MMA8451Q Z-Axis sticky

[basilfee]

Hello,

I have a customer that is developing an application using the MMA8451Q.  They are having issues where they sometimes see their module read "incorrect" data for the Z-axis.  The behavior is the Z-axis seems to get "stuck" at the max value, while the X and Y axis read application appropriate data.

Their product collects an amount of accelerometer data and sends it to the host periodically - (they call this sleep/awake cycles but it is at the product level).  Sometimes the Z-axis data is always the max value through the entire data collection period.  Other times, it starts at the max value and then begins to "work" (having correct data) for the Z-axis.   Still other times, the data is correct and then goes to the max value and is stuck there for the rest of the period.

Again, this "stuck at max value" only seems to be associated with the Z-axis data, the X&Y data is "correct" all the time.   Is this type of behavior indicative of a known failure as a result of exceeding the g rating for the axis or for any other known type of failure or misapplication?

Appreciate your help,

Basil

[TomasVaverka]

Hi Basil,

It sounds like a known problem which is partially described in the PCN14989 and PCN15484. Z-axis stiction failure usually has a positive railed output (0x7FFC).

Looking at our internal database, Joshevelle has been in touch with the customer as he created a Service Request as well. All additional communication should be primarily worked via this Service Request. 

Regards,

Tomas

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

[basilfee]

Tomas,

The customer has not entered a Service Request so this issue might be similar to another customer's issue, but there has been no communication with the customer - except through myself and the distributor.  The SR must be for a different customer.

The issue seems related to the descriptions in the PCNs you referenced.  However, these PCNs were effective January 2012 and January 2013 respectively which seems dated.  I have asked the customer for the date codes on the failing devices they have and they sent me the marking for two devices which are:

Device #1       Device #2

263                     263

8451                  8451

3MAF                AVAA

I don't know how to decode the datecodes to determine if they were prior to the effective date of the PCNs or not.  Can you/someone see if the PCNs apply to these devices?

Thanks,

Basil

[TomasVaverka]

Hi Basil,

I have just responded to this post via the SR# 1-3782330854. Please use it for any further communication on this issue.

Regards,

Tomas

[jonkoon]

Hi Tomas,

We are experiencing a similar failure to the one mentioned in this post.  Our parts are:

MMA8652QT

The codes on the top are:

652

MEH

Can you confirm that these are parts that might be suffering from stiction?  Is there a different process that I should go through to work out this issue?

Best Regards,

Jon

[david_diaz]

Hello Jon,

You may refer to the Case number 00086059 in order to get the response to your inquiry.

Please let me know if you have any further question.

Regards,

David