I am designing an inductive charging circuit to power up a small device with an odd shape. None of the off-the-shelf coils fit the dimension specified. I figured I needed to design my own coils like the one on the picture shown. I know how to draw a flex PCB and get it manufactured, my question is how do I calculate the dimension, thickness, shape, number of turns of this coil?


MOTOROLA MOTO 360 Charging Coil

  • \$\begingroup\$ You can either just realize it's just the secondary winding of a transformer, and put as many coils as you can in limited space whilst maintaining desired current capacity, or you follow the application notes of the charger IC manufacturer. \$\endgroup\$ – Marcus Müller Feb 8 at 7:32
  • \$\begingroup\$ I would have a look at A. S. Groove, Inductance calculations, various editions: once you know the mutual inductance you need to have, you can manage to design the two colis by using the techniques exposed in the book. \$\endgroup\$ – Daniele Tampieri Feb 8 at 7:59

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