Battery over-current charging protection circuit

Abstract

The invention discloses a battery over-current charging protection circuit. The circuit comprises a V2I voltage-to-current conversion module, an over-current charging protection threshold voltage setting module, a comparator, a negative high voltage bearing module, a positive power input port VDD, a grounding input port VSS, an input port OCP and an input port CS. The V2I voltage-to-current conversion module is electrically connected with the over-current charging pack threshold voltage setting module, the comparator is respectively connected with the negative high voltage bearing module and the over-current charging protection threshold voltage setting module in parallel, and the positive power supply input port VDD is a positive power supply. The grounding input port VSS is a negative power supply; the input port CS is a current induction input port, and the input port CS is connected with the battery. The invention belongs to the technical field of battery charging, and particularlyprovides a battery over-current charging protection circuit which is high in process adaptability, high in precision, high in safety and capable of covering wider application.

Description

technical field [0001] The invention belongs to the technical field of battery charging, and specifically refers to a battery overcurrent charging protection circuit. Background technique [0002] With the continuous rapid development of the Internet of Things, big data, and artificial intelligence technology, the era of the Internet of Everything has arrived, and the lithium battery industry is no exception. Therefore, higher requirements are put forward for the safety and reliability of lithium battery power supply. China National Standard No. 27 in 2014 was published, and the national mandatory standard "Safety Requirements for Lithium-ion Batteries and Battery Packs for Portable Electronic Products" (GB31241-2014) has been approved and published by the General Administration of Quality Supervision, Inspection and Quarantine and the National Standardization Management Committee. The safety requirements of all lithium battery products must meet this national standard. Amo...

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Problems solved by technology

[0003] In order to realize the over-current charging detection function, one of the most direct methods is to use a negative reference voltage and a comparator that supports negative common-mode input voltage, and directly input the negative voltage detected by the CS pin of the chip into the chip for comparison. One input terminal of the comparator, while the other input terminal of the comparator is connected to the negative reference reference voltage, but to generate a negative reference reference voltage and implement a comparator that supports negative common-mode input voltage, the design complexity and The cost of the product is unacceptable, and the requirements for process control are high. The yield rate of the packaged product is low, and the accuracy range and temperature characteristics are not up to the application standards of high-end lithium battery protection ICs. There are still certain potential safety hazards.

[0004] In the prior art, there is a type of overcurrent charging protection circuit that avoids the two difficulties of using a negative reference voltage generation circuit and a comparator that supports negative common-mode input voltage. Although it can meet the product requirements of some low-end application markets, However, it actually has relatively large defects or flaws, which cannot meet the high-precision requirements and parameter serialization of high-end lithium battery protection ICs, and there are certain potential safety hazards in use.

First, the overcurrent charging protection threshold voltage fluctuates greatly with the process, and a better manufacturing process is required to reduce the threshold voltage fluctuation at room temperature; second, even if the reference voltage trimming circuit is used to reduce the fluctuation caused by the process , there will still be a part of the product yield loss after packaging, which will lead to a significant increase in product cost; third, although the reference voltage trimming circuit can reduce the fluctuation range of the overcurrent charging protection threshold voltage at room temperature, it is The threshold voltage fluctuation in a wide temperature range is still large, that is, the accuracy is poor; fourth, when the absolute value of the overcurrent charging protection threshold voltage is small, due to its poor temperature characteristics, there are serious problems in working at lower or higher temperatures. It cannot meet the application requirements of small absolute value of the over-current charging protection threshold voltage, and it is easy to cause the over-current charging protection threshold voltage to become a positive value. In this way, not only the over-current charging protection function fails, but also other functions of the entire chip will be damaged. Exception, which is a serious security risk

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