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TMS320F28034: Question about Internal Temperature Sensor

Part Number: TMS320F28034
Other Parts Discussed in Thread: C2000WARE, CONTROLSUITE

Dear team:

My customer has a question about the Internal Temperature Sensor of F28034.

He found that the sampling value of the internal temperature sensor is basically the same as that of the external temperature probe in the range below 50 ℃. However, when the temperature exceeds 50 ℃, the deviation between the two values becomes larger and larger. The following are the specific reference values:

External temperature probe value: 55 ℃, DSP internal temperature sensor value: 58 ℃;

External temperature probe value: 69 ℃, DSP internal temperature sensor value: 107 ℃;

External temperature probe value: 80 ℃, DSP internal temperature sensor value: 140 ℃;

Is this test value normal?

Best regards

  • BTW,he use the Official routines from:

    C:\ti\c2000\C2000Ware_3_02_00_00\device_support\f2803x\examples\c28\adc_temp_sensor_conv

  • Green,

    While we don't give a max/min error for the internal temperature sensor translated temperature this does seem unexpected in terms of the error magnitude, esp since the 80C/140C measurement exceeds our expected operational temperature max of 125C.

    1)Can you confirm if the customer is calling the temperature sensor functions that return degC based on the passed value of the internal temp sensor?  Is customer using the examples from C2000Ware to implement this(there is a specific S/H requirement when sampling the temp sensor that is different than an outside ADC channel)

    2)When comparing to an external measurement, can you comment on the location of the external temperature sensor?  Is it mounted to the case of the C2000 MCU?

    Will wait for your reply before suggesting the next steps.

    Best,

    Matthew

  • Dear Matthew:

    My client tests with routines.  And the chip works well when the reading of the temperature sensor is 140 ℃.

    May you help me to test the chip temperature sensor when the case temperature  of the chip is 80 ℃? 

  • Green,

    Thanks for the new information.  I agree the device is likely not running out of specification, but some error in the temp sensor.  My comment was more of saying that since the max reading is >>125C.

    I'd like to confirm the following:

    1)Make sure we have downloaded the latest version of C2000Ware or controlSUITE(whichever the customer is using) and re-run the experiment and see if the results are the same.  There was a change in the sample and hold window used to measure the temperature sensor that was updated a while ago; but if customer is using one of the 1st revisions of controlSUITE it may be using the min ACQPS.

    2)Use CCS to read the following memory locations are reply back with the values to this thread(you may need to disable the memory map in CCS, I'm not sure if these are mapped in the default GEL.  If you read back 0x0000, then this is the issue.:

    0x3D7C6A
    0x3D7C72
    0x3D7C7A
    0x3D7C78

    Best,

    Matthew