Questions regarding the family of curves depicted in Figure 7 of the TMP20 datasheet. (SBOS466-DECEMBER 2009).
How is the temperature calculated from the 39 units under test? Using 1st or 2nd order functions?
Vo = –11.79 x T + 1.8528 [mV] → (-55°C < T < 130°C),
or
Vo = (–3.88 × 10–^6 × T^2) + (–1.15 × 10–^2 × T) + 1.8639 [V],
From looking at the data, it seems like a 2nd order correction would greatly increase the accuracy (±0.5°C). Would you agree?
What I'm wondering is why wouldn't the error curves look like this (see sketch below) when the temperature values are calculated with the 2nd order transfer function?
Hello Abhi,
I do understand that error will vary between an analog and digital out part. In this case, I'm talking about a specific analog out part (TMP20). I'm asking for information specific to this part and not temperature sensors in general.
What I'm saying is that the error curve over the full temperature range - for 39 parts - follows a 2nd degree function. Since this function can be estimated (best fit method) it would greatly increase the accuracy of the output. I don't understand why the error looks more deterministic than random.
Could Figure 7 be depicting values for row 1 in Table 1 (Temperature limits and maximum deviation seem to correspond → See ±1.41 on graph @ 130°C)
