Reverse connection prevention circuit for a battery

Abstract

The utility model discloses a kind of reverse connection prevention circuits of battery, it is related to circuit technical field, comprising: first MOS tube being connected between BAT+ end and P+ end, the drain of first MOS tube is connected with BAT+ end, the source of first MOS tube is connected with P+ end, the gate of first MOS tube is connected with second MOS tube, the drain of second MOS tube is connected with the gate of first MOS tube, the source of second MOS tube is connected between BAT- end and P- end, the gate of second MOS tube is connected with main control chip, main control chip is used to send on or off signal for second MOS tube, and first MOS tube is P channel MOS tube, and second MOS tube is N channel MOS tube. The utility model circuit simple structure, through the collaborative work of component in circuit, can effectively prevent battery reverse connection and backflow, protect electronic equipment and the safety of user, while ensuring the normal conduction and closure of circuit.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, specifically to a reverse connection protection circuit for batteries. Background Technology

[0002] With technological advancements, there's a growing demand for convenient access to various electronic devices, such as portable oxygen concentrators, portable ventilators, and portable micro-mesh nebulizers. These portable electronic devices indirectly function as personal / family doctors. Considering that some users engage in outdoor activities and require access anytime, anywhere, these portable electronic devices utilize rechargeable aluminum batteries.

[0003] For safety reasons and to prevent equipment failure, a circuit to prevent reverse connection of the battery needs to be designed. Utility Model Content

[0004] In view of this, the present invention provides a reverse connection protection circuit for batteries, thereby solving the problem of safety considerations and prevention of equipment failure when using portable electronic devices in the prior art.

[0005] According to a first aspect, embodiments of the present invention provide a reverse connection protection circuit for a battery, comprising: A first MOSFET is connected between the BAT+ and P+ terminals. The drain of the first MOSFET is connected to the BAT+ terminal, and the source of the first MOSFET is connected to the P+ terminal. A second MOSFET is connected to the gate of the first MOSFET. The drain of the second MOSFET is connected to the gate of the first MOSFET, and the source of the second MOSFET is connected between the BAT- and P- terminals. The gate of the second MOSFET is connected to the main control chip. The main control chip is used to send a turn-on or turn-off signal to the second MOSFET. The first MOSFET is a P-channel MOSFET, and the second MOSFET is an N-channel MOSFET.

[0006] In conjunction with the first aspect, in the first embodiment of the first aspect, the first MOSFET is a WSP9435 MOSFET.

[0007] In conjunction with the first aspect, in the second embodiment of the first aspect, the second MOSFET is an AO3400 type MOSFET.

[0008] In conjunction with the first aspect, in the third embodiment of the first aspect, a first resistor R1 is connected between the gate of the second MOS transistor and the main control chip.

[0009] In conjunction with the first aspect, in the fourth embodiment of the first aspect, the gate of the second MOS transistor is connected between the BAT- terminal and the P- terminal through the second resistor R2.

[0010] In conjunction with the first aspect, in the fifth embodiment of the first aspect, the drain of the second MOS transistor and the gate of the first MOS transistor are connected to the P+ terminal through a third resistor R3. One end of the third resistor R3 is connected between the drain of the second MOS transistor and the gate of the first MOS transistor, and the other end of the third resistor R3 is connected to the P+ terminal.

[0011] In conjunction with the first aspect, in the sixth embodiment of the first aspect, the BAT+ terminal and the P+ terminal, and the BAT- terminal and the P- terminal are connected by a number of capacitors.

[0012] In conjunction with the sixth embodiment of the first aspect, in the seventh embodiment of the first aspect, the capacitor includes a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4.

[0013] In conjunction with the seventh embodiment of the first aspect, in the eighth embodiment of the first aspect, the first capacitor C1 and the third capacitor C3 are polarized capacitors, the positive terminals of the first capacitor C1 and the third capacitor C3 are connected between the BAT+ terminal and the P+ terminal, and the negative terminals of the first capacitor C1 and the third capacitor C3 are connected between the BAT- terminal and the P- terminal.

[0014] This utility model's reverse connection protection circuit prevents reverse current flow when BAT+ / BAT- is reversed. The parasitic diode inside the first MOSFET effectively limits reverse current flow, resulting in a zero voltage at P+ / P-. When BAT+ / BAT- is correctly connected, the main control chip controls the switching on and off of the second MOSFET. When the second MOSFET is on, the circuit operates normally, and the P+ / P- voltage equals the BAT+ / BAT- output voltage (i.e., the battery voltage), with virtually no voltage drop. This also effectively addresses the temperature issue. The circuit has a simple structure, and through the coordinated operation of its components, it effectively prevents reverse battery connection and reverse current flow, protecting electronic equipment and user safety while ensuring normal circuit switching on and off. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] in: Figure 1 A circuit diagram of a reverse polarity protection circuit in the prior art is shown; Figure 2 A circuit diagram of the reverse connection protection circuit for the battery provided by this utility model is shown. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] With technological advancements, there's a growing demand for convenient access to various electronic devices, such as portable oxygen concentrators, portable ventilators, and portable micro-mesh nebulizers. These portable electronic devices indirectly function as personal / family doctors. Considering that some users engage in outdoor activities and require access anytime, anywhere, these portable electronic devices utilize rechargeable aluminum batteries.

[0021] For safety reasons and to prevent equipment failure, a circuit to prevent reverse connection of the battery needs to be designed.

[0022] like Figure 1 As shown, traditional battery reverse connection protection or reverse current protection circuits use diodes. The required reverse connection protection or reverse current protection function is achieved based on the characteristics of the positive and negative terminals of the diode. However, the voltage drop of diodes is relatively large. Even when using Schottky diodes, the voltage drop is still relatively large, such as 0.5V, which makes them unsuitable for high current applications. At the same time, this type of reverse connection protection circuit is prone to overheating, resulting in a high overall temperature of the device and a certain amount of battery capacity loss, which shortens the device's discharge time.

[0023] To address the aforementioned issues, this specification provides a reverse connection protection circuit for batteries. For example... Figure 2 As shown, the circuit includes: A first MOSFET is connected between the BAT+ and P+ terminals. The drain of the first MOSFET is connected to the BAT+ terminal, and the source of the first MOSFET is connected to the P+ terminal. A second MOSFET is connected to the gate of the first MOSFET. The drain of the second MOSFET is connected to the gate of the first MOSFET, and the source of the second MOSFET is connected between the BAT- and P- terminals. The gate of the second MOSFET is connected to the main control chip. The main control chip is used to send a turn-on or turn-off signal to the second MOSFET. The first MOSFET is a P-channel MOSFET, and the second MOSFET is an N-channel MOSFET.

[0024] When zero or negative voltage is applied to the gate of a MOSFET, the electric field between the gate and the channel is very small, and there are no electrons or holes in the channel. The MOSFET is in the off state, and the resistance between the drain and the source is very large, which can be regarded as an open circuit state.

[0025] When a positive voltage is applied to the gate, the electric field between the gate and the channel increases, forming an electron-hole channel within the channel. When a positive voltage is applied to the source and a relatively high voltage is applied to the drain, electrons flow from the source into the channel and then into the drain. At this time, the MOSFET is in the linear region, and the resistance between the drain and source gradually decreases as the gate voltage increases, enabling signal amplification. When a positive voltage is applied to the gate and reaches a certain value, the electron concentration in the channel reaches its limit, and the MOSFET is in the saturation region. In the saturation region, the channel resistance is almost zero, and the resistance between the drain and source is also very small, enabling switching control.

[0026] MOSFETs possess various parameter characteristics, the most important of which include drain current, transfer conductance, cutoff voltage, and saturation voltage. Drain current refers to the current flowing from the drain when the MOSFET is operating. In the cutoff region, the drain current is very small and can be ignored. In the linear and saturation regions, the drain current varies with the gate voltage and drain-source voltage, and is generally represented by the MOSFET's characteristic curve. Transfer conductance refers to the relationship between the drain current and the gate voltage when the MOSFET is operating, usually expressed as the change in drain current per unit area divided by the change in gate voltage per unit area. In the linear region, the transfer conductance is essentially a constant and can be used to describe the amplification characteristics of the MOSFET. Cutoff voltage is the drain-source voltage when the gate voltage is zero, indicating that the MOSFET is in the cutoff state. The cutoff voltage is an important parameter of the MOSFET, determining its cutoff characteristics and input resistance. Saturation voltage is the minimum drain-source voltage when the MOSFET is in saturation. The saturation voltage is another important parameter of the MOSFET, determining its saturation characteristics and output resistance.

[0027] Unlike diode-based reverse connection protection, MOSFETs offer advantages such as lower voltage drop, smaller size, higher efficiency, and greater safety and reliability. Furthermore, MOSFETs come in a wider variety of materials, offering more flexible selection and enabling more efficient discharge of battery power.

[0028] The principle behind this circuit's reverse current / reverse connection protection is as follows: When BAT+ / BAT- is reversed, the parasitic diode inside the first MOSFET, Q1-MOS, prevents the current from flowing in reverse, effectively limiting the reverse current. At this time, the P+ / P- voltage is 0, which protects the electronic device battery, motherboard, and testing / assembly staff. It also effectively protects user safety when the equipment malfunctions. When BAT+ / BAT- is correctly connected, since the ON position is connected to the I / O port of the main control chip (MCU), the main control MCU will give the ON pin a specific setting signal (high or low level), which can control the conduction and shutdown of the second MOSFET, namely Q2-MOS. When the second MOSFET Q2-MOS is on, the circuit works normally, the P+ / P- voltage is equal to the BAT+ / BAT- output voltage, which is the battery voltage, and there is basically no voltage drop, which also solves the temperature problem well.

[0029] Preferably, the first MOSFET is a WSP9435 MOSFET and the second MOSFET is an AO3400 MOSFET.

[0030] It should be noted that the power, voltage, and current vary depending on the product, and all component parameters can be adjusted accordingly.

[0031] If the battery current is large when the electronic device is in use, a corresponding heat dissipation device can be considered at the position of the first MOSFET Q1-MOS.

[0032] In this embodiment, the BAT+ terminal and the P+ terminal, and the BAT- terminal and the P- terminal are connected by several capacitors, such as a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The first capacitor C1 and the third capacitor C3 are polarized capacitors; their positive terminals are connected between the BAT+ terminal and the P+ terminal, and their negative terminals are connected between the BAT- terminal and the P- terminal.

[0033] In this embodiment, a first resistor R1 is connected between the gate of the second MOS transistor and the main control chip. The first resistor R1 is configured to provide a driving voltage to the gate of the second MOS transistor, thereby indirectly controlling the switching state of the second MOS transistor.

[0034] In this embodiment, the gate of the second MOS transistor is connected between the BAT- terminal and the P- terminal through the second resistor R2, and the second resistor R2 serves to protect the second MOS transistor.

[0035] In this embodiment, the drain of the second MOSFET and the gate of the first MOSFET are connected to the P+ terminal through a third resistor R3. One end of the third resistor R3 is connected between the drain of the second MOSFET and the gate of the first MOSFET, and the other end of the third resistor R3 is connected to the P+ terminal. The setting of the third resistor R3 can effectively limit the current flowing through the drain of the second MOSFET, thereby protecting the second MOSFET.

[0036] This utility model's reverse connection protection circuit prevents reverse current flow when BAT+ / BAT- is reversed. The parasitic diode inside the first MOSFET effectively limits reverse current flow, resulting in a zero voltage at P+ / P-. When BAT+ / BAT- is correctly connected, the main control chip controls the switching on and off of the second MOSFET. When the second MOSFET is on, the circuit operates normally, and the P+ / P- voltage equals the BAT+ / BAT- output voltage (i.e., the battery voltage), with virtually no voltage drop. This also effectively addresses the temperature issue. The circuit has a simple structure, and through the coordinated operation of its components, it effectively prevents reverse battery connection and reverse current flow, protecting electronic equipment and user safety while ensuring normal circuit switching on and off.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A reverse connection protection circuit for a battery, characterized in that, include: A first MOSFET is connected between the BAT+ terminal and the P+ terminal. The drain of the first MOSFET is connected to the BAT+ terminal, and the source of the first MOSFET is connected to the P+ terminal. A second MOSFET is connected to the gate of the first MOSFET. The drain of the second MOSFET is connected to the gate of the first MOSFET. The source of the second MOSFET is connected between the BAT- terminal and the P- terminal. The gate of the second MOSFET is connected to the main control chip. The main control chip is used to send a turn-on or turn-off signal to the second MOSFET. The first MOSFET is a P-channel MOSFET, and the second MOSFET is an N-channel MOSFET. A first resistor R1 is connected between the gate of the second MOSFET and the main control chip; The BAT+ and P+ terminals are connected to the BAT- and P- terminals via several capacitors. The capacitors include a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4; The first capacitor C1 and the third capacitor C3 are polarized capacitors. The positive terminals of the first capacitor C1 and the third capacitor C3 are connected between the BAT+ terminal and the P+ terminal, and the negative terminals of the first capacitor C1 and the third capacitor C3 are connected between the BAT- terminal and the P- terminal.

2. The reverse connection protection circuit for the battery according to claim 1, characterized in that, The first MOSFET used is the WSP9435 model.

3. The reverse connection protection circuit for the battery according to claim 1, characterized in that, The second MOSFET is an AO3400 model MOSFET.

4. The reverse connection protection circuit for the battery according to claim 1, characterized in that, The gate of the second MOSFET is connected between the BAT- terminal and the P- terminal through the second resistor R2.

5. The reverse connection protection circuit for the battery according to claim 1, characterized in that, The drain of the second MOSFET is connected to the gate of the first MOSFET via a third resistor R3 and to the P+ terminal. One end of the third resistor R3 is connected between the drain of the second MOSFET and the gate of the first MOSFET, and the other end of the third resistor R3 is connected to the P+ terminal.

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