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Release date：2019-12-12 Views：2050
1. Introduction
With the popularity of 4G network and the advent of 5g era, the battery capacity of mobile phone is increasing to meet the high energy consumption requirements of various applications such as mobile Internet. Using traditional charging technology, the charging time is longer and longer, which can not meet the daily needs. Fast charging technology emerges as the times require, which enables people to recover the power quickly by using the fragmented time, which has gradually become the standard configuration of more and more mobile phones.
There are two different technical routes for fast charging: high voltage small current fast charging and low voltage high current fast charging. The representative of high pressure fast charging is high pass. The first qc2.0 launched by Qualcomm around 2014 will increase the charging voltage from the traditional 5V to 9V / 12V and the charging power to 18W. However, there is an insurmountable disadvantage of high voltage fast charging, which is that the charging IC is heated seriously. When the 9V / 12V voltage output from the adapter enters the mobile phone, it will be depressurized and recharged by the buck charger inside the mobile phone. The traditional buck converter has low conversion efficiency under high voltage input conditions, resulting in the chip heating is very serious, and the power can not be further improved.
Oppo and Huawei are the representatives of low pressure direct charging technology. Oppo launched the vooc flash charging technology of 22.5w (5V / 4.5a) in 2014. Because the low-voltage fast charging does not need the voltage conversion of the intermediate stage, the real adapter can directly charge the battery, so the heating problem of charging IC is well solved. However, in order to solve the problems such as low current carrying capacity of microb interface and high resistance of traditional charging wire, low-voltage fast charging needs to customize charging interface and charging line, and the cost is higher than that of high-voltage fast charging scheme.
2. Charge pump fast charge
Charge pump is a kind of non inductive DC-DC converter, which uses capacitor as energy storage element to transform voltage and current. The half voltage charge pump (2:1 charge pump) can reduce the output voltage by half and double the output current. At the same time, the conversion efficiency can reach more than 97%, which is much higher than that of the ordinary charging IC. Thus, the heating problem of charging IC during high-voltage fast charging is well solved. In addition, since the charge pump can naturally realize the effect that the input current is half of the output current, the cost of wire and interface can be greatly reduced compared with the low-voltage direct charging scheme.
It can be seen that charge pump fast charging can perfectly resolve the contradiction between high voltage and high current, breaking through the limit of mobile phone fast charging.
Figure 1. Typical application of sc8551
c) Perfect protection mechanism
Sc8551 integrates 26 different protection mechanisms to ensure the safety and reliability of charging process. The protection mechanism can be divided into three types: 12 system level protection, 7 heavy charge pump related protection and 7 system level alarm. After the system level protection and charge pump related protection are triggered, sc8551 will stop charging and interrupt int. After the system level alarm is triggered, the int interrupt will also occur, but the charging will not stop.
4. Conclusion
Sc8551 is the first high voltage charge pump fast charging IC in China, which is compatible with charge pump fast charging and low voltage direct charging. The maximum charging current reaches 8A in charge pump fast charging mode and 6A in low voltage direct charging mode. With the excellent performance of heavy load efficiency and comprehensive protection mechanism, sc8551 is very suitable for high-power charging of mobile phones.
5. About Nanxin
Shanghai Nanxin Semiconductor Technology Co., Ltd. was established in Zhangjiang High Tech Park, Pudong, Shanghai at the end of 2015. Nanxin's start-up team is from Texas Instruments, with more than 10 years of industry experience, and has been working together for many years in the field of power supply. With the development of the company, Nanxin continues to introduce excellent talents and build a high-quality R & D team. At present, it has R & D teams from well-known semiconductor companies such as Texas Instruments, Lingte, Likai, ADI, Rohm and O2. Adhering to the product culture of continuous innovation, it is committed to providing IC solutions with high performance, high quality and high economic benefits for the industry.
In the field of fast charging and power management chips, SMIC has been leading the domestic peers. It has launched the industry's first buck boost boost battery charging management IC, which can realize bi-directional intelligent charging and discharging of up to 100W power in the range of 2.7-40v, and efficiently supports USB PD high-power charging and discharging applications can significantly reduce the charging time, and can be widely used in smart phones, pad, TV, notebook, car and other consumer electronics and charging peripheral products. At present, SMIC has launched the first domestic charging IC compatible with charge pump fast charging and low-voltage direct charging. With its excellent performance, Nanxin's IC products have frequently appeared in products of famous brands at home and abroad, such as Huawei, Samsung, Xiaomi, Anker, etc., and the sales volume has continued to grow rapidly.
In January 2018, SMIC announced the completion of a round of financing with tens of millions of RMB. In April 2019, SMIC announced once again that it had completed the round B financing of nearly RMB 100 million, which was led by Shanghai integrated circuit industry fund. Nanxin has been exploring and developing high-end chips, which has a strong first mover advantage. It is a pioneer in the wave of replacing domestic analog chips. With its solid technology and experience accumulation, it has established a leading brand image of "high-end China chip" with advanced technology, excellent quality and high cost performance.
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