Since this got bumped, I thought I’d take a look at Vishay’s subcircuit model for this thing.
* VO14642 CT SSR SPICE MODEL
* LED ANODE
* | LED Cathode
* | | Pin 4 SSR contact
* | | | Pin 5 CT
* | | | | Pin 6 SSR contact
* | | | | |
.SUBCKT VO14642_CT A C S1 DC S2
W1 DC S2 Vsensor SSR_switch
R2 DC C1 100Meg
W2 S1 DC Vsensor SSR_switch
F1 C C1 V1 1
V1 A C 0
Vsensor C1 DC 0
.model SSR_Switch CSW(Ron=0.125 Roff=500Meg It=2mA Ih=0.5ms)
It’s easier to analyze if you “decompile” the code back into a schematic, so that’s what I did and also made sure the “re-compiled” netlist matches the original.
This is actually my first time encountering F-sources and W-switches, so I had to study up on those. Therefore, I have to admit that it’s totally possible I might be missing something…but I don’t understand what they are trying to do with this model. At the minimum, it doesn’t properly model the LED voltage drop so the current between A and C is going to be way off. Additionally, the scheme with the F-source makes no sense to me and nothing ever flows through that 100meg resistor because Vsensor is always shorting it out. The hysteresis current on the W-switches are too high so they don’t turn on until 2.5mA through the non-existent LED.
If I slightly modify their scheme to something that makes more sense to me, I get something that works much better when hooked up in its intended operation.
W1 DC S2 V1 SSR_switch
W2 S1 DC V1 SSR_switch
V1 A C 1.3
.model SSR_Switch CSW(Ron=0.125 Roff=500Meg It=2m Ih=10u)
Then, you can take it step further by putting in an actual LED model, voltage controlled switches, and a couple resistors to model isolation resistance.
D1 A C LED
S1 S1 DC A C SSR_Switch
S2 DC S2 A C SSR_Switch
R1 S1 C 2t
R2 S2 A 2t
.model LED D(Is=10u Rs=2 N=8 Cjo=1n Tt=1n Xti=100)
.model SSR_Switch SW(Ron=0.125 Roff=500Meg Vt=1.1 Vh=10m)
Of course, you can take it even further by using actual FETs for the switches (to model sub-threshold conduction; useful for power dissipation) and also using non-throwaway values for the LED’s Cjo & Tt (to model turn on/off time). As the circuit designer, it’s up to you to know what you need modeled and if those properties are actually included in the model or not.
Anyway, the point of posting this is I thought it was a good example to show that manufacturer-supplied SPICE models shouldn’t be taken as gospel. Especially if it’s a subcircuit with only a few lines, it might be worth taking a closer look at before using it.