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I am trying to build a low-power system. One of the system parts is a Temperature sensing circuit (0 <T<60 C). Since I am have limited power (~500 uA 3V). I was lost as to which approach is the best in terms of less power consumption.

[high Accuracy and fast sampling are not necessary]

Types I am looking at:

  • NTC Thermistor
  • PTC Thermistor
  • Digital sensor

Which one have usually better for low power application? and do you recommend a certain model?

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    \$\begingroup\$ Recommendations for certain models are discouraged on this stack exchange. This may be an XY question -- if fast sampling isn't an issue, just about any sensor that's turned off most of the time may be a good choice. \$\endgroup\$
    – TimWescott
    Mar 12, 2021 at 19:45
  • \$\begingroup\$ What do you want do do with the measurement? I mean, if you read an NTC with digital electronics, this would turn into a digital sensor. So it wouldn't make much sense to compare NTC/PTC with a "digital sensor". \$\endgroup\$
    – Sim Son
    Mar 12, 2021 at 19:56
  • \$\begingroup\$ JFYI: a 100k NTC/PTC corresponds to ~30uA at 3V \$\endgroup\$
    – Sim Son
    Mar 12, 2021 at 19:59
  • \$\begingroup\$ @SimSon Thank you. \$\endgroup\$ Mar 12, 2021 at 20:40
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    \$\begingroup\$ Does this answer your question? How to operate a lower power thermistor power circuit? \$\endgroup\$
    – user16324
    Mar 12, 2021 at 21:22

1 Answer 1

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There are various way to approach the problem… an NTC/PTC has obviously as load its value at the temperature of interest (usually around 10kohms but even more depending on the model)

Active temperature sensors vary wildly: the almost overused LM35 needs about 100µA to work and gives an analog voltage, the TMP05 has a 600µA active mode but can be put in standby at some 10µA (output is a pulse duration by the way).

And now the most important trick of all: just power off the sensor when you don't need it. Even a PT100 RTD (which is a 100 ohm resistor, more or less) consume almost no power if you power it up only, say, every 5 seconds (depending on the application)

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