If statement for a value

Hello there,

I don't believe you can use an IF statement within the subcircuit model.

What you can do is to define a switch, with on and off resistances.

Take a look at ADG.lib in your LTspice /lib/sub directory for inspiration.

We do have subcircuit models for a large number of our analogue switches, so be sure to do a sync release and check to see if the analogue switch model you require isn't already there, so you don't need to reinvent the wheel.

Happy simulations!

Best regards,

Martin.

The analogue switch will be part of a more complex model, I'm not looking for an individual switch.
I don't know why I didn't think to look at one of the switch models. I don't appear to have an adg library but I have now downloaded the adg601 model which is not encrypted. It has a number of if statements but they all appear to have the same format that I am using, maybe it can't be done with a standard part like a resistor.

Yes, I understand.  Most analogue switch models use a number of switch assignments to model the behaviour.  As an example of a more complex model in ADG.lib, please see this fragment:

.subckt ADG5248F 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
C2 3 14 63p
C5 13 14 63p
S1 N046 13 14 N042 TN
S2 3 N046 N042 14 BN
S3 13 N049 N042 14 TP
S4 N049 3 14 N042 BP

...

.model N VDMOS(Kp=2m Vto= .5 Is=0 mtriode=1 Cgs=.049p Ksubthres=.4 nlev=3 gdsnoi=2)
.model P VDMOS(Kp=2m Vto=-.5 pchan Is=0 mtriode=1 Cgs=.049p Ksubthres=.4 nlev=3 gdsnoi=2)
.model TN SW(Ron=500 Roff=1G Vt=-.4 Vh=-.1)
.model BN SW(Ron=500 Roff=1G Vt=.6 Vh=-.1)
.model TP SW(Ron=500 Roff=1G Vt=.6 Vh=-.1)
.model BP SW(Ron=500 Roff=1G Vt=-.4 Vh=-.1)
.model ESD D(Ron=1 Roff=1G epsilon=1)
.model OR D(Ron=1 Roff=1G epsilon=.25)
.model OUT SW(Ron=150 Roff=10Meg Vt=.5 Vh=-.4)
.model 3V VDMOS(Kp=200m Vto=-3 Ksubthres=.1)
.model 20�A SW(Ron=20K Roff=10T Vt=.5 Vh=-10m Ilimit=20u level=2)
.model DC SW(Ron=190 Roff=1G Vt=-.5 Vh=-.4)
.ends ADG5248F
*

Where switches TN, BN, TP and NP are the top and bottom N- and P-Channel FETs.

ADG.lib should be found in C:\Users\...\Documents\LTspiceXVII\lib\sub

I hope that helps.

Yes, I understand.  Most analogue switch models use a number of switch assignments to model the behaviour.  As an example of a more complex model in ADG.lib, please see this fragment:

.subckt ADG5248F 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
C2 3 14 63p
C5 13 14 63p
S1 N046 13 14 N042 TN
S2 3 N046 N042 14 BN
S3 13 N049 N042 14 TP
S4 N049 3 14 N042 BP

...

.model N VDMOS(Kp=2m Vto= .5 Is=0 mtriode=1 Cgs=.049p Ksubthres=.4 nlev=3 gdsnoi=2)
.model P VDMOS(Kp=2m Vto=-.5 pchan Is=0 mtriode=1 Cgs=.049p Ksubthres=.4 nlev=3 gdsnoi=2)
.model TN SW(Ron=500 Roff=1G Vt=-.4 Vh=-.1)
.model BN SW(Ron=500 Roff=1G Vt=.6 Vh=-.1)
.model TP SW(Ron=500 Roff=1G Vt=.6 Vh=-.1)
.model BP SW(Ron=500 Roff=1G Vt=-.4 Vh=-.1)
.model ESD D(Ron=1 Roff=1G epsilon=1)
.model OR D(Ron=1 Roff=1G epsilon=.25)
.model OUT SW(Ron=150 Roff=10Meg Vt=.5 Vh=-.4)
.model 3V VDMOS(Kp=200m Vto=-3 Ksubthres=.1)
.model 20�A SW(Ron=20K Roff=10T Vt=.5 Vh=-10m Ilimit=20u level=2)
.model DC SW(Ron=190 Roff=1G Vt=-.5 Vh=-.4)
.ends ADG5248F
*

Where switches TN, BN, TP and NP are the top and bottom N- and P-Channel FETs.

ADG.lib should be found in C:\Users\...\Documents\LTspiceXVII\lib\sub

I hope that helps.