Battery charging protection circuit and battery charging protection device

Abstract

The utility model discloses a battery charging protection circuit, which is applied to a charging circuit, the charging circuit comprises a charging switch circuit and a microcontroller, the charging switch circuit is used for controlling the connection and disconnection of the charging circuit, and the microcontroller can detect the state of a battery and send out a control signal. The input end of the battery charging protection circuit is connected with the microcontroller, the output end of the battery charging protection circuit is connected with the charging switch circuit, and the battery charging protection circuit controls connection and disconnection of the charging switch circuit according to at least three control signals received at the same time. According to the invention, cooperative processing can be carried out on a plurality of control signals sent by the microcontroller, so that the charging switch circuit can still be controlled to be switched off when the microcontroller has a fault, dual protection for avoiding overcharge of the battery is realized, and the risk of safety accidents is effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of battery charging, especially to a battery charging protection circuit and a battery charging protection device. BACKGROUND

[0002] With the popularity of household mobile power tools, lithium batteries as their core power source, demand continues to grow, and in turn, the rapid development of the battery charger market. However, the design of most traditional chargers on the market currently has significant safety hazards, especially in the lithium battery protection circuit. The traditional charger usually only relies on an output pin of a microcontroller (MCU) to control the MOS tube in the circuit, and the charging protection function is realized by outputting high or low level. Although this single-point control design can meet the basic needs under normal circumstances, its safety is highly dependent on the stability of the MCU and the correct operation of the program.

[0003] Once the MCU fails due to hardware failure, program deviation, or external interference, its output pin may continuously output high or low level, causing the MOS tube to fail to normally cut off the charging circuit. In this case, the battery pack may continue to charge, and then cause overcharging problems. When the lithium battery is overcharged, not only will it significantly shorten the battery life, but it may also cause the internal chemical reaction of the battery to get out of control, generating a large amount of heat and gas, and eventually causing a fire, explosion, and other serious safety accidents, resulting in serious life safety and property loss. This design flaw makes the existing charging circuit have a major safety hazard in terms of safety, and cannot effectively cope with complex actual use environments. SUMMARY

[0004] The utility model aims at solving the technical problem that the existing charging circuit has safety hazards, and proposes a battery charging protection circuit and a battery charging protection device.

[0005] The technical problem of the utility model is solved by the following technical scheme:

[0006] A battery charging protection circuit applied to a charging circuit, the charging circuit comprising a charging switch circuit and a microcontroller, the charging switch circuit being used to control the connection and disconnection of the charging circuit, the microcontroller being able to detect the state of the battery and send a control signal, the input end of the battery charging protection circuit being connected with the microcontroller, the output end of the battery charging protection circuit being connected with the charging switch circuit, the battery charging protection circuit controlling the connection and disconnection of the charging switch circuit according to at least three control signals received at the same time.

[0007] In some embodiments, the following technical features are also included:

[0008] The battery charging protection circuit comprises a first signal driving circuit, a second signal driving circuit and a charging switch control circuit, and the microcontroller comprises a first pin, a second pin and a third pin; the input end of the first signal driving circuit is connected to the first pin, the input end of the second signal driving circuit is connected to the second pin, and the input end of the charging switch control circuit is connected to the third pin; the output end of the first signal driving circuit is connected to the input end of the second signal driving circuit and the charging switch control circuit, the output end of the charging switch control circuit is connected to the charging switch circuit, the first signal driving circuit and the second signal driving circuit respectively receive the control signals sent by the first pin and the second pin to control the connection and disconnection of the charging switch control circuit; the charging switch control circuit is used for receiving the control signal sent by the third pin and controlling the connection and disconnection of the charging switch circuit.

[0009] In some embodiments, the first signal driving circuit comprises a driving voltage source, a first signal driving triode, a first resistor and a second resistor; the base of the first signal driving triode is connected to the first pin through the first resistor, and the collector of the first signal driving triode is connected to the positive pole of the driving voltage source through the second resistor.

[0010] In some embodiments, the second signal driving circuit comprises a second signal driving triode, a third resistor and a fourth resistor; the base of the second signal driving triode is connected to the second pin through the third resistor, the collector of the second signal driving triode is connected to the emitter of the first signal driving triode through the fourth resistor, and the emitter of the second signal driving triode is grounded.

[0011] In some embodiments, the charging switch circuit comprises a charging switch MOS tube and a seventh resistor, and the charging switch control circuit comprises a charging switch control MOS tube, a fifth resistor, a sixth resistor and an eighth resistor; the fifth resistor is connected in parallel with the fourth resistor, the sixth resistor is connected across the gate and the source of the charging switch control MOS tube, the gate of the charging switch control MOS tube is connected to the emitter of the first signal driving triode through the fifth resistor, the source of the charging switch control MOS tube is connected to the emitter of the first signal driving triode in sequence through the sixth resistor and the fifth resistor, and the drain of the charging switch control MOS tube is connected to the charging switch MOS tube in sequence through the eighth resistor and the seventh resistor.

[0012] In some embodiments, the protection voltage output by the driving voltage source is 4.5-5.5V.

[0013] In some embodiments, the microcontroller adopts a SOP20.

[0014] In some embodiments, the control signal is a level signal.

[0015] The utility model discloses still provide following technical scheme:

[0016] A battery charging protection device, the battery charging protection device includes above-mentioned battery charging protection circuit.

[0017] The beneficial effects of the utility model compared with prior art include:

[0018] The battery charging protection circuit and the battery charging protection device provided by the utility model are connected with the microcontroller through the input end of the battery charging protection circuit, the output end of the battery charging protection circuit is connected with the charging switch circuit, the battery charging protection circuit controls the connection and disconnection of the charging switch circuit according to the at least three control signals received simultaneously, can realize the collaborative processing of multiple control signals sent by the microcontroller, thereby still can control the charging switch circuit to disconnect when the microcontroller fails, realizes the double protection of avoiding battery overcharge, effectively reduces the risk of safety accident.

[0019] Other beneficial effects in the embodiments of the utility model will be further described in the following. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the circuit diagram that the battery charging protection circuit in the embodiments of the utility model is applied to the charging circuit;

[0021] Figure 2 It is the circuit diagram of a kind of battery charging protection circuit in the embodiments of the utility model;

[0022] Figure 3 It is the circuit principle diagram that the battery charging protection circuit in the embodiments of the utility model is applied to the charging circuit.

[0023] BRIEF DESCRIPTION OF DRAWINGS:

[0024] 1, battery charging protection circuit;2, first signal drive circuit;3, second signal drive circuit;4, charging switch control circuit;R21, first resistance;R35A, second resistance;

[0025] Q4, first signal drive triode;R22, third resistance;R9A, fourth resistance;Q4A, second signal drive triode;R79, fifth resistance;R24, sixth resistance;Q16, charging switch control MOS tube;R6, seventh resistance;R11, eighth resistance;Q1, charging switch MOS tube. DETAILED DESCRIPTION

[0026] The utility model will be further described in the following by comparing with the drawings and combining preferred embodiment. It should be explained that the embodiment in the application and the feature in the embodiment can be combined mutually in the case where there is no conflict.

[0027] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood to indicate or imply relative importance or imply the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the utility model, the meaning of "multiple" is two or more than two, unless otherwise explicitly specified.

[0028] The traditional charging circuit only uses single-point control mode to realize charging safety guarantee: when the microcontroller (MCU) detects that the voltage of the battery meets the requirements through its PIN15 pin, the feedback is given to the microcontroller, and the microcontroller outputs a low-level signal through the PIN16 pin to make the charging switch MOS tube Q1 conductive, thereby charging the battery; when the battery reaches the full charge state, the PIN16 pin of the microcontroller is converted to output a high-level signal to make the charging switch MOS tube Q1 disconnected to terminate the charging, thereby avoiding overcharging of the battery. However, this scheme has significant safety hazards:

[0029] 1. Single-point dependency: the charging on-off logic completely depends on the output state of the MCU single pin (PIN16 pin), if the MCU causes the pin level to be abnormal due to program runaway, hardware failure or external interference, the charging switch MOS tube Q1 may be continuously conductive, causing the battery to overcharge;

[0030] 2. System vulnerability: the protection function needs the MCU to run continuously and stably, and once the power supply is abnormal or the program logic is wrong, the protection mechanism will be invalid;

[0031] 3. Risk uncontrollable: overcharging may cause the battery to lose control of heat, significantly increasing the risk of fire, explosion and other malignant accidents.

[0032] To solve the above technical defects, the utility model embodiment provides a battery charging protection circuit, which is applied to a charging circuit, as shown in Figure 1 and Figure 3 The charging circuit includes a charging switch circuit and a microcontroller, the charging switch circuit is used for controlling the connection and disconnection of the charging circuit, the microcontroller can detect the state of the battery and send a control signal, the input end of the battery charging protection circuit 1 is connected with the microcontroller, the output end of the battery charging protection circuit 1 is connected with the charging switch circuit, the battery charging protection circuit 1 controls the connection and disconnection of the charging switch circuit according to at least three control signals received simultaneously. Preferably, the model of the microcontroller adopts SOP20.

[0033] In one embodiment, as shown in Figure 2As shown, the battery charging protection circuit 1 comprises a first signal driving circuit 2, a second signal driving circuit 3, a charging switch control circuit 4, a microcontroller comprises a first pin PIN8, a second pin PIN7, a third pin PIN16; the input end of the first signal driving circuit 2 is connected to the first pin PIN8, the input end of the second signal driving circuit 3 is connected to the second pin PIN7, the input end of the charging switch control circuit 4 is connected to the third pin PIN16; the output end of the first signal driving circuit 2 is connected to the input end of the second signal driving circuit 3 and the charging switch control circuit 4 at the same time, the output end of the charging switch control circuit 4 is connected with the charging switch circuit, the first signal driving circuit 2 and the second signal driving circuit 3 control the communication and disconnection of the charging switch control circuit by receiving the control signals sent by the first pin PIN8 and the second pin PIN7 respectively; the charging switch control circuit 4 is used for receiving the control signal sent by the third pin PIN16 and controlling the communication and disconnection of the charging switch circuit.

[0034] The first signal driving circuit 2 comprises a driving voltage source, a first signal driving transistor Q4, a first resistor R21 and a second resistor R35A; the base of the first signal driving transistor Q4 is connected to the first pin PIN8 through the first resistor R21, and the collector of the first signal driving transistor Q4 is connected to the anode of the driving voltage source through the second resistor R35A. Preferably, the protection voltage output by the driving voltage source is 4.5-5.5V. The second signal driving circuit 3 comprises a second signal driving transistor Q4A, a third resistor R22 and a fourth resistor R9A; the base of the second signal driving transistor Q4A is connected to the second pin through the third resistor R22, the collector of the second signal driving transistor Q4A is connected to the emitter of the first signal driving transistor Q4 through the fourth resistor R9A, and the emitter of the second signal driving transistor Q4A is grounded. The charging switch circuit comprises a charging switch MOS tube Q1 and a seventh resistor R6, and the charging switch control circuit 4 comprises a charging switch control MOS tube Q16, a fifth resistor R79, a sixth resistor R24 and an eighth resistor R11; the fifth resistor R79 is connected in parallel with the fourth resistor R9A, the sixth resistor R24 is connected across the gate and the source of the charging switch control MOS tube Q16, the gate of the charging switch control MOS tube Q16 is connected to the emitter of the first signal driving transistor Q4 through the fifth resistor R79, the source of the charging switch control MOS tube Q16 is connected to the emitter of the first signal driving transistor Q4 in sequence through the sixth resistor R24 and the fifth resistor R79, and the drain of the charging switch control MOS tube Q16 is connected to the charging switch MOS tube Q1 in sequence through the eighth resistor R11 and the seventh resistor R6. Preferably, the control signal is a level signal.

[0035] The utility model embodiment further provides a battery charging protection device, the battery charging protection device comprises the battery charging protection circuit.

[0036] The principle of the battery charging protection circuit provided by the embodiment of the utility model is that the P MOS G gate of the charging switch MOS Q1 is controlled by the 7, 8 and 16 pins of the MCU simultaneously, and a high level signal is output through the first pin PIN8, a low level signal is output through the second pin PIN7, and a low level signal is output through the third pin PIN16, and only when the 7, 8 and 16 pins output the level meeting the requirement simultaneously, the charging function can be realized, for example, when the MCU program is deviated or damaged, the 7, 8 and 16 pins can only output high level signals or low level signals simultaneously, but when the three pins output high level signals or low level signals simultaneously, the charging switch control MOS Q16 cannot be turned on, so that the charging switch MOS Q1 cannot be turned on to output the charging for the battery, and the protection mechanism can effectively prevent the battery from overcharging and achieve the effect of protecting the battery. The battery charging protection circuit provided by the embodiment specifically includes the following working states:

[0037] 1. Normal charging state: when the adapter is connected to the AC power supply (AC), the MCU detects the battery state through the BS pin and the T / V pin, if the battery state is normal, the second pin PIN7 of the MCU outputs a low level signal, because the second pin PIN7 of the MCU is connected with the base of the second signal drive transistor Q4A through the third resistor R22, so the base of the second signal drive transistor Q4A is a low level signal, so the second signal drive transistor Q4A is not working at this time; the first pin PIN8 of the MCU outputs a high level signal, and the first signal drive transistor Q4 is turned on after the first resistor R21, so that the emitter voltage (about 5V) of the first signal drive transistor Q4 is divided by the sixth resistor R24 and the fifth resistor R79 to obtain a voltage of about 4V, so that the charging switch control MOS Q16 is turned on, when the charging switch control MOS Q16 is turned on, the third pin PIN16 of the MCU has output a low level signal at this time, so that the power supply voltage VCC is divided by the seventh resistor R6 and the eighth resistor R11, so as to provide a bias voltage for the gate source VGS of the charging switch MOS Q1, so that the charging switch MOS Q1 is turned on, and finally the battery charging function is realized.

[0038] 2. Abnormal protection state: when the MCU is abnormal due to program deviation or hardware damage, the 7, 8 and 16 pins of the MCU may output high level signals or low level signals simultaneously (because the output of each pin will be the same high or low level signal when the MCU is damaged).

[0039] When the 7, 8, 16 three pins of MCU output high level signal, at this time the first signal drive transistor Q4 and the second signal drive transistor Q4A are turned on, 5V voltage reaches the gate of the charging switch control MOS Q16 through the first signal drive transistor Q4, but because the second pin PIN7 of MCU also outputs high level signal, at this time the second signal drive transistor Q4A is also turned on, because the collector of the second signal drive transistor Q4A is connected with the gate of the charging switch control MOS Q16, so although the gate of the charging switch control MOS Q16 has 5V voltage at this time, because the second signal drive transistor Q4A is turned on, the 5V voltage of the gate of the charging switch control MOS Q16 is conducted to the ground through the second signal drive transistor Q4A, so that the charging switch control MOS Q16 cannot be turned on, and because the charging switch control MOS Q16 cannot be turned on, the G gate of the charging switch MOS Q1 is high level at this time, so that the charging switch MOS Q1 is also disconnected, because the charging switch MOS Q1 is disconnected, the output is no voltage output at this time, so that the battery is protected from overcharge and abnormality such as fire, and the safety of battery charging is ensured.

[0040] When the 7, 8, 16 three pins of MCU output low level signal, at this time the first signal drive transistor Q4 and the second signal drive transistor Q4A are not turned on, so that the gate of the charging switch control MOS Q16 has no voltage, although the third pin PIN16 of MCU outputs low level signal at this time, the charging switch control MOS Q16 still cannot be turned on, and because the charging switch control MOS Q16 cannot be turned on, although the G gate of the charging switch MOS Q1 is low level at this time, the charging switch MOS Q1 is still disconnected, because the charging switch MOS Q1 is disconnected, the output is no voltage output at this time, so that the battery is protected from overcharge and abnormality such as fire, and the safety of battery charging is ensured.

[0041] The above is further detailed description of the utility model in combination with specific / preferred embodiments, which cannot be deemed as limiting the specific implementation of the utility model to these descriptions. For ordinary skilled in the art to which the utility model belongs, without departing from the concept of the utility model, they can make some substitutions or variations to the described embodiments, and these substitutions or variations should be deemed as falling within the protection scope of the utility model. In the description of the specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the utility model. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the case of not mutually contradictory, the skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of different embodiments or examples. Although the embodiments of the utility model and its advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made in this paper without departing from the protection scope of the patent application.

Claims

1. A battery charging protection circuit, applied to a charging circuit, the charging circuit including a charging switch circuit and a microcontroller, the charging switch circuit being used to control the connection and disconnection of the charging circuit, the microcontroller being able to detect the state of the battery and issue a control signal, characterized in that: The input end of the battery charging protection circuit is connected with the microcontroller, and the output end of the battery charging protection circuit is connected with the charging switch circuit.

2. The battery charge protection circuit of claim 1, wherein: The battery charging protection circuit comprises a first signal driving circuit, a second signal driving circuit and a charging switch control circuit, and the microcontroller comprises a first pin, a second pin and a third pin; the input end of the first signal driving circuit is connected with the first pin, the input end of the second signal driving circuit is connected with the second pin, and the input end of the charging switch control circuit is connected with the third pin; the output end of the first signal driving circuit is simultaneously connected with the input ends of the second signal driving circuit and the charging switch control circuit, and the output end of the charging switch control circuit is connected with the charging switch circuit; the first signal driving circuit and the second signal driving circuit respectively receive the control signals sent by the first pin and the second pin to control the connection and disconnection of the charging switch control circuit; the charging switch control circuit is used for receiving the control signal sent by the third pin and controlling the connection and disconnection of the charging switch circuit.

3. The battery charge protection circuit of claim 2, wherein: The first signal driving circuit comprises a driving voltage source, a first signal driving transistor, a first resistor and a second resistor; the base of the first signal driving transistor is connected with the first pin through the first resistor, and the collector of the first signal driving transistor is connected with the positive pole of the driving voltage source through the second resistor.

4. The battery charge protection circuit of claim 3, wherein: The second signal driving circuit comprises a second signal driving transistor, a third resistor and a fourth resistor; the base of the second signal driving transistor is connected with the second pin through the third resistor, the collector of the second signal driving transistor is connected with the emitter of the first signal driving transistor through the fourth resistor, and the emitter of the second signal driving transistor is grounded.

5. The battery charge protection circuit of claim 4, wherein: The charging switch circuit comprises a charging switch MOS transistor and a seventh resistor, and the charging switch control circuit comprises a charging switch control MOS transistor, a fifth resistor, a sixth resistor and an eighth resistor; the fifth resistor is connected with the fourth resistor in parallel, the sixth resistor is connected across the gate and the source of the charging switch control MOS transistor, the gate of the charging switch control MOS transistor is connected with the emitter of the first signal driving transistor through the fifth resistor, the source of the charging switch control MOS transistor is sequentially connected with the emitter of the first signal driving transistor through the sixth resistor and the fifth resistor, and the drain of the charging switch control MOS transistor is sequentially connected with the charging switch MOS transistor through the eighth resistor and the seventh resistor.

6. The battery charge protection circuit of claim 3, wherein, The voltage output by the driving voltage source is 4.5-5.5V.

7. The battery charge protection circuit of claim 1, wherein, The microcontroller adopts a SOP20.

8. The battery charge protection circuit of claim 1, wherein, The control signal is a level signal.

9. A battery charge protection device, characterized by, The battery charging protection device comprises the battery charging protection circuit according to any one of claims 1-8.

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