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Q about Nichia White LED Ranking

Discussion in 'Electronic Design' started by Watson A.Name - 'Watt Sun', Jul 11, 2003.

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  1. 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.

    --
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    ###Got a Question about ELECTRONICS? Check HERE First:###
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    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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  2. Mark Jones

    Mark Jones Guest


    It isn't a date code, is it?
     
  3. 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
     
  4. 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
     
  5. 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.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  6. R.Lewis

    R.Lewis Guest


    Have a nice day anyway.
     
  7. 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.

    Yeah, he probably says something on this. Sorry about all that
    trouble with FedEx/Nichia.

    Jon
     
  8. 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:)

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  9. 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. :)
    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
    UPS guy probably got a hernia with that one!


    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  10. 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 ()
     
  11. 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!!

    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.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  12. R.Lewis

    R.Lewis Guest

     
  13. 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.

    Best regards,
    Spehro Pefhany
     
  14. 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
     
  15. 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
     
  16. 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?
     
  17. On Sun, 13 Jul 2003 18:30:16 +0000 (UTC), the renowned
    Yes, just the same one the OP asked about.
    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
     
  18. [snip]
    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.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  19. 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.


    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###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
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  20. 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 ()
     
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