Maker Pro
Maker Pro

Need Help, LTspice SCR model

A

amdx

Jan 1, 1970
0
Hi all, I found the following model of an SCR on the web. I have tried to
use it in a simple circuit and I can't seem to get it to work. It barely
turns on.
I would like a model for a 2N5060, I don't find one.
Is there something obviously wrong with this model?
Or, can someone give me a model of a small signal SCR?
Thanks, Mike
*SCR
*Extracted from PONT_DIPH.CIR file from EDN website.
*I renamed that file as SCR_CKT.CIR
* Anode
* | Cathode
* | | Trigger
* | | |
..subckt SCR 1 2 3
*
*Models used by the SCR Model:
..model STH VSwitch (ROn=0.1, VOff=0.5)
..model DLG D (Rs =25m)
*
*We assume that the SCR in the on-state is equivalent to 0.1 ohm:
SSCR 1 4 5 0 STH
VSCR 4 2 0V
*
*Trigger to cathode impedance is a 1k ohm resistance - fore simplification:
RTrig 3 2 1k
*
* The following circuit locks in the on-state when a 1mA current flows
*through the gate to the cathode with a positive anode to cathode voltage.
*This circuit locks in the off-state when the current through the SCr tends
*to become negative:
VPlus 6 0 2V
SiTrig 6 5 3 2 STH
CState 5 0 1uf IC=0
DLogic 5 8 DLG
HCur 8 0 poly(1) VSCR 1 10000
*
*The potential of node 5 reflects the state of the SCR. It is less than 2V
*for the off-state and between 1v and 2V in the on-stateh
..ends
 
H

Helmut Sennewald

Jan 1, 1970
0
amdx said:
Hi all, I found the following model of an SCR on the web. I have tried to
use it in a simple circuit and I can't seem to get it to work. It barely
turns on.
I would like a model for a 2N5060, I don't find one.
Is there something obviously wrong with this model?
Or, can someone give me a model of a small signal SCR?
Thanks, Mike
*SCR
*Extracted from PONT_DIPH.CIR file from EDN website.
*I renamed that file as SCR_CKT.CIR
* Anode
* | Cathode
* | | Trigger
* | | |
.subckt SCR 1 2 3

Hello Mike,

The SCR symbol in LTspice has the pin order Anode, Trigger, Cathode.
You could either make a new symbol SCR1 with the netlist order
Anode, Cathode, Trigger or you simply change the pin order in the
subcircuit.

Solution 1: Change the subcircuit line
* Anode
* | Trigger * | | Cathode
* | | |
.subckt SCR 1 3 2


Solution 2:

Make a copy SCR1.asy from the synbol SCR.asy.
Open the new symbol SCR1.asy and change the netlist order
of the gate/trigger pin to 3 and the the cathode pin to 2 as
required by the original subcircuit.


Both methods are ok. Take your choice.

Best regards,
Helmut
 
A

amdx

Jan 1, 1970
0
Helmut Sennewald said:
Hello Mike,

The SCR symbol in LTspice has the pin order Anode, Trigger, Cathode.
You could either make a new symbol SCR1 with the netlist order
Anode, Cathode, Trigger or you simply change the pin order in the
subcircuit.

Solution 1: Change the subcircuit line



Solution 2:

Make a copy SCR1.asy from the synbol SCR.asy.
Open the new symbol SCR1.asy and change the netlist order
of the gate/trigger pin to 3 and the the cathode pin to 2 as
required by the original subcircuit.


Both methods are ok. Take your choice.

Best regards,
Helmut
Thanks Helmut, good call, sharp of you to notice. I had already made
that change through the atribute editor. I'll revisit it just to make sure I
have the labels correct.
The change was in the writeup about the SCR file.
Thanks, Mike
 
Top