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TMS320F28335: ADC & operation temperature

kevin.huang_FJXM
Expert 2925 points
Part Number: TMS320F28335


HI TEAMS:

The main chip TMS320F28335PTPQ currently in use has encountered an abnormal current sampling problem during the client's use. After investigation, it has been confirmed that the main problem is the chip experiencing abnormalities in a high-temperature environment. The main phenomenon is:

1. The single board operates in a high-temperature environment, and there is a jump in the current sampling value. After investigation, it is found that the input signal of the current sampling pins (ADCINA0, ADCINA1, ADCINA2) of the main chip is normal, but there is a jump in the register value;

2. Under the ambient temperature of+75 ℃~+85 ℃, abnormal jumps will occur in the sampling values. The higher the temperature, the more frequent the sampling value jumps.

3. There are currently 4 PCS with this issue

Could you please help me point out where the problem lies or how to solve it?

 

  • 0
    TI__Guru* 80820 points

    Kevin,

    Do we know the magnitude of the code jumps/error from the expected?  There will be some amount of gain(and to a lesser extent offset) error drift over temperature.  This should be somewhat gradual, and constant. 

    For example once we are at a higher temp I would not expect to see "jumps" per se, just a different amount of error at that temp.  Based on the above I don't think that is what is happening, but wanted to get that clear.

    Some more questions:

    1)Is customer using internal or external ADC reference

    2)From above: what is the expected ADC code and what is the abnormal ADC code

    3)Can customer comment on the ADC trigger for the start of conversion

    4)When this occurs does it just show up on a single channel/conversion or multiple channels/conversion

    5)Any commonality to the error prone sample, i.e. is it first conversion of a sequence, last, middle?

    6)What are the system clock, ADC clock settings,  and ACQPS values?

    7)Confirm that this is not seen on all devices, just a subset?

    8)Any changes to the PCB/design recently from the customer?  Even a change in BOM/supplier?

    Best,

    Matthew