LED luxeon datasheet graph

I am trying to build a circuit to recreate the graph (forward current of LED vs forward voltage) shown in the Luxeon rebel color data sheet p.14.

I looked up the specs for that particular model (green)
.model LXML-PM01-average D(Is=8.0330e-8 Rs=.4818 N=7.0005 mfg=Lumileds type=LED)
and added the Is, Rs and N parameters to a D1N4148 in pSpice.

The data sheet states that the typical forward voltage of the green LED is 3.05V at a current of 350mA, I might be completely misinterpreting something, but I thought that the forward voltage of the LED would be (350mA x Rs).

I used a supply voltage of 10V and calculated my series resistor from (10-3.05)/R =350mA

The circuit is then a 10V supply with a 20 Ohm resistor and I did a DC sweep from 0-10V and plotted I(D1) Vs. V(D1), which gives me a graph does not look very like the one on the datasheet.

Would anyone be able to help me by telling me what I am doing wrong? Am I misinterpreting something completely?

I don't have Spice documentation handy at the moment but there are many parts which make up the diode model. Amongst other things the reproduce the shape of the diode voltage/current curve. You are assuming the model is simply a resistor but it is a lot more complex and includes a voltage element which reproduces the 'knee' in the characteristics. The Rs will just be an extra resistance in series with a voltage element. That will dictate the slope of the V-I curve after the knee.

Keith

So when I change the parameters Rs, Is and N of the D1N4148 diode I also have to change some other parameters? I assumed (perhaps wrongly) that the exponential equation of the diode would be relatively the same as that of the LED. I was going to use the LED model MLED96, but it had an extra port which I wasn't too sure what to do with.

As I say, I haven't any documentation handy at the moment but the forward volts drop at the knee is a result of the bandgap so will be different in an LED as it is different between silicon and germanium. I would expect an LED model to reflect that difference.

Keith