TVS diode in LT spice

tirsdag den 8. november 2022 kl. 20.12.57 UTC+1 skrev John Larkin:

it shouldn't and when I just tried it didn't. Vfwd 0.7V, Vrev 38.65 if I change Vfwd and Vrev ot the same it gets symmetrical

type and mfg is not part of the model parameters if you try to make a model with them you get and error, afaict they are just for the selection dialog

Try this:

Version 4 SHEET 1 880 680 WIRE 16 96 -16 96 WIRE 80 96 16 96 WIRE 192 96 160 96 WIRE 224 96 192 96 WIRE -16 128 -16 96 WIRE 224 128 224 96 WIRE -16 224 -16 192 WIRE 224 224 224 192 FLAG 224 224 0 FLAG -16 224 0 FLAG 16 96 A FLAG 192 96 B SYMBOL TVSdiode 208 128 R0 WINDOW 0 63 22 Left 2 WINDOW 3 52 45 Left 2 SYMATTR InstName D1 SYMATTR Value SMBJ24CA SYMATTR Description Diode SYMATTR Type diode SYMBOL current 80 96 R270 WINDOW 0 50 31 VRight 2 WINDOW 3 80 -24 VRight 2 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value SINE(0 50m 1) SYMBOL TVSdiode -32 128 R0 WINDOW 0 63 22 Left 2 WINDOW 3 52 45 Left 2 SYMATTR InstName D2 SYMATTR Value SMCJ33A SYMATTR Description Diode SYMATTR Type diode TEXT 272 216 Left 2 !.tran 0 4 0

What am I missing?

tirsdag den 8. november 2022 kl. 21.05.45 UTC+1 skrev John Larkin:

D1 is symmetric, as expected from the model; Vfwd = Vrev .model SMBJ24CA D(Ron=.65 Roff=50Meg Vfwd=25 epsilon=6 Vrev=25 revepsilon=6 Vpk=24 mfg=Littlefuse type=TVS)

D2 is not, as expected from the model; Vfwd != Vrev .model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65 Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)

don't know, what do you see?

Oh, they hijacked Vfwd. I missed that.

I got up at 5 AM. That's my excuse.