we are using the self-test on the LSM6DS3USTR and it has started to fail and is shutting down our production. Is there a known problem that would create this situation? If there is no answer, we may need to shut down the self test to resume productio

[DGree.6]

This is quite urgent!

[Eleon BORLINI]

Hi @DGree.6​ ,

let me better understand the issue... the self test started to fail during your production test in a systematic way (on all the parts) or only sometimes?

In the first case, did you try to test an old LSM6DS3USTR which was good to check if it is still good now?

In the second case, can you share the log of your test in more detail (for example, which axis is failing, or is the test output too low or too high)?

-Eleon

[DGree.6]

It is NOT all devices that are failing. Most are still passing. We did have a software change and I am asking that they revert back to be sure that’s not it. (It’s not very likely, but we must do this test!)
We also have one device that was quite a surprise. When heated up so that the IMU temperature is 38°C, it passes. When cooled down to 25°C, it fails. With only a sample of one, this isn’t much of an indicator.
This started around Wednesday afternoon, and since that moment, the failure rate is 18%. And there have been enough older devices tested since then and have passed to convince me this is something new.
The self-test does not provide ANY answer. So your question about too low or too high doesn’t make sense as I have no data for these failures.
Dale

[Eleon BORLINI]

Hi Dale,

>> The self-test does not provide ANY answer. So your question about too low or too high doesn’t make sense as I have no data for these failures.

As defined in the AN4889 application note at p.117, the self test is the calculation at room temperature (about 25°C, so better to run the self-test in this condition) of the logical AND of the following statements, which are composed of numeric values:

|Min(ST_X)| <=|OUTX_ST-OUTX_NOST| <= |Max(ST_X)|
AND
|Min(ST_Y)<=|OUTY_ST-OUTY_NOST| <= |Max(ST_Y)|
AND
|Min(ST_Z)| <=|OUTZ_ST-OUTZ_NOST| <=|MAX(ST_Z)|

Different thing is if your software doesn't output the single values, but only the PASS / FAIL flag...

>>  We did have a software change and I am asking that they revert back to be sure that’s not it. (It’s not very likely, but we must do this test!)

This is a good way to start narrow down the issue. Please be sure your engineers are discarding the initial data as described

May I ask you if you changed the device LOT from last Wednesday afternoon? You can check it reading the marking on the top of the package.

-Eleon

[Eleon BORLINI]

Hi @DGree.6​ ,

Please let me know if you eventually managed your issue, or in case if we can give further suggestions to you.

-Eleon

[DGree.6]

The firmware changes have corrected this problem. Last week, the “failed�? no-read units all passed, with only a couple of exceptions. There are only a few loose ends to follow up on.
Thanks for the support.
Dale