Problems setting up the STWLC38

ggeorge_42 · ‎2024-03-27

Hello,

We plan to use the STWLC38 for power in a new wearable design.

We purchased the STEVAL-WLC38RX and STEVAL-WBC86TX kits to get familiar and experiment with the ICs.

Now we are trying to adapt the Rx of the STEVAL-WLC38RX as used in a wearable device and followed the application diagram from the STWLC38 datasheet (Figure 13. STWLC38 basic application diagram in Rx mode), using the recommended coil (Wurth 760308101219). We also changed the Cs and Cd capacitors as recommended.

The STEVAL-WBC86TX board was not modified.

The problem is that the power reception from the STEVAL-WBC86TX is not enough to reach 5V at the output.

We tried changing the Cs according to STDES-WLC38WA (TN1440) as well as some other values with better results, but not enough. In the chart of WPSTUDIO Vrect looks unstable, with lots of ripple and Vout is OFF.

Do you have any suggestions on how to tune the Rx circuit with the new coil?

Thank you,

G.Giannopoulos

willzhou · ‎2024-04-01

Hi
1.You can google FT260 driver or find at this link
https://github.com/STwirelesscharger/Python_FT260_ST_WLC

2.TX SS TO (Signal Strength or Ping Timeout). This probably has to do with the coupling of Tx/Rx coils (very different diameters)
Yes it is, coupling is bad and tx can not decode SS packet

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