Hi > On Jun 5, 2017, at 7:30 AM, Attila Kinali <att...@kinali.ch> wrote: > > On Mon, 5 Jun 2017 01:18:59 +0100 > Adrian Godwin <artgod...@gmail.com> wrote: > >> Where do digital sensors (e.g. ds1820 and some more recent parts from TI) >> fit into this ? > > AFAIK, these are all band-gap temperature sensors. But unlike a discrete > sensor, you have the problem that they only contain a low resolution > ADC on die (somewhere between 8 and 14 bit). If your goal is to measure > temperature and report it with an accuracy of about 1°C, then these are > the easiest to use sensors you can buy. Sensor noise doesn't really matter > with them, as it is dominated by the low ADC resolution. I don't have any > long term stability data on those, but given their use-case I do not think > that they are very stable.
Based on using them in a lot of designs, they are indeed quite stable. They are not going to rival a thermistor or an RTD, but compared to their resolution they are stable. Put another way, if they read out at the (say) 0.5 C level, you can come back a year later and the temperature repeats at < the 0.5 C level. None of this is simple or straightforward. All temperature sensors have a sensitivity to strain. They all exhibit some level of hysteresis. That can make aging measurements a bit challenging. Bob > Although long term stability might not be an > issue at all, again due to low ADC resolution. > > > If you need better precision, accuracy, or stability, then choosing one > of the modern delta-sigma ADCs that directly support thermistors > (e.g. like AD7124) is not much more difficult, though a bit more expensive > (around 10USD instead of 5USD like for an TMP107). Additionally you need > to calbirate the system, which means you need a reference temperature sensor > and a setup with which you can produce different temperatures. Though for > an oven kind of temperature control, one can live without calibration. > > > Attila Kinali > -- > You know, the very powerful and the very stupid have one thing in common. > They don't alters their views to fit the facts, they alter the facts to > fit the views, which can be uncomfortable if you happen to be one of the > facts that needs altering. -- The Doctor > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.