Release Time:2013-6-18 13:33:44 Sourc:国芯网 Translate:

The QI standard is mainly for the uniform global wireless charging standard, and mainly for universal digital products. There are tons of wireless charging solutions options out there in the world, and finding one that’s actually good for your product can be confusing. So to help you get ready, we’ve put together a guide of what to look for in a wireless charger for you. The following five aspects of the wireless charging scheme or module of several parameters for your reference:

  • First, the conversion efficiency;
    At present, the efficiency of inductive charging technology conversion is generally between 50% -80%. It has been considered very good for achieving more than 70% efficiency. It does not only involve the hardware design of circuit technology and low-power components of choice, but also software design. Software design to match the parameters of the circuit resonance so as to achieve the best conversion efficiency. The conversion efficiency is the wireless receiving output power that divided by the input power obtained percentage:
    For example, Wireless charging scheme Operating voltage nominal input is DC12V~1A, the wireless output is 5V~1A. Measured in the wireless receiver output is 5V~500MA, the input is 12V~280MA,
    Then the program efficiency is (5 * 0.5) / (12 * 0.28) = 0.74, the conversion efficiency was 74%.
    In view of this additional explanation is that the test coil is the relatively best state if the deviation of the output power will change.
  • Second, the charging distance:
    Now the wireless inductive principle to achieve the power within 5W wireless charging scheme are in the distance of 3-7mm. The best distance is of 3-5mm. With more power scheme relative coil diameter and coil diameter, launch and receive relative distance can be a little further.
  • Third, working temperature:
    Taking the mobile phone wireless charging product as an example, the general power is between 2W and 5W, and the 70% efficiency temperature can generally be controlled at 40 degrees. Generally, the temperature is generally higher if the schemes are with low conversion efficiency. because the loss of power is turned into heat.
  • Fourth, the magnetic separator – – to reduce the temperature and avoid magnetic radiation
    The resonant frequency made by electromagnetic induction wireless power is between 50 and 500KHZ. This belongs to the medical frequency. Magnetic radiation on the human body can be neglected, but if the magnetic radiation shielding is not good, it will bring potential safety hazard to the product.Due to the coil is generally attached to the product, the battery and other conductors in the product will absorb the electromagnetic radiation emitted by the coil. The temperature will slowly increase during working a long time, which could burn the product and cause harm to human health. Therefore, the wireless charger coil must be attached magnetic separator. The application of magnetic separator is particularly important in the wireless charging scheme. It is not only to avoid magnetic radiation products but also for the overall efficiency of the product to play an important role.
    Magnetic separators are usually placed on the bottom and top of both coils respectively so that electromagnetic energy is trapped in the middle, which in turn increases efficiency and reduces the temperature. The quality of the magnetic separators in the market is mixed. Good quality magnetic insulation effect is obvious. As general, ferrite effect is relatively good and the price is relatively expensive. The general quality magnetic leakage flux relative large, its overall performance also play some discount. Some cheap wireless charging module is not even equipped with this interval. Therefore, a considerable part of the magnetic energy is scattered around or absorbed by other devices. The corresponding transmitting coil needs to provide more energy to ensure that the receiving coil has enough power. Therefore, it is difficult to test the overall performance if only test the output power of the instrument.


  • Fifth, standby power consumption and service life
    Standby power consumption is related to the hardware and software designation and the selection of entire circuit and the quality of components (including magnetic separation). If the standby power consumption under the conditions of the same output power is smaller, indicating that the overall performance of the product is more superior. Especially for some launchers to long-term power standby products must pay attention to this parameter. Small standby current not only saves energy but also directly affects the product’s life. Of course, we must understand that there is a certain proportional relationship between the standby current and the total output power of the scheme, that is, the larger the total output power of the scheme is, the larger the standby current is. But how much power standby power is much better to be considered? There is not a good definition. If the wireless charging receiver rated output power is 3W under the condition of the optimal charging distance and conversion efficiency of the premise, then the standby power consumption should be within 0.5W. The data is difficult to test, maybe the best way is to power off the wireless charger for a long time to check the temperature. The best one must be the lowest temperature one.

Through the above five points on the wireless charging scheme parameters, we can summarize the method of selecting a reliable wireless charging scheme:

  1.  It is best to confirm with your supplier whether to provide patent.
  2.  Whether the use of magnetic separator is very important. It is the product performance and cost’s important indicators.
  3.  When getting the sample, the first thing to do is testing the standby power and the input and output power on nominal distance. Thus to calculate the conversion efficiency.
  4.  In the burn-in test, it can be divided into the standby test and load test. In the load test different stages, the temperature of the coil junction and other individual locations should be checked.
  5.  Monitor the stability of the product throughout the charge. Monitor whether there is charging power-down and voltage floating phenomenon.
  6.  Calculate the time to the actual charge your product to full, so you can get the actual wireless charging power.


  • Charging intelligent management refers to the charging device with an automatic control function. Such as being full of equipment or after charging device is removed from the charging base will automatically power down or sleep and other functions, this feature can be better to achieve environmental protection and power saving, safe and convenient.
  • Security identification function. Because wireless charging is the use of electromagnetic induction to achieve the transmission of electricity, so the electromagnetic wave is sensitive to metal or conductive liquid. Therefore, if a metal conducting object (such as an iron, a cell, a bare cellphone, a key, etc.) is placed on the launcher at power on, they absorb the electromagnetic energy and are converted to heat. Over time, the temperature will gradually increase and continue to bring potential safety problems. Therefore, the safety identification function is to identify these objects. Only the original device will receive the power, other objects will not have any response.

As the saying goes, people always get what they pay for. The same power conditions, circuit design and the selection of components and the application of high-quality magnetic separator on the stability and safety of the product is essential. As we testing, if the main components on the same circuit use brand components, the efficiency will be over 10%. The efficiency has improved significantly when using the high-quality magnetic separator instead of using the ordinary magnetic separator. And the standby power consumption also declined. So if your product positioning is high-quality, it is recommended to consider the quality and the price instead of blinding about low prices.