Anti-backflow charging circuit and charging device

Abstract

The present application proposes an anti-backflow charging circuit and charging device, which uses a buck-boost converter (BUCK-BOOST) to adjust the charging current, and also uses a digital-to-analog converter (DAC) to set the current threshold to ensure that when the switch tube in the converter unit switches between on and off, a suitable current is generated for transition, thereby preventing overcurrent from affecting the operation of the sampling resistor and the switch tube; and when the input current power is small, the buck-boost converter can adjust the voltage of the charging current, so that the power when the battery is charging can be reduced, thereby preventing circuit failure caused by a too fast drop in the charging voltage. Therefore, the anti-backflow charging circuit and charging device proposed in the present application not only effectively prevent current backflow, but also ensure the stable operation and efficiency of the charging circuit.

Description

Technical Field

[0001] The present application relates to the technical field of charging circuits, and in particular to an anti-backflow charging circuit and a charging device. Background Art

[0002] There are a large number of different electronic devices on the market today, such as smartphones, tablets, and laptops, each with its own unique charging requirements. When using a high-voltage charger to charge a low-voltage device, current backflow can occur, whereby current flows backward from the device being charged into the charger. This can not only damage the device but also pose serious safety risks such as fires and explosions. Furthermore, current backflow can damage the device's delicate electronic components, impacting its performance and lifespan.

[0003] To address the problem of current backflow, the following anti-backflow technologies are currently commonly used: the first is to use the forward conductive characteristics of the diode to prevent current backflow. However, this method has low charging efficiency due to the high power consumption of the diode, and requires the addition of a heat sink to dissipate heat for the diode, which occupies a large space. The second is to use a sampling resistor to sample the charging current, set the charging current forward threshold based on the sampled current, and then control the conduction and cutoff of the MOS tube through a comparator to prevent current backflow. However, since this method uses a comparator to control the conduction and cutoff of the MOS tube, when the MOS tube switches from cutoff to conduction, overcurrent will be generated in the circuit, causing unstable operation of the sampling resistor and MOS tube, or even damage.

[0004] It can be seen that with the continuous development of electronic technology, the design and application of anti-backflow charging circuits should be continuously optimized and improved. Summary of the Invention

[0005] The embodiments of the present application provide an anti-backflow charging circuit and a charging device, which can solve the problems of low efficiency and instability in the anti-backflow charging circuit.

[0006] In a first aspect, an embodiment of the present application provides an anti-backflow charging circuit, which includes: a converter unit and a battery, the converter unit is connected to the battery, the converter unit is used to receive an input current, adjust the input current to a charging current, and then transmit the charging current to the battery to charge the battery; a sampling unit, the sampling unit is connected to the battery, and is used to sample the charging current of the battery, thereby obtaining a sampled current and amplifying the sampled current; a comparator unit, the comparator unit is connected to the sampling unit, and the comparator unit is used to receive a current threshold and an amplified sampled current, and compare the current threshold with the amplified sampled current. to output a corresponding level signal; when the amplified sampling current is less than the current threshold, the comparator unit outputs a first level signal; when the amplified sampling current is greater than or equal to the current threshold, the comparator unit outputs a second level signal; a control unit, the control unit is respectively connected to the comparator unit and the converter unit, to receive the level signal output by the comparator unit, and control the conduction or cutoff of the switch tube in the converter unit according to the level signal; when the control unit receives the first level signal, the control unit controls the switch tube in the converter unit to be cut off; when the control unit receives the second level signal, the control unit controls the switch tube in the converter unit to be turned on.

[0007] Furthermore, the control unit includes a digital-to-analog converter, which is connected to the comparator unit to generate a current threshold and transmit the current threshold to the comparator unit.

[0008] Furthermore, the control unit includes an interconnection manager and a signal processor. The interconnection manager is connected to the comparator unit and the signal processor respectively to receive and process the level signal output by the comparator unit, and transmit the processed level signal to the signal processor.

[0009] Furthermore, the signal processor is used to receive the level signal processed by the interconnection manager and output a corresponding control signal according to the processed level signal; when the signal processor receives a first level signal, it sends a first control signal; when the signal processor receives a second level signal, it sends a second control signal.

[0010] Furthermore, the control unit also includes a driving module, which is connected to the signal processor and the converter unit respectively, for receiving the control signal output by the signal processor, and controlling the switch tube in the converter unit to be turned on or off according to the control signal; when the driving module receives a first control signal, the driving module controls the switch tube in the converter unit to be turned off; when the driving module receives a second control signal, the driving module controls the switch tube in the converter unit to be turned on.

[0011] Furthermore, the converter unit includes a buck-boost converter, which is connected to the power supply and the battery respectively. The buck-boost converter is used to receive the input current output by the power supply and adjust the input current to a charging current to charge the battery; the buck-boost converter is also connected to a drive module, wherein when the drive module receives a first control signal, the drive module controls the switch tube in the buck-boost converter to be cut off; when the drive module receives a second control signal, the drive module controls the switch tube in the buck-boost converter to be turned on.

[0012] Furthermore, the sampling unit includes a sampling module, which is connected to the battery and is used to receive the charging current of the battery and sample the charging current to obtain a sampled current.

[0013] Furthermore, the sampling unit further includes a current amplifier, which is connected to the sampling module and the comparator unit respectively to receive the sampling current, amplify the sampling current, and then transmit the amplified sampling current to the comparator unit.

[0014] Furthermore, the comparator unit includes an analog comparator, which is respectively connected to the current amplifier, the digital-to-analog converter and the interconnection manager. The analog comparator is used to receive the current threshold and the sampling current amplified by the current amplifier, and compare the current threshold with the amplified sampling current value to output a corresponding level signal; when the amplified sampling current is less than the current threshold, the analog comparator outputs a first level signal; when the amplified sampling current is greater than or equal to the current threshold, the analog comparator outputs a second level signal.

[0015] On the second aspect, the embodiment of the present application also proposes a charging device, which includes a power supply and an anti-backflow charging circuit, the anti-backflow charging circuit is connected to the power supply, and the power supply is used to provide input current for the anti-backflow charging circuit; wherein the anti-backflow charging circuit includes: a converter unit and a battery, the converter unit is connected to the battery, the converter unit is used to receive the input current, and adjust the input current to a charging current, and then transmit the charging current to the battery to charge the battery; a sampling unit, the sampling unit is connected to the battery to sample the charging current of the battery, thereby obtaining the sampling current and amplifying the sampling current; a comparator unit, the comparator unit is connected to the sampling unit, and the comparator unit is used to receive the current threshold and the amplified The comparator unit samples the current and compares the current threshold with the amplified sampling current to output a corresponding level signal; when the amplified sampling current is less than the current threshold, the comparator unit outputs a first level signal; when the amplified sampling current is greater than or equal to the current threshold, the comparator unit outputs a second level signal; a control unit is connected to the comparator unit and the converter unit respectively to receive the level signal output by the comparator unit and control the switch tube in the converter unit to be turned on or off according to the level signal; when the control unit receives the first level signal, the control unit controls the switch tube in the converter unit to be turned off; when the control unit receives the second level signal, the control unit controls the switch tube in the converter unit to be turned on.

[0016] The beneficial effects of the embodiments of the present application compared with the prior art are as follows: the anti-backflow charging circuit, i.e., the charging device, proposed in the present application, adjusts the charging current by adopting a buck-boost converter (BUCK-BOOST), and also adopts a digital-to-analog converter (DAC) to set the current threshold to ensure that when the switch tube in the converter unit switches between on and off, a suitable current is generated for transition, thereby preventing overcurrent from affecting the operation of the sampling resistor and the switch tube; and when the input current power is small, the buck-boost converter can adjust the voltage of the charging current, so that the power of the battery during charging can be reduced, thereby preventing circuit failure caused by a too rapid drop in the charging voltage. Therefore, the anti-backflow charging circuit and charging device proposed in the present application not only effectively prevent current backflow, but also ensure the stable operation and efficiency of the charging circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit block diagram of an anti-backflow charging circuit proposed in an embodiment of the present application;

[0018] Figure 2 This is a circuit diagram of an anti-backflow charging circuit proposed in an embodiment of the present application;

[0019] Figure 3This is a schematic diagram of a charging device proposed in an embodiment of the present application.

[0020] Description of main component symbols

[0021] Anti-backflow charging circuit 10

[0022] Converter unit 11

[0023] Buck-boost converter 111

[0024] Battery 12

[0025] Sampling unit 13

[0026] Sampling module 131

[0027] Current amplifier 132

[0028] Comparator unit 14

[0029] Analog comparator 141

[0030] Control unit 15

[0031] Digital-to-analog converter 151

[0032] Interconnect Manager 152

[0033] Signal processor 153

[0034] Driver module 154

[0035] Charging device 100

[0036] Power Supply 20 DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0039] The terms "first" and "second" in the specification of this application and the accompanying drawings are used to distinguish different objects, not to describe a specific order. In addition, the term "comprising" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to the process, method, product, or apparatus.

[0040] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0041] There are a large number of different electronic devices on the market today, such as smartphones, tablets, and laptops, each with its own unique charging requirements. When using a high-voltage charger to charge a low-voltage device, current backflow can occur, whereby current flows backward from the device being charged into the charger. This can not only damage the device but also pose serious safety risks such as fires and explosions. Furthermore, current backflow can damage the device's delicate electronic components, impacting its performance and lifespan.

[0042] To address the problem of current backflow, the following anti-backflow technologies are currently commonly used: the first is to use the forward conductive characteristics of the diode to prevent current backflow. However, this method has low charging efficiency due to the high power consumption of the diode, and requires the addition of a heat sink to dissipate heat for the diode, which occupies a large space. The second is to use a sampling resistor to sample the charging current, set the charging current forward threshold based on the sampled current, and then control the conduction and cutoff of the MOS tube through a comparator to prevent current backflow. However, since this method uses a comparator to control the conduction and cutoff of the MOS tube, when the MOS tube switches from cutoff to conduction, overcurrent will be generated in the circuit, causing unstable operation of the sampling resistor and MOS tube, or even damage.

[0043] The present application proposes an anti-backflow charging circuit 10, which solves the above problem by adopting a buck-boost converter to adjust the charging current and a digital-to-analog converter (DAC) to set the current threshold.

[0044] See also Figure 1 , is a circuit block diagram of the anti-backflow charging circuit 10 proposed in an embodiment of the present application. The anti-backflow charging circuit 10 includes:

[0045] The converter unit 11 and the battery 13 are connected to the battery 12. The converter unit 11 is configured to receive input current, adjust the input current into a charging current, and then transmit the charging current to the battery 12 to charge the battery 12. In some embodiments, the converter unit 11 can be connected to a power source to receive input current transmitted by the power source. The converter unit 11 can include a buck-boost converter.

[0046] The sampling unit 13 is connected to the battery 12 and is used to sample the charging current of the battery 12, thereby obtaining the sampled current and amplifying the sampled current. In some embodiments, the sampling unit 13 may include a sampling resistor.

[0047] Comparator unit 14 is connected to sampling unit 13 and is configured to receive a current threshold and an amplified sampled current, and compare the current threshold with the amplified sampled current to output a corresponding level signal. In some embodiments, comparator unit 14 may include an analog comparator.

[0048] When the amplified sampled current is less than the current threshold, the comparator unit 14 outputs a first level signal; when the amplified sampled current is greater than or equal to the current threshold, the comparator unit 14 outputs a second level signal. In some embodiments, the first level signal can be a low level signal, and the second level signal can be a high level signal.

[0049] Control unit 15 is connected to comparator unit 14 and converter unit 11, respectively, to receive the level signal output by comparator unit 14 and control the switching tube in converter unit 11 to turn on or off according to the level signal. In some embodiments, control unit 15 may include a digital-to-analog converter (DAC) to generate the current threshold.

[0050] When the control unit 15 receives a first level signal, the control unit 15 controls the switch tube in the converter unit 11 to be turned off; when the control unit 15 receives a second level signal, the control unit 15 controls the switch tube in the converter unit 11 to be turned on.

[0051] The anti-backflow charging circuit 10 proposed in the present application adjusts the charging current by adopting a buck-boost converter (BUCK-BOOST), and also adopts a digital-to-analog converter (DAC) to set the current threshold to ensure that when the switch tube in the converter unit switches between on and off, a suitable current is generated for transition, thereby preventing overcurrent from affecting the operation of the sampling resistor and the switch tube; and when the input current power is small, the buck-boost converter can adjust the voltage of the charging current, so that the power when the battery is charging can be reduced, thereby preventing circuit failure caused by a too fast drop in the charging voltage. Therefore, the anti-backflow charging circuit 10 proposed in the present application not only effectively prevents current backflow, but also ensures the stable operation and efficiency of the charging circuit.

[0052] See also Figure 2 In the embodiment of the present application, the converter unit 11 includes a buck-boost converter 111. The buck-boost converter 111 is connected to the power supply and the battery 12, respectively. The buck-boost converter 111 is configured to receive an input current output by the power supply and adjust the input current to a charging current to charge the battery 12.

[0053] In some embodiments, after receiving the input current from the power supply, the buck-boost converter 111 adjusts the input current based on the relationship between the required charging voltage of the battery 12 and the voltage of the input current to ensure circuit stability and efficiency when charging the battery 12. If the voltage of the input current is lower than the required charging voltage of the battery 12, the buck-boost converter 111 performs a boost operation on the input current; if the voltage of the input current is higher than the required charging voltage of the battery 12, the buck-boost converter 111 performs a buck operation on the input current.

[0054] In the embodiment of the present application, the sampling unit 13 includes a sampling module 131 and a current amplifier 132. The sampling module 131 is connected to the battery 12 and is used to receive the charging current of the battery 12 and sample the charging current to obtain a sampled current. The current amplifier 132 is connected to the sampling module 131 and the comparator unit 14 respectively to receive the sampled current, amplify the sampled current, and then transmit the amplified sampled current to the comparator unit 14.

[0055] In some embodiments, the sampling module 131 may include a sampling resistor, an RC filter, an analog-to-digital converter, and a single-chip microcomputer (or processor). One end of the sampling resistor is connected to the battery 12, and the other end of the sampling resistor is grounded. Specifically, when the sampling resistor samples the charging current of the battery 12, a voltage difference is generated across the sampling resistor, which is proportional to the charging current, that is, U=IR, where U is the voltage across the sampling resistor, I is the charging current, and R is the resistance of the sampling resistor. The RC filter is connected to the sampling resistor and is used to filter the voltage across the sampling resistor to filter out noise and interference signals in the sampled current to ensure the accuracy of the sampling. The analog-to-digital converter is connected to the RC filter and the single-chip microcomputer (or processor) respectively, and is used to receive the voltage signal processed by the filter and convert it. Then, the single-chip microcomputer (or processor) reads the voltage value converted by the analog-to-digital converter and uses the formula I=U / R to calculate the size of the charging current, that is, to obtain the sampled current. Furthermore, the current amplifier 132 may be a current sensing amplifier, which is connected to the single-chip microcomputer (or processor) to obtain the sampling current transmitted by the single-chip microcomputer (or processor) and amplify the sampling current.

[0056] In the embodiment of the present application, the comparator unit 14 includes an analog comparator 141, and the control unit includes a digital-to-analog converter 151. The analog comparator 141 is connected to the current amplifier 132 and the digital-to-analog converter 151, respectively. The analog comparator 141 is configured to receive the current threshold value generated by the digital-to-analog converter 151 and the sampled current amplified by the current amplifier 132, and compare the current threshold value with the amplified sampled current value to output a corresponding level signal.

[0057] When the amplified sampled current is less than the current threshold, the analog comparator 141 outputs a first level signal; when the amplified sampled current is greater than or equal to the current threshold, the analog comparator 141 outputs a second level signal. In some embodiments, the first level signal can be a low level signal, and the second level signal can be a high level signal.

[0058] In some embodiments, the control unit 15 may be a digital controller. The digital controller may store program code and data. These program codes may execute various control logics and algorithms to generate the required digital signals. The digital-to-analog converter 151 then receives the digital signals and generates current thresholds based on the digital signals. It is understood that the control unit may generate multiple digital signals as needed, and the digital-to-analog converter 151 may also generate multiple current thresholds based on the multiple digital signals.

[0059] In some embodiments, the analog comparator 141 may be a hysteresis comparator. The hysteresis comparator may form a hysteresis interval by introducing a positive feedback mechanism. The hysteresis interval can effectively prevent frequent output jumps caused by slight fluctuations of the input signal near the threshold, thereby improving the comparator's anti-interference capability. For example, when the analog comparator 141 receives multiple current thresholds generated by the digital-to-analog converter 151, it can select an appropriate hysteresis interval and current threshold based on specific needs and the specific design of the anti-backflow charging circuit 10.

[0060] It can be understood that when the switch tube in the converter unit 11 switches between cutoff and on, the change in charging current causes the current threshold generated by the digital-to-analog converter 151 to change, and the analog comparator 141 can select a suitable current threshold to compare with the sampled current, so that the anti-backflow charging circuit 10 can transition with minimal current change, thereby avoiding the generation of overcurrent and further avoiding circuit failure.

[0061] It can be understood that when the power of the input current received by the converter unit 11 decreases, this will also cause the current threshold generated by the digital-to-analog converter 151 to change, and the analog comparator 141 can select a suitable current threshold to compare with the sampling current, so that the anti-backflow charging circuit 10 can transition with minimal current change, thereby avoiding the charging current voltage from dropping too quickly, and thus avoiding circuit failure.

[0062] In the embodiment of the present application, the control unit 15 further includes an interconnection manager 152 and a signal processor 153. The interconnection manager 152 is connected to the comparator unit 14 and the signal processor 153 respectively, so as to receive and process the level signal output by the comparator unit 14, and transmit the processed level signal to the signal processor 153.

[0063] Specifically, the interconnection manager 152 is connected to the analog comparator 141 to receive and process the level signal output by the analog comparator 141 .

[0064] In some embodiments, the interconnection manager 152 is used to route the level signal output by the analog comparator 141 to the signal processor 153 to achieve flexible interconnection of the level signal between the analog comparator 141 and the signal processor 153. The interconnection manager 152 can also be used to filter the level signal output by the analog comparator 141 to improve the stability and reliability of the level signal.

[0065] In the embodiment of the present application, the signal processor 153 is configured to receive the level signal processed by the interconnection manager 152 and output a corresponding control signal according to the processed level signal.

[0066] When the signal processor 153 receives a first level signal, it sends a first control signal; when the signal processor 153 receives a second level signal, it sends a second control signal.

[0067] In some embodiments, the control unit 15 may be a digital controller. The digital controller may store program code and data, which may execute various control logics and algorithms to generate a desired pulse width modulated signal (PWM signal). For example, the control unit 15 may generate a corresponding PWM signal based on a level signal received by the signal processor 153. The signal processor 153 may be a programmable logic block (PLB), which may receive the pulse width modulated signal (PWM signal) generated by the control unit 15 and process the PWM signal (e.g., decoding the PWM signal and converting it into a digital or analog signal) to generate a control signal.

[0068] In some embodiments, the signal processor 153 may directly receive and transmit a PWM signal. Furthermore, the control signal sent by the signal processor 153 may be a PWM signal. Specifically, the first control signal and the second control signal are different PWM signals.

[0069] In an embodiment of the present application, the control unit 15 also includes a driving module 154, which is connected to the signal processor 153 and the converter unit 11 respectively, so as to receive the control signal transmitted by the signal processor 153 and control the switch tube in the converter unit 11 to be turned on or off according to the control signal.

[0070] When the driving module 154 receives the first control signal, the driving module 154 controls the switch tube in the converter unit 11 to be turned off; when the driving module 154 receives the second control signal, the driving module 154 controls the switch tube in the converter unit 11 to be turned on.

[0071] Specifically, the driver module 154 is connected to the buck-boost converter 111. When the driver module 154 receives a first control signal, the driver module 154 controls the switch in the buck-boost converter 111 to be turned off; when the driver module 154 receives a second control signal, the driver module 154 controls the switch in the buck-boost converter 111 to be turned on.

[0072] In some embodiments, the driving module 154 may be a driving circuit. The driving circuit may receive a PWM signal transmitted by the signal processor 153 and control the on / off switching of a switching element (such as a MOSFET, IGBT, etc.) according to the duty cycle of the PWM signal, thereby achieving load control. Furthermore, the driving circuit may also generate a feedback signal to the signal processor 153, so that the signal processor 153 may further adjust the PWM signal according to the feedback signal to form a closed-loop control of the anti-backflow charging circuit 10.

[0073] See also Figure 3 The present application also provides a charging device 100. The charging device 100 includes a power supply 20 and an anti-backflow charging circuit 10 according to any one of claims 1 to 9. The anti-backflow charging circuit 10 is connected to the power supply 20, and the power supply 20 is used to provide input current to the anti-backflow charging circuit 10.

[0074] The anti-backflow charging circuit 10 includes:

[0075] The converter unit 11 and the battery 13 are connected to the battery 12. The converter unit 11 is configured to receive input current, adjust the input current into a charging current, and then transmit the charging current to the battery 12 to charge the battery 12. In some embodiments, the converter unit 11 is connected to a power source to receive input current transmitted by the power source. The converter unit 11 may include a buck-boost converter.

[0076] The sampling unit 13 is connected to the battery 12 and is used to sample the charging current of the battery 12, thereby obtaining the sampled current and amplifying the sampled current. In some embodiments, the sampling unit 13 may include a sampling resistor.

[0077] Comparator unit 14 is connected to sampling unit 13 and is configured to receive a current threshold and an amplified sampled current, and compare the current threshold with the amplified sampled current to output a corresponding level signal. In some embodiments, comparator unit 14 may be an analog comparator.

[0078] When the amplified sampled current is less than the current threshold, the comparator unit 14 outputs a first level signal; when the amplified sampled current is greater than or equal to the current threshold, the comparator unit 14 outputs a second level signal. In some embodiments, the first level signal can be a low level signal, and the second level signal can be a high level signal.

[0079] The control unit 15 is connected to the comparator unit 14 and the converter unit 11, respectively, to receive the level signal output by the comparator unit 14 and control the on / off state of the switch in the converter unit 11 according to the level signal. In some embodiments, the control unit 15 may include a digital-to-analog converter (DAC) to generate the current threshold.

[0080] When the control unit 15 receives a first level signal, the control unit 15 controls the switch tube in the converter unit 11 to be turned off; when the control unit 15 receives a second level signal, the control unit 15 controls the switch tube in the converter unit 11 to be turned on.

[0081] The anti-backflow charging circuit 10 and charging device 100 proposed in this application use a buck-boost converter to adjust the charging current, and also use a digital-to-analog converter (DAC) to set the current threshold to ensure that when the switch tube in the converter unit switches between on and off, a suitable current is generated for transition, thereby preventing overcurrent from affecting the operation of the sampling resistor and the switch tube; and when the input current power is small, the buck-boost converter can adjust the voltage of the charging current, so that the power when the battery is charging can be reduced, thereby preventing circuit failure caused by a too rapid drop in the charging voltage. Therefore, the anti-backflow charging circuit 10 and charging device 100 proposed in this application not only effectively prevent current backflow, but also ensure the stable operation and efficiency of the charging circuit.

[0082] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments should fall within the scope of protection claimed in the present application.

Claims

1. A backflow prevention charging circuit, characterized in that: The anti-backflow charging circuit includes: a converter unit and a battery, wherein the converter unit is connected to the battery, and is configured to receive an input current, adjust the input current into a charging current, and then transmit the charging current to the battery to charge the battery; a sampling unit connected to the battery to sample the charging current of the battery, thereby obtaining a sampled current, and amplifying the sampled current; a comparator unit connected to the sampling unit, configured to receive a current threshold and an amplified sampling current, and compare the current threshold with the amplified sampling current to output a corresponding level signal, wherein the comparator unit includes an analog comparator; When the amplified sampling current is less than the current threshold, the comparator unit outputs a first level signal; When the amplified sampling current is greater than or equal to the current threshold, the comparator unit outputs a second level signal; a control unit, the control unit being connected to the comparator unit and the converter unit respectively, for receiving a level signal output by the comparator unit and controlling the switch tube in the converter unit to be turned on or off according to the level signal; When the control unit receives the first level signal, the control unit controls the switch tube in the converter unit to be turned off; When the control unit receives the second level signal, the control unit controls the switch tube in the converter unit to turn on; The control unit includes a digital-to-analog converter, which is connected to the comparator unit to generate the current threshold and transmit the current threshold to the comparator unit; The converter unit includes a buck-boost converter, which is connected to a power source and the battery respectively, and is used to receive an input current output by the power source and adjust the input current to a charging current to charge the battery; The control unit includes an interconnection manager and a signal processor, wherein the interconnection manager is connected to the comparator unit and the signal processor respectively, so as to receive and process the level signal output by the comparator unit, and transmit the processed level signal to the signal processor; The signal processor is used to receive the level signal processed by the interconnection manager and output a corresponding control signal according to the processed level signal; When the signal processor receives the first level signal, it sends a first control signal; When the signal processor receives the second level signal, it sends a second control signal; The control unit further includes a driving module, which is connected to the signal processor and the converter unit respectively, and is used to receive a control signal output by the signal processor and control the switch tube in the converter unit to be turned on or off according to the control signal; The buck-boost converter is also connected to the driving module, wherein: When the driving module receives the first control signal, the driving module controls the switch tube in the buck-boost converter to be turned off; When the driving module receives the second control signal, the driving module controls the switch tube in the buck-boost converter to be turned on; The control unit generates a plurality of digital signals according to requirements, and the digital-to-analog converter generates a plurality of current thresholds according to the plurality of digital signals; When the switch tube in the converter unit switches between cutoff and on, the change in the charging current causes the current threshold generated by the digital-to-analog converter to change, and the analog comparator selects an appropriate current threshold to compare with the sampled current so that the anti-backflow charging circuit transitions with minimal current change.

2. The anti-backflow charging circuit according to claim 1, characterized in that: When the driving module receives the first control signal, the driving module controls the switch tube in the converter unit to be turned off; When the driving module receives the second control signal, the driving module controls the switch tube in the converter unit to be turned on.

3. The anti-backflow charging circuit according to claim 1, wherein: The sampling unit includes a sampling module, which is connected to the battery and configured to receive a charging current of the battery and sample the charging current to obtain the sampled current.

4. The anti-backflow charging circuit according to claim 3, characterized in that: The sampling unit further includes a current amplifier, which is connected to the sampling module and the comparator unit respectively to receive the sampling current, amplify the sampling current, and then transmit the amplified sampling current to the comparator unit.

5. The anti-backflow charging circuit according to claim 4, characterized in that: The analog comparator is connected to the current amplifier, the digital-to-analog converter, and the interconnection manager respectively, and is used to receive the current threshold generated by the digital-to-analog converter and the sampled current amplified by the current amplifier, and compare the current threshold with the amplified sampled current value to output a corresponding level signal; When the amplified sampling current is less than the current threshold, the analog comparator outputs a first level signal; When the amplified sampling current is greater than or equal to the current threshold, the analog comparator outputs a second level signal.

6. A charging device, characterized in that: The charging device comprises a power supply and the anti-backflow charging circuit according to any one of claims 1 to 5, wherein the anti-backflow charging circuit is connected to the power supply, and the power supply is used to provide input current to the anti-backflow charging circuit; Wherein, the anti-backflow charging circuit includes: a converter unit and a battery, wherein the converter unit is connected to the battery, and the converter unit is configured to receive the input current, adjust the input current into a charging current, and then transmit the charging current to the battery to charge the battery; a sampling unit connected to the battery to sample the charging current of the battery, thereby obtaining a sampled current, and amplifying the sampled current; a comparator unit connected to the sampling unit, configured to receive a current threshold and an amplified sampling current, and compare the current threshold with the amplified sampling current to output a corresponding level signal, wherein the comparator unit includes an analog comparator; When the amplified sampling current is less than the current threshold, the comparator unit outputs a first level signal; When the amplified sampling current is greater than or equal to the current threshold, the comparator unit outputs a second level signal; a control unit, the control unit being connected to the comparator unit and the converter unit respectively, for receiving a level signal output by the comparator unit and controlling the switch tube in the converter unit to be turned on or off according to the level signal; When the control unit receives the first level signal, the control unit controls the switch tube in the converter unit to be turned off; When the control unit receives the second level signal, the control unit controls the switch tube in the converter unit to turn on; The control unit includes a digital-to-analog converter, which is connected to the comparator unit to generate the current threshold and transmit the current threshold to the comparator unit; The converter unit includes a buck-boost converter, which is connected to the power supply and the battery respectively, and is used to receive an input current output by the power supply and adjust the input current to a charging current to charge the battery; The control unit includes an interconnection manager and a signal processor, wherein the interconnection manager is connected to the comparator unit and the signal processor respectively, so as to receive and process the level signal output by the comparator unit, and transmit the processed level signal to the signal processor; The signal processor is used to receive the level signal processed by the interconnection manager and output a corresponding control signal according to the processed level signal; When the signal processor receives the first level signal, it sends a first control signal; When the signal processor receives the second level signal, it sends a second control signal; The control unit further includes a driving module, which is connected to the signal processor and the converter unit respectively, and is used to receive a control signal output by the signal processor and control the switch tube in the converter unit to be turned on or off according to the control signal; The buck-boost converter is also connected to the driving module, wherein: When the driving module receives the first control signal, the driving module controls the switch tube in the buck-boost converter to be turned off; When the driving module receives the second control signal, the driving module controls the switch tube in the buck-boost converter to be turned on; The control unit generates a plurality of digital signals according to requirements, and the digital-to-analog converter generates a plurality of current thresholds according to the plurality of digital signals; When the switch tube in the converter unit switches between cutoff and on, the change in the charging current causes the current threshold generated by the digital-to-analog converter to change, and the analog comparator selects an appropriate current threshold to compare with the sampled current so that the anti-backflow charging circuit transitions with minimal current change.

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