Q about Nichia White LED Ranking

  • Thread starter Watson A.Name - 'Watt Sun
  • Start date
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Watson A.Name - 'Watt Sun

Guest
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
Watson A.Name - 'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find
any info about the ranking system, which seems to be some kind
of deep Nichia secret.

The first batch I bought was rank B2S, and the one I got today
is B2R. I'd like to find out what the diff is and what the
characters mean, hopefully at the URL of some Nichia web page.
Can anyone point me in the right direction? I just ran into
passwords on the Japanese site. Thank you.
Click to expand...

It isn't a date code, is it?
 
On Thu, 10 Jul 2003 20:21:28 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.
Click to expand...
There are color ranks and luminous intensity ranks. I'm pretty
sure Don Klipstein will jump in here. But until then:

S is a higher intensity rank than R
R is a higher intensity rank than Q

That is, assuming that the drive current is the same (20mA,
usually.) From one data sheet I have, S is about twice the mcd
as Q. R is somewhere between the two.

The A0/B1/B2/C0 part is a color ranking. They will specify the
CIE (x,y) values for these on the data sheet.

Jon
 
On Fri, 11 Jul 2003 03:02:23 -0400, the renowned "Mark Jones"
<127.0.0.1> wrote:

Watson A.Name - 'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find
any info about the ranking system, which seems to be some kind
of deep Nichia secret.

The first batch I bought was rank B2S, and the one I got today
is B2R. I'd like to find out what the diff is and what the
characters mean, hopefully at the URL of some Nichia web page.
Can anyone point me in the right direction? I just ran into
passwords on the Japanese site. Thank you.


It isn't a date code, is it?
Click to expand...
It's the color rank and brightness rank

S = 7800 min mcd
R = 5520 ~ 7800 mcd
Q = 3900 ~ 5520 mcd

The ICI Chromaticity diagram on the data sheet shows where the color
ranks a0, b1, b2, c0 fall. You'll have to register (free) to download
it.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
In article <j6psgv8537ij8ecoslbgb88g7gs5mo7dlg@4ax.com>,
jkirwan@easystreet.com mentioned...
On Thu, 10 Jul 2003 20:21:28 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.

There are color ranks and luminous intensity ranks. I'm pretty
sure Don Klipstein will jump in here. But until then:

S is a higher intensity rank than R
R is a higher intensity rank than Q

That is, assuming that the drive current is the same (20mA,
usually.) From one data sheet I have, S is about twice the mcd
as Q. R is somewhere between the two.

The A0/B1/B2/C0 part is a color ranking. They will specify the
CIE (x,y) values for these on the data sheet.

Jon
Click to expand...
Thanks a lot. I lit up a few with the CV/CC PS and I found that the
new batch B2R sems to have a more prominent blue ring than the
original B2S batch, but I don't have a way to measure candelas. I'll
have to do a bit more checking. I thought the B2S batch was pretty
good. I'll check Don's website for more info.

Damn, I hate Nichia. They ship FedEx and insist on requiring a
signature, so I have to drive all the way over to the Fullerton FedEx
to sign for them and pick them up. On the way over as I got close to
FedEx, there were flares blocking the whole street and cop cars behind
the flares, so I couldn't make a right turn. I looked down the street
behind the cops, and the whole big street was completely vacant of
cars for a half mile! Well, except for a single fire truck. So I
went up aways and turned onto the side street and got caught in the
traffic jam caused by this blockade - it was at 6 PM, rush hour. I
finally got there, and on the way home I went past the other end of
the street that was blocked off, but I couldn't see any indication of
what the hubb-bubb was all about. I looked for it in the newspaper
online, but nothing. Maybe a hazmat spill? I dunno. And then later
on the way home, I had a flat tire - damn. One of those lousy
firestone pieces of sh!!, good riddance!

Thanks again.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
"Watson A.Name - 'Watt Sun'" <alondra101@hotmail.com> wrote in message
news:MPG.19789c8425983d9d989a6a@news.inreach.net...
In article <j6psgv8537ij8ecoslbgb88g7gs5mo7dlg@4ax.com>,
jkirwan@easystreet.com mentioned...
On Thu, 10 Jul 2003 20:21:28 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.

There are color ranks and luminous intensity ranks. I'm pretty
sure Don Klipstein will jump in here. But until then:

S is a higher intensity rank than R
R is a higher intensity rank than Q

That is, assuming that the drive current is the same (20mA,
usually.) From one data sheet I have, S is about twice the mcd
as Q. R is somewhere between the two.

The A0/B1/B2/C0 part is a color ranking. They will specify the
CIE (x,y) values for these on the data sheet.

Jon

Thanks a lot. I lit up a few with the CV/CC PS and I found that the
new batch B2R sems to have a more prominent blue ring than the
original B2S batch, but I don't have a way to measure candelas. I'll
have to do a bit more checking. I thought the B2S batch was pretty
good. I'll check Don's website for more info.

Damn, I hate Nichia. They ship FedEx and insist on requiring a
signature, so I have to drive all the way over to the Fullerton FedEx
to sign for them and pick them up. On the way over as I got close to
FedEx, there were flares blocking the whole street and cop cars behind
the flares, so I couldn't make a right turn. I looked down the street
behind the cops, and the whole big street was completely vacant of
cars for a half mile! Well, except for a single fire truck. So I
went up aways and turned onto the side street and got caught in the
traffic jam caused by this blockade - it was at 6 PM, rush hour. I
finally got there, and on the way home I went past the other end of
the street that was blocked off, but I couldn't see any indication of
what the hubb-bubb was all about. I looked for it in the newspaper
online, but nothing. Maybe a hazmat spill? I dunno. And then later
on the way home, I had a flat tire - damn. One of those lousy
firestone pieces of sh!!, good riddance!
Click to expand...

Have a nice day anyway.
 
On Fri, 11 Jul 2003 11:07:13 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

In article <j6psgv8537ij8ecoslbgb88g7gs5mo7dlg@4ax.com>,
jkirwan@easystreet.com mentioned...
On Thu, 10 Jul 2003 20:21:28 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.

There are color ranks and luminous intensity ranks. I'm pretty
sure Don Klipstein will jump in here. But until then:

S is a higher intensity rank than R
R is a higher intensity rank than Q

That is, assuming that the drive current is the same (20mA,
usually.) From one data sheet I have, S is about twice the mcd
as Q. R is somewhere between the two.

The A0/B1/B2/C0 part is a color ranking. They will specify the
CIE (x,y) values for these on the data sheet.

Jon

Thanks a lot. I lit up a few with the CV/CC PS and I found that the
new batch B2R sems to have a more prominent blue ring than the
original B2S batch, but I don't have a way to measure candelas.
Click to expand...
The S should be the same device in every way except that it just
happens to be brighter at the same current. I believe they
simply bin these things and sell the S at a higher price than
the R or Q.

The prominent blue ring may be a complex effect. If I recall,
there is a phosphor coating which converts the normally bluer
emissions (from our perspective), through a process of
fluorescence, and re-emits a number of longer wavelengths which
when all combined together gives our eye the impression of a
whiter output.

I have not put these things on my spectrophotometer, but I'd
guess that there would be several peaks emitted. And if I were
to grind off the plastic (and the phosphors) and then examine
the output, it would probably be a single distribution up in the
blue range somewhere. The phosphors simply absorb some of that,
convert a little of it to phonons or heat, and re-emit the rest
as longer wavelengths. But I'm guessing here.

Anyway, the bluer ring is probably due to the brighter emissions
in a periphery which doesn't get the full benefit of the
phosphor for your viewing situation. In the weaker R case, this
light level is less and you don't notice it as much. But in the
stronger S case, it shows up much better.

Well, that's my hypothesis anyway.


I'll
have to do a bit more checking. I thought the B2S batch was pretty
good. I'll check Don's website for more info.
snip
Click to expand...
Yeah, he probably says something on this. Sorry about all that
trouble with FedEx/Nichia.

Jon
 
In article <gtctgvgrm9skg2vn3tkkhrrfmqaasm6v4u@4ax.com>,
speff@interlog.com mentioned...
On Fri, 11 Jul 2003 03:02:23 -0400, the renowned "Mark Jones"
127.0.0.1> wrote:

Watson A.Name - 'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find
any info about the ranking system, which seems to be some kind
of deep Nichia secret.

The first batch I bought was rank B2S, and the one I got today
is B2R. I'd like to find out what the diff is and what the
characters mean, hopefully at the URL of some Nichia web page.
Can anyone point me in the right direction? I just ran into
passwords on the Japanese site. Thank you.


It isn't a date code, is it?

It's the color rank and brightness rank

S = 7800 min mcd
R = 5520 ~ 7800 mcd
Q = 3900 ~ 5520 mcd

The ICI Chromaticity diagram on the data sheet shows where the color
ranks a0, b1, b2, c0 fall. You'll have to register (free) to download
it.
Click to expand...
Ok, that's why I apparently got the #!$*% password. Thank you. I
guess that means that I won't be getting quite as much light out of
the B2R batch as I got out from the B2S batch. No problem, I'll just
put a few more LEDs in there.. :eek:)


Best regards,
Spehro Pefhany
Click to expand...
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article <283ugv48mpnb2uc116bidg8crdh31b7fri@4ax.com>,
jkirwan@easystreet.com mentioned...
On Fri, 11 Jul 2003 11:07:13 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

In article <j6psgv8537ij8ecoslbgb88g7gs5mo7dlg@4ax.com>,
jkirwan@easystreet.com mentioned...
On Thu, 10 Jul 2003 20:21:28 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Thank you.

There are color ranks and luminous intensity ranks. I'm pretty
sure Don Klipstein will jump in here. But until then:

S is a higher intensity rank than R
R is a higher intensity rank than Q

That is, assuming that the drive current is the same (20mA,
usually.) From one data sheet I have, S is about twice the mcd
as Q. R is somewhere between the two.

The A0/B1/B2/C0 part is a color ranking. They will specify the
CIE (x,y) values for these on the data sheet.

Jon

Thanks a lot. I lit up a few with the CV/CC PS and I found that the
new batch B2R sems to have a more prominent blue ring than the
original B2S batch, but I don't have a way to measure candelas.

The S should be the same device in every way except that it just
happens to be brighter at the same current. I believe they
simply bin these things and sell the S at a higher price than
the R or Q.
Click to expand...
The Nichia site gives no way to determine what rank I'm getting when I
order. And I ordered 100 at $2 each, so the price is the same no
matter what the rank is. Actually the order is processed thru the
Thomas Register web site. I will have to commend them on the speedy
delivery, tho. :)

snip

Yeah, he probably says something on this. Sorry about all that
trouble with FedEx/Nichia.
Click to expand...
Thanks. UPS just drops the packages at the neighbor's apt. But not
FedEx. You shoulda seen her when I had an 80 pound power supply
package delivered! :p

Jon
Click to expand...
UPS guy probably got a hernia with that one!


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article <MPG.1977cd175290b3a5989a5b@news.inreach.net>, Watson A.Name -
'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.
Click to expand...
For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring data.
The range for the middle rank is roughly 84% to 120% of that millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.

You can register online with Nichia for free and get a password.

- Don Klipstein (don@misty.com)
 
In article <slrnbgv0gi.9n5.don@manx.misty.com>, don@manx.misty.com
mentioned...
In article <MPG.1977cd175290b3a5989a5b@news.inreach.net>, Watson A.Name -
'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.

For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring data.
The range for the middle rank is roughly 84% to 120% of that millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.

You can register online with Nichia for free and get a password.
Click to expand...
Thanks. I didn't notice until someone else mentioned that I had to
register. One thing since last order, the price came down a nickel.
:) At two bucks, it's a _lot_ cheaper than the $4 or more that the
retail stores like Rat Snack charge for a poorer quality, lower output
white LED. If you don't want to buy directly from Nichia, you can get
'em from Paul Wilcoxson's whitelightled.com web site for $1.50 each in
small quantities. I just didn't want to wait for him to come back
from vacation.

I fired up a half dozen with 15 ohm V dropping resistors in series,
all across a 3.9V supply. I'm surprised that the individual V drops
across the LEDs vary by as much as a tenth of a volt. And it seems
that the LEDs drop a lower voltage, something like 3.3V instead of the
more typical 3.5 or so that earlier ones dropped. Did they do
something to the LEDs to change them? Weird.

Lotsa light, tho. Watt Sun!!


- Don Klipstein (don@misty.com)
Click to expand...
BTW, I ordered a few of the Arc AAA keyfob f'lights at $14 each from
their website, but I just checked and they're not on sale anymore. I
hope they still have enough left to fill my order. They apparently
have a newer version out.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
"Watson A.Name - 'Watt Sun'" <alondra101@hotmail.com> wrote in message
news:MPG.197a27b95404bb7f989a7a@news.inreach.net...
In article <slrnbgv0gi.9n5.don@manx.misty.com>, don@manx.misty.com
mentioned...
In article <MPG.1977cd175290b3a5989a5b@news.inreach.net>, Watson
A.Name -
'Watt Sun' wrote:
I got on Nichia's website and I found the explanation for the
NSPW500BS LED nomenclature, but I looked for and couldn't find any
info about the ranking system, which seems to be some kind of deep
Nichia secret.

The first batch I bought was rank B2S, and the one I got today is B2R.
I'd like to find out what the diff is and what the characters mean,
hopefully at the URL of some Nichia web page. Can anyone point me in
the right direction? I just ran into passwords on the Japanese site.

For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top
rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring
data.
The range for the middle rank is roughly 84% to 120% of that
millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever
had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.

You can register online with Nichia for free and get a password.

Thanks. I didn't notice until someone else mentioned that I had to
register. One thing since last order, the price came down a nickel.
:) At two bucks, it's a _lot_ cheaper than the $4 or more that the
retail stores like Rat Snack charge for a poorer quality, lower output
white LED. If you don't want to buy directly from Nichia, you can get
'em from Paul Wilcoxson's whitelightled.com web site for $1.50 each in
small quantities. I just didn't want to wait for him to come back
from vacation.

I fired up a half dozen with 15 ohm V dropping resistors in series,
all across a 3.9V supply. I'm surprised that the individual V drops
across the LEDs vary by as much as a tenth of a volt. And it seems
that the LEDs drop a lower voltage, something like 3.3V instead of the
more typical 3.5 or so that earlier ones dropped. Did they do
something to the LEDs to change them? Weird.

Lotsa light, tho. Watt Sun!!
Click to expand...
Look at the specs for forward voltage..
I think you should have been pleasantly surprised that in your batch the
forward voltage differences were so small.
Next time it may be very different
 
On Sat, 12 Jul 2003 03:35:46 +0000 (UTC), the renowned
don@manx.misty.com (Don Klipstein) wrote:
For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring data.
The range for the middle rank is roughly 84% to 120% of that millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.
Click to expand...
I ran across an older version of a data sheet for the same part and
they gave *different* definitions for the brightness ranks. This is
VERY confusing. Presumably if I'm making a product I care about the
actual brightness of the part, not where it falls in their production
process distribution. If they keep redefining the part numbers, you
can't be sure whether a shipment you get from a distributor is "old" R
or "new" R. Granted, they say you get what you get, and they don't
guarantee the quantities in each rank, but the upper and lower
brackets/limits ALSO change.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Sun, 13 Jul 2003 18:50:42 +0100, the renowned "R.Lewis"
<h.lewis@connect-2.co.uk> wrote:

Look at the specs for forward voltage..
I think you should have been pleasantly surprised that in your batch the
forward voltage differences were so small.
Next time it may be very different
Click to expand...
I don't think I've ever seen a spec (or distribution chart) for
"typical" variations in Vf on an LED. Minimums are rare too. It's nice
to see actual measurements.

Just eyeballing the graph of Vf vs. Ifp, it looks like that +/- 50mV
drop would result in If variation of around +/-11% at the 15mA-ish
level if they were just paralleled.

Related questions frequently come up here- we have some real numbers
for a change.

Note that there is a strong negative tempco on these LEDs, about 1
volt change from -30'C to 80'C or -9mV/K. So, if they are not
thermally coupled closely current "hogging" can occur.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Sun, 13 Jul 2003 17:59:50 GMT, Spehro Pefhany
<speff@interlog.com> wrote:

On Sat, 12 Jul 2003 03:35:46 +0000 (UTC), the renowned
don@manx.misty.com (Don Klipstein) wrote:

For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring data.
The range for the middle rank is roughly 84% to 120% of that millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.

I ran across an older version of a data sheet for the same part and
they gave *different* definitions for the brightness ranks. This is
VERY confusing. Presumably if I'm making a product I care about the
actual brightness of the part, not where it falls in their production
process distribution. If they keep redefining the part numbers, you
can't be sure whether a shipment you get from a distributor is "old" R
or "new" R. Granted, they say you get what you get, and they don't
guarantee the quantities in each rank, but the upper and lower
brackets/limits ALSO change.
Click to expand...
It can be pretty difficult to get consistency with LEDs, anyway.
For example, when buying 7-seg digits or using arrays of LEDs in
any instrument, you have to be very careful or else you wind up
with some which appear a little brighter/dimmer than their
neighbors *and* a little oranger or redder or ..., as well.

It's why, in fact, I set up a spectrophotometer, calibrated
tungsten lamp with precise distance and current control for
amplitude calibration, mercury-argon lamp for spectral
calibration (doublets and so on to develop the polynomial or
sin-approx for pixel positions), the mechanicals for testing and
the software required to properly bin LEDs on apparent hue and
brightness.

Even batches of LEDs from the same lot aren't the same in hue or
brightness, I'm guessing because of variations over the surface
of the wafers (edge effects on thermals, for example) and other
intraprocess variations. So getting everything to look just
right is a real pain.

And this doesn't even deal drift variations over time. Trying
to make optical standards out of LEDs (holding them at stable
temperature and current in order to try and achieve and hold a
calibrated optical output) requires bake times of over 200 hours
and constant monitoring to observe drift patterns. By the end
of that time, those you can use have stabilized and are showing
very gradual drift slopes. Most of them, though, are still
showing erratic drift changes and are simply thrown away as
unusable for standards.

Jon
 
On Sun, 13 Jul 2003 18:30:16 +0000 (UTC), the renowned
don@manx.misty.com (Don Klipstein) wrote:

In article <ng73hvs3d74sl6di0g73ptqbmkbdcl8nrs@4ax.com>, Spehro Pefhany wrote:
On Sat, 12 Jul 2003 03:35:46 +0000 (UTC), the renowned

I ran across an older version of a data sheet for the same part and
they gave *different* definitions for the brightness ranks. This is
VERY confusing. Presumably if I'm making a product I care about the
actual brightness of the part, not where it falls in their production
process distribution. If they keep redefining the part numbers, you
can't be sure whether a shipment you get from a distributor is "old" R
or "new" R. Granted, they say you get what you get, and they don't
guarantee the quantities in each rank, but the upper and lower
brackets/limits ALSO change.

By any chance was this NSPW500BS?
Click to expand...
Yes, just the same one the OP asked about.

I have purchased them when the middle
of R was 5600 mcd and I believe it's now 6200 mcd. I remember Nichia
saying something to the effect that their measurements ran low before.
When a typical NSPW500BS was dimmer than 5600 mcd, were they ranked with
the middle rank R?
Click to expand...
These are just two data points, I have no way of knowing if there are
other data sheets out there.

Rank New: (Min/Typ/Max ) Old: (Min/Typ/Max )

S 7800/9200/11000 6800/8000/9500
R 5520/6400/7800 4800/5600/6800
Q 3900/4600/5520 3400/4000/4800

Part # NSPW500BS NSPW500BS
(same)

Old ones were ranked a, b, c color; the new ones, a0,b1,b2,c0, so
that could be used to tell the difference- if you had them in hand and
had the whole part number.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
In article <ng73hvs3d74sl6di0g73ptqbmkbdcl8nrs@4ax.com>, Spehro Pefhany wrote:
On Sat, 12 Jul 2003 03:35:46 +0000 (UTC), the renowned

I ran across an older version of a data sheet for the same part and
they gave *different* definitions for the brightness ranks. This is
VERY confusing. Presumably if I'm making a product I care about the
actual brightness of the part, not where it falls in their production
process distribution. If they keep redefining the part numbers, you
can't be sure whether a shipment you get from a distributor is "old" R
or "new" R. Granted, they say you get what you get, and they don't
guarantee the quantities in each rank, but the upper and lower
brackets/limits ALSO change.
Click to expand...
By any chance was this NSPW500BS? I have purchased them when the middle
of R was 5600 mcd and I believe it's now 6200 mcd. I remember Nichia
saying something to the effect that their measurements ran low before.
When a typical NSPW500BS was dimmer than 5600 mcd, were they ranked with
the middle rank R?
 
In article <bes5sp$h7u$1@thorium.cix.co.uk>, h.lewis@connect-2.co.uk
mentioned...
[snip]

I fired up a half dozen with 15 ohm V dropping resistors in series,
all across a 3.9V supply. I'm surprised that the individual V drops
across the LEDs vary by as much as a tenth of a volt. And it seems
that the LEDs drop a lower voltage, something like 3.3V instead of the
more typical 3.5 or so that earlier ones dropped. Did they do
something to the LEDs to change them? Weird.

Lotsa light, tho. Watt Sun!!


Look at the specs for forward voltage..
I think you should have been pleasantly surprised that in your batch the
forward voltage differences were so small.
Next time it may be very different
Click to expand...
I was under the apparently mistaken impression that there was some
uniformity in a batch, but apparently not in that particular
parameter. I guess light output, color, etc. doesn't have to
correspond to voltage drop.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article <ng73hvs3d74sl6di0g73ptqbmkbdcl8nrs@4ax.com>,
speff@interlog.com mentioned...
On Sat, 12 Jul 2003 03:35:46 +0000 (UTC), the renowned
don@manx.misty.com (Don Klipstein) wrote:

For at least many Nichia white LEDs as of when I last checked, the
rankings were Q, R, and S. (Other colors can be different - the top rank
for at least many of their green ones is T.) The middle rank is largely
centered around the millicandela given in the non-password-requiring data.
The range for the middle rank is roughly 84% to 120% of that millicandela
figure. The top rank has its center roughly 140% of that figure and the
bottom rank has its center roughly 71% of that figure.
In my experience with at least a dozen Nichia orders, I doubt I ever had
a bottom rank one, and when I had any of the center rank they seemed to
usually be somewhere in the top half of the range of the center rank.

I ran across an older version of a data sheet for the same part and
they gave *different* definitions for the brightness ranks. This is
VERY confusing. Presumably if I'm making a product I care about the
actual brightness of the part, not where it falls in their production
process distribution. If they keep redefining the part numbers, you
can't be sure whether a shipment you get from a distributor is "old" R
or "new" R. Granted, they say you get what you get, and they don't
guarantee the quantities in each rank, but the upper and lower
brackets/limits ALSO change.
Click to expand...
To my thinking, the part number should include the rank, and the data
sheet should define that. If it were a JEDEC part, then the company
could not just change the data sheet specs since they would already be
registered with JEDEC. But since the fox is in charge of the chicken
house, there's not much that one can do. Not that I'm complaining
about their quality, which is superior. Like Don said, above.

I was reading some candlepower forums discussions about the Luxeons,
which seem to have a very wide spread of parameters, leading some
people in the discussions to say that the LumiLeds QC is abysmal.


Best regards,
Spehro Pefhany
Click to expand...

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article <MPG.197b84502932ce7e989a7d@news.inreach.net>, Watson A.Name -
'Watt Sun' wrote:
In article <bes5sp$h7u$1@thorium.cix.co.uk>, h.lewis@connect-2.co.uk
mentioned...
[snip]

I fired up a half dozen with 15 ohm V dropping resistors in series,
all across a 3.9V supply. I'm surprised that the individual V drops
across the LEDs vary by as much as a tenth of a volt. And it seems
that the LEDs drop a lower voltage, something like 3.3V instead of the
more typical 3.5 or so that earlier ones dropped. Did they do
something to the LEDs to change them? Weird.

Lotsa light, tho. Watt Sun!!


Look at the specs for forward voltage..
I think you should have been pleasantly surprised that in your batch the
forward voltage differences were so small.
Next time it may be very different

I was under the apparently mistaken impression that there was some
uniformity in a batch, but apparently not in that particular
parameter. I guess light output, color, etc. doesn't have to
correspond to voltage drop.
Click to expand...
I remember a few times I had batches of 10 Nichia LEDs, and measured the
voltage drop, and within a batch they were only spread out over about .1
volt. And light output, according to a solar cell at very close range,
seemed to vary only a few percent within a batch.
*No guarantee* that it will always be this way, and differences from one
lot to another can be more.

- Don Klipstein (don@misty.com)
 
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