MMA8491Q Accuracy

[marcvandegaar]

Hi Everybody,

I am actually evalutating the 3 axis accelerometer MMA8491Q using the XTRINSIC-SENSE evaluation board.

I am disapointed what the accuracy seems to be.

The evaluation board just lays on a table. There are no movements nor vibration at all.

The application just read the 3 coordinates every 500ms. As I look at the results, I see absolute deviations from one reading to the other going upto 50mG (0.05G). I have more or less the same maximum deviations on all 3 axis.

Is that the best accuracy one can expect from this device or is there something I am missing?

Would the MMA8451 be more accurate (its resolution is 4 times higher than the MMA8491Q)?

Thank you for your help

Marc

[TomasVaverka]

Hi Marc,

Your results correspond to ours as you can see in Figure 9 of the AN4296. Unfortunately it is not possible to achieve higher precision with this accelerometer.

Yes, I would recommend using either the MMA8451Q (only I²C) or FXLS8471Q (I²C or SPI). When I selected the lowest possible ODR (1.56Hz), the ±2g range and used both Low Noise (LNOISE bit = 1) and High Resolution (SMODS = 1) modes, the deviation did not exceed 0.5mg!

Best regards,

Tomas

PS: If my answer helps to solve your question, please mark it as "Correct". Thank you.

[marcvandegaar]

Thank you very much Tomas for your answer.

I will evaluate the MMA8451Q.