein the second resistor and the third resistor are connected in series between an output terminal of the differential amplifier and a ground voltage, and a first node between the second resistor and the third resistor is used as an output terminal of the voltage dividing circuit to output the divided voltage.

5. The current limiting circuit of claim 1, wherein the freewheel unit includes:

the first inductor is connected between the first switch and the output end;

and the first capacitor is connected between a second node and the ground voltage, wherein the second node is a connection point between the first inductor and the output end.

6. The current limiting circuit of claim 5, wherein the freewheel unit further includes:

and the anode of the diode is connected with the ground voltage, and the cathode of the diode is connected with a third node, wherein the third node is a connection point between the first inductor and the first switch.

7. The current limiting circuit of claim 2, further comprising:

and the conversion circuit is connected with the current detection unit and the first switch to convert the control signal output by the current detection unit into a control signal matched with the first switch so as to control the opening and the closing of the first switch.

8. The current limiting circuit of claim 7, wherein the switching circuit comprises:

the first conversion circuit comprises a second switch and a fourth resistor, wherein the fourth resistor and the second switch are connected in series between a fourth node and a ground voltage, the fourth node is a connection point between the first switch and the first resistor, the control end of the second switch is connected with the output end of the voltage acquisition and control unit, and the connection point between the second switch and the fourth resistor is used as an output node of the first conversion circuit so as to convert a control signal output by the voltage acquisition and control unit into a first control signal;

the second conversion circuit comprises a fifth resistor, a third switch and a fourth switch, wherein the fifth resistor, the third switch and the fourth switch Guan Chuanlian are arranged between the fourth node and the ground voltage, control ends of the third switch and the fourth switch are respectively connected with an output node of the first conversion circuit to receive the first control signal, a connection point between the third switch and the fourth switch is used as an output node of the second conversion circuit to convert the first control signal output by the first conversion circuit into a second control signal, and a control end of the first switch receives the second control signal to be in an on or off state based on control of the second control signal.

9. The current limiting circuit of claim 8, wherein the second switch is an N-MOS transistor, the fourth switch is an N-MOS transistor, and the third switch is a P-MOS transistor.

10. The current limiting circuit of claim 8, wherein the conversion circuit further comprises:

and the output end of the voltage acquisition and control unit is connected to the first voltage through the sixth resistor.

11. A current limiting method for use in a current limiting circuit according to any one of claims 1 to 10, the current limiting method comprising:

detecting whether the supply current input by the input end of the current limiting circuit exceeds a current detection threshold value;

when the supply current does not exceed the current detection threshold, a first switch between the input end and the output end of the current limiting circuit is controlled to be in an on state, so that the output end of the current limiting circuit supplies power to a load and charges a follow current unit;

and when the supply current exceeds a current detection threshold value, controlling the first switch to be in an off state so as to stop a power supply connected with the input end of the current limiting circuit from supplying power to the load, and supplying power to the load by the follow current unit.

12. An electronic device comprising a current limiting circuit as claimed in any one of claims 1-10.