LIS331HH self-test output change with voltage

[SVozl.1]

We have performed the self test on two prototype boards,

as instructed in this post: https://community.st.com/s/question/0D50X00009XkXegSAF/lis331hh-understanding-self-test

The x and y differences are around 135, which is in the range, but on the z axis we get around 380, which according to the datasheet, is just enough to no pass the self test.

The datasheet also specifies that the "Self-test output changes with the power supply" and that the product was calibrated at 2.5V.

Our question is the following:

Can the fact that we use a different supply voltage (3.3V) be the reason why the self test (just barely) fails or does the range of the self test already account for potencial differences?

Best regards!

[Eleon BORLINI]

Hi @Sašo Vozli�?​ ,

are both the prototype boards failing the self test?

And did you follow the self test procedure as suggested on the C drivers on Github --> lis331dlh_self_test.c?

The Vdd could slightly impact the data on this product, but should not make the difference between pass and fail. Please be sure to be in a controlled environment during the self test.

-Eleon

[SVozl.1]

Hi Eleon,

yes, both are failing the self test. We'll try to run a test with 2.5V instead of 3.3V.

We did follow the procedure.

On a related note, how does a negative self test sign impact the results?

Do we just change the sign on the specified ranges?

Do we have to run the self test in both directions?

PS: If the self test fails with the positive sign, but passed with the negative one, how do we interpert that?

Best regards,

Sašo