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MSPM0G1506: About operating in high-humidity environments.

Tao_2199
Genius 5860 points

Part Number: MSPM0G1506

Hello,
My customer is asking about operating in high-humidity environments.
They are using MSPM0G1506 in their application and have observed a phenomenon where ADC conversion values fluctuate in high-humidity environments.
(Question)
1) Is a guaranteed operating humidity range specified for the MSPM0G150x series?
We couldn't find it in the datasheet but would the following links be helpful?

Qualification summary
www.ti.com/.../home

JESD22-A102/JESD22-A118
JESD22-A101/JESD22-A110

2)About impact on internal OPA, ADC, and Vref in high-humidity environments(over 80%).
We have observed a drop in the output voltage of the I-V conversion circuit using an internal OP amp under conditions where humidity exceeds 80%.
The output voltage is being converted by an internal ADC, and since fluctuations are observed  in the AD counts, they guess that the internal reference voltage (Vref) is changing.
Is there a possibility that high-humidity environments could affect the internal OPA, ADC or Vref in the MSPM0G150x series?

This issue occurs with a frequency of approximately one in ten units.
Would you give comments and advice about the operating under high-humidity environments?

Regards,
Tao_2199

  • 0
    TI__Genius 14320 points

    Hello Tao,

    In theory, the high humidity won't affect MCU work. Could you please help to confirm more details with customer. 

    • How customer control the high humidity? Through control temperature? Could you please share more details of customer test environment?
    • You mean ADC conversion result will have fluctuate. Could you please help to quantify the error?
    • Is it possible that the high humidity affect other device on customer board, such as the voltage source? 

    BR,

    Janz Bai

  • 0 in reply to Janz Bai
    Genius 5860 points

    Helllo Jnaz,

    I have received a reply from them.

    >How customer control the high humidity? Through control temperature? Could you please share more details of customer test environment?

    ->The testing environment is a chamber with controllable temperature and humidity. The generated conditions were 25–25.3°C and 75–77% humidity.

    >You mean ADC conversion result will have fluctuate. Could you please help to quantify the error?

    ->The fluctuation in the count value is 33 counts (compared to an environment of 22.8°C and 57.6% humidity; standard laboratory conditions).

    >Is it possible that the high humidity affect other device on customer board, such as the voltage source? 

    ->I would like to contact you via email because they wish to share the circuit diagrams, which are considered confidential information.

    Regards,
    Tao_2199

  • 0 in reply to Tao_2199
    TI__Genius 14320 points

    Hello Tao,

    Thanks for your quick response. About the ADC conversion fluctuation, I found you mean is 33 count. Could you please help to give more explanation about the 33counts, does it mean "if the ADC is 12bit, the max count is 4096 (2^12), the ADC conversion fluctuation is just 3, the error is just Vref/4096 * 3?"

    And it seems that the ADC conversion result is compared under "22.8C and 57.6%" and "25-25.3C and 75-77%", could customer try to compare the ADC conversion result under "22.8C and 80%" and "22.8C and 57.6%" or compare the result under "25-25.3C and 75-77%" and "25-25.3C and > 80%". In other words, keep the temperature same.

    And about the system schematic, if customer share with us, we can just review the MCU module. About whether the device on the board will be affected by humidity, it needs customer to check accroding to the other device spec in their datasheet. 

    BR,

    Janz Bai

  • 0 in reply to Janz Bai
    Genius 5860 points

    Helllo Jnaz,

    Thank for your quick response.

    >. Could you please help to give more explanation about the 33counts, 

    ->The "33 counts" means the fluctuation (diffrence) in the conversion results between normal humidity (57.6%) and high humidity (75–77%).
    33 counts = AD count @ 57.6% − AD count @ 75–77%

    ADC is 12-bit, and Vref is 1.4 V.
    The maximum count is 4096 (2^12), meaning the fluctuation value corresponds to Vref/4096 × 33.

    >could customer try to compare the ADC conversion result under "22.8C and 80%" and "22.8C and 57.6%" or compare the result under "25-25.3C and 75-77%" and "25-25.3C and > 80%". 

    ->They will verify whether it occurs under the same conditions.

    I have requested friendship to you for private message

    I would like to share their circuit diagrams with you, so please let me know how I should go about doing so.

    Regards,
    Tao_2199