Intelligent lithium ion battery charging controller application design

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Overview:
Rechargeable lithium-ion battery chargers are widely used in life. This article introduces Linear's new intelligent lithium-ion battery charge controller LTC4007, which can control large-current charging of multi-cell lithium-ion batteries and provide status indication. Interface for easy external expansion of applications. The practical application shows that the various parameters of the charging circuit designed with LTC4007 as the core can meet the design requirements.

1. Introduction With the development of high technology, various electronic products continue to move toward low power consumption and miniaturization, so that people can carry it around in their lives. A common feature of these products is the use of batteries as a power source, such as mobile phones, MP4, portable measuring equipment and other products. There are many types of batteries. Currently, lithium-ion batteries are widely used. Compared with traditional lead-acid and nickel-cadmium batteries, these batteries have higher specific energy, less self-discharge, higher operating voltage, longer service life, less pollution, etc. Advantages, but lithium-ion batteries also have their own shortcomings, which have strict requirements on charging current, voltage, temperature, etc., if you are not careful, it may cause damage and scrapping of the battery.
The LTC4007EGN chip introduced in this article is a new lithium-ion battery intelligent charging controller from Linear, which is customized according to the characteristics of lithium-ion batteries. It has high current constant current, constant voltage and timed charging for three- or four-cell lithium-ion battery packs. Various functions such as overheat protection, the practical application shows that the controller can charge large currents to the lithium battery pack, and its small SSOP24 package is especially suitable for applications with high integration and limited board space.

2. Controller introduction
The LTC4007 package is shown in Figure 1, which has the following performance characteristics:
(1) charging a 3- or 4-cell lithium-ion battery pack;
(2) Conversion efficiency is as high as 96%;
(3) The maximum output current exceeds 4A;
(4) The charging voltage accuracy can reach ±0.8%;
(5) Built-in overheat protection function;
(6) With AC adapter current limit function;
(7) Charging current output monitoring;
(8) Working status indication: charging, C/10 charging current, adapter connection, battery low voltage, input current limit, fault.

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