I was trying to model a reflective type optocoupler from NJR p/n NJL5908AR.

Unfortunately NJR doesn't have spice model available for these parts.

While I was searching for spice model on web, I found an application note by CEL (could not attach for some reason) for PS2561F optocoupler, thinking that I will be able to model reflective type optocoupler by taking reference from PS2561F model.

Note: Application note is from California Electronics Laboratories, AN3017

The spice model code is pasted at the end.

The statement which I don't understand is:

"Gctr C B TABLE

+ {If(V(T)<3m,

+ ((-94570000000*PWR(V(T),5)+694000000*PWR(V(T),4)

+ -1951000*PWR(V(T),3)+2918*PWR(V(T),2)-0.2827*V(T)+0.00001958)*0.92/550),

+ ((-24590*PWR(V(T),4)+3484*PWR(V(T),3)-178.1*PWR(V(T),2)+3.983*V(T)

+ -0.004788)*0.96/550))}

+ (0,0) (0.1m, 0.1m)"

This is (I suppose) the polynomial equation for CTR (Current transfer ratio) and multiplying CTR values with the forward current (in terms of voltage) using behavioural model.

Now since the part from NJR NJL5908AR doesn't have CTR mentioned since its a reflective type I guess, I have drawn a graph by using the characteristics graph b/w output current vs Forward current and derive the polynomial using trend line property of excel, but I am not getting proper simulation results.

SPICE MODEL Below:

* the maximum ratings as called out in the data sheet.

*

* Please note that the model can't duplicate exact device performance in the

* real world under all conditions and they can't replace the breadboarding

* for final design verification.

*

* Note: CTR is modelled base on sample A in the data sheet. Please refer to the

* data sheet for details.

*********************************************************************************

* A = PIN 1: diode anode

* K = PIN 2: diode cathode

* E = PIN 3: BJT emitter

* C = PIN 4: BJT collector

.SUBCKT PS2381 A K E C

D1 A D LED

Vsense D K 0

Hd R 0 Vsense 1

Rd R T 100k

Cd T 0 20p

Gctr C B TABLE

+ {If(V(T)<3m,

+ ((-94570000000*PWR(V(T),5)+694000000*PWR(V(T),4)

+ -1951000*PWR(V(T),3)+2918*PWR(V(T),2)-0.2827*V(T)+0.00001958)*0.92/550),

+ ((-24590*PWR(V(T),4)+3484*PWR(V(T),3)-178.1*PWR(V(T),2)+3.983*V(T)

+ -0.004788)*0.96/550))}

+ (0,0) (0.1m, 0.1m)

Q1 C B E detector

.model LED D IS=1p N=1.999644 RS=0 BV=6 IBV=10u

+ CJO=10p EG=1.424 TT=500n

.model detector NPN IS=100p BF=550 NF=1.3 BR=50 TF=2n TR=1.5n

+ CJE=15p CJC=20p VAF=100 ISS=0 CJS=1p

.ends

*$

Thanks in advance.

sunney