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ADXL213 replacement recommendations?


I am currently using an ADXL213 as a 2-axis inclinometer. I am looking for a 3-axis part, but have not yet figured out all the differences between parts. I need at least 0.1 degree resolution for angles up to 20 degrees, and I would prefer low current and high accuracy. I currently sample around 60Hz.

What's confusing for me is that there are several 2-axis parts that I thought would also work fine, and are cheaper. I did not choose the current part - I'm wondering if the ADXL213 is better in some other way that I have missed? The PWM interface doesn't count unless it affords better precision.

Does anybody know how the ADXL213 is better, and what else I need to look for in a 3-axis part?

  • We're not supposed to post to the forum and open a support ticket for the same thing - but it's been 5 days.

    Is this the wrong channel?  Is there a different sales support channel I should use instead?

  • Michael,

    Are you looking for 3-axis parts because you would like to switch to 3-axis inclination sensing?  Our lowest noise part currently is the ADXL203.  Noise is an important parameter for the resolution you are targeting but does your application have a wide temperature range and do you perform any initial calibration?

    http://www.analog.com/en/mems-sensors/mems-inertial-sensors/adxl203/products/product.html

    regards,

    Venkat

  • I am looking for a 3-axis part so that I can support multiple orientations of the inclinometer (portrait vs landscape) - I will be able to determine the orientation in software and select the proper axis. However, before I drop the ADXL213, I need to make sure I understand why it was chosen.

    I hadn't been thinking of the ADXL213 as an analog sensor - but I guess it is, if a good alternative is the ADXL203. The ADXL203 does have a better noise figure. I think we're set up for a 5 Hz bandwidth (Cx and Cy are 1uF) - so I should expect 72ug of noise from the ADXL213, and about 49ug of noise from the ADXL203. Does the noise floor determine the resolution of the sensor (aside from the resolution of the sampling equipment)? If that's the case, then that's why it was selected - we have a 32-bit input capture timer, while we only have a 10-bit ADC on our board.

    Unfortunately, the ADXL213 is the only sensor with a PWM interface - in order to go to a 3-axis sensor, I either need to go to a digital chip or I need to pair it with a high-res ADC.

  • Michael,

    That's correct, sensor noise floor determines the resolution other than the ADC.  3-axis digital accelerometers would be a good choice.  You can try the ADXL362.  It's an ultra low power part and offers noise density down to 175ug/rtHz in the low noise mode.

    regards,

    Venkat