WO2024050730A1

WO2024050730A1 - Current limiting circuit, current limiting method, and electronic device

Info

Publication number: WO2024050730A1
Application number: PCT/CN2022/117634
Authority: WO
Inventors: 刘生辉; 潘启辉; 肖想民; 樊胡兵; 卢良飞; 覃志华; 谢绍伟
Original assignee: 海能达通信股份有限公司
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2024-03-14

Abstract

Disclosed in the present application are a current limiting circuit, a current limiting method, and an electronic device. The circuit comprises: an input end for connecting to a power supply source; an output end for connecting to a load; a first switch connected between a current sensing unit and a freewheeling unit; the freewheeling unit connected between the output end and the first switch; and the current sensing unit connected between the input end and the first switch, so as to detect a supplied current supplied to the load by the power supply source. When the current sensing unit detects that the supplied current does not exceed a current sensing threshold value, the current sensing unit controls the first switch to be in a turned-on state, such that the power supply source supplies power to the load, and charges the freewheeling unit; otherwise, the current sensing unit controls the first switch to be in a turned-off state, such that the power supply source stops supplying power to the load, and the freewheeling unit supplies power to the load. In this way, the present application can perform rapid over-current protection on a power circuit, automatically reduce the power of a load and prevent the load from being powered off, and can also prevent the interruption of power supply to the load due an abnormal power source.

Description

A current limiting circuit, current limiting method and electronic equipment

【Technical field】

The present application relates to the field of current protection technology, and in particular to a current limiting circuit, a current limiting method and electronic equipment.

【Background technique】

In the state of impedance mismatch, the radio frequency transmission system has a huge demand for power supply current, with a pulse duration of more than ten milliseconds. However, when the impedance returns to normal, the radio frequency transmission system's demand for power supply current will be doubled. Then, when designing the power supply of the radio frequency transmission system, the overcurrent protection threshold must be set according to the maximum normal operation requirements.

The existing current limiting protection circuit adds a current detection unit to the power supply path, sends the signal detected by the current detection unit to the chip, and controls the gate of the radio frequency amplifier through the chip to control the size of the power supply current. This solution takes a long time from the time the current detection unit detects the signal to controlling the power supply current, and it cannot provide overcurrent protection in a short time (10us).

[Content of the invention]

The main technical problem solved by this application is to provide a current limiting circuit, current limiting method and electronic equipment, which can quickly protect the power circuit from overcurrent, enable the load to operate continuously, and prevent the load from being damaged.

In order to solve the above technical problems, the first aspect of this application provides a current limiting circuit. The circuit includes an input terminal for connecting to a power supply; an output terminal for connecting to a load; a first switch connected to the current detection unit and the continued between the current power supply; the freewheeling unit is connected between the output terminal and the first switch; the current detection unit is connected between the input terminal and the first switch to detect the supply current supplied by the power supply to the load; wherein, when the current detection unit It is detected that the supply current does not exceed the current detection threshold, and the current detection unit controls the first switch to be in an open state, so that the power supply supplies power to the load and charges the freewheeling 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, causing the power supply to stop supplying power to the load, and the freewheeling unit supplies power to the load.

In order to solve the above technical problems, the second aspect of the present application provides a current limiting method. The method includes: detecting whether the supply current input to the input end of the current limiting circuit exceeds the current detection threshold; when the supply current does not exceed the current detection threshold, The first switch between the input terminal and the output terminal of the current limiting circuit is controlled to be in an open state, so that the output terminal of the current limiting circuit supplies power to the load and charges the freewheeling unit; when the supply current exceeds the current detection threshold, the first switch is controlled The switch is in an off state, so that the power supply connected to the input end of the current limiting circuit stops supplying power to the load, and the freewheeling unit supplies power to the load.

In order to solve the above technical problems, the 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: different from the prior art, this application provides a current limiting circuit, which includes an input terminal, an output terminal, a first switch, a freewheeling unit and a current detection unit. The input end is connected to the power supply, and the output end is connected to the load; the first switch is connected between the freewheeling unit and the current detection unit, and is used to control the input end to supply power to the load; the freewheeling unit is connected between the output end and the first switch, with To supply power to the load after the first switch is turned off; the current detection unit is connected between the input terminal and the first switch to detect the supply current supplied by the power supply to the load, determine whether the supply current exceeds the current detection threshold, and control the first The switch is turned on and off to protect the power circuit from overcurrent. Compared with the existing technology, the current detection unit controls the first switch, so that the first switch can be quickly disconnected after an abnormality occurs in the load. Further, after the first switch is turned off, a freewheeling unit can be used to supply power to the load, so that the load can continue to work and prevent damage to the load caused by abnormal interruption of power supply by the power supply.

[Picture description]

Figure 1 is a schematic structural diagram of an embodiment of a current limiting circuit provided by this application;

Figure 2 is a schematic structural diagram of the voltage acquisition and control unit provided by this application;

Figure 3 is a schematic structural diagram of another embodiment of the current limiting circuit provided by this application;

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

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

FIG. 6 is a schematic flowchart of an embodiment of the current limiting method provided by this application.

【Detailed ways】

The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of this application.

It should be noted that there are descriptions involving “first”, “second”, etc. in the embodiments of the present application. The descriptions of “first”, “second”, etc. are only for descriptive purposes and cannot be understood as instructions or instructions. implying its relative importance or implicitly specifying the quantity of the technical feature indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features.

Reference herein to "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of this phrase 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 skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

Please refer to FIG. 1 , which is a schematic structural diagram of an embodiment of a current limiting circuit provided by the present application.

In this embodiment, the current limiting circuit includes an input terminal 10 , an output terminal 20 , a first switch Q1 , a freewheeling unit 30 , and a current detection unit 40 . The input terminal 10 is used to connect the power supply; the output terminal 20 is used to connect the load; the first switch Q1 is connected between the freewheeling unit 30 and the current detection unit 40. The first switch Q1 can be a MOS tube, which includes a gate, a source pole and drain; the freewheeling unit 30 is connected between the output terminal 20 and the first switch Q1; the current detection unit 40 is connected between the input terminal 10 and the first switch Q1 to detect the power supply to the load. supply current. Among them, 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 open state so that the supply power supplies power to the load and charges the freewheeling unit 30; when the current detection unit 40 When it is detected 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 supplies power to the load through the freewheeling unit 30 .

The current detection threshold can be set according to the load requirements. For example, the current provided by the power supply is 2A, and the load needs to supply 1A when it is working normally. If the load fails and the required supply current increases to 2A, the current detection threshold can be set between 1-2A, so that the current detection When the unit 40 detects that the supply current provided by the power supply exceeds the current detection threshold, it controls the first switch Q1 to turn off, and the freewheeling unit 30 supplies power to the load in time.

In this embodiment, the current detection unit controls the first switch, so that the first switch can be quickly disconnected after an abnormality occurs in the load. Further, after the first switch is turned off, a freewheeling unit can be used to supply power to the load, so that the load can continue to work and prevent damage to the load caused by abnormal interruption of power supply by the power supply.

Please continue to refer to FIG. 1 , the current detection unit 40 includes a first resistor R1 and a voltage acquisition and control unit 401 . The first resistor R1 is disposed on the power supply loop 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 both ends of the first resistor R1 to detect the voltage across the first resistor R1 Difference, based on the voltage difference across the first resistor R1 and the preset voltage detection threshold corresponding to the current detection threshold, a control signal is sent to control the first switch Q1 to turn on or off. In a specific implementation, the first end of the first resistor R1 (that is, the voltage collection terminal A in Figure 1) is connected to the input terminal 10, and the second end of the first resistor R1 (that is, the voltage collection terminal B in Figure 1 ) is connected to the first switch Q1, and the user determines whether the supply current supplied to the load exceeds the current detection threshold by comparing the voltage difference across the first resistor R1 with the preset voltage detection threshold. If the voltage difference across the first resistor R1 is higher than the preset voltage detection threshold, the first switch Q1 is controlled to be turned off; 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. . The preset voltage detection threshold can be set based on the current detection threshold.

Please refer to Figure 2, which is a schematic structural diagram of the voltage acquisition and control unit provided by this application. In this 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 terminal (pin 8 in Figure 2) and the second input terminal (pin 7 in Figure 2) of the differential amplifier 4011 are respectively connected to the first terminal and the second terminal of the first resistor R1 to receive The voltage across the first resistor R1 is then obtained as the voltage difference across the first resistor R1, and the voltage difference across the first resistor R1 is amplified.

The voltage dividing circuit 4012 is connected to the output end of the differential amplifier 4011 (pin 2 in Figure 2) to divide the amplified voltage difference across the 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 are connected in series between the output end of the differential amplifier 4011 and the ground voltage, and the second resistor R4 and the third resistor R6 are connected in series between the output end of the differential amplifier 4011 and the ground voltage. The first node A between the resistors R6 serves as the output terminal of the voltage dividing circuit 4012 to output the divided voltage.

The first input terminal of the comparator 4013 receives the preset voltage detection threshold, and the second input terminal (pin 3 in Figure 2) receives the divided voltage output by the voltage dividing circuit 4012 to compare the preset voltage detection threshold and the divided voltage. voltage, thereby generating a corresponding control signal. The control signal includes 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 one embodiment, the divided voltage higher than the preset voltage detection threshold may not be converted and the received voltage may be output. The original value of the divided voltage that is higher than the preset voltage detection threshold. The original value of the divided voltage is the operating voltage that represents the logic high level; the voltage that is lower than the preset voltage detection threshold can be converted and the ground voltage is output. The ground voltage is the operating voltage that represents the logic low level. In another embodiment, the divided voltage higher than the preset voltage detection threshold can be converted to output the working voltage of the comparator. The working voltage of the comparator is the working voltage representing the logic high level. In this embodiment , the operating voltage of the comparator can be 3.3V; voltages lower than the preset voltage detection threshold are also converted, and the ground voltage is output, and the ground voltage is the operating voltage representing a logic low level. It can be understood that the first input terminal of the comparator 4013 receives a preset voltage detection threshold that can be set according to user needs.

In a specific implementation, the voltage acquisition and control unit 401 can use a high-side shunt monitor (such as INA200, INA201 or INA202) with a voltage output and an integrated comparator 4013. If the voltage acquisition and control unit 401 is an INA200, it includes The differential amplifier 4011 can amplify the voltage difference across R1 20 times, and can provide a voltage reference of 0.6V threshold (ie, preset voltage detection threshold). Assume that the current flowing through the first resistor R1 is I, then the voltage difference across the first resistor R1 is IR1. After amplifying the voltage difference 20 times, the amplified voltage difference is 20IR1. The divided voltage obtained after passing through the voltage dividing circuit 4012 is is 20IR1*R6/(R4+R6), compare 20IR1*R6/(R4+R6) and 0.6V through comparator 4013. If 20IR1*R6/(R4+R6) is greater than 0.6V, the output indicates a logic high level The operating voltage, if 20IR1*R6/(R4+R6) is less than 0.6V, the output represents the operating voltage of logic low level.

Please continue to refer to FIG. 1 . In one embodiment, the freewheeling unit 30 may include a first inductor L1 and a first capacitor C1 . The first capacitor C1 is connected between the second node B and the ground voltage. The second node B is the A connection point between the inductor L1 and the output terminal 20 , the first inductor L1 is connected between the first switch Q1 and the output terminal 20 . Further, the freewheeling unit 30 may also include a diode D1. The anode of the diode D1 is connected to the ground voltage, and the cathode is connected to the third node C. The third node C is the 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 freewheeling unit 30. In this embodiment, the diode D1 can be a zener diode D1, which is connected reversely in the circuit. When the current is too large, the reversely connected diode D1 can be broken down, so that the diode D1 can be quickly discharged through the broken down diode D1 to prevent damage to the rear end. load. In another embodiment, the freewheeling unit 30 may include a first inductor L1, a first capacitor C1 and a MOS transistor.

Please refer to FIG. 3 , which is a schematic structural diagram of another embodiment of a current limiting circuit provided by the present application.

The current limiting circuit may also include a conversion circuit 50 connected to the current detection unit 40 and the first switch Q1 to convert the control signal output by the current detection unit 40 into a control signal matching the first switch Q1 to control the first switch. Turning on and off Q1. In one embodiment, the conversion circuit 50 includes several resistors and switches. The control signal output by the current detection unit 40 is a high voltage representing a logic high level. The control signal of the first switch Q1 may be a low voltage representing a logic low level. The voltage is converted through the conversion circuit, so that the control signal output by the current detection unit 40 can be converted into a control signal matching the first switch Q1.

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. The second switch Q3 and the fourth resistor R3 are connected in series between the fourth node D and the ground voltage. The fourth node D is the first switch Q1 and the first resistor. The connection point of R1 and the control end of the second switch Q3 are connected to the output end of the voltage acquisition and control unit 401. The connection point between the second switch Q3 and the fourth resistor R3 serves as the output node of the first conversion circuit 501 to convert the voltage The control signal output by the acquisition and control unit 401 is converted into a first control signal. That is to say, the control signal output by the voltage acquisition and control unit 401 can 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, if the control signal output by the voltage acquisition and control unit 401 is a high voltage representing a logic high level, then the first control signal may be a voltage representing a logic low level. Flat low voltage.

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

Further, the conversion circuit 50 may also include a sixth resistor R5. The output end of the voltage acquisition and control unit 401 is connected to the first voltage through the sixth resistor R5. The first voltage may be the output voltage of other power sources. The sixth resistor is used to determine the high voltage received by the second switch Q3 indicating a logic high level. If the output terminal of the voltage acquisition and control unit 401 outputs a logic high level, after being pulled up by the sixth resistor R5, a high voltage representing a logic high level is output, and the second switch Q3 receives the high voltage representing a logic high level. Then it is turned on immediately, so that the output node of the first conversion circuit 501 outputs a ground voltage. The ground voltage represents a high voltage with a logic high level, which can be recognized as a logic low level. In this way, the voltage can be collected and controlled. The logic high level output by the unit 401 is converted into a logic low level. At this time, the corresponding first control signal is the ground voltage indicating the logic low level.

The second conversion circuit 502 includes a fifth resistor R2, a third switch Q2 and a fourth switch Q4, wherein 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 The control terminals of the third switch Q2 and the fourth switch Q4 are respectively connected to the output node of the first conversion circuit 501 to receive the first control signal. The connection point between the third switch Q2 and the fourth switch Q4 serves as the second conversion circuit 502 The output node is to convert the first control signal output by the first conversion circuit 501 into a second control signal. The control end of the first switch Q1 receives the second control signal, so that the control based on the second control signal is in an on or off state. .

In one embodiment, the fourth switch Q4 is an N-MOS tube; the third switch Q2 is a P-MOS tube. The P-MOS tube is turned on when the received level is lower than a certain value and turned off when it is higher than a certain value; A control signal is a high voltage representing a logic high level. The third switch Q2 is turned off after receiving the first control signal, and the fourth switch Q4 is turned on after receiving the first control signal, so that the output node of the second conversion circuit 502 (ie, the output node between the third switch Q2 and the fourth switch Q4 Connection point) outputs ground voltage, which can be recognized as a logic low level. The output node of the second conversion circuit 502 is connected to the gate of the first switch Q1 (ie, the 4-pin of the first switch Q1 in FIG. 3), so that the source of the first switch Q1 (ie, the 4-pin of the first switch Q1 in FIG. 3) There is a voltage difference between pins 1-3) and the gate, which turns on the first switch Q1.

In another embodiment, the first control signal is a ground voltage indicating a logic low level, the fourth switch Q4 is an N-MOS transistor; the third switch Q2 is a P-MOS transistor, and one end of the fifth resistor R2 is connected to the first The source connection of switch Q1. The third switch Q2 is turned on after receiving the first control signal, and the fourth switch Q4 is turned off after receiving the first control signal. The high voltage passing through the fifth resistor R2 will cause the output node of the second conversion circuit 502 (ie, the third switch The connection point between Q2 and the fourth switch Q4) outputs a high voltage representing a logic high level, 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 source of the first switch Q1. The gate of a switch Q1 is connected, which causes the gate and source of the first switch Q1 to be connected, thereby causing the first switch Q1 to be turned off.

Please refer to Figures 3-5 in combination. Figure 4 is a schematic diagram of the first current limiting result of the current limiting circuit; Figure 5 is a schematic diagram of the second current limiting result of the current limiting circuit.

In a specific implementation, the current limiting circuit provided by this application is connected to the load, and the first resistor R1 is 50mΩ, the second resistor R4 is 1kΩ, and the third resistor R6 is 0.423kΩ. According to the above formula 20IR1*R6/ (R4+R6)=0.6V, the current limit value I (i.e., current detection threshold) is calculated to be 2.01A. As shown in Figure 4, the monitoring software monitors changes in the supply current supplied to the load by the power supply in the circuit. When the load is normal, the change in supply current is the first line segment in Figure 4; when the load fails, the change in supply current The change corresponds to the second line segment in the figure. The second line segment gradually increases, indicating that the supply current gradually increases; when the supply current increases to 2.05A, the first switch Q1 is turned off, and the freewheeling power supply supplies power to the load. At this time, the supply current changes For the third line segment in the figure, the supply current value drops to 1.25A.

Further, as shown in Figure 5, the sixth line segment in Figure 5 is the waveform of the first switch Q1, and the seventh line segment is the op amp output waveform. It can be calculated by calculation software that the response time of the overcurrent circuit in this embodiment is is 940 ns, and the response time is the 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.

It can be seen from the above results that the current limiting circuit provided in this application can quickly shut down the power supply after an abnormality occurs in the load, and use the freewheeling unit 30 to provide power to avoid damaging the load.

Please refer to FIG. 1 and FIG. 4 in conjunction. In one embodiment, the current detection unit 40 controls the first switch Q1 to turn off after detecting that the supply current of the power supply to the load exceeds the current detection threshold for the first time. After the first switch Q1 is turned off, the supply current supplied to the load by the power supply drops to zero. Therefore, within a very short time after the first switch Q1 is turned off, the current detection unit 40 can detect the supply current supplied to the load. is lower than the current detection threshold, thereby controlling the first switch Q1 to turn on. If the load is still in an abnormal state at this time, it will be detected that the supply current exceeds the current detection threshold again, and the first switch Q1 is controlled to be turned off again. Therefore, during the time period from when the load is abnormal to when it returns to normal, the first switch Q1 has been in a state of continuous closing and opening, as shown in Figure 4. The fourth line segment in Figure 4 is the waveform of the switch on state, and the fifth line segment in Figure 4 is the waveform of the switch on state. Area means that the switch is constantly off and on.

Please refer to Figure 6. Figure 6 is a schematic flowchart of an embodiment of a current limiting method provided by this application. The current limiting method is applied in any of the above implementations of the current limiting circuit. The current limiting method includes:

S610: Detect whether the supply current input to the input terminal of the current limiting circuit exceeds the current detection threshold.

S620: When the supply current does not exceed the current detection threshold, the first switch between the input terminal and the output terminal of the current limiting circuit is controlled to be in an open state, so that the output terminal of the current limiting circuit supplies power to the load and charges the freewheeling unit.

S630: 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 to the input end of the current limiting circuit stops supplying power to the load, and the freewheeling unit supplies power to the load.

Specifically, this application uses a current detection unit to detect whether the supply current input to the input end of the current limiting circuit exceeds the current detection threshold, wherein the current detection unit includes 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 for normal operation of the load. The current detection threshold can be set between the current provided by the power supply and the current required for normal operation of the load. For example, the current provided by the power supply is 2A, which is required for normal operation of the load. The supply current is 1A, and the current detection threshold can be set to any value between 1-2A.

The high-side shunt monitor in the current detection unit can output different control signals according to whether the supply current input at the input end of the current limiting circuit exceeds the current detection threshold. Furthermore, the current detection unit can also include a conversion circuit, through which the high-side The control signal output by the side shunt monitor is converted into a control signal of the first switch, and then controls the first switch to be turned on and off. When the first switch is in the open state, the output end of the current limiting circuit supplies power to the load and charges the freewheeling unit; when the first switch is in the off state, the freewheeling unit supplies power to the load.

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

The above descriptions are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of the present application, or directly or indirectly applied to other related technologies fields are equally included in the scope of patent protection of this application.

Claims

A current limiting circuit, characterized by including:

Input terminal, used to connect the power supply;

The output terminal is used to connect the load;

The first switch is connected between the current detection unit and the freewheeling unit; the freewheeling unit is connected between the output terminal and the first switch; the current detection unit is connected between the input terminal and the between the first switches to detect the supply current supplied by the power supply to the load;

Wherein, 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 open state so that the power supply supplies power to the load and supplies power to the load. The freewheeling unit is charged; 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 to stop the power supply. Power is supplied to the load, and the freewheeling unit supplies power to the load.
The current limiting circuit according to claim 1, characterized in that the current detection unit includes:

A first resistor is provided on the power supply loop formed by the input terminal, the first switch and the output terminal;

A voltage acquisition and control unit is connected to both ends of the first resistor to detect a voltage difference across the first resistor, based on the voltage difference across the first resistor and a preset voltage corresponding to the current detection threshold. Detect the threshold and send a control signal to control the first switch to turn on or off.
The current limiting circuit according to claim 2, characterized in that the voltage acquisition and control unit includes:

A differential amplifier, the first input terminal and the second input terminal are respectively connected to the two ends of the first resistor to receive the voltage difference between the two ends of the first resistor and amplify the voltage difference between the two ends of the first resistor. ;

A voltage dividing circuit connected to the output end of the differential amplifier to divide the amplified voltage difference between the two ends of the first resistor to generate a divided voltage;

A comparator, a first input terminal receiving the preset voltage detection threshold, and a second input terminal receiving the divided voltage output by the voltage dividing circuit to compare the preset voltage detection threshold and the divided voltage, thereby generating corresponding control signal.
The current limiting circuit of claim 3, wherein the voltage dividing circuit includes a second resistor and a third resistor, wherein the second resistor and the third resistor are connected in series at the output of the differential amplifier. The first node between the terminal and the ground voltage, and between the second resistor and the third resistor serves as the output terminal of the voltage dividing circuit to output the divided voltage.
The current limiting circuit according to claim 1, characterized in that the freewheeling unit includes:

A first inductor connected between the first switch and the output terminal;

The first capacitor is connected between the second node and the ground voltage, where the second node is the connection point between the first inductor and the output terminal.
The current limiting circuit according to claim 5, characterized in that the freewheeling unit further includes:

A diode has an anode connected to the ground voltage and a cathode connected to a third node, where the third node is a connection point between the first inductor and the first switch.
The current limiting circuit according to claim 2, further comprising:

A conversion circuit is connected to the current detection unit and the first switch to convert the control signal output by the current detection unit into a control signal matching the first switch to control the opening and closing of the first switch.
The current limiting circuit according to claim 7, characterized in that the conversion circuit includes:

The first conversion circuit includes a second switch and a fourth resistor, wherein the fourth resistor and the second switch are connected in series between a fourth node and the ground voltage, and the fourth node is a connection between the first switch and the ground voltage. The connection point between the first resistor, the control end of the second switch is connected to the output end of the voltage acquisition and control unit, and the connection point between the second switch and the fourth resistor serves as the An output node of the first conversion circuit to convert the control signal output by the voltage acquisition and control unit into a first control signal;

The second conversion circuit includes a fifth resistor, a third switch and a fourth switch, wherein the fifth resistor, the third switch and the fourth switch are connected in series between the fourth node and the ground voltage, And the control terminals of the third switch and the fourth switch are respectively connected to the output node of the first conversion circuit to receive the first control signal, and the connection between the third switch and the fourth switch The point is used as the output node of the second conversion circuit to convert the first control signal output by the first conversion circuit into a second control signal. The control end of the first switch receives the second control signal to The control based on the second control signal is in an on or off state.
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.
The current limiting circuit according to claim 8, wherein the conversion circuit further includes:

A sixth resistor, wherein the output end of the voltage acquisition and control unit is connected to the first voltage through the sixth resistor.
A current limiting method, characterized in that it is applied in the current limiting circuit according to any one of claims 1 to 10, and the current limiting method includes:

Detect whether the supply current input to the input terminal of the current limiting circuit exceeds the current detection threshold;

When the supply current does not exceed the current detection threshold, the first switch between the input terminal and the output terminal of the current limiting circuit is controlled to be in an open state, so that the output terminal of the current limiting circuit supplies power to the load and continues to the load. flow unit charging;

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 to the input end of the current limiting circuit stops supplying power to the load, and the freewheeling unit is the load power supply.
An electronic device, characterized in that the electronic device includes the current limiting circuit according to any one of claims 1-10.