Fixed frequency and voltage regulation scheme of Qi v1.2.4 protocol

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	Qi v1.2.3	Qi v1.2.4
Tx type	MP-A11	MP-A11
Certification registration	BPP+FOD Extensions	EPP
notes ：BPP – Basic Power Profile,EPP – Extended Power Profile

Apple launcher is supported in the market 7.5W Fast charging Wireless charging transmitter scheme

（ One ） Variable frequency architecture — Traditional scheme

working principle ： The transmitting power can be adjusted by changing the operating frequency ; In some transmission frequency bands, it will cause certain interference to the mobile phone circuit ;

At present, the transmitter with frequency conversion architecture in the market generally adopts A11 or A11a, Only through BPP authentication , Power transmitter power is generally greater than 5W Less than 10W, No, Q Value detection circuit ,FOD（ Metal foreign matter detection ） The performance is obviously inferior to the performance BPP+FOD Extensions and EPP The transmitter of the authentication scheme

（ Two ） Fixed frequency architecture ： Phase modulation 、 Voltage regulation 、 Adjust the duty cycle

（1） Fixed frequency modulation duty cycle architecture — Domestic irregular army programme

working principle ： By fixing the operating frequency , Adjust the transmission power by changing the duty cycle ;

Poor transient response ： When the input voltage changes , Will affect the output stage , Cause sudden change of voltage at the wireless receiving end , Mobile phone charging is unstable

Generally no Q Value detection circuit , stay FOD The detection will be poor , Also does not agree with EPP requirement , Do not conform to the MFi standard ; The advantage of this architecture lies in its high cost performance

（2） Fixed frequency and phase modulation architecture

working principle ： Fixed AC frequency , Adjust the phase to adjust the output power ; Phase modulation requires a large inductance , yes LCL The way , Inductance sacrifices energy , Low efficiency , And the noise is quite loud .

（3） Constant frequency and voltage regulation architecture — Apple's official standard solution

working principle ： Fixed operating frequency , For dynamic load power demand , Dynamic power output is realized by adjusting the amplitude of AC voltage ; It can effectively avoid interfering with the frequency band of the mobile phone , Minimize the interference of wireless charging on mobile phones , Yes Q Value detection circuit , stay FOD More sensitive in detection , accord with EPP The requirements of .

The apple in MFi Proposed at the meeting 7.5W The fast charging adopts the structure of constant frequency and voltage regulation , use MP-A11 Topology ; The working frequency is fixed at 127kHz about , The duty cycle is constant 50%; The so-called duty cycle , For the half bridge , The proportion of the opening time of the upper tube in the whole cycle . Because it is the whole bridge , therefore 50% The duty cycle means that the transmitted energy is the maximum .

On behalf of the manufacturer ：NXP、IDT、CPS（ Easy impact wireless ）; At present, it is known that apple, which is produced in large scale and adopts constant frequency and voltage regulation structure, is on the market 7.5W The emitter , Except what Apple officially recommends mophie、Belkin outside , also RAVPower、Spigen、Anker etc. . The first two use NXP programme , The latter three adopt easy impact wireless （CPS） The plan .NXP As the official supplier of Apple Wireless charger , Naturally, it is the benchmark of the constant frequency and voltage regulation scheme , Of course, the cost will be higher

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