RTD Platinum sensor Spice model

[EFISys]

Does anybody have a spice model or can show me how to make one for a 20 ohm platinum ptc sensor with self heating ? I need to simulate it in a closed loop bridge circuit, I am an old fart that normally just uses paper and changes parts but this circuit is all smd.

Thanks doug W

[Tien_P]

Hi Doug,

Multisim doesn't have a RTD but you can use a voltage control resistor (VCR) to emulate the RTD.  You can find the VCR in library by going to the "Basic" group and highlighting the "basic virtual" family.  The input to this component in voltage but you can pretend it's temperature and resistance will change accordingly. 

[OStep]

Doug,

If you can provide me with the characteristic equations, I can try to create a model for you.

Thanks

[EFISys]

Thanks, the spec I have is 20.75ohm @ 0c, self heating = 2mw, 1m/sec air , resistance change = temp C x 0.105 +20.75 = resistance at new temp. (100C x 0.105 +20.75 = new res of 31.25.) For now I need for an airflow of 0.  i have been playing with the VCR but can't get it to do anything yet.

Thanks again

Doug W

[OStep]

Doug,

I created a simple RTD model that you can try. Use the TEMP pin to supply the external environment temperature as a voltage signal.

Take a look at the SPICE model and you should be able to figure out what's going on. Basically, its just a variable resistor modeled as I=V/R(temp), where temp is the adjusted temperature, a function of the external temperature and the power across the device. 

Hope that helps!

[guruhari]

Hiee ...I need to design the RTD circuit using orCAD pspice......Do we hace any component for RTD sensor in pspice??

and if its not ter can any1 helps me out tis with design.

with spice file..thank you.

Guru