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TMP431: Remote temperature error

na na78
Guru 16770 points
Part Number: TMP431


Hi

Our custoemr has following questions about TMP431.

1.
Figure 7 and 9 in datasheet offer remote temperature error against Rs and Cdiff.

Regarding to the remote temperature error in figure 7,does it mean that reading value from the remote temperature register is larger 2 degree than the actual temperature on remote IC?

2.
How to consider maximum remote temperature error?
According to datasheet, TEremote is offered by +-5 degree as maximum.
Is it possible to consider TEremote is upper limit of the remote temperature error?
Or, should we consider additional factor for the remote temperature error?

3.
The customer faced the circumstance that the remote temperature error is increased
as higher ambient temperature (over 80 degree).
what is caused mainly?

BestRegards

  • 0
    TI__Mastermind 28075 points

    Hello na na78,

    1. The 2 degree offset error in that image is specific to the ground collector-connected transistor configuration shown in part (a) of figure 11. The 2 degree C error is relative to actual temperature, but it can be reduced by setting the n-factor correction register. 

    2. 5 C of error is the maximum error when the TMP431 is directly exposed to temperatures exceeding 100 C.This value applies assuming that:

    1. Your register settings are correct
    2. PCB leakage current is negligible
    3. Series resistance and differential capacitance are within requirements 
    4. Environmental noise has been managed

    Section 11 of the datasheet gives some layout recommendations that should be followed as closely as possible. If you are seeing errors in excess of the datasheet specs one of these is likely the cause. 

    3. Error will always begin to increase as you approach the edges of the device range, but it shouldn't be outside the datasheet spec. Check to ensure that all the recommendations listed have been followed.  The customer can also check if the supply voltage is drifting with temperature, that can contribute some additional error to the measurement.

    Best Regards,

    Brandon Fisher