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CCS/TMS320F28035: Internal temperature sensor is unstable

user4364972
Prodigy 40 points

Part Number: TMS320F28035
Other Parts Discussed in Thread: CONTROLSUITE

Tool/software: Code Composer Studio

Hello,

     When we develop digit power product (DC/DC converter),we need to sample the internal temperature of the TMS320F28035.

    When our product working, there may be some interrupt in the circuit, we found the temperature value is unstable.

          AD Value : 1750 = 0℃ ;  Unit: 0.18℃ / AD Value; (Descripted in Datasheet of TMS320F2803x Series)

It means a little interrupt in VDDA supply (For example VDDA add 82.5mV = 1/40 * 3.3V) ,the temperature changed about 18℃;

Is there any way to decrease the error in the digit power for soft setting or hard circuit setting?

All above.

  • 0
    Guru 192875 points
    Hi,

    Did you go through these threads:
    e2e.ti.com/.../97621
    e2e.ti.com/.../595268

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    TI__Guru 60865 points
    Hi '4972

    There are functions provided in ControlSUITE / C2000 Ware that use slope + offset values stored in OTP to turn the temperature sensor reading into an absolute temperature. This will be much better than using the typical slope/offset values provided in the datasheet since the values are calibrated for each device.

    The ADC voltage reference shouldn't change significantly with changes in VDDA unless you are using the ADC in external reference mode with VDDA connected to VREFHI - you wouldn't want to do this since this device has an internal refernece that you can use instead even if you don't want to provide a clean external reference voltage input to VREFHI.