On Tue, 8 Nov 2022 12:37:01 -0800 (PST), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
>tirsdag den 8. november 2022 kl. 21.05.45 UTC+1 skrev John Larkin:
>> On Tue, 8 Nov 2022 11:36:04 -0800 (PST), Lasse Langwadt Christensen
>> <lang...@fonz.dk> wrote:
>>
>> >tirsdag den 8. november 2022 kl. 20.12.57 UTC+1 skrev John Larkin:
>> >> .model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65
>> >> Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)
>> >>
>> >> That's in the standard library. It behaves like a symmetric zener.
>> >
>> >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
>> Try this:
>>
>
>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)
>
>>
>> What am I missing?
>
>don't know, what do you see?
>
>https://imgur.com/OPZl629
>
Oh, they hijacked Vfwd. I missed that.
I got up at 5 AM. That's my excuse.
Reply by Lasse Langwadt Christensen●November 8, 20222022-11-08
tirsdag den 8. november 2022 kl. 21.05.45 UTC+1 skrev John Larkin:
> On Tue, 8 Nov 2022 11:36:04 -0800 (PST), Lasse Langwadt Christensen
> <lang...@fonz.dk> wrote:
>
> >tirsdag den 8. november 2022 kl. 20.12.57 UTC+1 skrev John Larkin:
> >> .model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65
> >> Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)
> >>
> >> That's in the standard library. It behaves like a symmetric zener.
> >
> >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
> Try this:
>
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)
On Tue, 8 Nov 2022 11:36:04 -0800 (PST), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
>tirsdag den 8. november 2022 kl. 20.12.57 UTC+1 skrev John Larkin:
>> .model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65
>> Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)
>>
>> That's in the standard library. It behaves like a symmetric zener.
>
>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
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?
Reply by Lasse Langwadt Christensen●November 8, 20222022-11-08
tirsdag den 8. november 2022 kl. 20.12.57 UTC+1 skrev John Larkin:
> .model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65
> Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)
>
> That's in the standard library. It behaves like a symmetric zener.
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
> Why? Does "type" do that? There are unipolar TVS diodes, too.
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
Reply by John Larkin●November 8, 20222022-11-08
.model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65
Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS)
That's in the standard library. It behaves like a symmetric zener.
Why? Does "type" do that? There are unipolar TVS diodes, too.