Linkcom Manufacturing Co., Ltd

Q1. Heating Issue Due to Magnetic Misalignment

Q: If the smartphone’s MagSafe magnetic ring is misaligned with the transmitter coil by about 50%, and this condition is maintained for a long time, will it cause heating?

Answer: Yes. If the TX/RX coils are only about 50% aligned, the transmission efficiency will decrease, which will cause heat generation. Once the temperature reaches the protection threshold, the OTP (Over-Temperature Protection) function will be triggered, and charging stability will decrease, which may result in the device being unable to charge.

 

Q2. Charging Start Mechanism During Overheating

Q: If the situation in Question 1 does indeed cause heating, when the transmitter side is overheated, will the system limit charging startup or activate a protection mechanism?

Answer: Yes. It will enter OTP protection mode, stop charging, allow the temperature to drop, and then resume charging.

 

Q3. Qi2 Behavior During Abnormal Overheating

Q: During normal charging under Qi2, if the module experiences abnormal overheating, what happens exactly? Is the behavior like one of the following examples?
If not A or B, what is the recovery behavior of our module?

• Example A: Stops power output when overheating, and automatically resumes after temperature drops below a specific temperature.
• Example B: Stops power output when overheating and does NOT automatically resume (power must be unplugged and reconnected).

Answer: When the temperature exceeds the OTP set value, charging stops. After the temperature decreases, charging will automatically resume. Please refer to the following specification for details:

There is an NTC resistor inside the module to provide OTP for the module. The module can adjust output power according to the different temperatures. It starts to decrease output power when the temperature exceeds 55 °C (output power decreases 1 W for every 1 °C increase). The module stops running when the temperature exceeds 72 °C and resumes operation when the temperature drops below 55 °C.

 

Q4. Effect of Heating on Charging Efficiency

Q: Will heating cause the charging efficiency to drop significantly? For example, if efficiency drops to 66%, then 22.7W would be required, and the current power supply of 9V/2.5A (22.5W) would not meet the power demand?

Answer: Yes. It is possible that 9V @ 2.5A may not be sufficient.

 

Q5. Current Requirement in the Specification

Q: The specification states “DC Mode: 9V ≥ 2.22A.” Does this mean that using only 9V/2.22A may result in abnormal operation?

Answer: Under standard test conditions, it meets the requirement. However, in actual usage scenarios such as those mentioned in Question 1 and Question 7, if the TX/RX coils are not properly aligned, efficiency will drop rapidly. In that case, it would fall outside the specified test conditions.

 

Q6. Conversion Efficiency

Q: According to the specification, the maximum efficiency is 78%. In actual use (with a 1mm barrier in between and magnetic attachment), is it possible for efficiency to drop below 70%?

Answer: Same as Question 5.

 

Q7. 1mm Metal Plate Between TX and RX

Q: The device uses magnetic attachment, and there is a 1mm thick metal plate in between.
I believe efficiency should not be too poor.

Answer: There must not be any metallic material between the TX and RX coils. If metal is present, it will trigger FOD (Foreign Object Detection). (This is very important, the 1mm metal plate must be removed.)