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TMP61-Q1: Any way to increase the slope

Alex Yeh
Expert 4765 points
Part Number: TMP61-Q1
Other Parts Discussed in Thread: TMP61, TMP63, TMP64

Hi Team,

With using the TMP61-Q1, is there any way to improve the resolution especially in low temperature range? Thanks.

Regards,

Alex

  • 0
    TI__Genius 9675 points

    Hi Alex,

    The resolution you are referring to is limited by the 12 bit ADC. In reference to the TMP61, there are two options.

    1) Bias the TMP61 with a current source. This will give you more dynamic range as can be seen in the chart below.

    2) Leverage oversampling methods in software to increase the ADC bit resolution. With the increased bit resolution the variance in voltage is more detectable. Ever 4x over sample you will get an increase of 2 bits resolution. So for a 4x oversample your ADC resolution is effectively 14 bits. With an 8x oversample the resolution increases to 16 bits. This is described in detail in our thermistor design tool which can be found on the TMP61 product folder. 

    Jalen

  • 0 in reply to Jalen Tate89
    TI__Expert 4765 points

    Hi Jalen,

    If customer change from TMP61 to TMP63 or TMP64, ideally the resistance changes versus temperature world be larger right?

    Would it be another solution to help RnD improve the low temp worse differentiate issue?

    Thanks.

    Alex

  • 0 in reply to Alex Yeh
    TI__Guru* 90906 points

    Alex - 

    the TMP6x devices are not resistive. They are active silicon devices and the resolution or step size is linear across the temperature range. IF you want to increase the dynamic range of the device, Jalen has given you one of the two methods - either drive the part with a current source or use an op amp to gain up the response. However - why do you think you need to increase the dynamic range on one end of the temp range? is it because you/or the customer is/are familiar with having to do that with an NTC when it is hot? if so, that is not really necessary with the TMP6x, you can "zoom" in on the signal by oversampling it, as Jalen suggested. Is that an option here?