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ADC12D1620QML-SP: TMP461 as a temperature sensor for the ADC internal diode

Itai Eden
Intellectual 280 points
Part Number: ADC12D1620QML-SP
Other Parts Discussed in Thread: TMP461, TMP461-SP, , TMP461EVM

Hi,

In order to allow ADC calibration due to temperature changes, I wish to monitor its junction temperature using a remote sensor.

Is the TMP461 suitable for the ADC1620QML-SP temperature monitoring.

If so, are there any equations for the TMP461 and ADC  that support that (Temperature as a function of voltage for example)?

Regards,

Itai

  • 0
    TI__Guru* 91947 points

    Itai,

    We are looking into this.

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Mastermind 43930 points
    Hi Itai
    The TMP461 has not yet been validated with the thermal diode on this ADC, but that work will be happening this week.
    I'll let you know when I have more information.
    Best regards,
    Jim B
  • 0 in reply to Jim Brinkhurst1
    Intellectual 280 points

    Hi Jim,

    This validation is very important for us.

    we're relying on the TMP461 to measure the temperature of the ADC12D1620 for on the fly calibration (that is required by the ADC).

    Are there any other space qualified temperature sensors that you know of?

    Regards,

    Itai.

  • 0 in reply to Itai Eden
    TI__Prodigy 10 points

    Hi Itai,

    While Jim provides inputs on the validation with ADC12D1620, I wanted to add that the TMP461-SP final product will be available soon. You can get additional details, and order engineering samples (\EM) now here: http://www.ti.com/product/TMP461-SP 

  • 0 in reply to Sriram Narayanan
    TI__Mastermind 43930 points
    Hi Itai
    The TMP461 provides a direct temperature readout over the I2C interface.
    Preliminary testing shows good correlation between a thermo-couple measurement of the package top to the TMP461 reported diode temperature. I think the results are already adequate to confirm it can be used to monitor the ADC for changes in temperature from the previous calibration point. (even if there is a temperature offset, as long as the delta measurement is close enough the reading is useful).
    I'll perform some more measurements on Wednesday of next week.
    Best regards,
    Jim B
  • 0 in reply to Jim Brinkhurst1
    Intellectual 280 points

    Let me see if I understood correctly.

    You made a comparison of the following:

    1. Temperature readins from the TMP461 when  connected to the ADC12D1620 

    2. Temperature of a thermocouple connected to the  ADC package top.

    Did I understand correctly?

    Itai

  • 0 in reply to Itai Eden
    TI__Mastermind 43930 points

    Hi Itai

    Your understanding is correct.

    1) Correct. The TMP461 external diode connections are tied to the DIODE +/- connections of the ADC.

    2) The testing used a thermocouple connected to the top of the ADC package.

    I am making additional measurements with the ADC power turned on, but with PDI=PDQ=1 to minimize power consumption. In this condition the junction and package top temperature will be very similar. I will let you know the results tomorrow.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    TI__Expert 3186 points

    Dear Jim, Sriram,

    Is there any design example showing the TMP461-SP working with the ADC12D1620QML-SP ?

    Have you tested the two devices together ?

    Can you advise any function or measured graph of the results ?

    Best regards,

    Nir.

  • 0 in reply to Nir Flysher
    TI__Mastermind 43930 points

    Hi Nir and Sriram

    I gathered some data using TMP461EVM connected to ADC12D1620QML-SP EVM thermal diode. Connections between the 2 EVMs were simple wires between Diode+ to Diode+ and Diode- to Diode- of each board. I did increase the digital filtering to Level 2, averaging 8 consecutive samples to reduce variation due to noise.

    I have limited means of forcing the temperature but did get some results over a 20 degree range using a heat gun to warm the ADC EVM.

    In general the temperature measurement difference was less than 1 degree C. Slightly higher offsets were seen right after heating the board with the heat gun. I expect these errors were due to the offset between the top of the package temperature using the Fluke thermocouple, and the actual temperature of the ADC die.

    TMP461

    Fluke 179

    Difference

    Notes:

    20.375

    21.2

    -0.825

    20.4375

    21.3

    -0.8625

    23.8

    24.3

    -0.5

    31.6

    31.8

    -0.2

    31.3

    31

    0.3

    30.5

    30.3

    0.2

    30

    30

    0

    29

    29

    0

    27.5

    27.7

    -0.2

    27

    27.3

    -0.3

    26

    26.4

    -0.4

    42

    40.6

    1.4

    Just after heating board and DUT and thermocouple with heat gun

    41

    39.7

    1.3

    Just after heating board and DUT and thermocouple with heat gun

    40

    38.9

    1.1

    Just after heating board and DUT and thermocouple with heat gun

    39

    38

    1

    Just after heating board and DUT and thermocouple with heat gun

    37

    36.3

    0.7

    36

    35.3

    0.7

    35

    34.4

    0.6

    34

    33.6

    0.4

    33

    32.7

    0.3

    32

    31.9

    0.1

    28

    28.4

    -0.4

    26.5

    27.1

    -0.6

    Best regards,

    Jim B