Interpretation of the Latest Standard of Wireless Charging and Analysis of Apple 7.5W Program

In early March of this year, the WPC Wireless Charging Alliance released the latest Qi standard for V1.2.4 on its official website. It is reported that the agreement will be enforced on March 8. After that, the wireless charging product of the ID number registered with the WPC shall follow the V1. 2.4 The standard is over-certified instead of the previous V1.2.3. The more obvious changes are as follows:

(A) Registered product categories change from BPP, BPP+FOD, EPP to BPP, EPP; (B) EPP increases the temperature rise requirement; (C) Magnetic material detection in 7cm diameter area of ​​Tx new coil; (D) ) Increased Tx product protection guidelines for NFC/RFID cards; QI released this new standard. QI standard certification and support for Apple's 7.5W fast charging solution have become the focus of discussion in the industry. Let's look at it together. The two hot topics that the industry is currently following/discussing:

Hot topic No.1

Regarding the QI standard certification, the current market discussion is more, Apple 7.5W and Samsung 10W is over 5W (BPP) or 15W (EPP)?

According to analysis and analysis by senior industry technicians and certified persons in the industry, most of the current launcher programs supporting Apple 7.5W and Samsung 10W fast charging are based on QI 5W, and they are not fully implemented. In accordance with the QI standard to do fast charging agreement, so in the over-certification should also be only V1.4.4 BPP certification. In addition, currently supports Apple's 7.5W shipments of the largest 10W high-end fast charging program, if It is not realistic for every manufacturer to do 100,000+/EPP certification, and this is also very unfavorable for the promotion and popularization of QI in the world. Hot topic No.2

Which of the programs currently supporting Apple's 7.5W is strong?

It is understood that the operating frequency is set at 127KHZ ~ 128KHZ, through the adjustment of power (regulation, adjust the duty cycle) can achieve Apple 7.5W fast charge, the two circuit topology is as follows:

Fixed-frequency voltage regulator (15W-based): Main control chip + 2 bridge drive + buck circuit + op amp (some manufacturers to + crystal) Fixed frequency modulation duty cycle (10W-based): master chip + 2 bridge drive + op amp (some manufacturers want + crystal)

First of all, first briefly introduce what is the fixed-frequency voltage regulator, fixed-frequency modulation of the duty cycle. Fixed-frequency voltage regulation means that by adjusting the voltage to adjust / control the transmitter output power, fixed-frequency modulation by adjusting the duty cycle Adjust / control the output power of the transmitter. Apple's original adapter fast charging mode is fixed frequency regulator, which naturally has its own considerations of Apple. It should be pointed out that the performance of the two programs are basically the same, that can achieve the Apple The 7.5W fast charge, but in the dynamic input fixed-frequency voltage regulator program will have a slight advantage, and the fixed frequency modulation duty cycle is better when the circuit design more concise. If you say that the biggest difference between the two, That is the cost of PCBA. In terms of PCBA cost, the fixed-frequency voltage regulation scheme is higher, and the fixed-frequency modulation duty ratio is relatively moderate. In the case of QI certification, the constant-frequency voltage regulation is EPP, which requires about 160,000/ The cost of the funds; the fixed tone frequency can be selected over BPP or EPP, over BPP costs only about 30,000 /, EPP is also needed 160,000 /.

Although fixed-frequency voltage regulation, fixed-frequency modulation can achieve Apple's 7.5W fast charge, but each chip maker's fixed-frequency voltage regulation and fixed-frequency modulation and duty cycle are not the same, an important difference It is based on whether or not an external crystal oscillator is used. According to Ren Lianfeng, director of research and development of the new page Microelectronics, the accuracy requirement of the fixed-frequency program of Apple is ±6Hz. Currently, domestic wireless charger manufacturers mainly adopt two methods to achieve the accuracy requirement of ±6Hz. This type of external crystal oscillator is used. Some domestic manufacturers use 8M or 12M crystal oscillators, so that the frequency accuracy of the crystal oscillator can basically meet the requirements of Apple's 7.5W fast charge. However, there are also software companies to improve the frequency accuracy through internal software algorithms (the second Kinds), so that the accuracy can meet the Apple 7.5W fast charge requirements. The biggest difference between these two methods is that the former uses an external crystal oscillator, for the discrete components, the need for additional manufacturers to purchase, the cost is higher; while the latter does not need to purchase another crystal The cost is lower.

At present, the vast majority of wireless charging companies in China use the first external crystal oscillator, and the second one is still relatively small. As a wireless charging chip and solution provider, the new page uses a second type of microelectronics. Can achieve through the chip's internal software algorithms to improve the clock accuracy, achieve the performance of the use of external crystal performance, to achieve support for Apple 7.5W fast charge, the advantage of doing so is that when the customer product needs iterative update support Apple fast charge, only Need to upgrade the program on the original circuit board without re-layout, greatly reducing the cost, while also reducing the discrete components, streamlining the pressure regulator architecture.

The new page microelectronics integrates the performance of external crystal oscillators into the chip, that is, using internal software algorithms to improve the clock accuracy. This is actually a manifestation of the new page microelectronics doing SOC integration. With the rise of wireless charging and As the market matures, it can be foreseen that SoC integration will be the mainstream trend of wireless charging in the future, so in the wireless charging this, step by step integration work is the right path. It is understood that the current new page of microelectronics is Research and development of the next generation of highly integrated wireless charging transmitter chips and solutions.

At present, the new page Microelectronics supports Apple's 7.5W transmitter program with a fixed-frequency duty cycle program, fixed-frequency voltage regulator program two. The main control chip, the fixed-frequency modulation duty cycle program is equipped with NY7502A, fixed-frequency modulation The pressure scheme is equipped with NY7505. The two main control chips are independently developed integrated ICs, which are more convenient for secondary development and can be optimized according to customer needs. At the same time, both solutions have Q value detection. The circuit is more sensitive in terms of FOD detection and complies with EPP/BPP requirements.

Since the end of last year, the shipment of new page microelectronics wireless charging chips has continuously increased, especially since this year, and now the new page of microelectronics has provided wireless charging chips and solutions for hundreds of customers. According to the new page group directors Dr. Lin Guijiang revealed that recently, the new page of microelectronics is in depth cooperation with a number of large electronic chip manufacturers and power supply manufacturers to jointly develop the trillion-scale wireless charging market.

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