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Self test output change for LIS331DLH

mgrelet
Associate
Posted on October 16, 2013 at 18:02

Hi,

We have developed a product which uses the LIS331DLH accelerometer and are happy with the results so far.

My issue concerns the self test output change which can be higher than stated in specifications. The datasheets indicates between 120 and 550 or 140 and 750 lsb depending on the axis. However, I have seen output changes above 1000 lsb.

Can we still use the boards, does it mean that the component has been damaged during the assembly process? The measurements seem consistent otherwise when comparing with the gravity.

Should we raise the level of the thresholds in our code, if so what level would be recommended?

Thanks

Marc
3 REPLIES 3
jari
Associate II
Posted on March 25, 2015 at 11:10

Hi,

I have similar issues with the LIS331DLH. When we enable the ST mode changes are slightly over the specs.

XYZ values received from the sensor are divided by 16 (this shifts 16bit->12bit and keeps +/- sign correct).

If we use specs mentioned in the datasheet none of sensor will pass the test.

It looks that if we shift 16bit -> 11bit then self test readings are as typically vales defined in the datasheet.

To ST: Could you please confirm how XYZ values should handle or do you have any example source code where the self-test is executed and result should be PASS?

BR

Jari

jari
Associate II
Posted on March 25, 2015 at 16:54

And operating voltage is +3.3V for the LIS331.

BR

Jari
jari
Associate II
Posted on March 27, 2015 at 15:33

I'll share ST's reply with you:

Resolution Summary: SOLUTION PROPOSED BY SUPPORTER - 27/3/2015 14:54:30 :

Hi,

axis XY: min. 300, max. 950

axis Z: min. 400, max. 1150

for Vdd=3.3V

Rgds

Vladimir