A charging current limiting protection circuit and charger

Abstract

The present application discloses a charging current limiting protection circuit and a charger, wherein the charging current limiting protection circuit comprises: an input unit, comprising a power supply terminal and a ground terminal; an output unit, connected to the input unit, the output unit comprising a first terminal and a second terminal, the first terminal of the output unit being connected to the power supply terminal, and the second terminal being connected to the ground terminal to form a circuit loop; a first switch tube, arranged between the power supply terminal of the input unit and the output unit, for controlling the connection between the input unit and the output unit; a current limiting control unit, connected to the control terminal of the first switch tube, for controlling the on / off of the first switch tube according to detecting the current in the circuit loop and whether the current exceeds a set value, thereby controlling the connection between the input unit and the output unit; wherein the set value is adjustable. Through the above structure, the adjustment capability of the maximum output capacity of the charger is improved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, in particular to a charging current limiting protection circuit and a charger. Background Art

[0002] The cost of purchasing chargers in places like aging rooms where there is a high demand for chargers is high, and the maximum output capacity of the charger cannot be adjusted, which results in a high cost for purchasing corresponding chargers for different projects. Summary of the invention

[0003] The main technical problem solved by the present application is to provide a charging current limiting protection circuit and a charger to improve the regulation capability of the maximum output capacity of the charger.

[0004] To solve the above problems, the first aspect of the present application provides a charging current limiting protection circuit, which includes: an input unit, including a power supply end and a ground end; an output unit, connected to the input unit, the output unit including a first end and a second end, the first end of the output unit is connected to the power supply end, and the second end is connected to the ground end to form a circuit loop; a first switch tube, arranged between the power supply end of the input unit and the output unit, for controlling the connection between the input unit and the output unit; a current limiting control unit, connected to the control end of the first switch tube, for controlling the on / off of the first switch tube according to detecting the current in the circuit loop and whether the current exceeds a set value, thereby controlling the connection between the input unit and the output unit; wherein the set value is adjustable.

[0005] In a specific embodiment, the current limiting control unit includes: a current sensing resistor, which is arranged between the ground terminal of the input unit and the second terminal of the output unit, and is used to detect the current in the circuit; a first comparator, including a non-inverting input terminal, an inverting input terminal and an output terminal, the non-inverting input terminal of the first comparator is connected to the current sensing resistor, the inverting input terminal of the first comparator is connected to the voltage divider resistor, the output terminal of the first comparator is connected to the first switch tube, and the first comparator is used to determine whether the current in the circuit loop is greater than a set value, so as to control the output terminal to output a high level or a low level, thereby controlling the on / off of the first switch tube.

[0006] In a specific embodiment, the voltage-dividing resistor includes a first resistor and a second resistor; the inverting input terminal of the first comparator is connected to the first resistor and the second resistor respectively, and the set value is adjusted by the ratio of the first resistor to the second resistor; wherein, one of the first resistor and the second resistor is a variable resistor, and the other is a fixed resistor.

[0007] In a specific embodiment, the current limiting control unit further includes: a voltage regulator connected to the inverting input terminal of the first comparator, and configured to provide a stable voltage to the inverting input terminal of the first comparator.

[0008] In a specific embodiment, the current limiting control unit also includes: a second switch tube, connected to the output end of the first comparator and the control end of the first switch tube, and used to control the on / off of the first switch tube according to the high level or low level output by the first comparator.

[0009] In a specific embodiment, the control end of the second switch tube is connected to the output end of the first comparator, the input end is connected to the ground end of the input unit, and the output end is connected to the control end of the first switch tube, so as to control the first switch tube to disconnect when the current exceeds the set value, so as to limit the current in the circuit loop within the set value; wherein, the first switch tube is a Pmos tube.

[0010] In a specific embodiment, the charging current limiting protection circuit also includes: a logic chip, wherein the input end of the logic chip is connected to the output end of the second switch tube, and the output end of the logic chip is connected to the control end of the first switch tube, and is used to control the on / off of the first switch tube according to the output of the first switch tube.

[0011] In a specific embodiment, the charging current limiting protection circuit also includes: a temperature control unit, including a thermistor, connected to the logic control end of the logic chip, for detecting temperature and controlling the current in the circuit loop through the logic chip according to the temperature.

[0012] In a specific embodiment, the temperature control unit includes: a second comparator, wherein the non-inverting input terminal of the second comparator is connected to the first voltage-dividing resistor, the inverting input terminal is connected to the second voltage-dividing resistor, and the output terminal is connected to the logic control terminal of the logic chip, and is used to control the level signal output to the logic control terminal of the logic chip according to the first voltage-dividing resistor and the second voltage-dividing resistor; wherein the first voltage-dividing resistor or the second voltage-dividing resistor includes a thermistor.

[0013] In order to solve the above-mentioned problem, the second aspect of the present application provides a charger, which adopts the charging current limiting protection circuit described in any embodiment of the above-mentioned first aspect.

[0014] The beneficial effect of the present application is: the current limiting control unit controls the on and off of the first switch tube according to the detected current, thereby limiting the maximum output current of the circuit, wherein the current limiting control unit can adjust the maximum output current, thereby adjusting the maximum output capacity of the loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 This is a structural schematic diagram of an embodiment of a charging current limiting protection circuit of the present application;

[0017] Figure 2 This is a structural schematic diagram of a specific embodiment of the charging current limiting protection circuit of the present application;

[0018] Figure 3 This is a structural schematic diagram of another specific embodiment of the charging current limiting protection circuit of the present application;

[0019] Figure 4 It is a structural schematic diagram of a specific embodiment of the temperature control unit of the present application. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "said", and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless otherwise clearly indicated above, and "multiple" generally includes at least two, but does not exclude the inclusion of at least one.

[0022] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0023] It should be understood that the terms "include", "comprises" or any other variations used herein are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0024] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The presence of the phrase at each location in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] This application provides a charging current limiting protection circuit. Figure 1 , Figure 1 This is a schematic diagram of the structure of an embodiment of the charging current limiting protection circuit of the present application. Figure 1 As shown, the charging current limiting protection circuit includes:

[0027] The input unit 10 includes a power terminal VIN and a ground terminal GND.

[0028] The output unit 20 is connected to the input unit 10. The output unit 20 includes a first terminal VBUS and a second terminal GND1. The first terminal VBUS of the output unit 20 is connected to the power terminal VIN, and the second terminal GND1 is connected to the ground terminal GND. The input unit 10 and the output unit 20 form a circuit loop.

[0029] The first switch tube 30 is disposed between the power supply terminal VIN of the input unit 10 and the output unit 20, and is used to control the connection between the input unit 10 and the output unit 20. In a specific embodiment, the first switch tube 30 is a MOS tube, including an input terminal, an output terminal and a control terminal. The input terminal of the first switch tube 30 is connected to the input unit 10, and the output terminal is connected to the output unit 20. The on / off of the path between the input unit 10 and the output unit 20 is controlled by controlling the on / off of the input terminal and the output terminal of the first switch tube 30. In other embodiments, the first switch tube 30 can also be other control devices, which are not limited here.

[0030] The current limiting control unit 40 is connected to the control end of the first switch tube 30 and is used to control the on / off of the first switch tube 30. Specifically, it is used to detect the current in the circuit loop and determine whether the current exceeds the set value, and control the on / off of the first switch tube 30 according to whether the current exceeds the set value, thereby controlling the on / off of the input unit 10 and the output unit 20 circuit.

[0031] In this embodiment, the set value is adjustable. When the current in the loop exceeds the set value, the first switch tube 30 is controlled to be disconnected, thereby limiting the current in the entire loop to not exceed the set value, so as to achieve the purpose of current limiting. When the current does not exceed the set value, the first switch tube 30 is kept on.

[0032] For more details, please refer to Figure 2 , Figure 2 This is a schematic diagram of a specific embodiment of the charging current limiting protection circuit of the present application. Figure 2As shown, in a specific embodiment, the current limiting control unit 40 includes a current sensing resistor R0 and a first comparator 41. The current sensing resistor R0 is set at the ground terminal GND of the input unit 10 and the second terminal GND1 of the output unit 20, and is used to detect the current in the circuit loop. The first comparator 41 includes a non-inverting input terminal, an inverting input terminal and an output terminal. The non-inverting input terminal of the first comparator 41 is connected to the current sensing resistor R0, the inverting input terminal of the first comparator 41 is connected to the voltage dividing resistor R12, and the output terminal is connected to the control terminal of the first switch tube 30, and is used to compare the current on the current sensing resistor R0 and the voltage dividing resistor R12, so as to control the output terminal to output a high level or a low level, thereby controlling the on / off of the first switch tube 30. Specifically, when the voltage of the non-inverting input terminal of the first comparator 41 is greater than the voltage of the inverting input terminal, a high level is output; when the voltage of the inverting input terminal of the first comparator 41 is not greater than the voltage of the inverting input terminal, a low level is output. Specifically, the first switch tube 30 is a Pmos tube. When the first comparator 41 outputs a high level, the first switch tube 30 is turned off; when the first comparator 41 outputs a low level, the first switch tube 30 is turned on. That is, when the current flowing through the current sensing resistor R0 is greater than the current flowing through the voltage divider resistor R12, the first switch tube 30 is controlled to be turned off. The voltage divider resistor R12 includes a variable resistor, which can be used to adjust the set value of the current.

[0033] Specifically, the voltage-dividing resistor R12 includes a first resistor R1 and a second resistor R2, wherein one of the first resistor R1 and the second resistor R2 is a variable resistor and the other is a fixed resistor.

[0034] In a specific embodiment, the first resistor R1 is a fixed resistor, and the second resistor R2 is a variable resistor. One end of the first resistor R1 is connected to the inverting input terminal of the first comparator 41, and the other end is connected to the input terminal VIN. One end of the second resistor R2 is connected to the inverting input terminal of the first comparator 41, and the other end is connected to the ground line. Among them, the first resistor R1 is used for voltage division, and the second resistor R2 is used to adjust the set value. Specifically, the second resistor R2 can be a variable resistor.

[0035] Furthermore, it also includes a voltage regulator tube 42, which is connected to the inverting input terminal of the first comparator 41, and is used to provide a stable voltage to the inverting input terminal of the first comparator 41 to avoid affecting the comparison result of the first comparator 41. By making the inverting input terminal of the first comparator 41 unaffected by the circuit loop, the inverting input terminal of the first comparator 41 changes with the current in the loop, thereby detecting the current in the loop, and controlling whether the first switch tube 30 is turned on according to whether the current change exceeds the set value, thereby controlling the charging circuit. Specifically, the voltage regulator tube 42 is connected to the other end of the first resistor R1, and the first resistor R1 is a fixed resistor, so as to provide a stable voltage to the first resistor R1, so that the current value on the first resistor R1 is fixed. The other end of the second resistor R2 is grounded, and by changing the resistance value of the second resistor R2, the current flowing through the second resistor R2 can be changed, thereby changing the ratio of the first resistor R1 to the second resistor R2, thereby changing the set value (limit value) of the inverting input terminal of the first comparator 41.

[0036] In a specific embodiment, the resistance of the current sensing resistor R0 is 0.01R, the resistance of the first resistor R1 is 10K, and the resistance and current limiting of the second resistor R2 are shown in the following table.

[0037] Current Limitation R1 R2 5A 10K 204R 4A 10K 162R 3A 10K 121R 2A 10K 81R 1A 10K 40R

[0038] In this embodiment, the resistance value of the second resistor R2 is adjusted according to the above table, thereby adjusting the limit value of the current in the limiting loop. When the resistance value of the second resistor R2 is 204R, the limit value is 5A, and when the current in the loop exceeds 5A, the first switch tube 30 is controlled to be disconnected; when the resistance value of R2 is 162R, the limit value is 4A, and when the current in the loop exceeds 4A, the first switch tube 30 is controlled to be disconnected.

[0039] In this specific embodiment, the voltage regulator tube 42 is a three-terminal voltage regulator tube. Specifically, the first end and the second end of the voltage regulator tube 42 are connected to the input terminal VIN and the other end of the first resistor R1, and the third end is grounded. In other embodiments, the voltage regulator tube 42 can also be a two-terminal voltage regulator tube, which is not limited here. Among them, a resistor is also provided between the voltage regulator tube 42 and the input terminal VIN, which is not limited here.

[0040] Furthermore, in order to make the detection of the non-inverting input terminal of the first comparator 41 more stable, the non-inverting input terminal of the first comparator 41 is also connected to a capacitor, one end of the capacitor is connected to the non-inverting input terminal of the first comparator 41, and the other end is connected to the ground terminal GND. One end of the current sensing resistor R0 is connected to the non-inverting input terminal of the first comparator 41, and the other end is connected to the ground terminal GND. Among them, one end of the capacitor is connected to one end of the current sensing resistor R0, and a protection resistor is provided between the capacitor and the current sensing resistor R0 to protect the current sensing resistor R0.

[0041] In the above embodiment, the output end of the first comparator 41 may be directly connected to the control end of the first switch tube 30 , or may be indirectly connected.

[0042] In a further embodiment, a second switch tube 43 is further included, and the second switch tube 43 is connected between the output end of the first comparator 41 and the control end of the first switch tube 30, and is used to control the on / off of the first switch tube 30 according to the level signal (high level or low level) output by the output end of the first comparator 41. Specifically, when the current exceeds the set value, the first comparator 41 outputs a high level, and the second switch tube 43 controls the first switch tube 30 to be turned off.

[0043] Specifically, the control end of the second switch tube 43 is connected to the output end of the first comparator 41, the input end is connected to the ground end GND of the input unit 10, and the output end is connected to the control end of the first switch tube 30, and is used to control the first switch tube 30 to disconnect when the current exceeds the set value, thereby limiting the current in the loop within the set value. In other embodiments, the input end of the second switch tube 43 can also be connected to a low-level signal line, which is not limited here.

[0044] The input end of the second switch tube 43 is also connected to the non-inverting input end of the first comparator 41. A diode D1 is also provided between the input end of the second switch tube 43 and the non-inverting input end of the first comparator 41.

[0045] The output end of the second switch tube 43 is also connected to the input end of the first switch tube 30. A fixed resistor is also provided between the output end of the second switch tube 43 and the input end of the first switch tube 30.

[0046] The second switch tube 43 uses an Nmos tube. When the gate is at a low level, Vgs < 0, and the second switch tube 43 is not turned on. At the same time, the first switch tube 30 uses a high-power Pmos tube. When Nmos is not turned on, the source of Pmos is pulled high by VIN. At this time, Vgs < 0, Pmos is turned on, and the input terminal VIN can directly supply power to the second terminal VBUS of the output unit 20; on the contrary, when the entire loop current is > 4A, the comparator outputs a high level, Nmos is turned on; Pmos is turned off, and the entire path is in a cut-off state, so that the maximum current of the entire power supply path can be stabilized within the set value.

[0047] In a further embodiment, the charging current limiting protection circuit further includes: a logic chip 50. For details, please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of another specific embodiment of the charging current limiting protection circuit of the present application. Figure 3As shown, the input end of the logic chip 50 is connected to the output end of the second switch tube 43, and the output end of the logic chip 50 is connected to the control end of the first switch tube 30, which is used to control the on / off of the first switch tube 30 according to the output of the first switch tube 30. The input end of the logic chip 50 is also a power supply end. Specifically, the logic chip 50 also includes a grounding end, the grounding end of the logic chip 50 is connected to the ground line, and the grounding end of the logic chip 50 is also connected to the input end of the logic chip 50 through a capacitor. Among them, the output end of the second switch tube 43 is connected to the input end of the logic chip 50. When the second switch tube 43 is turned on, a low-level signal is provided to the logic chip 50, the logic chip 50 does not work, and the first switch tube 30 is disconnected. The input end / power supply end of the logic chip 50 is also connected to the output end VIN of the input unit 10 through a resistor. When the second switch tube 43 is turned off, the logic chip 50 works normally, and the first switch tube 30 is controlled to be turned on by the logic chip 50.

[0048] The logic chip 50 also includes a connection with the CC terminal of the output unit 20 . After detecting that CC is effectively connected, the logic chip 50 can control its output terminal to turn on the first switch tube 30 .

[0049] The logic chip 50 further includes a logic control terminal CTL.

[0050] In this specific embodiment, a temperature control unit 60 is further included. The temperature control unit 60 is connected to the logic control terminal CTL of the logic chip 50 to detect the temperature and control the current in the circuit loop through the logic chip 50 according to the temperature. When the logic chip 50 is working, the logic control terminal CTL of the logic chip 50 can control the CC line of the output unit 20 to output different currents to broadcast the current on the first terminal VBUS. In a specific embodiment, when the CTL input is low level, I CC =180uA, I VBUS =1.5A; when CTL input is high level, I CC =330uA, I VBUS =3A. The temperature control unit 60 includes a thermistor for sensing temperature changes.

[0051] Please read further Figure 4 , Figure 4 This is a schematic diagram of the structure of a specific embodiment of the temperature control unit of the present application. Figure 4 As shown, specifically, the temperature control unit 60 includes a second comparator 61 whose in-phase input terminal is connected to the first voltage-dividing resistor R34, whose inverting input terminal is connected to the second voltage-dividing resistor R56, and whose output terminal is connected to the logic control terminal CTL of the logic chip 50, and is used to control the level signal (including high level and low level) output to the logic control terminal CTL of the logic chip 50 according to the first voltage-dividing resistor R34 and the second voltage-dividing resistor R56.

[0052] Specifically, the first voltage-dividing resistor R34 includes a third resistor R3 and a fourth resistor R4, and the second voltage-dividing resistor R56 includes a fifth resistor R5 and a sixth resistor R6. The non-inverting input terminal of the second comparator 61 is respectively connected to the third resistor R3 and the fourth resistor R4, and the reverse input terminal of the second comparator 61 is respectively connected to the fifth resistor R5 and the sixth resistor R6. Further, one end of the first voltage-dividing resistor R34 is connected to the power supply terminal VIN, and the other end is grounded; one end of the second voltage-dividing resistor R56 is connected to the power supply terminal VIN, and the other end is grounded. Specifically, the fourth resistor R4 is a thermistor, the third resistor R3 is connected to the power supply terminal VIN, and the fourth resistor R4 is grounded.

[0053] Furthermore, the output terminal of the second comparator 61 is also connected to the input terminal VIN of the input unit 10 through a resistor. The non-inverting input terminal of the second comparator 61 is also connected to the output terminal of the second comparator 61 through a resistor, and is connected to the input terminal VIN of the input unit 10 through a resistor. The resistors here all play a filtering role.

[0054] Furthermore, the output terminal of the second comparator 61 is also connected to the logic control terminal CTL of the logic chip 50 through a resistor.

[0055] In this embodiment, the current of the entire loop can be controlled by adding a thermistor to the circuit. Specifically, when the thermistor NTC detects that the temperature exceeds a preset temperature (such as 33°C), the output terminal CTL of the second comparator 61 changes from a high level to a low level signal, thereby controlling the current of the logic chip 50 to decrease / jump from a first current value (such as 3A) to a second current value (such as 1.5A). Among them, neither the first current value nor the second current value exceeds the set value (limit value) of the current.

[0056] In order to prevent the output of the second comparator 61 from oscillating back and forth when the temperature of the thermistor reaches the set temperature, a hysteresis resistor is added to the output end. When the measured temperature changes within a certain range (31-35 degrees), the current will not jump.

[0057] Furthermore, if one wishes to change the temperature threshold of the current change, the resistance values ​​of the third resistor R3 and the fourth resistor R4 may be adjusted.

[0058] The second switch tube 43 is used to control whether the logic chip 50 is working, and the temperature control unit 60 is used to control the working current of the logic chip 50. The temperature control unit 60 adjusts its specific working current within the set value range of the current.

[0059] It should be noted that the above-mentioned charging current limiting protection circuit also includes components such as resistors, capacitors and diodes used for filtering, which are not described one by one here.

[0060] The present application also provides a charger, which includes the charging current limiting protection circuit described in any of the above embodiments.

[0061] The beneficial effects of this embodiment are as follows: 1. Current limiting is performed by hardware, and the value of the current limiting can be adjusted without software control. 2. The circuit structure and the selected components are low in cost. In places where chargers are needed more, such as aging rooms, peripherals can be powered directly, saving the cost of chargers. 3. The output of the comparator adopts the form of hysteresis. At this time, the current size changes due to the temperature change in a range, which can avoid the current jumping back and forth at a certain temperature point.

[0062] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A charging current limiting protection circuit, characterized in that: The charging current limiting protection circuit comprises: An input unit, including a power supply terminal and a ground terminal; an output unit connected to the input unit, the output unit comprising a first end and a second end, the first end of the output unit being connected to the power end, and the second end being connected to the ground end to form a circuit loop; A first switch tube is provided between the power supply end of the input unit and the output unit, and is used to control the connection between the input unit and the output unit; A current limiting control unit is connected to the control end of the first switch tube, and is used to control the on / off of the first switch tube according to detecting the current in the circuit loop and whether the current exceeds a set value, thereby controlling the connection between the input unit and the output unit; wherein the set value is adjustable.

2. The charging current limiting protection circuit according to claim 1, characterized in that: The current limiting control unit comprises: A current-sensing resistor, disposed between the ground terminal of the input unit and the second terminal of the output unit, for detecting the current in the circuit loop; The first comparator includes a non-inverting input terminal, an inverting input terminal and an output terminal. The non-inverting input terminal of the first comparator is connected to the current sensing resistor, the inverting input terminal of the first comparator is connected to the voltage dividing resistor, and the output terminal of the first comparator is connected to the first switch tube. The first comparator is used to determine whether the current in the circuit loop is greater than a set value to control the output terminal to output a high level or a low level, thereby controlling the on / off of the first switch tube.

3. The charging current limiting protection circuit according to claim 2, characterized in that: The voltage-dividing resistor includes a first resistor and a second resistor; The inverting input terminal of the first comparator is connected to the first resistor and the second resistor respectively, and the set value is adjusted by the ratio of the first resistor to the second resistor; Among them, one of the first resistor and the second resistor is a variable resistor, and the other is a fixed resistor.

4. The charging current limiting protection circuit according to claim 3, characterized in that: The current limiting control unit also includes: A voltage regulator is connected to the inverting input terminal of the first comparator and is used to provide a stable voltage to the inverting input terminal of the first comparator.

5. The charging current limiting protection circuit according to claim 2, characterized in that: The current limiting control unit also includes: The second switch tube is connected to the output end of the first comparator and the control end of the first switch tube, and is used to control the on / off of the first switch tube according to the high level or low level output by the first comparator.

6. The charging current limiting protection circuit according to claim 5, characterized in that: The control end of the second switch tube is connected to the output end of the first comparator, the input end is connected to the ground end of the input unit, and the output end is connected to the control end of the first switch tube, and is used to control the first switch tube to be disconnected when the current exceeds a set value, so as to limit the current in the circuit loop within the set value; Wherein, the first switch tube is a Pmos tube.

7. The charging current limiting protection circuit according to claim 4, characterized in that: The charging current limiting protection circuit also includes: A logic chip, wherein the input end of the logic chip is connected to the output end of the second switch tube, and the output end of the logic chip is connected to the control end of the first switch tube, and is used to control the on / off of the first switch tube according to the output of the first switch tube.

8. The charging current limiting protection circuit according to claim 7, characterized in that: The charging current limiting protection circuit also includes: The temperature control unit includes a thermistor connected to the logic control terminal of the logic chip, and is used to detect temperature and control the current in the circuit loop through the logic chip according to the temperature.

9. The charging current limiting protection circuit according to claim 8, characterized in that: The temperature control unit comprises: A second comparator, wherein the non-inverting input terminal of the second comparator is connected to the first voltage-dividing resistor, the inverting input terminal is connected to the second voltage-dividing resistor, and the output terminal is connected to the logic control terminal of the logic chip, and is used to control the level signal output to the logic control terminal of the logic chip according to the first voltage-dividing resistor and the second voltage-dividing resistor; wherein the first voltage-dividing resistor or the second voltage-dividing resistor includes a thermistor.

10. A charger, characterized in that: The charger comprises the charging current limiting protection circuit as described in any one of claims 1 to 9 above.

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