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MSP430AFE253: performance variation in the low power mode.

Ashe Controls
Prodigy 10 points

Part Number: MSP430AFE253

Tool/software:

Dear Tech team,

We are using above part for the loop powered process indicator in the 4-20 mA loop. Its a indicator using low power 7 segment displays.

we have manufactured total 100 Qty cards & 40 pieces are found working OK but in other 60 cards are having issues.

There is a flickering of display during operation in balance 60 units & we have to replace the microcontroller multiple times to get stable display results, creating losses in inventory. 

Please suggest how to solve the problem as we are not able to proceed for the production.

  • 0
    TI__Guru 71216 points

    Hello Ashe,

    I don't have enough information about your application to determine a possible cause.  The flickering might indicate something is causing a slight delay during the 7-segment updates.  This delay might have something to do with the 3 Sigma-Delta ADCs and the time it takes to perform a conversion.  If a conversion takes longer than expected, the results could be delayed.

    Is there any specific information you can provide?

  • 0 in reply to Dennis Lehman
    Prodigy 10 points

    Dear sir,

    the problem is not occurring in all the MCUs. 40% MCUs are working ok with no flickering issues. problem seen in 60 MCUs with flickering. there is a variation in the internal parts of the MCU from IC to IC. The instrument is working on 3.5 miliA at start up.  How to solve this issue as we need to replace the MCUs to get expected results.

    Please let me know, additional information you needed..

    please take this on priority 

    our production is on hold, next batch of 720 MCUs is on hold on mouser for MSP430

  • 0 in reply to Ashe Controls
    TI__Guru 71216 points

    Ok, can you tell me is the operating voltage on the device?  Do you know what clock frequency the device is running at?  You mention startup current is 3.5mA.  Is this the current the device is consuming (taken with a measurement), or is 3.5mA the max available current for the device to operate on?  Reason I ask these questions is the typical current operating at 3.3V and 12MHz clock frequency is 4mA.  If the circuit that provides power to the device is limited to 3.5mA, then this could be an issue.

    Also, is this the first time you are manufacturing this product with MSP430AFE253, or have you used this device in the past and not seen this problem?

    Do you or someone at your location have the ability to perform some debugging (take some measurements, possibly modify code, etc.).  I may need to ask for schematics and copy of portions of the firmware.  Will this be ok.

    In addition to the above lets start the failure analysis process by filling out a customer return form -> https://www.ti.com/support-quality/additional-information/customer-returns.html

  • 0 in reply to Dennis Lehman
    Guru 26435 points

    I think that a key part of the device description is "loop powered".  So the current available to the MSP430 (and displays) will depend on the state of that loop.

  • 0 in reply to David Schultz
    TI__Guru 71216 points

    Thank you David for response Slight smile

    Ashe - was David's comment helpful to you in determining why these devices may not be behaving correctly?

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