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Original question:

DP83TG720S-Q1: There is a confirmation about the concept of the calculation formula of the temperature sensor.

DP83TG720S-Q1: Temperature output code

Sambon
Prodigy 70 points
Part Number: DP83TG720S-Q1
Other Parts Discussed in Thread: DP83TC811R-Q1,

Hi,

I have some DP83TG720S-Q1 EVM.

I notice that "temperature_output_code" is different value in each EVM under the same conditions.

Is this "errata" or "specification" ?

Regards,

Sambon

  • 0
    TI__Genius 16030 points

    Hi Sambon,

    Can you please share the measured value of the code on different EVMs? There is an expected part to part variation and lets check if you are within the limit.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 70 points
    Hi Vikram,
    I share the measured value of the code on different EVMs.
    Could you please check these results whether is spec or errata ?
    Temperature Condition : 24 degree
    Board No "110" ( "110" is written on the connector )
    reg_add：047b
    read_data:5d00
    * [0x047B] [14:7] for selected sensor's output code: BA (hex) → 186(dec)
    Board No "116" ( "116" is written on the connector )
    reg_add：047b
    read_data:5580
    * [0x047B] [14:7] for selected sensor's output code: AB (hex) → 171(dec)
    Board No "120" ( "120" is written on the connector )
    reg_add：047b
    read_data:4d00
    * [0x047B] [14:7] for selected sensor's output code: 9A (hex) → 154(dec)
    Board No "124" ( "124" is written on the connector )
    reg_add：047b
    read_data: 4f80
    * [0x047B] [14:7] for selected sensor's output code: 9F (hex) → 159(dec)
  • 0 in reply to Sambon
    TI__Genius 16030 points

    Hello Sambon,

    There is some delay in getting the required information because of holidays. I hope to get back to you with clarification by 29th December.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 70 points

    Good evening Vikram,

    Thank you for your hard work.

    I'm looking forward to your answer.

    Regards,

    Sambon

  • 0 in reply to Sambon
    TI__Genius 16030 points

    Hello Sambon,

    We expect worst case part to part variation of about +/-21C. +/-7.5C is the accuracy of the temperature sensor on a single part. So worst case (uncalibrated) part to part variation can be 21*2 + 7.5*2 = 57C. Part to part temperature difference what you are getting is (186-154 = 32)*1.5C = 48C. So this is within the expectation. You may make accuracy +/-7.5C by calibrating out the part to part variation as explained in datasheet. 

    Just to confirm that procedure is correct, can you please confirm that you are doing the following :

    Step 1 : Program register 0x0467 = 0x6004

    Step 2 : Program register 0x046A = 0x00A6

    Step 3 : Program register 0x046A = 0x00A3

    Step 4 : Program register 0x0468 = 0x4920

    Step 5 : Read register 0x047B[14:7] for the value of temperature_output_code.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 70 points

    Hi Vikram,

    Thanks you for your reply. I'm doing step1-5.

    My understanding is that this chip must be calibrated in a strict  temperature controlled environment(e.g. thermostatic chamber) before use.

    Is it correct ?

    In addition, how do you expect this temperature monitor feature to be used?

    Regards,

    Sambon

  • 0 in reply to Sambon
    Prodigy 70 points

    Hi Vikram,

    I know you are busy, but  could you please reply ?

    Thank you,

    Regards,
    Sambon

  • 0 in reply to Sambon
    TI__Genius 16030 points

    Hello Sambon,

    Sorry for the delay. I missed following up on this conversation. 

    Yes, without calibration, we expect accuracy of ~ +/-28C. With calibration, we expect accuracy of +/-7.5C.

    Calibration procedure is in the datasheet.

    What is the accuracy requirement of your application? Are you looking for a particular accuracy in a narrow temperature range : what is it? 

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 70 points

    Hi, Vikram,

    I want to check the temperature the phy ic as possible as high accuracy.

    The target accuracy is same as DP83TC811R-Q1.

    Which is more high accuracy, DP83TC811R-Q1 or DP83TG720S-Q1 ?

    Thank you,

    Regards,

    Sambon

  • +1 in reply to Sambon
    TI__Genius 16030 points

    Hello Sambon,

    720 should be more accurate for full temperature range.

    --

    Regards,

    Vikram