Lithium battery charging protection circuit and vehicle-mounted automatic diagnosis system

Abstract

The utility model discloses a lithium battery charging protection circuit and a vehicle-mounted automatic diagnosis system, and relates to the technical field of electronic circuits. The system comprises a charging management chip, a first filter circuit, a second filter circuit and a battery voltage sampling circuit, the first filter circuit, the second filter circuit and the battery voltage sampling circuit are connected with the charging management chip, the first filter circuit is connected with a system power supply input end, the second filter circuit is connected with a charging lithium battery, and the battery voltage sampling circuit is connected with a main control chip. The main control chip monitors the charging voltage of the lithium battery in real time and judges whether the lithium battery is over-voltage or over-current so as to control the charging management chip to control whether the lithium battery is charged or not. According to the lithium battery charging protection circuit, overvoltage or overcurrent charging of the lithium battery can be avoided, overvoltage and overcurrent of the battery and even fire or explosion accidents are avoided, and the use performance of a product is ensured.

Description

Technical Field

[0001] The utility model of the application relates to the field of circuit electronic technology, and in particular to a lithium battery charging protection circuit and an on-board automatic diagnosis system. Background Art

[0002] With the popularity of electric vehicles and the widespread application of OBD (On-Board Diagnostics) equipment in the field of automotive diagnosis, lithium batteries have been widely used as the power source of OBD equipment. However, due to the characteristics of lithium batteries, when the charging voltage or charging current exceeds a certain range, it may cause battery overvoltage, overcurrent, and even cause fire or explosion accidents. Therefore, how to effectively protect lithium batteries from overvoltage and overcurrent has become a problem that needs to be solved urgently. Utility Model Content

[0003] In view of this, the purpose of the utility model embodiment of the present application is to provide a lithium battery charging protection circuit and an on-board automatic diagnostic system. The lithium battery charging protection circuit protects the rechargeable lithium battery by controlling the output of a safe and stable voltage to ensure that the lithium battery will not be overcharged, leaked, or catch fire due to overvoltage or overcurrent charging.

[0004] The technical solution adopted by the utility model to solve the above technical problems is as follows:

[0005] According to one aspect of an embodiment of the utility model, a lithium battery charging protection circuit is provided, including a charging management chip, a first filter circuit connected to the charging management chip, a second filter circuit and a battery voltage sampling circuit, wherein the first filter circuit is connected to a system power input terminal, the second filter circuit is connected to a rechargeable lithium battery, and the battery voltage sampling circuit is connected to a main control chip. The main control chip monitors the charging voltage of the lithium battery in real time and determines whether the lithium battery is over-voltage or over-current, thereby controlling the charging management chip to control whether to charge the lithium battery.

[0006] Among them, the battery voltage sampling circuit includes a resistor R510, a resistor R511 and a switch P-MOS tube, one end of the resistor R510 is connected to the output end OUT of the charging management chip, the other end of the resistor R510 is connected to the source of the switch P-MOS tube, the gate of the switch P-MOS tube is connected to the resistor R511, the resistor R511 is grounded, and the drain of the switch P-MOS tube is connected to the main control chip through a resistor.

[0007] Among them, the model of the charging management chip is SN2024.

[0008] Among them, the first filtering circuit includes capacitor C501, capacitor C502 and capacitor C503 connected in parallel, one end of the capacitor C501, capacitor C502 and capacitor C503 is connected to the system power input end, and the other end is connected to the power input pin IN of the charging management chip, the capacitance value of the capacitor C501 is greater than the capacitance value of the capacitor C502, and the capacitor C503 is a backup capacitor, and the capacitance value can be set according to actual needs.

[0009] Among them, the second filtering circuit includes capacitor C506 and capacitor C507, the capacitor C506 and capacitor C507 are connected in parallel, one end of the capacitor C506 and capacitor C507 is connected to the charging input end of the lithium battery, and the other end is connected to the power output pin of the charging management chip.

[0010] Among them, the temperature detection TS pin of the charging management chip is connected to a thermistor R506 and a resistor R507 arranged in parallel, connected to the power input pin IN of the charging management chip through the thermistor R506, and connected to the enable CHG pin of the charging management chip through the resistor R507.

[0011] Among them, the enable CHG pin of the charging management chip is connected to the resistor R512, and is connected to the main control chip through the resistor R512.

[0012] Among them, the I SET2 pin of the charging management chip is connected to the ground through the resistor R504, and the I SET pin of the charging management chip is connected to the ground through the resistor R501.

[0013] Wherein, the PRETERM pin of the charging management chip is connected to the ground through a resistor R502.

[0014] The present application also provides an on-vehicle automatic diagnosis system, including a rechargeable lithium battery, a main control chip and the lithium battery charging protection circuit described above.

[0015] Compared with the prior art, when the charging voltage or charging current of lithium batteries exceeds a certain range during multiple charging processes, it may cause battery overvoltage, overcurrent, and even cause fire or explosion accidents. The lithium battery charging protection circuit of the present application outputs a stable and safe voltage through the first filter circuit and the second filter circuit, and the main control chip monitors the voltage or current output to the lithium battery by the battery voltage sampling circuit in real time. When the voltage or current is detected to be abnormal, the main control chip controls the level of the enable pin of the charging management chip to control whether to prohibit charging the lithium battery. When the abnormality is restored, the charging of the lithium battery is controlled. When the abnormality exceeds the predetermined number of times and is still not resolved three times, the server is reported to alarm. The present application can ensure that the lithium battery will not be over-voltage or over-current charged through the lithium battery charging protection circuit, avoid battery overvoltage, overcurrent, and even cause fire or explosion accidents, and ensure the performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 This is a structural block diagram of a lithium battery charging protection circuit according to an embodiment of the utility model;

[0018] Figure 2 This is a circuit schematic diagram of a lithium battery charging protection circuit according to an embodiment of the utility model;

[0019] Figure 3 It is a structural block diagram of a vehicle-mounted automatic diagnosis system according to an embodiment of the utility model. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0021] See also Figure 1 to Figure 2 , which is a lithium battery charging protection circuit provided by the embodiment of the utility model, which is applied to vehicle-mounted terminals, such as vehicle-mounted OBD, fire safety warning system, communication base station, etc., to protect the charging of lithium batteries on the equipment. For the convenience of explanation, only the parts related to this embodiment are shown.

[0022] Embodiment 1

[0023] See also Figure 1 , Figure 2 Combined with Figure 3 As shown, an embodiment of the present application provides a lithium battery charging protection circuit, which can prevent accidents such as overvoltage, overcurrent, and even fire or explosion of the lithium battery when the charging voltage or charging current exceeds a certain range when charging the lithium battery in the OBD device.

[0024] The lithium battery charging protection circuit includes a charging management chip 10, a first filter circuit 20 connected to the charging management chip 10, a second filter circuit 30 and a battery voltage sampling circuit 40, wherein the first filter circuit 20 is connected to the system power input terminal VCC, the second filter circuit 30 is connected to the battery voltage sampling circuit 40 to output a voltage to charge the lithium battery 100, and the battery voltage sampling circuit 40 is connected to the main control chip 200. The main control chip 200 monitors the charging voltage of the lithium battery in real time and determines whether the lithium battery is over-voltage or over-current, thereby controlling the charging management chip 10 to control whether to charge the lithium battery.

[0025] The battery voltage sampling circuit 40 includes a resistor R510, a resistor R511 and a switch P-MOS tube, one end of the resistor R510 is connected to the output end OUT of the charging management chip 10, the other end of the resistor R510 is connected to the source of the switch P-MOS tube, the gate of the switch P-MOS tube is connected to the resistor R511, the resistor R511 is grounded, and the drain of the switch P-MOS tube is connected to the main control chip 200 through a resistor. The charging voltage of the lithium battery can be monitored in real time through the main control chip 200.

[0026] In this embodiment, the model of the charging management chip 10 is SN2024.

[0027] The first filter circuit 20 includes a capacitor C501, a capacitor C502, and a capacitor C503 connected in parallel, one end of the capacitor C501, the capacitor C502, and the capacitor C503 is connected to the system power input terminal, and the other end is connected to the power input pin IN of the charging management chip 10, the capacitance value of the capacitor C501 is greater than the capacitance value of the capacitor C502, and the capacitor C503 is a backup capacitor, and the capacitance value can be set according to actual needs. The stability of the system input voltage can be improved by the first filter circuit 20.

[0028] The second filter circuit 30 includes a capacitor C506 and a capacitor C507, which are connected in parallel, one end of the capacitor C506 and the capacitor C507 are connected to the charging input end of the lithium battery, and the other end is connected to the power output pin of the charging management chip. The filtering of the second filter circuit 30 can provide a stable charging voltage to the lithium battery, avoiding the instability of the charging voltage of the lithium battery and affecting the performance of the lithium battery.

[0029] The temperature detection TS pin of the charging management chip is connected to a thermistor R506 and a resistor R507 arranged in parallel, connected to the power input pin IN of the charging management chip through the thermistor R506, and connected to the enable CHG pin of the charging management chip through the resistor R507.

[0030] The enable CHG pin of the charging management chip is connected to the resistor R512, and is connected to the main control chip through the resistor R512.

[0031] The I SET2 pin of the charging management chip is connected to the ground through a resistor R504. The I SET pin of the charging management chip is connected to the ground through a resistor R501.

[0032] The PRETERM pin of the charging management chip is connected to the ground via a resistor R502.

[0033] When the lithium battery charging protection circuit of the utility model of the present application is used in an OBD device, the charging management chip 10 can automatically adjust the charging current and voltage output to the lithium battery, wherein the maximum charging voltage is set to 4.2V and the maximum charging current is set to 0.2C.

[0034] The present application uses the main control chip 200 to monitor in real time the battery voltage sampling circuit 40 to collect the voltage output to the lithium battery and combines the charging curve data of the lithium battery to determine whether the lithium battery is over-voltage or over-current. If there is an abnormality in the voltage or current, the CHG_N pin of the charging management chip is controlled to be pulled down, and the charging management chip is controlled to prohibit charging the lithium battery. Then the main control chip combines the real-time monitored charging voltage of the lithium battery and the charging curve data of the lithium battery to determine again whether the current or voltage abnormality is resolved. If it is released, the control of the CHG_N pin of the charging management chip will be restored after three minutes, and it will be judged again whether the charging voltage or current of the lithium battery is abnormal. If it is abnormal for three consecutive times, the control will keep turning off the charging management chip enable and report the server alarm; if it is not released, the SYS_5V power supply of the system input will be turned off, and the power supply to the charging management chip 10 will be prohibited. At the same time, sampling will be resumed after three minutes to perform the above judgment. If it is abnormal for three consecutive times, the battery charging will be turned off and the server alarm will be reported. In this way, the voltage and current of the lithium battery are judged and monitored in real time, so as to ensure that the lithium battery will not be overcharged or over-current charged, resulting in overcharge, leakage, and fire.

[0035] If an extreme abnormality occurs, that is, the charging management chip 10 is damaged (when the input (5V) of the charging management chip is directly short-circuited with the output), the battery voltage can be judged by software ADC sampling. If the battery voltage exceeds 4.2V or the charging current exceeds 0.2C during the sampling period, the input power enable of the charging management chip is turned off and an alarm is reported to the server. Thus, charging of the lithium battery is stopped to prevent overvoltage or overcurrent, effectively preventing the risk of battery fire and explosion.

[0036] The lithium battery charging protection circuit described in the present application outputs a stable and safe voltage through the first filtering circuit and the second filtering circuit, and the main control chip monitors the battery voltage sampling circuit 40 in real time to collect the voltage or current output to the lithium battery. When the voltage or current is detected to be abnormal, the main control chip 200 controls the level of the enable pin of the charging management chip to control whether to prohibit charging the lithium battery. When the abnormality is restored, the charging of the lithium battery is controlled. When the abnormality exceeds the predetermined number of times and is still not resolved three times, the server alarm is reported.

[0037] And when the power management chip is abnormal, this application can also judge the lithium battery charging voltage through software ADC sampling. If the battery voltage exceeds the threshold, the input power enable of the charging management chip is turned off and the server alarm is reported. This application combines hardware and software control and double-layer protection to ensure that the lithium battery will not be over-voltage or charge overcurrent exceeds a certain range, which may cause battery overvoltage, overcurrent, and even cause fire or explosion accidents, ensuring product performance.

[0038] Embodiment 2

[0039] See also Figure 3 As shown, an embodiment of the present application also provides an on-board automatic diagnostic system, which includes a rechargeable lithium battery 100, a main control chip 200 and a lithium battery charging protection circuit 101. The lithium battery charging protection circuit is described in detail in Example 1 and will not be repeated here.

[0040] The lithium battery charging protection circuit 10 is connected to the rechargeable lithium battery 100, and the main control chip 200 monitors the charging voltage output by the lithium battery charging protection circuit 10 to the rechargeable lithium battery 100 in real time to ensure that the charging voltage of the rechargeable lithium battery 100 is within a normal and safe range, thereby preventing the lithium battery from over-voltage or over-current, or even fire or explosion accidents when the lithium battery is over-voltage or charging over-current exceeds a certain range.

[0041] Compared with the prior art lithium batteries, during multiple charging processes, when the charging voltage or charging current exceeds a certain range, it may cause battery overvoltage, overcurrent, and even cause fire or explosion accidents. The present application can ensure that the charging voltage of the lithium battery is always within a safe charging voltage range through a lithium battery charging protection circuit, which may cause battery overvoltage, overcurrent, and even cause fire or explosion accidents.

[0042] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the present invention is not limited by this. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention shall be within the scope of the present invention.

Claims

1. A lithium battery charging protection circuit, characterized in that: It includes a charging management chip, a first filtering circuit connected to the charging management chip, a second filtering circuit and a battery voltage sampling circuit. The first filtering circuit is connected to the system power input terminal, the second filtering circuit is connected to the rechargeable lithium battery, and the battery voltage sampling circuit is connected to the main control chip. The main control chip monitors the charging voltage of the lithium battery in real time and determines whether the lithium battery is over-voltage or over-current, thereby controlling the charging management chip to control whether to charge the lithium battery.

2. The lithium battery charging protection circuit according to claim 1, characterized in that: The battery voltage sampling circuit includes a resistor R510, a resistor R511 and a switch P-MOS tube, one end of the resistor R510 is connected to the output end OUT of the charging management chip, the other end of the resistor R510 is connected to the source of the switch P-MOS tube, the gate of the switch P-MOS tube is connected to the resistor R511, the resistor R511 is grounded, and the drain of the switch P-MOS tube is connected to the main control chip through a resistor.

3. The lithium battery charging protection circuit as claimed in claim 2, characterized in that: The model of the charging management chip is SN2024.

4. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The first filtering circuit includes capacitor C501, capacitor C502 and capacitor C503 connected in parallel, one end of the capacitor C501, capacitor C502 and capacitor C503 is connected to the system power input end, and the other end is connected to the power input pin IN of the charging management chip, the capacitance value of the capacitor C501 is greater than the capacitance value of the capacitor C502, and the capacitor C503 is a backup capacitor, and the capacitance value can be set according to actual needs.

5. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The second filtering circuit includes a capacitor C506 and a capacitor C507, and the capacitor C506 and the capacitor C507 are connected in parallel. One end of the capacitor C506 and the capacitor C507 is connected to the charging input end of the lithium battery, and the other end is connected to the power output pin of the charging management chip.

6. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The temperature detection TS pin of the charging management chip is connected to a thermistor R506 and a resistor R507 arranged in parallel, connected to the power input pin IN of the charging management chip through the thermistor R506, and connected to the enable CHG pin of the charging management chip through the resistor R507.

7. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The enable CHG pin of the charging management chip is connected to the resistor R512, and is connected to the main control chip through the resistor R512.

8. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The ISET2 pin of the charging management chip is connected to the ground through a resistor R504, and the ISET pin of the charging management chip is connected to the ground through a resistor R501.

9. The lithium battery charging protection circuit as claimed in claim 3, characterized in that: The PRETERM pin of the charging management chip is connected to the ground via a resistor R502.

10. An on-board automatic diagnostic system, characterized in that: It comprises a rechargeable lithium battery, a main control chip and a lithium battery charging protection circuit as described in any one of claims 1 to 9.

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