Lithium battery converter

Along with the digital products such as the widespread use of mobile phones, laptops and other products,Lithium ion batteries with excellent performance is widely used in such products, and gradually to other areas of application development products in recent years.In 1998, Tianjin institute of power began commercial production of lithium ion battery.Traditionally, people called the lithium ion battery also lithium battery now, lithium ion battery has become the mainstream.

Lithium battery is a kind of lithium metal or lithium alloy anode materials, the use of water battery electrolyte solution.First appear in the lithium battery from the great inventor Thomas Edison, use the following response: Li + MnO2 = LiMnO2 for the REDOX reaction, the reaction of discharge.Due to the lithium chemistry is very lively, making lithium metal processing, storage, use, very high demand on the environment.So, the lithium battery has not been applied for a long time.The lithium battery has now become the mainstream.Due to the lithium chemistry is very lively, making lithium metal processing, storage, use, to the environment requirement is very high, so the lithium battery production under special environment conditions.But because of the many advantages of lithium-ion batteries, lithium batteries are widely used in electronic instruments, digital products and home appliances.However, most lithium batteries are secondary batteries, there is also a disposable batteries.A few of the secondary battery life and safety of more bad.

Figure 1. The main functions of the charging control chip

Figure 2 charge characteristic instance

Laptop battery driven time depends on a full charge when the battery voltage, if the battery voltage is higher then drive for a long time, so high voltage battery as well as much as possible.But in order to safely for lithium ion batteries, the need to control the charging voltage, make its not exceed the allowable voltage value of the lithium ion battery.Set the charging voltage, as well as considering the voltage precision, and want to keep certain allowance, so that it is not beyond the upper limit of safety.Usually, charging set voltage + 100 mv changes will cause the change of the battery capacity plus or minus 10%.

Because the Nch/Nch synchronous rectifier type synchronous part used the FET, as a result, the output voltage is lower than that of the low input voltage Duty condition, efficiency is also higher.Constant current charging, large current makes the computer case fever.Asynchronous mode rectifier with synchronous rectifier compared with no booster circuit, also need not CB capacitance and the boost diode, can be made up of simple external circuit, the layout of the wiring so components is relatively easy.

Fujitsu semiconductor lithium-ion battery charging control chip voltage accuracy of plus or minus 0.5%, on the basis of fully considering the safety margin, rated maximum voltage security charge.In addition, the charging voltage and charging current of the initial setup without resistance, to cut the use of components (BOM).In addition, Fujitsu added Nch/for its product lineup Nch synchronous rectifier type and Pch/Di asynchronous rectifier type two kinds of different function of the product for the user to choose from.

Fujitsu microelectronics MB39A132 / MB39A134 has a constant pressure control loop and two constant current control loop, according to the residual voltage of battery automatic switch charging mode, to control the charging.This series of products also have the chip when the standby can be independently ACOK function, and without an external resistor to set the initial charging current and voltage setting function.

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