SMD code marking reference? (LSM6DS3)

RMaia · ‎2022-05-14

I have a short strip of tape that's supposed to be LSM6DS3's, but the SMD marking code on them is different from the other tapes I have (which where correctly organized and labeled).

So, is there a table where I can look up the codes that refer to the LSM6DS3 to find out if these chips are indeed what they're supposed to be? I tried looking for this info in the datasheet and product info page but could not find anything...

Thanks!

Tesla DeLorean · ‎2022-05-26

https://community.st.com/s/question/0D53W00000VfytlSAB/what-is-the-difference-between-the-marking-sh-and-s2-for-the-part-number-lsm6ds3

"They should be basically the same product, "S2" for the LSM6DS3 and "SH" for the LSM6DS3H.

Can you please check if the WHO_AM_I (0Fh) register value is the same for both devices? Should be 69h."

"They are very similar devices in terms of mechanical and electrical performance, but the DS3H can work in Mode3 (has an auxiliary SPI). You can see it from the p.18 of both datasheets."

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View solution in original post

RMaia · ‎2022-05-26

Ok, so I soldered one of the chips on a breakout PCB for testing and it simply didn't work. Not a problem with the soldering. To be sure, I tried another chip from the same tape. Same results, won't even show up under an I2C scan of all possible slave addresses.

So under closer inspection and comparison with a known and confirmed working LSM6DS3 chip, the chips from this "dubious" tape are completely different. Check one of the attached images, the correct LSM6 is on the left, the "non-working" chip is on the right.

Now that I know for sure it isn't an LSM6 as it was supposed to be, comes the next question: which chip is this?

I also attached one photo of the markings on it. Does anyone know how to "translate" them? Or at least point me to a reference for ST sensors markings?

Tesla DeLorean · ‎2022-05-26

https://community.st.com/s/question/0D53W00000VfytlSAB/what-is-the-difference-between-the-marking-sh-and-s2-for-the-part-number-lsm6ds3

"They should be basically the same product, "S2" for the LSM6DS3 and "SH" for the LSM6DS3H.

Can you please check if the WHO_AM_I (0Fh) register value is the same for both devices? Should be 69h."

"They are very similar devices in terms of mechanical and electrical performance, but the DS3H can work in Mode3 (has an auxiliary SPI). You can see it from the p.18 of both datasheets."

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Up vote any posts that you find helpful, it shows what's working..

RMaia · ‎2022-05-26

That's interesting to know, I wasn't aware the DS3H existed.

I did think of checking the WHO_AM_I code, but I couldn't even get an I2C address acknowledge on both 0x6A and 0x6B. Also tried scanning for the whole range (0x00 to 0x7F), and no address returned an ACK. So there's no way I could even connect to it to probe the WHO_AM_I return...

Could they be "stuck" in SPI mode? Even with the CS pin tied to VCC (3V3) on startup?

Eleon BORLINI · ‎2022-05-27

Hi @RMaia ,

can you share us the scope plots of the I2C lines?

-Eleon