CN216649275U

CN216649275U - Lithium battery protection and passivation prevention circuit

Info

Publication number: CN216649275U
Application number: CN202123385924.2U
Authority: CN
Inventors: 冯时; 杨鑫; 陶文强; 胡波
Original assignee: Sino Tech Smart Energy Technology Chengdu Co ltd
Current assignee: Sino Tech Smart Energy Technology Chengdu Co ltd
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2022-05-31
Anticipated expiration: 2031-12-29

Abstract

The utility model discloses a lithium battery protection and passivation prevention circuit, which comprises: the device comprises a lithium battery, a discharge circuit, an AD detection circuit and a lithium battery output control circuit U1; the output end of the lithium battery is respectively connected with the input end of the discharge circuit, the input end of the AD detection circuit and the input end of the lithium battery output control circuit U1; the utility model solves the problems that a layer of passive film is formed on the surface of the lithium ion battery which does not work for a long time and the lithium ion battery is reversely charged.

Description

Lithium battery protection and passivation prevention circuit

Technical Field

The utility model relates to a battery protection circuit, in particular to a lithium battery protection and passivation prevention circuit.

Background

At present, the power supply mode of the civil and commercial Internet of things is mainly alkaline batteries and lithium ion batteries, the alkaline batteries are mostly used according to market research, the alkaline batteries are mainly easy to purchase and convenient to replace, the Internet of things gas meter is controlled within 50uA according to national standard power consumption, the lithium batteries can meet the requirement of the age limit through calculation, but the lithium batteries are greatly influenced by temperature and environment, if the lithium batteries cannot reach the service life, the replacement is troublesome, and therefore, the use of various manufacturers is not achieved at present. In order to complete the actions of communication, liquid crystal, switch valve and the like after power failure in practical use, most gas meter manufacturers adopt an alkaline battery to match with a small-capacity lithium ion battery, the alkaline battery is used as a main power supply for supplying power, when the electric quantity of a main power supply is insufficient or power failure occurs, the main power supply is switched to a standby lithium ion battery for supplying power, the lithium ion battery cannot be reversely charged during switching, the reverse charging easily causes damage or explosion of the lithium ion battery, meanwhile, the lithium ion battery can form a passivation film on the surface which does not work for a long time, the longer the time, the thicker the passivation film is, and if the lithium ion battery is unreasonably utilized, large current cannot be released when the lithium ion battery is needed.

In order to solve the problem that a lithium ion battery is not reversely charged and passivated, a conventional reverse leakage prevention conventional mode is to use a silicon tube similar to 1N4007, but the voltage drop is large, and the power supply requirements of communication modules similar to NB and CAT.1 cannot be met.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects in the prior art, the lithium battery protection and passivation prevention circuit provided by the utility model solves the problems that a layer of passivation film is formed on the surface of a lithium ion battery which does not work for a long time, and the lithium ion battery is reversely charged.

In order to achieve the purpose of the utility model, the utility model adopts the technical scheme that: a lithium battery protection and anti-passivation circuit comprising: the lithium battery, the discharge circuit, the AD detection circuit and the lithium battery output control circuit U1;

the output end of the lithium battery is respectively connected with the input end of the discharge circuit, the input end of the AD detection circuit and the input end of the lithium battery output control circuit U1.

Further, the discharge circuit includes: the transistor comprises a resistor R1, a resistor R2, a triode Q1, a resistor R3, a capacitor C1, a resistor R4, a resistor R5 and a PMOS tube M1;

one end of the resistor R1 is used as a discharge control end of the discharge circuit, and the other end of the resistor R1 is respectively connected with one end of the resistor R2 and the base electrode of the triode Q1; the collector of the triode Q1 is grounded, and the emitter of the triode Q1 is respectively connected with the other end of the resistor R2 and one end of the resistor R3; the other end of the resistor R3 is respectively connected with one end of a capacitor C1, one end of a resistor R4 and the grid electrode of the PMOS transistor M1; the drain electrode of the PMOS tube M1 is grounded, and the source electrode of the PMOS tube M1 is connected with one end of a resistor R5; the other end of the resistor R5 is connected with the other end of the resistor R4 and the other end of the capacitor C1 respectively and is used as an input end of the discharge circuit.

The beneficial effects of the further scheme are as follows: when the discharge control end is at a high level, the triode Q1 is not conducted, and when the discharge control end is at a low level, the voltage difference between the emitter and the base of the triode Q1 is greater than the turn-on threshold voltage, the triode Q1 is conducted, so that the resistor R3 is grounded, the resistance value of the resistor R4 is far greater than that of the resistor R3, and further, the voltage between the gate and the source of the PMOS transistor M1 is approximately equal to the output voltage of the lithium battery, so that the source and the drain of the PMOS transistor M1 are conducted.

Further, the resistor R5 is a high power resistor.

Further, the transistor Q1 is a PNP transistor.

Further, the AD detection circuit includes: a resistor R6, a grounding resistor R7 and a grounding capacitor C1;

the grounding resistor R7 is respectively connected with one end of a grounding capacitor C1 and one end of a resistor R6 and is used as an AD sampling end of the AD detection circuit; the other end of the resistor R6 is used as the input end of the AD detection circuit.

Further, the discharge circuit includes: the transistor comprises a resistor R8, a grounding resistor R9, a triode Q2, a resistor R10, a grounding resistor R11, a resistor R12 and an NMOS transistor M2;

the base electrode of the triode Q2 is respectively connected with one end of a resistor R8 and a grounding resistor R9, the emitter electrode of the triode Q2 is grounded, and the collector electrode of the triode Q2 is respectively connected with one end of a resistor R10, a grounding resistor R11 and the grid electrode of an NMOS tube M2; the other end of the resistor R8 is used as a discharge control end of the discharge circuit; the other end of the resistor R10 is connected with one end of the resistor R12 and is used as the input end of the discharge circuit; the drain of the NMOS transistor M2 is connected with the other end of the resistor R12, and the source thereof is grounded.

The beneficial effects of the further scheme are as follows: when the discharge control end is at a high level, the triode Q2 is turned on, so that the gate voltage of the NMOS transistor M2 is very low, the source and the drain of the NMOS transistor M2 cannot be turned on, and when the discharge control end is at a low level, the triode Q2 is turned off, and the source and the drain of the NMOS transistor M2 are turned on through the voltage division of the resistor R11 and the resistor R10.

Further, the resistor R12 is a high power resistor.

Further, the transistor Q2 is an NPN transistor.

The utility model has the beneficial effects that:

1. through the use of a discharge circuit, for preventing passivation of the lithium battery.

2. The lithium battery is not reversely charged through the lithium battery output control circuit U1.

Drawings

FIG. 1 is a circuit diagram of a lithium battery protection and passivation prevention circuit;

FIG. 2 is a discharge circuit of embodiment 2;

fig. 3 is a circuit diagram of the lithium battery output control circuit U1;

fig. 4 is a current-voltage curve diagram of the lithium battery output control circuit U1.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the utility model as defined and defined in the appended claims, and all matters produced by the utility model using the inventive concept are protected.

Example 1:

as shown in fig. 1, a lithium battery protection and passivation prevention circuit includes: the lithium battery, the discharge circuit, the AD detection circuit and the lithium battery output control circuit U1;

The discharge circuit includes: the transistor comprises a resistor R1, a resistor R2, a triode Q1, a resistor R3, a capacitor C1, a resistor R4, a resistor R5 and a PMOS tube M1;

When the discharge control end is at a high level, the triode Q1 is not conducted, and when the discharge control end is at a low level, the voltage difference between the emitter and the base of the triode Q1 is greater than the turn-on threshold voltage, the triode Q1 is conducted, so that the resistor R3 is grounded, the resistance value of the resistor R4 is far greater than that of the resistor R3, and further, the voltage between the gate and the source of the PMOS transistor M1 is approximately equal to the output voltage of the lithium battery, so that the source and the drain of the PMOS transistor M1 are conducted.

The resistor R5 is a high-power resistor and is used for discharging voltage and current.

The triode Q1 is a PNP type triode, the model of the triode Q1 is 8550, and the model of the PMOS tube is 3401.

In this embodiment, the lithium battery may be 18650 or 14250, and when the PMOS transistor M1 is turned on, the lithium battery passes through the resistor R5 and then reaches the PMOS transistor M1 to form a loop, so as to wake up the battery, thereby preventing the passivation of the lithium battery.

The AD detection circuit includes: a resistor R6, a grounding resistor R7 and a grounding capacitor C1;

The voltage of the lithium battery is divided by the R6 and the R7 to transmit an analog signal of the voltage of the battery to an AD detection module part in the singlechip, the values of R6 and R7 are necessary to be reasonable, the resistance value is too small and can be overheated, the power consumption is high, and the serious temperature drift can be caused if the value is too large. In the present embodiment, R6 has a value of 2 M.OMEGA.and R7 has a value of 1 M.OMEGA..

The electric quantity of the lithium battery is monitored at any time through the AD detection circuit.

Example 2:

in addition to embodiment 1 described above, the discharge circuit is replaced with the structure of the present embodiment, and as shown in fig. 2, the discharge circuit includes: the transistor comprises a resistor R8, a grounding resistor R9, a triode Q2, a resistor R10, a grounding resistor R11, a resistor R12 and an NMOS transistor M2;

When the discharge control end is at a high level, the triode Q2 is switched on, so that the gate voltage of the NMOS tube M2 is very low, the source and the drain of the NMOS tube M2 cannot be switched on, and when the discharge control end is at a low level, the triode Q2 is switched off, and the source and the drain of the NMOS tube M2 are switched on through the voltage division of the resistor R11 and the resistor R10, so that the discharge of the lithium battery is realized.

The resistor R12 is a high power resistor and functions in accordance with the resistor R5.

The transistor Q2 is an NPN type transistor.

Example 3:

on the basis of the foregoing embodiment 1 or 2, U1 is MAX40203 as shown in fig. 3, and the on/off of the MOS transistor therein is controlled by EN, so as to achieve the conduction from VDD to the OUT terminal. When the average current is 50mA, as shown in FIG. 4, the relation between the forward current and the forward voltage shows that when the current is about 50mA, the voltage drop of the voltage is within 100mV, which can be basically ignored. The input that the lithium battery power was inserted to the VDD pin, the OUT pin connects the load port, and the singlechip is connected to the EN foot, when the singlechip detected main power supply alkaline battery electric quantity not enough or fall the power, accessible singlechip control EN foot, the output of effectual management lithium battery voltage with end, make the electric quantity of lithium cell obtain make full use of, increase of service life.

The utility model monitors the electric quantity of the lithium battery, fully utilizes the electric quantity and fully uses the lithium battery. Compared with the prior art, the prior art conventionally uses a silicon tube similar to 1N4007, but the voltage drop is large, so that the power supply requirements of communication modules similar to NB-IoT and CAT.1 cannot be met, and if a Schottky diode is used, the leakage current of a main power supply can flow to a lithium battery, so that the lithium battery is damaged. In the prior art, a battery capacitor is added, and the battery capacitor is equivalent to a load, so that the battery capacity is effectively stored and circulated. However, the current cost of the battery capacitor is higher, the price of the battery capacitor is about 8RMB on the market, and compared with the technology of the utility model, the cost is increased by a lot.

Claims

1. A lithium battery protection and passivation prevention circuit, comprising: the lithium battery, the discharge circuit, the AD detection circuit and the lithium battery output control circuit U1;

the output end of the lithium battery is respectively connected with the input end of the discharge circuit, the input end of the AD detection circuit and the input end of the lithium battery output control circuit U1;

the discharge circuit is used for discharging the lithium battery; the AD detection circuit is used for collecting the voltage of the lithium battery; the lithium battery output control circuit U1 is used for controlling the voltage output of the lithium battery.

2. The lithium battery protection and passivation prevention circuit of claim 1, wherein the discharge circuit comprises: the transistor comprises a resistor R1, a resistor R2, a triode Q1, a resistor R3, a capacitor C1, a resistor R4, a resistor R5 and a PMOS tube M1;

3. The lithium battery protection and passivation prevention circuit of claim 2, wherein the resistor R5 is a high power resistor.

4. The lithium battery protection and passivation prevention circuit as claimed in claim 2, wherein the transistor Q1 is a PNP type transistor.

5. The lithium battery protection and passivation prevention circuit of claim 1, wherein the AD detection circuit comprises: a resistor R6, a grounding resistor R7 and a grounding capacitor C1;

6. The lithium battery protection and passivation prevention circuit of claim 1, wherein the discharge circuit comprises: the transistor comprises a resistor R8, a grounding resistor R9, a triode Q2, a resistor R10, a grounding resistor R11, a resistor R12 and an NMOS transistor M2;

7. The lithium battery protection and passivation prevention circuit of claim 6, wherein the resistor R12 is a high power resistor.

8. The lithium battery protection and passivation prevention circuit as claimed in claim 6, wherein the transistor Q2 is an NPN transistor.