I have an automotive temperature sensor. Its datasheet states it can handle a maximum of 5mW. I will be running it using 5v (hopefully directly from the Arduino but you might suggest it is safer for me to use an external supply?).
The temperature sensor has a resistance of around 10k ohms at -5 degrees centigrade (that's 41 of your strange fahrenheit thingies) and 30 ohms at 160 centigrade (320F).
In order to measure the temperature using an Arduino I am going to use a good old voltage divider using an R2 of 5k ohms. This provides a voltage range of 1.68v to just under 5v and a max power of a hair under 5mW so all good there.
Using the planned voltage divider, when the sesnor is at its minimum resistance (highest temp) of 30 ohms, is the analog pin seeing high current (167mA)? If I understand it correctly, the Arduino pin has very high (>1M ohm) resistance meaning almost zero current flow. Am I right?
I have already killed one of these sensors (not my fault - poor info provided at sale) so am treading carefully and still have my L-plates on!