Charging protection circuit, charging protection method and charging protection device

Abstract

The invention discloses a charging protection circuit, a charging protection method and a charging protection device, and relates to the technical field of equipment charging, and the disclosed charging protection circuit comprises a voltage sampling module, a charging port type detection module, a voltage comparison module and a current limiting module. The input end of the voltage sampling module is connected with a battery of to-be-charged equipment, and the output end of the voltage sampling module is connected with the first input end of the voltage comparison module; the second input end of the voltage comparison module is connected with a preset reference power supply, the output end of the voltage comparison module is connected with the first input end of the current limiting module, and the output end of the current limiting module is connected with the battery; the input end of the charging port type detection module is connected with a USB interface in the charger, the output end of the charging port type detection module is connected with the second input end of the current limiting module, and the third input end of the current limiting module is connected with the USB interface. The problem that the service life of an equipment battery is damaged by instantaneous large current can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of device charging, and in particular to a charging protection circuit, a charging protection method and a charging protection device. Background Art

[0002] As the core component of the charger, the switch charging chip undertakes multiple tasks such as current conversion, voltage adjustment and power management, and occupies an important position in the charging process. However, although the switch charging chip integrates the above functions, when the battery to be charged is at a low voltage and the USB interface type is non-SDP, the charger equipped with this chip may still generate a large current that threatens the battery life when connected to the device to be charged. For example, when the SGM41513A switch charging chip is used, once it is connected to the DCP charger, a 2A high current lasting about 300 milliseconds will briefly appear between the SGM41513A and the battery port of the device to be charged. Therefore, when the device is charging, how to avoid instantaneous high currents from damaging the battery life of the device to be charged is a technical problem that has yet to be solved by those skilled in the art. Summary of the invention

[0003] The main purpose of this application is to provide a charging protection circuit, a charging protection method and a charging protection device, aiming to solve the technical problem of how to prevent instantaneous large current from damaging the battery life of the device to be charged.

[0004] To achieve the above object, the present application proposes a charging protection circuit, which includes: a voltage sampling module, a charging port type detection module, a voltage comparison module and a current limiting module;

[0005] The input end of the voltage sampling module is connected to the battery of the device to be charged, and the output end of the voltage sampling module is connected to the first input end of the voltage comparison module;

[0006] The second input terminal of the voltage comparison module is connected to a preset reference power supply, the output terminal of the voltage comparison module is connected to the first input terminal of the current limiting module, and the output terminal of the current limiting module is connected to the battery;

[0007] The input end of the charging port type detection module is connected to the USB interface in the charger, the output end of the charging port type detection module is connected to the second input end of the current limiting module, and the third input end of the current limiting module is connected to the USB interface.

[0008] In one embodiment, the charging port type detection module includes: a NOT gate logic circuit, a first resistor, a first MOS tube and a first switch;

[0009] The input end of the NOT gate logic circuit is connected to the data negative signal pin of the USB interface, and the output end of the NOT gate logic circuit is connected to the first end of the first resistor;

[0010] The second end of the first resistor is connected to the gate of the first MOS tube;

[0011] The source of the first MOS tube is grounded, and the drain of the first MOS tube is connected to the second input end of the current limiting module;

[0012] A first end of the first switch is connected to a data positive signal pin of the USB interface, and a second end of the first switch is connected to a preset power source.

[0013] In one embodiment, the voltage comparison module includes: an amplifier;

[0014] The non-inverting input terminal of the amplifier is connected to the output terminal of the voltage sampling module, and the inverting input terminal of the amplifier is connected to the reference power supply;

[0015] The output terminal of the amplifier is connected to the first input terminal of the current limiting module.

[0016] In one embodiment, the voltage comparison module further includes: a second resistor and a third resistor;

[0017] A first end of the second resistor is connected to the output end of the voltage sampling module, and a second end of the second resistor is connected to the in-phase input end of the amplifier;

[0018] A first end of the third resistor is connected to the reference power supply, and a second end of the third resistor is connected to the inverting input terminal of the amplifier.

[0019] In one embodiment, the voltage comparison module further includes: a fourth resistor and a fifth resistor;

[0020] A first end of the fourth resistor is connected to the output end of the amplifier, and a second end of the fourth resistor is connected to the first input end of the current limiting module;

[0021] A first end of the fifth resistor is connected to the inverting input end of the amplifier, and a second end of the fifth resistor is connected to the second end of the fourth resistor.

[0022] In one embodiment, the current limiting module includes: a second MOS tube, a current control chip and an ID resistance unit;

[0023] The gate of the second MOS tube is connected to the output end of the voltage comparison module, the source of the second MOS tube is grounded, and the drain of the second MOS tube is connected to the output end of the charging port type detection module and the first end of the ID resistor unit;

[0024] The second end of the ID resistance unit is connected to the current limiting pin of the current control chip;

[0025] The output pin of the current control chip is connected to the battery;

[0026] The power input pin of the current control chip is connected to the power voltage pin of the USB interface.

[0027] In one embodiment, the ID resistor unit includes: a sixth resistor and a seventh resistor;

[0028] A first end of the sixth resistor is connected to the drain of the second MOS tube, and a second end of the sixth resistor is connected to the current limiting pin of the current control chip;

[0029] A first end of the seventh resistor is grounded, and a second end of the seventh resistor is connected to a current limiting pin of the current control chip.

[0030] In one embodiment, the charging protection circuit further includes: a filter circuit;

[0031] The input end of the filter circuit is connected to the output end of the voltage comparison module, and the output end of the filter circuit is connected to the first input end of the current limiting module.

[0032] In addition, in order to solve the above problems, the present application also proposes a charging protection method, which is applied to the charging protection circuit as described above, and the charging protection method includes:

[0033] Acquire the battery voltage of the device to be charged through the voltage sampling module, and compare the battery voltage with the voltage of the reference power supply through the voltage comparison module to obtain a voltage comparison result;

[0034] Detect the type of the USB interface in the charger through the charging port type detection module to obtain the interface type detection result;

[0035] The current limiting module outputs a charging current based on the interface type detection result and the voltage comparison result to charge the device to be charged.

[0036] In addition, the present application also proposes a charging protection device, which includes the charging protection circuit as described above.

[0037] In the present application, the proposed charging protection circuit includes: a voltage sampling module, a charging port type detection module, a voltage comparison module and a current limiting module; the input end of the voltage sampling module is connected to the battery of the device to be charged, and the output end of the voltage sampling module is connected to the first input end of the voltage comparison module; the second input end of the voltage comparison module is connected to a preset reference power supply, the output end of the voltage comparison module is connected to the first input end of the current limiting module, and the output end of the current limiting module is connected to the battery; the input end of the charging port type detection module is connected to the USB interface in the charger, the output end of the charging port type detection module is connected to the second input end of the current limiting module, and the third input end of the current limiting module is connected to the USB interface.

[0038] In the present application, through the connection between the charging port type detection module and the current limiting module, the interface type result detected by the charging port type detection module can be used to control whether the current limiting function in the current limiting module is effective. In addition, the present application can also connect the voltage comparison module and the current limiting module so that when the current limiting function is effective, the current output by the current limiting module matches the comparison result of the voltage comparison module. Therefore, even if the battery to be charged is at a low voltage and the USB interface type is non-SDP, the instantaneous large current can be limited to a charging current that meets the battery voltage and the USB interface type through the present application. Therefore, the present application solves the technical problem that the instantaneous large current damages the battery life of the device to be charged. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0041] Figure 1 This is a schematic diagram of module connection of the first embodiment of the charging protection circuit of the present application;

[0042] Figure 2 This is a schematic diagram of a charging port type detection module of an embodiment of a charging protection circuit of the present application;

[0043] Figure 3 This is a schematic diagram of a voltage comparison module of an embodiment of a charging protection circuit of the present application;

[0044] Figure 4This is a schematic diagram of a current limiting module of an embodiment of a charging protection circuit of the present application;

[0045] Figure 5 This is a schematic diagram of the module structure of the charging protection device of this application.

[0046] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

[0047] Description of Figure Numbers:

[0048] 10. Voltage sampling module; 20. Charging port type detection module; 30. Voltage comparison module; 40. Current limiting module; 50. Battery; 60. Reference power supply; 70. USB interface; S1. First switch; U1. NOT gate logic circuit; A1. Amplifier; R1~R7. First resistor to seventh resistor; Q1. First MOS tube; VBAT. Battery voltage; VREF. Reference voltage; Q2. Second MOS tube; ISET. Current limiting pin; U2. Current control chip; USB_DP. Data positive signal pin; USB_DM. Data negative signal pin; CURRENT_SEL. First input terminal of current limiting module; SDP_ON. Second input terminal of current limiting module; VBUS_IN. Third input terminal of current limiting module; VCHG. Output terminal of current limiting module; VOUT. Output pin of current control chip; VIN. Power input pin of current control chip; VCC. Power supply; S. Source; G. Gate; D. Drain. DETAILED DESCRIPTION

[0049] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0050] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0051] As the core component of the charger, the switch charging chip undertakes multiple tasks such as current conversion, voltage adjustment and power management, and occupies an important position in the charging process. However, although the switch charging chip integrates the above functions, when the battery to be charged is at a low voltage and the USB interface type is non-SDP, the charger equipped with this chip may still generate a large current that threatens the battery life when connected to the device to be charged. For example, when the SGM41513A switch charging chip is used, once it is connected to the DCP charger, a 2A high current lasting about 300 milliseconds will briefly appear between the SGM41513A and the battery port of the device to be charged. Therefore, when the device is charging, how to avoid instantaneous high currents from damaging the battery life of the device to be charged is a technical problem that has yet to be solved by those skilled in the art.

[0052] In order to solve the above problems, the present application proposes a charging protection circuit. The charging protection circuit in the present application includes: a voltage sampling module, a charging port type detection module, a voltage comparison module and a current limiting module; the input end of the voltage sampling module is connected to the battery of the device to be charged, the output end of the voltage sampling module is connected to the input end of the voltage comparison module, and the input end of the voltage comparison module is also connected to a preset reference power supply; the output end of the voltage comparison module is connected to the input end of the current limiting module, and the output end of the current limiting module is connected to the battery; the input end of the charging port type detection module is connected to the USB interface in the charger, and the output end of the charging port type detection module is connected to the input end of the current limiting module; the input end of the current limiting module is connected to the USB interface.

[0053] In the present application, through the connection between the charging port type detection module and the current limiting module, the interface type result detected by the charging port type detection module can be used to control whether the current limiting function in the current limiting module is effective. In addition, the present application can also connect the voltage comparison module and the current limiting module so that when the current limiting function is effective, the current output by the current limiting module matches the comparison result of the voltage comparison module. Therefore, even if the battery to be charged is at a low voltage and the USB interface type is non-SDP, the instantaneous large current can be limited to a charging current that meets the battery voltage and the USB interface type through the present application. Therefore, the present application solves the technical problem that the instantaneous large current damages the battery life of the device to be charged.

[0054] Please refer to Figure 1 , Figure 1 This is a connection diagram of the first embodiment of the charging protection circuit of the present application. In this embodiment, the charging protection circuit includes: a voltage sampling module 10, a charging port type detection module 20, a voltage comparison module 30 and a current limiting module 40;

[0055] The input end of the voltage sampling module 10 is connected to the battery 50 of the device to be charged, and the output end of the voltage sampling module 10 is connected to the first input end of the voltage comparison module 30;

[0056] The second input terminal of the voltage comparison module 30 is also connected to a preset reference power supply 60, the output terminal of the voltage comparison module 30 is connected to the first input terminal of the current limiting module 40, and the output terminal of the current limiting module 40 is connected to the battery 50;

[0057] The input end of the charging port type detection module 20 is connected to the USB interface 70 in the charger, the output end of the charging port type detection module 20 is connected to the second input end of the current limiting module 40 , and the third input end of the current limiting module 40 is connected to the USB interface 70 .

[0058] It should be noted that when the voltage of the battery 50 to be charged is too low, and the battery 50 is charged through the non-SDP type USB charging interface 70 and the chip such as SGM41513A, a transient large current will be generated when the charging circuit is connected, thereby damaging the life of the battery 50. Therefore, the present application can detect whether the USB charging interface 70 is of the SDP type through the charging port type detection module 20, and determine whether the voltage of the battery 50 is lower than the preset value through the voltage comparison module 30, and then can output the charging current that will not damage the battery life through the current limiting module 40 according to the type of the USB charging interface and the voltage of the battery 50. Therefore, the present application can solve the problem of transient large current damaging the battery life.

[0059] Please refer to Figure 2 In a feasible implementation manner, the charging port type detection module 20 includes: a NOT gate logic circuit U1, a first resistor R1, a first MOS tube Q1 and a first switch S1;

[0060] The input end of the NOT gate logic circuit U1 is connected to the data negative signal pin USB_DM of the USB interface 70, and the output end of the NOT gate logic circuit U1 is connected to the first end of the first resistor R1;

[0061] The second end of the first resistor R1 is connected to the gate G of the first MOS transistor Q1;

[0062] The source S of the first MOS transistor Q1 is grounded, and the drain D of the first MOS transistor Q1 is connected to the second input terminal SDP_ON of the current limiting module 40;

[0063] A first end of the first switch S1 is connected to a data positive signal pin USB_DP of the USB interface 70 , and a second end of the first switch S1 is connected to a preset power source VCC.

[0064] In this embodiment, the first end of the first switch S1 and the input end of the NOT gate logic circuit U1 together constitute the input end of the charging port type detection module 20 ; the drain D of the first MOS transistor Q1 constitutes the output end of the charging port type detection module 20 .

[0065] It should be noted that in Figure 2In the embodiment, the second input terminal SDP_ON of the current limiting module is an access point between the charging port type detection module 20 and the current limiting module 40 , that is, the charging port type detection module 20 is connected to the current limiting module 40 through SDP_ON.

[0066] Specifically, when the first switch S1 is closed, USB_DP is connected to VCC, and USB_DP is pulled up to the level of VCC, which can be considered as a high level. When the USB interface 70 is of SDP type and in idle state, USB_DM is generally at a low level, and after passing through the NOT gate, the G pole becomes a high level, thereby turning on the first MOS tube Q1, so that SDP_ON is in an open state. On the contrary, if the USB interface 70 is of non-SDP type, the first MOS tube Q1 will be turned off, so that SDP_ON is in a closed state.

[0067] It should be noted that when the switch charging chip is SGM41513A, the module for detecting the charging port type needs to be triggered before the BC1.2 detection of SGM41513A to indicate the safety of the charging circuit.

[0068] Please refer to Figure 3 , in a feasible implementation manner, the voltage comparison module 30 includes: an amplifier A1;

[0069] The non-inverting input terminal of the amplifier A1 is connected to the output terminal of the voltage sampling module 10, and the inverting input terminal of the amplifier A1 is connected to the reference power supply 60;

[0070] The output terminal of the amplifier A1 is connected to the first input terminal CURRENT_SEL of the current limiting module 40 .

[0071] In a feasible implementation manner, the voltage comparison module 30 further includes: a second resistor R2 and a third resistor R3;

[0072] A first end of the second resistor R2 is connected to the output end of the voltage sampling module 10, and a second end of the second resistor R2 is connected to the in-phase input end of the amplifier A1;

[0073] A first end of the third resistor R3 is connected to the reference power supply 60 , and a second end of the third resistor R3 is connected to the inverting input end of the amplifier A1 .

[0074] In a feasible implementation manner, the voltage comparison module 30 further includes: a fourth resistor R4 and a fifth resistor R5;

[0075] A first end of the fourth resistor R4 is connected to the output end of the amplifier A1, and a second end of the fourth resistor R4 is connected to the first input end CURRENT_SEL of the current limiting module 40;

[0076] A first end of the fifth resistor R5 is connected to the inverting input end of the amplifier A1 , and a second end of the fifth resistor R5 is connected to the second end of the fourth resistor R4 .

[0077] In this embodiment, the first end of the second resistor R2 and the first end of the third resistor R3 together constitute the input end of the voltage comparison module 30 , and the second end of the fourth resistor R4 and the second end of the fifth resistor R5 together constitute the output end of the voltage comparison module 30 .

[0078] It should be noted that the reference power supply 60 is used to provide a reference voltage, which is a standard for evaluating whether the battery voltage is too low. Figure 3 VBAT is the voltage value collected by the voltage sampling module 10 , VREF is the reference voltage, and the first input terminal CURRENT_SEL of the current limiting module is the access point between the voltage comparison module 30 and the current limiting module 40 .

[0079] In this embodiment, amplifier A1 is used as a comparator to compare the input battery voltage VBAT and the reference voltage VREF, and output the corresponding level. In a feasible implementation, when the switch charging chip is SGM41513A, the reference voltage VREF can be set to 3.45V. Specifically, when VBAT is greater than VREF, CURRENT_SEL outputs a control signal of high level, and when VBAT is less than VREF, CURRENT_SEL outputs a control signal of low level.

[0080] In addition, the second resistor R2 and the third resistor R3 can reduce the sensitivity of the voltage comparison module 30 to noise and interference signals. For example, when there is noise signal interference, the second resistor R2 and the third resistor R3 can make the voltage change generated by the noise signal on the resistor smaller, reduce the impact of the noise signal on the input end of the amplifier A1, and improve the stability and anti-interference ability of the circuit. The fourth resistor R4 and the fifth resistor R5 can adjust the current output by the amplifier A1 to avoid the output current of the amplifier A1 being too large, which may cause the device connected to the output end of the amplifier A1 to malfunction.

[0081] Please refer to Figure 4 In a feasible implementation manner, the current limiting module 40 includes: a second MOS tube Q2, a current control chip U2 and an ID resistance unit;

[0082] The gate G of the second MOS transistor Q2 is connected to the output end of the voltage comparison module 30, the source S of the second MOS transistor Q2 is grounded, and the drain D of the second MOS transistor Q2 is connected to the output end of the charging port type detection module 20 and the first end of the ID resistance unit;

[0083] The second end of the ID resistance unit is connected to the current limiting pin I SET of the current control chip U2;

[0084] The output pin of the current control chip U2 is connected to the battery 50;

[0085] The power input pin of the current control chip U2 is connected to the power voltage pin of the USB interface 70 .

[0086] Further, in a feasible implementation manner, the ID resistor unit includes: a sixth resistor R6 and a seventh resistor R7;

[0087] A first end of the sixth resistor R6 is connected to the drain D of the second MOS transistor Q2, and a second end of the sixth resistor R6 is connected to the current limiting pin I SET of the current control chip U2;

[0088] A first end of the seventh resistor R7 is grounded, and a second end of the seventh resistor R7 is connected to a current limiting pin I SET of the current control chip U2 .

[0089] It can be understood that VCHG is the access point between the current limiting module 40 and the battery 50, that is, the output end of the current limiting module 40. The third input end VBUS_IN of the current limiting module is the access point between the current limiting module 40 and the power supply voltage pin in the USB interface 70. The sixth resistor R6 in the ID resistor unit corresponds to the case where the battery voltage VBAT is higher than the reference voltage VREF, and the seventh resistor R7 corresponds to the case where the battery voltage VBAT is lower than the reference voltage VREF. Preferably, the model of the current control chip can be SGM40561.

[0090] Specifically, if the charging port is SDP, the SDP_ON path is turned on, and the circuit of the voltage comparison module will be bypassed, thereby making the current limiting function of the current limiting module 40 invalid; if the charging port is detected to be non-SDP, the SDP_ON path is disconnected, and the current limiting circuit works normally, which is controlled by the level of the CURRENT_SEL pin. When the reference voltage VREF is 3.45V, when VBAT is greater than 3.45V, CURRENT_SEL inputs a high level, and the second MOS tube Q2 path is turned on. At this time, the ID resistance (sixth resistor R6) of the ISET pin of the current control chip U2 is about 280 ohms, corresponding to the maximum limiting current of 4A. When VBAT is less than 3.45V, CURRENT_SEL inputs a low level, and the second MOS tube Q2 path is open. At this time, the ID resistance (seventh resistor R7) of I SET is 2200 ohms, corresponding to the maximum limiting current of 450mA. Therefore, the present application can adjust the size of the charging current according to the battery voltage VBAT when the USB charging interface is a non-SDP type, thereby avoiding the problem of damaging the battery life.

[0091] Furthermore, in a feasible implementation manner, the charging protection circuit further includes: a filter circuit;

[0092] The input end of the filter circuit is connected to the output end of the voltage comparison module 30 , and the output end of the filter circuit is connected to the first input end CURRENT_SEL of the current limiting module 40 .

[0093] It is understandable that the present application can further improve the accuracy of the voltage comparison result received by the current limiting module 40 by connecting a filter circuit between the voltage comparison module 30 and the current limiting module 40, thereby improving the accuracy of the charging current control.

[0094] In the present application, through the connection between the charging port type detection module 20 and the current limiting module 40, the interface type result detected by the charging port type detection module 20 can be used to control whether the current limiting function in the current limiting module 40 is effective. In addition, the present application can also connect the voltage comparison module 30 and the current limiting module 40 so that when the current limiting function is effective, the current output by the current limiting module 40 matches the comparison result of the voltage comparison module 30. Therefore, even if the battery 50 to be charged is at a low voltage and the USB interface 70 type is non-SDP, the instantaneous large current can be limited to a charging current that meets the battery voltage VBAT and the USB interface 70 type through the present application. Therefore, the present application solves the technical problem that the instantaneous large current damages the battery life of the device to be charged.

[0095] In addition, in order to solve the above problems, the present application also proposes a charging protection method, which is applied to the charging protection circuit as described above; the charging protection method comprises steps S10 to S30:

[0096] Step S10, obtaining the battery voltage of the device to be charged through the voltage sampling module, and comparing the battery voltage with the voltage of the reference power supply through the voltage comparison module to obtain a voltage comparison result;

[0097] Step S20, detecting the type of the USB interface in the charger by the charging port type detection module to obtain an interface type detection result;

[0098] Step S30: outputting a charging current through a current limiting module based on the interface type detection result and the voltage comparison result to charge the device to be charged.

[0099] It is understandable that the voltage of the reference power supply is the reference voltage, and the voltage comparison results include: the battery voltage is greater than the reference voltage, and the battery voltage is less than the reference voltage. The interface type detection results include: the interface is an SDP type, and the interface is a non-SDP type.

[0100] In this embodiment, since the interface type and battery voltage will affect whether a transient high current will be generated in the charging circuit, the present application obtains the interface type detection result through the charging port type detection module and obtains the battery voltage through the voltage comparison module, so as to limit the maximum charging current in the scenario of transient high current to avoid the problem of battery life damage.

[0101] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the charging protection method of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0102] In addition, please refer to Figure 5 , the present application also proposes a charging protection device, which includes the charging protection circuit as described above.

[0103] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0104] In addition, in the embodiments of the present application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0105] In this application, the descriptions involving "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0106] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0107] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A charging protection circuit, characterized in that: The charging protection circuit includes: a voltage sampling module, a charging port type detection module, a voltage comparison module and a current limiting module; The input end of the voltage sampling module is connected to the battery of the device to be charged, and the output end of the voltage sampling module is connected to the first input end of the voltage comparison module; The second input terminal of the voltage comparison module is connected to a preset reference power supply, the output terminal of the voltage comparison module is connected to the first input terminal of the current limiting module, and the output terminal of the current limiting module is connected to the battery; The input end of the charging port type detection module is connected to the USB interface in the charger, the output end of the charging port type detection module is connected to the second input end of the current limiting module, and the third input end of the current limiting module is connected to the USB interface.

2. The charging protection circuit according to claim 1, characterized in that: The charging port type detection module includes: a NOT gate logic circuit, a first resistor, a first MOS tube and a first switch; The input end of the NOT gate logic circuit is connected to the data negative signal pin of the USB interface, and the output end of the NOT gate logic circuit is connected to the first end of the first resistor; The second end of the first resistor is connected to the gate of the first MOS tube; The source of the first MOS tube is grounded, and the drain of the first MOS tube is connected to the second input end of the current limiting module; A first end of the first switch is connected to a data positive signal pin of the USB interface, and a second end of the first switch is connected to a preset power source.

3. The charging protection circuit according to claim 1, characterized in that: The voltage comparison module includes: an amplifier; The non-inverting input terminal of the amplifier is connected to the output terminal of the voltage sampling module, and the inverting input terminal of the amplifier is connected to the reference power supply; The output terminal of the amplifier is connected to the first input terminal of the current limiting module.

4. The charging protection circuit according to claim 3, characterized in that: The voltage comparison module also includes: a second resistor and a third resistor; A first end of the second resistor is connected to the output end of the voltage sampling module, and a second end of the second resistor is connected to the in-phase input end of the amplifier; A first end of the third resistor is connected to the reference power supply, and a second end of the third resistor is connected to the inverting input terminal of the amplifier.

5. The charging protection circuit according to claim 3, characterized in that: The voltage comparison module further includes: a fourth resistor and a fifth resistor; A first end of the fourth resistor is connected to the output end of the amplifier, and a second end of the fourth resistor is connected to the first input end of the current limiting module; A first end of the fifth resistor is connected to the inverting input end of the amplifier, and a second end of the fifth resistor is connected to the second end of the fourth resistor.

6. The charging protection circuit according to claim 1, characterized in that: The current limiting module includes: a second MOS tube, a current control chip and an ID resistance unit; The gate of the second MOS tube is connected to the output end of the voltage comparison module, the source of the second MOS tube is grounded, and the drain of the second MOS tube is connected to the output end of the charging port type detection module and the first end of the ID resistor unit; The second end of the ID resistance unit is connected to the current limiting pin of the current control chip; The output pin of the current control chip is connected to the battery; The power input pin of the current control chip is connected to the power voltage pin of the USB interface.

7. The charging protection circuit according to claim 6, characterized in that: The ID resistor unit includes: a sixth resistor and a seventh resistor; A first end of the sixth resistor is connected to the drain of the second MOS tube, and a second end of the sixth resistor is connected to the current limiting pin of the current control chip; A first end of the seventh resistor is grounded, and a second end of the seventh resistor is connected to a current limiting pin of the current control chip.

8. The charging protection circuit according to claim 1, characterized in that: The charging protection circuit further includes: a filter circuit; The input end of the filter circuit is connected to the output end of the voltage comparison module, and the output end of the filter circuit is connected to the first input end of the current limiting module.

9. A charging protection method, characterized in that: The charging protection method is applied to the charging protection circuit according to any one of claims 1 to 8, and the charging protection method comprises: Acquire the battery voltage of the device to be charged through the voltage sampling module, and compare the battery voltage with the voltage of the reference power supply through the voltage comparison module to obtain a voltage comparison result; Detect the type of the USB interface in the charger through the charging port type detection module to obtain the interface type detection result; The charging current is outputted through a current limiting module based on the interface type detection result and the voltage comparison result to charge the device to be charged.

10. A charging protection device, characterized in that: The charging protection device comprises a charging protection circuit as described in any one of claims 1 to 8.

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