WP3W-RK Reference Kit Manual
© 2016 Integrated Device Technology, Inc
5
May 16, 2016
Coil Spacer (Upside-down Coil)
A good wireless power transfer system should maintain a small separation gap between the transmitter coil and the receiver coil. For the
reference board, the receiver coil has been mounted upside-down on the P9027LP-R-EVK board. The PCB area under the Rx coil is used as
a spacer (0.5mm) to simulate the thickness of a wearable device case, and there is no copper conductor. While the coil itself is protected by
non-conductive encapsulation, it is recommended to use some type of spacer to achieve optimal power transfer efficiency.
Similarly a 0.8mm plastic spacer is placed on top of the Tx coil to simulate the casing of a final transmitter product. With both spacers the total
distance between the coils is about 1.5mm.
Separating the Coil from the Spacer
The P9027LP-R-EVK reference board has been precisely tuned for the stock coil attached to the board. The PCB has been designed with a
score line enabling users to snap-off of the active PCB section. When doing so, carefully peel the coil off from the Rx PCB. Once the coil is off,
it is recommended to use scissors to cut the active board area along the score lines. To see a video demonstration, visit:
www.IDT.com/WP3W-RK
.
If it is necessary to extend the length of the coil leads when working on prototype, it’s best to unsolder them from the PCB prior to separating
the active PCB area from the rest of the board.
Performance Characteristics
Figure 5. Typical Efficiency Curve for 30mm Coil
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Eff
ici
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Iout (mA)
Vin=5V, Vout=5V, Iout=600mA, Tx=P9235A-R, Tx coil=760308101103, Spacer=1.5mm,
Rx coil=760308102213, Rx=P9027LP-R, No air flow, Room temperature
