R03 Carbon battery.Highly integrated single-chip lithium battery protection solution

　　Highly integrated single-chip lithium battery protection solution

　　At present, lithium batteries are used more and more widely, from mobile phones, MP3, MP4, GPS, toys and other portable devices to gas meters that need to continuously save data, and their market capacity has reached hundreds of millions per month. In order to prevent the battery life from being affected by abnormal conditions such as overcharge, over-discharge, and over-current of the lithium battery, a lithium battery protection device is usually used to prevent damage to the battery due to abnormal conditions.

　　The circuit principle of the lithium battery protection device is shown in Figure 1, which is mainly implemented by the battery protection control IC and the external discharge switch M1 and charging switch M2. When the p+/p- terminal is connected to the charger and the battery is charged normally, M1 and M2 are both in the conductive state; when the control IC detects a charging abnormality, M2 is turned off to terminate charging. When the p+/p- terminal is connected to the load and the battery is discharging normally, both M1 and M2 are turned on; when the control IC detects a discharge abnormality, M1 is turned off to terminate the discharge.

　　Figure 1: Circuit principle of lithium battery protection device.

　　Several existing lithium battery protection solutions

　　In recent years, there has been a trend in the industry to package several chips together to improve integration and reduce the area of the final solution. The lithium battery protection market is no exception. The two lithium battery protection solutions A and B in Figure 3 appear to integrate the two chips in Figure 2 into one chip, but in fact the controller IC and switch chip inside the package are still separate and come from different sources. manufacturer, this solution just seals the two together, commonly known as "two cores in one".

　　Figure 3: “Two cores in one” lithium battery protection solution.

　　Since the two internal chips actually come from different manufacturers, their shapes cannot match well, resulting in different final package shapes, and in many cases a universal package cannot be used. This kind of package is relatively large and cannot save peripheral components, so this "two-core-in-one" solution actually does not save much space. In terms of cost, although the cost of two packages is reduced to the cost of one package, because this package is usually relatively large, some are not universal packages, and some need to use chip stacking packaging in order to reduce the package size, so it is different from the traditional package. Compared with the two chip solutions, the cost advantage is not obvious.

　　Although the above "two-core-in-one" solution and single-chip anode protection solution bring certain advantages to users in terms of solution area and cost, the advantages are still not obvious. These solutions also bring some disadvantages. Therefore, in the process of competing with mature traditional solutions for customers, they can only fight price wars by reducing gross profit margins. Since the real original cost of these solutions has no obvious advantage, with the price reduction of the control IC and switch tube chips of the traditional solutions, these "two-core-in-one" solutions or positive electrode protection solutions have not been able to shake the market dominance of the traditional solutions. status.

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