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TDK Qi compliant planar wireless power coil offering multiple benefits

Date: 22/08/2022
TDK has introduced its new recently developed MP-A28 Wireless Power Pattern Coil for wireless charging devices. The Qi compliant planar wireless power coil uses a unique copper patterning technology to benefit the end-user.

TDK part number to order this coil is WCT38466-N0E0SST01, whereas Wireless Power Consortium [WPC] has designated this new coil as MP-A28. This coil features intricate coil patterns that cannot be duplicated by the use of discrete wires and yields tight trace width and gap control which can only be achieved by using finest etching process. This coil's copper trace thickness can be changed accurately at ease and flexible way as per the needs of application requirements.

TDK has applied its expertise in copper plating processes to construct metal coil structures used within power inductors to make this wireless power coils. TFM power inductor series from TDK is made using this plating process of high aspect plating (HAP) copper technology to increase the coil pattern’s cross-sectional area to reduce direct current resistance (DCR).

Advantages of this coil includes:

Better control and shaping of the magnetic field (H), reduction/ removal of the low efficiency (“dead”) areas around the edges of the complete coil.
Thinner and lighter over all charger designs utilizing the MP-A28 coil assembly, improving magnetic coupling and efficiency, Tx coil weight reduction, complete coil’s inductance (Ls) and resistance (Rs) values do not vary as they do with wire wound coils.
Keep the magnetic field away from any neighboring metal objects and limits the magnetic flux getting into other areas of the charging device such as mobile phone.
Improvement in efficiency is achieved in the event of misalignment between the Tx coil and the Rx coil within the to-be-charged device.
Increase each effective turn’s surface area to minimize copper trace alternating current (AC) skin effects so that efficiency is increased.
Many of the duplicate electronic parts associated with the tri-coil’s structure can be eliminated and thus reducing part count and BOM costs.
The MP-A28 requires single driver, switch and resonant capacitor bank (Cs) and may also eliminate thermistors.
Supports robust automotive design. The MP-A28 also has an optional EMI metal mesh screen that is a separate 30 um thick layer. This screen is intended to help meet the automotive CISPR 25 requirements.
The coil is available with either copper leads or it can be supplied with connector/header pins to provide easy assembly when connecting to the main PCB containing the charging circuit’s components.
Adding the NFC coil to the existing wireless power coil structure comes at a minimal cost. The NFC antenna then uses the existing ferrite shield eliminating the need for dual shields and the corresponding cost. This reduces the required area needed to implement both technologies, as they are usually placed side by side, as well as reducing weight.