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MSP430F149: MSP430F149 A/D convertor problem

Jiri Kopelent
Prodigy 30 points
Part Number: MSP430F149

Hi,

I use MSP430F149 for years with same firmware and everything was OK till now. MCUs from last delivery works, but their A/D convertor show results which are lower than real value of measured voltage is. The difference is same for all new MCUs and it's 150mV lower that real voltage is. As a reference is used the internal voltage reference.

Does anybody idea where the problem could be? Is there any change in structure of MCU MSP430F149? Firmware, PCB, everything is same, only A/D measure lower voltage realyty is.

Many thanks in advance for your help / ideas

Kind Regards,

Jiri

  • 0
    TI__Mastermind 27600 points
    Hello Jiri,

    I'm not aware of any recent changes to the MSP430F149. This is one of our longest shipping devices, probably close to 20 years.

    How many units are you seeing the issue on? Do you have any previous units to swap in an compare that they work the same on your board?

    Thanks,
    JD
  • 0 in reply to JD Crutchfield
    Prodigy 30 points

    Hello JD,

    when I use any MCU from new revision (marking on body of IC is: 4CAPC1WG4, M430F149, REV S) all ones give same wrong result of A/D conversion. When I place on the same board MCU from "Old" revision (full marking on the body is: 7AE18ETG4, M430F149, REV N), results from A/D conversions are correct. Of course in ALL MCUs is running same firmware.

    Any Idea what is different between both revisions?

    Many thanks in advance for your ideas

    Best Regards,

    Jiri

  • 0 in reply to Jiri Kopelent
    TI__Mastermind 27600 points
    Hey Jiri,

    From a design standpoint, Rev S and Rev N are exactly the same. We have to do revisions for small sourcing or fabrication changes over time, but this doesn't change the device.

    What voltage references are you using for the ADC?

    Do you have an ADC calibration routine on this design?

    Thanks,
    JD
  • 0 in reply to JD Crutchfield
    Prodigy 30 points

    Hi JD,

    I use internal reference voltage 2.5V.

    Your notice regarding internal calibration brings solution - my small fault in the routine :-( I several check it, but didn't see. After your notice I said - "There MUST be a mistake" - and I really found it.

    Many thanks for your support

    Best Regards,

    Jiri

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