LTSpice LED Modeling

Thread Starter

GuyElec

Joined Apr 12, 2024
12
I was wondering if there is a way to change parameters of NSCW100 LED in LTSPice? I like the Vf of 3.5 but would like a max current 180mA for the LED instead of 80mA I believe.
 

ericgibbs

Joined Jan 29, 2010
18,988
Hi Guy,
Welcome to AAC.
In the LTSpice folders, find Cmp folder, then open the standard.dio file in a text editor.
All diodes are listed.
Make a copy of the NSCW text group, rename it, then change the mA value and Save the standard.dio
E

model NSCW100 D(Is=16.88n Rs=8.163 N=9.626 Cjo=42p Xti=200 Iave=30m Vpk=5 mfg=Nichia type=LED)
 

eetech00

Joined Jun 8, 2013
4,004
I was wondering if there is a way to change parameters of NSCW100 LED in LTSPice? I like the Vf of 3.5 but would like a max current 180mA for the LED instead of 80mA I believe.
One I/V value does not and LED make...:)
The usual practice is to find the LED datasheet for the LED you intend to use and match the If-Vf curve.
 

Thread Starter

GuyElec

Joined Apr 12, 2024
12
One I/V value does not and LED make...:)
The usual practice is to find the LED datasheet for the LED you intend to use and match the If-Vf curve.
Ya you are right, looking at it now I also got the wrong Vf was thinking of another LED that I looked at. Probably need something more like the picture
 

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Thread Starter

GuyElec

Joined Apr 12, 2024
12
Was wondering about a DC sweep of the attached circuit to take the current flow and voltage node readings. The source is regulated at 29.5V and the CCR is driving the LEDs at 97mA.
 

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ericgibbs

Joined Jan 29, 2010
18,988
Hi Guy,
Please post your asc file
E

Update:
You can simplify the number of LED's by using the n=7 option, set the n value to suit your number of LED's
 

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Last edited:

Thread Starter

GuyElec

Joined Apr 12, 2024
12
Hi guy,
What are you trying to measure with this simulation?
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current flow and voltage node readings, along with the drop of voltage possibly as it goes down the string. This is from a power supply that is 29.5Volts. The CCR is set to 97mA which I just used a source since the ORCAD model of IS32LT3177 just kept crashing.
 

eetech00

Joined Jun 8, 2013
4,004
Was wondering if I also have the string set up correctly? Need to see the Vf at the bottom node. Thanks
You can configure it as post #8 but replace R1 with a current source of 97m.
This won't show the behavior of a CCR but will allow you measure the value across the last LED.
 

Thread Starter

GuyElec

Joined Apr 12, 2024
12
I have a model for the CCR I am using but have trouble opening it do to some directory issues, how do I solve this issue? Thanks
 
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