Wireless charging coils from Vishay

Operation is at up to +105°C, and the company is claiming smaller footprints than its previous-generation devices.

“The high moisture resistance of the devices results from their specialised shield coating,” said the company. “In addition, the coils’ high saturation powdered iron makes them immune to the temperature fluctuations and sharp inductance drop-off behaviour observed in ferrite-based solutions. Shield material selection is critical, as it is used to boost the inductance of the coil, contain flux leakage and maximise flux directivity.”

Featuring a self-binding, enamelled copper winding, the IWAS3222CZEB190JR1 receive coil has 19.6μH inductance, a Q of 28.5 at 200 kHz, and 357mΩ dc resistance.

IWTX4646DCEB240JR1, IWTX47R0DAEB6R3JR1, and IWTX47R0EBEB240JR1 are transmit coils with inductance between 6.3 and 24μH, dc resistance down to 40mΩ, Q up to 200, and heat rating current up to 7A – with saturation up to 22A.

“For additional durability, the transmit coils feature a silk-covered litz wire that protects against scratching and wire deformation, provides improved insulation, and reduces the electrical skin effect and proximity losses,” said Vishay. “In addition, IWTX4646DCEB240JR and IWTX47R0EBEB240JR1 are manufactured with an alpha winding that eliminates wire cross-over and achieves the lowest profile.”

Applications are expected in hand-held battery-powered tools, diagnostic instruments, therapeutic instruments, drones, phones, tablets, gaming controllers and wearables.

As an example, find the IWTX4646DCEB240JR1 transmit coil on this web page