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So basically AS3933 has 3 pins (LF1P, LF2P, LF3P) which need to be connected to pins of 3d antenna (CAS143-47 in this case) and to common ground LFN. My CAS143-47 antenna has 8 pins with 3 pairs of pins (2-3, 8-7, 6-5) corresponding to X,Y and Z coils of antenna and 2 other pins (1-4) and I have no idea about what to do with those 2 and where to connect them. Should they be connected to ground or left floating? Here's how I've been thinking about connecting those two chips:

LF1P of AS3933 jointly wired to pins 2 and 3 of CAS.

LF2P of AS3933 jointly wired to pins 8 and 7 of CAS.

LF3P of AS3933 jointly wired to pins 6 and 5 of CAS.

Leave 1 and 4 pins of CAS floating or ground them?

Here's datasheets for both chips:

AS3933: http://www1.futureelectronics.com/doc/AUSTRIAMICROSYSTEMS/AS3933-BQFT.pdf

Sumida CAS143-47: https://datasheet.octopart.com/CAS143-47-Sumida-datasheet-17276700.pdf

Any advice is appreciated.

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1 Answer 1

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LF1P of AS3933 jointly wired to pins 2 and 3 of CAS.

LF2P of AS3933 jointly wired to pins 8 and 7 of CAS.

LF3P of AS3933 jointly wired to pins 6 and 5 of CAS.

Wiring both ends of the antenna coils to the same pin is the wrong approach here.

The AS3933 product page lists a demo kit package, which includes sample schematics, board layout and BOM.

This shows the antennas wired between LFnP and LFN.

excerpt of schematic, showing the three antennas

Leave 1 and 4 pins of CAS floating or ground them?

The CAS143-47 has three coils, wired to six of the eight pins. There is no commentary for pins 1 and 4, and I'd suggest you leave them floating with only the pad underneath... it's possible these pins are used for other purposes in other products - for example CAS143-26 (which is described in the same datasheet) has the y-axis wired differently.

pinout for the 3-axis antenna

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  • \$\begingroup\$ Thanks a lot. That is really helpful. So to my understanding (please correct me if I'm wrong, I'm kind of new to this.) my connection should be as follows; X[5] - LF1P, Y[7] - LF2P, Z[2] - LF3P and X[6],Y[8],Z[3] - LFN \$\endgroup\$
    – Angela
    Apr 4 at 3:26
  • \$\begingroup\$ Looks correct to me! \$\endgroup\$
    – Attie
    Apr 4 at 11:04
  • \$\begingroup\$ Thank you so much! I'll get working on it right away. I'll let you know how it goes. xoxo \$\endgroup\$
    – Angela
    Apr 4 at 11:20

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