FDC6236L Multisim Model

[saregister]

I have a PSpice Model for the Fairchild Semiconductor FDC6326L Integrated Load Switch.  It is a multicomponent part consisting of 2 MOSFETs inside a SSOT-6 package. I'm not concerned about the footprint at all, but I can't seem to get a spice model working after trying about 30 different methods for the last 4+ hours. I've gone through the tutorial that was posted in another thread, and it doesn't quite explain what I'm looking for.  The best I've been able to get so far is with only having 2 errors in the Netlist.  The errors are each not enough nodes found for each Q1 and Q2. 

If there is a way to attach the component model for what I have right now, I'll do that.

[Tien_P]

Hi Saregister,

Anything line that starts with an asterisk (*) is a comment and will be ignored by the SPICE simulator. A Spice model begins with a .subckt statement which is shown below:

.SUBCKT FDC6326LQ1 20 10 30 50
*20=DRAIN 10=GATE 30=SOURCE 50=VTEMP

After the model name(FDC6326LQ1) there are four numbers, this tells you the model have 4 pins.  The last pin in this model (pin 50) is Vtemp, this information is from the comment line just below the .subckt line.  If  you look at the datasheet for this part, there is no vtemp pin so the purpose for this pin is for simulation only.  Likely, it takes a voltage input and uses it for the operating temperature. 

The model I downloaded from Fairchild shows that both the P and N MOS in the same file and they are not connected to each other.  Base on this, I recommend you create two separate components, if want to join the model internally, you have to modify the model.  I've split the model into two separate files and they are attached.

When you create the P and N MOS component, you can create a 4 pin symbol with the extra pin for Vtemp.  If you don't care about the Vtemp pin, just delete the last node in on the .subckt line and you can use the regular 3 pins symbol.  You subkct line should now look like this:

.SUBCKT FDC6326LQ2 20 10 30

If you have any problems, post a file with the component placed, I will point out where you went wrong.

[saregister]

Thanks for the assist Tien.  I have removed the 50 from my model, and created 2 separate models as well.  one for pmos and one for nmos. I place them in my circuit and get a simulation error that says "Attemped to reference the voltage of an unconnected subckt terminal or a node that doesn't exist". I've attached my multisim circuit for you to view. I can't find a way to attach just the part model. 

Thanks,

-Scott

[OStep]

saregister,

The 4th pin of the model is used for specify operating temperatures using voltages. The symbol must have as many or more (but not fewer) pins than the model. Presently it does not and hence the error. 

Inspecting the model, it appears that this temperature pin is referenced to 25degC. So if you want to simulate this device at say 100degC, you would connect a 75V voltage source to this pin as I have done in the attached example. I would confirm this with Fairchild.

I added extra pins to the NMOS and PMOS to expose this pin.  You should not leave this pin unconnected. 

Althought when I ran the simulation, I noticed that the output does not appear to be switching as I toggle interactive switch J1. I would test the models in isolation (e.g create a basic pull-up inverter using only the NMOS) 

Thanks,

[saregister]

Thanks Max, and Thanks again Tien.  It is much appreciated. 

I've decided to just order some parts and play with them in the lab for now as I was taking too much time trying to figure out how to simulate them.  When I have a few spare minutes next time I'll look into the solution you gave Max. 

Thanks again,

-Scott