A lithium battery secondary protection circuit

Abstract

The utility model discloses a lithium battery secondary protection circuit, including N three -terminal fuse, a battery secondary protection chip and N -way fuse control circuit, N three -terminal fuse is parallel to each other, and is connected in series on the positive pole charging line of lithium battery, the battery secondary protection chip gathers each cell voltage of lithium battery, connects each way fuse control circuit, and each way fuse control circuit is connected control control end of one three -terminal fuse respectively. MOS pipe source of N -way fuse control circuit shares same jumper terminal Jump ground. The jumper terminal Jump still has the pull -down resistance in parallel. The utility model discloses to prevent the production process secondary protection starting fuse, MOS pipe source of N -way fuse control circuit shares same jumper terminal Jump ground. In order to prevent the MOS possible suspension and lead to the interference, lead to the fuse fusing, increased the pull -down resistance.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery protection, and in particular to a secondary protection circuit for lithium batteries. 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] Traditional lithium battery protection circuits rely on fuses for secondary protection. When a large current needs to be applied, multiple fuses are required. To prevent the secondary protection from triggering the fuses during production, multiple jumper terminals are added between the fuses and the control switch. If these jumper terminals disconnect, the MOSFET and ground will be left floating. Utility Model Content

[0004] The purpose of this utility model is to overcome the above-mentioned technical problems and provide a secondary protection circuit for lithium batteries.

[0005] The technical solution of this utility model is:

[0006] A secondary protection circuit for a lithium battery includes N three-terminal fuses, a secondary battery protection chip, and N fuse control circuits. The N three-terminal fuses are connected in parallel and in series with the positive charging line of the lithium battery. The secondary battery protection chip collects the voltage of each cell of the lithium battery and connects to each fuse control circuit. Each fuse control circuit is connected to the control terminal of a three-terminal fuse.

[0007] Preferably, the fuse control circuit uses a MOSFET, with the gate of the MOSFET connected to the protection control terminal of the battery secondary protection chip, the drain connected to the control terminal of a three-terminal fuse, and the source grounded through a jumper terminal.

[0008] Preferably, the sources of the MOS transistors in the N-way fuse control circuit share the same jumper terminal for grounding.

[0009] Preferably, the jumper terminal is also connected in parallel with a pull-down resistor.

[0010] Preferably, the secondary protection chip for the battery is BM3051.

[0011] The advantages of this utility model are:

[0012] To prevent secondary protection activation and fuse blown during production, this invention connects the drain of a MOSFET to the control terminal of a three-terminal fuse, while the source is grounded via a jumper terminal. The sources of the MOSFETs in the N-channel fuse control circuit share the same jumper terminal. To prevent the fuse from blowing due to interference caused by a potentially floating MOSFET, a pull-down resistor is added. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0014] Figure 1 This is a schematic diagram of the secondary protection circuit for lithium batteries according to this utility model. Detailed Implementation Example

[0015] like Figure 1 As shown, the lithium battery secondary protection circuit of this utility model includes three three-terminal fuses F1-F3, a battery secondary protection chip BM3051, and three fuse control circuits. The N three-terminal fuses are connected in parallel and in series with the positive charging line of the lithium battery. The battery secondary protection chip U2 collects the voltage of each cell of the lithium battery through resistors R16-R19. The protection control terminal CO is connected to each fuse control circuit. Each fuse control circuit is connected to the control terminals SCF1-SCF3 of a three-terminal fuse.

[0016] The three-way fuse control circuits share the same structural principle. Taking the first path as an example, it uses a MOSFET Q23. The gate of the MOSFET Q23 is connected to the protection control terminal CO of the battery's secondary protection chip through a resistor R20. The drain is connected to the control terminal SCF1 of a three-terminal fuse F1, and the source is grounded through jumper terminal J1. A resistor R21 and a capacitor C15 are also connected between the gate and the source. The sources of the MOSFETs in the three-way fuse control circuits share the same jumper terminal J1 for grounding. A pull-down resistor is also connected in parallel to jumper terminal J1.

[0017] To prevent secondary protection activation and fuse blown during production, this invention connects the drain of a MOSFET to the control terminal of a three-terminal fuse, while the source is grounded via a jumper terminal. The sources of the MOSFETs in the N-channel fuse control circuit share the same jumper terminal. To prevent the fuse from blowing due to interference caused by a potentially floating MOSFET, a pull-down resistor is added.

[0018] 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 secondary protection circuit for a lithium battery, characterized in that, It includes N three-terminal fuses, a battery secondary protection chip, and N fuse control circuits; the N three-terminal fuses are connected in parallel and in series with the positive charging line of the lithium battery; the battery secondary protection chip collects the voltage of each cell of the lithium battery and connects to each fuse control circuit, and each fuse control circuit is connected to the control terminal of a three-terminal fuse.

2. The lithium battery secondary protection circuit according to claim 1, characterized in that, The fuse control circuit uses a MOSFET. The gate of the MOSFET is connected to the protection control terminal of the secondary protection chip of the battery, the drain is connected to the control terminal of a three-terminal fuse, and the source is grounded through the jumper terminal.

3. The lithium battery secondary protection circuit according to claim 2, characterized in that, The sources of the MOS transistors in the N-way fuse control circuit share the same jumper terminal for grounding.

4. The lithium battery secondary protection circuit according to claim 3, characterized in that, The jumper terminal is also connected in parallel with a pull-down resistor.

5. The lithium battery secondary protection circuit according to claim 1, characterized in that, The battery secondary protection chip is BM3051.

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