Choosing the correct resitor value for lm335.

A basic question from someone who is new to electronics and does not want to damage his components.
My desire is to connect a lm355 temperature sensor to a board using a 3.3v power source.

Ensure the LM335 is biased properly with a current ranging 0.4 mA to 5 mA. For optimum
accuracy, R1 is picked such that 1 mA flows through the sensor.


Does this mean I can simply apply Ohm's law V = I * R?

3.3/0.001 = 3300 Ohm

Bildschirmfoto 2018-01-19 um 09.30.06.png

Almost, but you have to think of the voltage acrss the LM335 as well. That's 10mV per K, so at room temperature (20C = 293K) that's already 2,93V. So powering it from 3,3V might be a bit tricky. Because if you want 1mA at room temperature you end up with (3,3V - 2,93V) / 1mA = 370Ohm. But it has a minimum of 0,4mA which is reached at 3,3V - 370Ohm x 0,4mA = 3,15V across the LM355 which is 315K = 41,6C. The 5mA max is reached at -128C so that's not a problem I guess :stuck_out_tongue: