Electronic Circuits and Projects Forum

hi Logan,
The LM335 works from -40C to +100C, output is 10mV/C rise for each 1Cdefg rise in temperature.

What resistor are you asking about.?

E.

Originally Posted by Little Ghostman

Sorry my screen capture isnt working but if you look at the link in my first post and on page 6 under typical applications the drawing shows a resistor marked R1 but dosnt give a value, also it indicates that the output is in kelvin that is indicated on the same drawing
thank you mr gibbs

L,
You want to have ~1mA flowing thru the LM335
At room temperature [say 25C] the LM335 will have ~+2.98V drop across it.
So using a+5V supply, you need to drop from 5V to say 3V at 1mA, so that [5-3]/.001 =2K ohms =R1

Do you follow OK.?
E

EDIT:
NOTE: 298K - 25C = 273K, so from -273K at 10mV/K rise will give +2.73V at 0Cdeg and at +10C +2.83V, so it goes higher/lower by 10mV for every 1Cdeg high or lower,.

Originally Posted by Little Ghostman

thank you mr gibbs that realy explains it well for me! so if i am using it at say a higher temp (i am not) then i look at the graph and get the voltage drop from that and redo the calculations thats very very helpful thank you
logan
p.s reinstalled snagit and now have screen capture again! no idea why it wasnt working

Did you see my Edit on the last Post, more information added

Originally Posted by Little Ghostman

so do you mean with the 2k resistor it will go up 10mv per degree C? so 25Cis 2.83v and then each C after that is another 10mv?

L,
The 10mV change per 1Cdeg is the typical value from the datasheet.

Yes, if you set it for 25C and 2.98V output, it will change by 10mV/C, BUT using only a 5V supply you will reach a point where the output voltage will limit.

Consider a temperature of +100C [its max value] thats 3.73Vout, say 4Vmax.

I would suggest you set it up and plot Vout versus temperature, over the temperature range you intend to use it.. lets know