White LED Spice Model
Jim Thompson
points of a real device. Unfortunately I've misplaced which actual
device number it was :-(
******************************************************************
**** My White LED ****
.SUBCKT MyWhiteLED A K
D_D1 N_1 0 D1N4148
F_F1 N_3 K VF_F1 1
VF_F1 N_2 N_1 0V
E_E1 N_2 0 N_3 K 0.228
R_R1 A N_3 5
.ENDS MyWhiteLED
******************************************************************
Schematic and PSpice simulation results at...
Newsgroups: alt.binaries.schematics.electronic
Message-ID: <qo41l5llt9mtna5be...@4ax.com>
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson
<To-Email-Use-Th...@My-Web-Site.com/Snicker> wrote:
>Here's a white LED Spice model that I created by fitting to data
>points of a real device. Unfortunately I've misplaced which actual
>device number it was :-(
>
>******************************************************************
>**** My White LED ****
>.SUBCKT MyWhiteLED A K
>D_D1 N_1 0 D1N4148
>F_F1 N_3 K VF_F1 1
>VF_F1 N_2 N_1 0V
>E_E1 N_2 0 N_3 K 0.228
>R_R1 A N_3 5
>.ENDS MyWhiteLED
>******************************************************************
>
>Schematic and PSpice simulation results at...
>
>Newsgroups: alt.binaries.schematics.electronic
>
>Message-ID: <qo41l5llt9mtna5be...@4ax.com>
>
> ...Jim Thompson
If you have data points for other LED's... measure VF at many currents
(*)... PULSED to avoid heating, send the data to me and I'll make a
model for them.
(*) Measure VF at IF = 0.1mA 0.2mA 0.5mA 1mA 2mA 5mA 10mA 20mA 50mA
Paul Hovnanian P.E.
HP-41C.
The model I get from your curve is:
.MODEL MyWhiteLED D
+ IS = 4.4249E-9
+ N = 8.3923
+ RS = 7.7980
No subcircuits required.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
Ask not for whom the <CONTROL-G> tolls.
Jon Kirwan
<Pa...@Hovnanian.com> wrote:
>I found my old HP-41C curve fit program card. Then I found my old
>HP-41C.
>
>The model I get from your curve is:
>
>.MODEL MyWhiteLED D
>+ IS = 4.4249E-9
>+ N = 8.3923
>+ RS = 7.7980
>
>No subcircuits required.
That N looks frightening.
Jon
Paul Hovnanian P.E.
Yes, but it seems to work for the white LED (probably a blue LED) curve.
I haven't gotten into the physics of the problem, but the emmission
coefficient (N) seems to track the band gap of the junction involved. So
this isn't as bizarre as it appears.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
"Yee-Ha!" is not an adequate foreign policy.
Jim Thompson
<Pa...@Hovnanian.com> wrote:
>Jon Kirwan wrote:
>>
>> On Wed, 27 Jan 2010 19:28:57 -0700, "Paul Hovnanian P.E."
>> <Pa...@Hovnanian.com> wrote:
>>
>> >I found my old HP-41C curve fit program card. Then I found my old
>> >HP-41C.
>> >
>> >The model I get from your curve is:
>> >
>> >.MODEL MyWhiteLED D
>> >+ IS = 4.4249E-9
>> >+ N = 8.3923
>> >+ RS = 7.7980
>> >
>> >No subcircuits required.
>>
>> That N looks frightening.
>
>Yes, but it seems to work for the white LED (probably a blue LED) curve.
>I haven't gotten into the physics of the problem, but the emmission
>coefficient (N) seems to track the band gap of the junction involved. So
>this isn't as bizarre as it appears.
Here's a white LED Spice model that I created by fitting to data
points of a real device:
******************************************************************
**** My White LED ****
.SUBCKT MyWhiteLED A K
D_D1 N_1 0 D1N4148
F_F1 N_3 K VF_F1 1
VF_F1 N_2 N_1 0V
E_E1 N_2 0 N_3 K 0.228
R_R1 A N_3 5
.ENDS MyWhiteLED
******************************************************************
Retrieve the original posting at...
Newsgroups: alt.binaries.schematics.electronic
Subject: White LED Spice Model
Date: Fri, 15 Jan 2010 09:18:31 -0700
Message-ID: <qo41l5llt9mtna5be...@4ax.com>
X-Newsreader: Forte Agent 6.00/32.1186
to see simulation versus data points.
Jim Thompson
<Pa...@Hovnanian.com> wrote:
>I found my old HP-41C curve fit program card. Then I found my old
>HP-41C.
>
>The model I get from your curve is:
>
>.MODEL MyWhiteLED D
>+ IS = 4.4249E-9
>+ N = 8.3923
>+ RS = 7.7980
>
>No subcircuits required.
I'm not sure if that will work over temperature.
It would be interesting if someone could take data at several
different temperatures. It'll be tricky, you have to be quick or
self-heating will screw up the result. Maybe with a plotting curve
tracer?
Jim Thompson
<Pa...@Hovnanian.com> wrote:
>I found my old HP-41C curve fit program card. Then I found my old
>HP-41C.
>
>The model I get from your curve is:
>
>.MODEL MyWhiteLED D
>+ IS = 4.4249E-9
>+ N = 8.3923
>+ RS = 7.7980
>
>No subcircuits required.
BTW: "your curve"? Whose curve? You clip too much, Paul.
Paul Hovnanian P.E.
> On Wed, 27 Jan 2010 19:28:57 -0700, "Paul Hovnanian P.E."
> <Pa...@Hovnanian.com> wrote:
>
>>I found my old HP-41C curve fit program card. Then I found my old
>>HP-41C.
>>
>>The model I get from your curve is:
>>
>>.MODEL MyWhiteLED D
>>+ IS = 4.4249E-9
>>+ N = 8.3923
>>+ RS = 7.7980
>>
>>No subcircuits required.
>
> I'm not sure if that will work over temperature.
>
> It would be interesting if someone could take data at several
> different temperatures. It'll be tricky, you have to be quick or
> self-heating will screw up the result. Maybe with a plotting curve
> tracer?
That's a good point. N is often used as a 'fudge factor' for Vt, so for wild
values of N (greater than 2.0 or less than 1.0) it would be reasonable to
expect that nVt may vary with temp (or other conditions) in some different
manner than kT/q.
Where I've seen weird values of N pop up, SPICE started to fall apart for
anything other then approximate values. It was time to toss the standard
model and go with something cooked up by the physicists.
--
Paul Hovnanian pa...@hovnanian.com
----------------------------------------------------------------------
Have gnu, will travel.
Paul Hovnanian P.E.
> On Wed, 27 Jan 2010 19:28:57 -0700, "Paul Hovnanian P.E."
> <Pa...@Hovnanian.com> wrote:
>
>>I found my old HP-41C curve fit program card. Then I found my old
>>HP-41C.
>>
>>The model I get from your curve is:
>>
>>.MODEL MyWhiteLED D
>>+ IS = 4.4249E-9
>>+ N = 8.3923
>>+ RS = 7.7980
>>
>>No subcircuits required.
>
> BTW: "your curve"? Whose curve? You clip too much, Paul.
Sorry. I took your spice model from your post, ran it for 70 current points
and poked every tenth one into my program. I didn't have the table function
values (the PDF you posted in a.b.s.e which I assume were your original
measured data points). By the way, there appears to be an outlying data
point in your graph.
So I was actually curve fitting to your curve fit.
Jim Thompson
EG is also a variable of interest.
Jim Thompson
<pa...@hovnanian.com> wrote:
>Jim Thompson wrote:
>
>> On Wed, 27 Jan 2010 19:28:57 -0700, "Paul Hovnanian P.E."
>> <Pa...@Hovnanian.com> wrote:
>>
>>>I found my old HP-41C curve fit program card. Then I found my old
>>>HP-41C.
>>>
>>>The model I get from your curve is:
>>>
>>>.MODEL MyWhiteLED D
>>>+ IS = 4.4249E-9
>>>+ N = 8.3923
>>>+ RS = 7.7980
>>>
>>>No subcircuits required.
>>
>> BTW: "your curve"? Whose curve? You clip too much, Paul.
>
>Sorry. I took your spice model from your post, ran it for 70 current points
>and poked every tenth one into my program. I didn't have the table function
>values (the PDF you posted in a.b.s.e which I assume were your original
>measured data points). By the way, there appears to be an outlying data
>point in your graph.
>
>So I was actually curve fitting to your curve fit.
I finally figured that out ;-) I first thought someone I had filtered
out, like from googlegroups, had posted some data ;-)
The "outlying data point" is an unknown, so PSpice stops and _holds_
at the last PWL data point.
Paul Hovnanian P.E.
Right. That kicks in when you model diode's temperature dependence. But
here's a question: What happens to the original subcircuit based model,
which is based on a 1N4148? The activation energy isn't specified, so
you're going to get Spice's default (probably for a silicon diode). As
we are dealing with a (probably) blue LED, the chemistry will be
diffeent, and we probably should find a more appropriate value for EG.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
professor; n, One who talks in someone else's sleep.
Jim Thompson
<Pa...@Hovnanian.com> wrote:
I agree. My subcircuit fit was accidentally fallen into while just
noodling around ;-)
If someone will take data at 3 or more temperatures, I'll try to fit
it.
Paul Hovnanian P.E.
Evidently the PSpice people haven't learned anything about dry-labbing and
tossing undesirable data points out from the climatologists. ;-)
Jim Thompson
<pa...@hovnanian.com> wrote:
;-)
PWL HOLDS at the last entered data point. Perhaps I can create one
that continues the last SLOPE ?:-)