Analyze digital product lithium battery charging control DC

Digital product lithium battery charge control DC/DC converter circuit diagram analysis With the widespread use of digital products such as mobile phones, notebook computers and other products, lithium batteries have been widely used in such products, with excellent performance, and gradually in recent years Apply to other product areas. In 1998, Tianjin Electric Power Research Institute began commercial processing of lithium batteries. Traditionally, lithium batteries, also known as lithium batteries, have become mainstream. Lithium batteries are batteries in which lithium metal or lithium alloy is used as the negative electrode material and a non-aqueous electrolyte solution is used as the electrolyte. The first lithium battery invented by the great inventor Thomas Edison used the following reaction: lithium + MnO2 u003d LiMnO2. Because the chemical properties of metal lithium are very active, the production, storage, and use of metal lithium have very high environmental requirements. Therefore, lithium batteries have not been used for a long time. Lithium batteries are now the mainstream. Due to the very active chemical properties of lithium metal, there are high environmental requirements for the production, storage and application of lithium metal, so the processing of lithium batteries should be carried out under special environmental conditions. However, because lithium batteries have many advantages, they are widely used in electronic products, digital products and household appliances. However, most lithium batteries are secondary batteries, and there are also disposable batteries. A few secondary batteries have poor life and safety. The battery drive time of a notebook computer depends on the voltage when the battery is fully charged. If the battery voltage is high, the driving time is long. Therefore, it is best to end the charging with a high voltage as much as possible. However, in order to safely charge the lithium battery, the charging voltage must be controlled so that it does not exceed the allowable voltage value of the lithium battery. When setting the charging voltage, it is necessary to consider the voltage accuracy and maintain a certain margin so that it does not exceed the safety upper limit. Under normal circumstances, the charging setting voltage changes ±100mV, and the battery capacity changes ±10%. Since the synchronization part of the Nch/Nch synchronous rectifier uses FETs, in the low duty cycle state, when the output voltage is lower than the input voltage, the power will increase. When charging with constant current, a large current short circuit causes the case to heat up. Compared with the synchronous rectifier, the asynchronous rectifier has no boost circuit, no CB capacitor and boost diode, and can be composed of a simple external circuit, so the device layout and wiring are relatively simple. The voltage accuracy of Fujitsu Semiconductor's lithium battery charging control chip can reach ±0.5%, and the maximum voltage is added for safe charging on the basis of full consideration of safety margin. In addition, the charging voltage and charging current are initially set without external resistors, which reduces the number of components in use (BOM). In addition, Fujitsu has added Nch/Nch synchronous rectifiers and Pch/Di asynchronous rectifiers to meet different functions. Fujitsu's MB39A132/MB39A134 has 1 constant voltage control loop and 2 constant current control loops, which can automatically switch the charging mode according to the battery's remaining voltage to control charging. This series of products also have the ACOK function of chip standby and independent operation, as well as the initial setting function of charging current and voltage, and no external resistance is required. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: What fields are lithium cobalt oxide batteries commonly used in?