18650 lithium rechargeable battery

　　Four major development directions of switching 18650 lithium rechargeable battery technology

　　Currently, switching power supplies made in China account for 80% of the world market, but we have almost no share in the high-end market. Our country is currently short of energy, and the 18650 lithium rechargeable battery industry is an industry closely related to energy consumption. Therefore, the government and academic groups need to provide guidance on the development direction of 18650 lithium rechargeable battery in several aspects.

　　1. Rapid development of non-isolated DC/DC technology

　　In recent years, non-isolated DC/DC technology has developed rapidly. Currently, a set of electronic equipment or electronic systems requires the 18650 lithium rechargeable battery system to provide multiple voltage levels due to different loads. For example, desktop PCs require four voltages: +12V, +5V, +3.3V, -12V and +5V for standby. Motherboards require 2.5V, 1.8V, 1.5V or even 1V, etc. It is impossible to provide so much voltage output in a set of AC/DC, and most low-voltage 18650 lithium rechargeable battery currents are very large, so many non-isolated DC/DCs have been developed, and they can basically be divided into two categories. One type contains power switching components inside, called DC/DC converter. The other type does not contain a power switch and requires an external power MOSFET, which is called a DC/DC controller. According to the circuit function, there are STEP-DOWN to reduce voltage, BOOST to boost voltage, BUCK-BOOST or SEPIC to increase and decrease voltage, and INVERTOR to convert positive pressure into negative pressure. Among them, the one with the most varieties and the fastest development is STEP-DOWN, which reduces blood pressure. According to the size of the output current, it is divided into single-phase, two-phase and multi-phase. The control method is mainly PWM, and a small part is PFM.

　　In non-isolated DC/DC conversion technology, TI's pre-detection gate drive technology uses digital technology to control synchronous BUCK. The DC/DC conversion efficiency using this technology can reach up to 97%, among which TPS40071 and others are its representative products. In the BOOST boost method, there are also synchronous BOOST products that use MOSFETs instead of diodes. In the low-voltage domain, efficiency increases are substantial, and efforts are being made to further eliminate MOSFET body diode conduction and reverse recovery problems.

　　2. Switching 18650 lithium rechargeable battery blows the horn of digitalization

　　At present, in the entire electronic analog circuit system, televisions, audio equipment, photo processing, communications, networks, etc. have gradually realized digitization, and the last bastion without digitization is the 18650 lithium rechargeable battery field. In recent years, the research momentum of digital 18650 lithium rechargeable battery has continued unabated and the results have been increasing. Companies leading the way in power digitization include TI and Microchip. TI not only has advantages in DSP, but also merged with UNITRODE, a professional PWMIC manufacturer. The company has used TMS320C28F10 to make a 48V output high-power power module for communications, in which the PFC and PWM parts are completely digitally controlled. Now, TI has developed a variety of digital PWM control chips. Currently, they are mainly UCD7000 series, UCD8000 series and UCD9000 series, which will become the pathfinders of the next generation of digital power supplies. They generally include both hardware parts and software programming. The hardware part includes the PWM logic part, clock, analog-to-digital conversion of the amplifier loop, digital-to-analog conversion, digital processing, driving, detection and processing of synchronous rectification, etc.

　　At present, the competition in the 18650 lithium rechargeable battery field is mainly about performance and price, so digital 18650 lithium rechargeable battery still has a long way to go. However, the clarion call for digitalization in the 18650 lithium rechargeable battery field has already sounded.

　　3. Continuous optimization of primary PWM control IC

　　Active clamping technology has been enduring for more than ten years. Since the expiration of VICOR's patented technology in 2002, new active clamping control ICs developed by various companies have sprung up, providing users with sufficient choose.

　　TI, which controlled early active clamp control technology, not only maintained the original UCC3580 series, but also developed the UCC2891-94 with superior performance. It uses a current mode control method and combines high-side clamping and low-side clamping. Two control schemes provide brand-new control techniques. OnSemi first launched the NCP1560 control chip with low voltage (100V) active clamping, and then launched the NCP1280 control chip for high-voltage applications. It not only solved the power requirements of LCDTV plasma TV, but now it is directed towards the next generation of fanless PCs. 18650 lithium rechargeable battery.

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