Lithium battery protection circuit with electric quantity detection function

Abstract

The utility model discloses a lithium battery protection circuit with electric quantity detection, which comprises a protection unit and an electric quantity detection unit, the protection unit adopts a protection chip U1 to protect over-voltage, under-voltage and over-current in the charging and discharging process of a lithium battery, and the electric quantity detection unit adopts an electric quantity detection chip U2 to detect the capacity of the lithium battery in real time. The electric quantity detection chip U2 adopts a CW2017, a CELL pin of the CW2017 collects battery voltage, and an SDA pin and an SCL pin output battery electric quantity data to a battery management system through an I2C bus. According to the lithium battery protection circuit with the electric quantity detection function, the protection chip is adopted to protect the charging and discharging process of the lithium battery, and the electric quantity detection chip is adopted to detect the capacity of the lithium battery in real time. According to the utility model, one-time charging overvoltage protection and one-time discharging undervoltage protection can be realized, and the specific capacity of the battery can be detected in real time through the electric quantity detection chip in the charging and discharging process.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to a lithium battery protection circuit with charge detection. Background Technology

[0002] Lithium batteries have advantages such as high energy density, long service life, high rated voltage, high power handling capacity, low self-discharge rate, light weight, and strong adaptability to high and low temperatures. However, they also have disadvantages such as poor safety and the need for protection circuits to prevent overcharging, over-discharging, overcurrent, short circuit, and over-temperature protection.

[0003] The existing lithium battery protection circuit design schemes have the following problems:

[0004] Traditional lithium battery protection circuits can only protect lithium batteries from overvoltage, undervoltage, and charge / discharge current. They cannot detect the actual capacity of the battery, and the battery capacity cannot be determined from the battery voltage during the charge / discharge process. Utility Model Content

[0005] The purpose of this invention is to provide a lithium battery protection circuit with charge detection.

[0006] The technical solution of this utility model is:

[0007] A lithium battery protection circuit with power detection includes a protection unit and a power detection unit. The protection unit uses a protection chip U1 to protect the lithium battery from overvoltage, undervoltage, and overcurrent during charging and discharging. The power detection unit uses a power detection chip U2 to detect the capacity of the lithium battery in real time.

[0008] Preferably, the power detection chip U2 is a CW2017. The CELL pin of the CW2017 collects the battery voltage, and the SDA and SCL pins output the battery power data to the battery management system through the I2C bus.

[0009] Preferably, the I2C bus is further provided with an isolation circuit, which includes MOS transistors Q3 and Q4 connected in series on the SDA and SCL lines respectively; the gates of MOS transistors Q3 and Q4 are connected to a high level through resistors R10 and R11 respectively.

[0010] Preferably, matching resistors R8 and R12 are connected in series on the SDA lines at both ends of the MOS transistor Q3; and matching resistors R9 and R13 are connected in series on the SCL lines at both ends of the MOS transistor Q4.

[0011] Preferably, the positive and negative charging terminals P+ and P- of the lithium battery are connected to the positive and negative terminals B+ and B- of the lithium battery, respectively, wherein charging and discharging MOSFETs Q1 and Q2 are connected in series between the negative charging terminal P- and the negative terminal B- of the lithium battery.

[0012] The protection chip U1 uses R5492. The VDD pin of R5492 is connected to the positive terminal B+ of the battery through resistor R1 and grounded through capacitor C2; the V- pin of R5492 is connected to the negative charging line through resistor R2; the Cout and Dout pins of R5492 are connected to the gates of charging and discharging MOSFETs Q1 and Q2, respectively.

[0013] Preferably, it also includes a 3.3V voltage regulator chip U3, which converts the battery voltage into a stable 3.3V voltage. The 3.3V voltage provides the operating voltage to the power detection chip CW2017 and serves as the high level of the isolation circuit.

[0014] The advantages of this utility model are:

[0015] 1. The lithium battery protection circuit with power detection provided by this utility model uses a protection chip to protect the lithium battery during the charging and discharging process, and a power detection chip to detect the capacity of the lithium battery in real time. This utility model can realize overvoltage protection during charging and undervoltage protection during discharging. During the charging and discharging process, the power detection chip can detect the specific capacity of the battery in real time.

[0016] 2. The battery capacity detection provided by this utility model transmits data via I2C, enabling centralized management of multi-channel battery data acquisition. A MOS transistor isolation circuit is designed on the I2C, and the on / off state of the MOS transistor is controlled by the high and low levels of the MOS transistor source to achieve signal level isolation. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0018] Figure 1 This is a schematic diagram of the lithium battery protection circuit with charge detection according to this utility model. Detailed Implementation

[0019] A lithium battery protection circuit with power detection includes a protection unit and a power detection unit. The protection unit uses a protection chip U1 to protect the lithium battery from overvoltage, undervoltage, and overcurrent during charging and discharging. The power detection unit uses a power detection chip U2 to detect the capacity of the lithium battery in real time.

[0020] like Figure 1As shown, the positive and negative charging terminals P+ and P- of the lithium battery are connected to the positive and negative terminals B+ and B- of the lithium battery, respectively. A charging / discharging MOSFET Q1 and Q2 are connected in series between the negative charging terminal P- and the negative terminal B- of the lithium battery. The protection chip U1 uses an R5492. The VDD pin of the R5492 is connected to the positive terminal B+ of the battery through a resistor R1 and grounded through a capacitor C2. The V- pin of the R5492 is connected to the negative charging line through a resistor R2. The Cout and Dout pins of the R5492 are connected to the gates of the charging / discharging MOSFETs Q1 and Q2, respectively.

[0021] The power detection chip U2 uses a CW2017. The CW2017's CELL pin collects the battery voltage, and the SDA and SCL pins output battery power data to the battery management system via the I2C bus. This invention can achieve overvoltage protection during charging and undervoltage protection during discharging. During charging and discharging, the power detection chip can detect the battery's capacity in real time.

[0022] The I2C bus is also equipped with an isolation circuit, which includes MOSFETs Q3 and Q4 connected in series on the SDA and SCL lines, respectively. The gates of MOSFETs Q3 and Q4 are connected to a high level through resistors R10 and R11, respectively. Matching resistors R8 and R12 are connected in series on the SDA line across MOSFET Q3, and matching resistors R9 and R13 are connected in series on the SCL line across MOSFET Q4.

[0023] Figure 1 It also includes a 3.3V voltage regulator chip, which converts the battery voltage into a stable 3.3V voltage. The 3.3V voltage provides the operating voltage to the power detection chip CW2017 and serves as the high level of the isolation circuit.

[0024] The battery capacity detection provided by this utility model transmits data via I2C, enabling centralized management of multi-channel battery data acquisition. A MOS transistor isolation circuit is designed on the I2C, and the on / off state of the MOS transistor is controlled by the high and low levels of the MOS transistor source to achieve signal level isolation.

[0025] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All modifications made in accordance with the spirit and essence of the main technical solution of this utility model should be included within the scope of protection of this utility model.

Claims

1. A lithium battery protection circuit with charge detection, characterized in that: It includes a protection unit and a power detection unit. The protection unit adopts a protection chip U1 to protect the lithium battery from overvoltage, undervoltage and overcurrent during the charging and discharging process. The power detection unit adopts a power detection chip U2 to detect the capacity of the lithium battery in real time. The power detection chip U2 adopts CW2017, the CELL pin of CW2017 collects the battery voltage, and the SDA and SCL pins output the battery power data to the battery management system through the I2C bus; The positive and negative charging terminals P+ and P- of the lithium battery are connected to the positive and negative electrodes B+ and B- of the lithium battery respectively, wherein the charging and discharging MOS tubes Q1 and Q2 are connected in series between the negative charging terminal P- and the negative electrode B- of the lithium battery; The protection chip U1 adopts R5492, the VDD pin of R5492 is connected to the positive electrode B+ of the battery through the resistor R1, and is grounded through the capacitor C2; the V- pin of R5492 is connected to the negative charging line through the resistor R2; the Cout and Dout pins of R5492 are respectively connected to the gates of the charging and discharging MOS tubes Q1 and Q2.

2. The lithium battery protection circuit for charge detection according to claim 1, characterized in that: The I2C bus is also provided with an isolation circuit, which includes MOS tubes Q3 and Q4 connected in series to the SDA and SCL lines respectively; the gates of the MOS tubes Q3 and Q4 are connected to a high level through resistors R10 and R11 respectively.

3. The lithium battery protection circuit for charge detection according to claim 2, characterized in that: Matching resistors R8 and R12 are respectively connected in series to the SDA lines at both ends of the MOS tube Q3; matching resistors R9 and R13 are respectively connected in series to the SCL lines at both ends of the MOS tube Q4.

4. The lithium battery protection circuit for charge detection according to claim 2, characterized in that: It also includes a 3.3V voltage regulator chip U3, which converts the battery voltage into a stable 3.3V voltage. The 3.3V voltage provides working voltage to the power detection chip CW2017 and serves as the high level of the isolation circuit.

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