LED specification - All about 3mm & 5mm LED's

Discussion in 'LEDs and Optoelectronics' started by Vikrant Mohanty, Feb 19, 2018.

  1. Vikrant Mohanty

    Vikrant Mohanty

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    I want to maintain a specification table for available monochrome LED's, based on which I am having certain development to be complete. I found the data varies from manufacture to manufacture for same LED. So, I decide to consider a 10-15% tolerance in LED's specifications. Below is the specification snap -

    upload_2018-2-19_23-23-30.png

    which I prepared after considering few manufacturers datasheet. Rest fields are blank, as I didn't get any detail about that.

    So, my humble request to the reader is to help me in filling the remaining detail, if they have any idea on it. Also, all your comments are always welcome.

    Thanks
     
    Vikrant Mohanty, Feb 19, 2018
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  2. Vikrant Mohanty

    BobK

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    This is a fool's errand. You cannot rely on the size and color of the LED to tell you anything.

    Bob
     
    BobK, Feb 19, 2018
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  3. Vikrant Mohanty

    Robert_fay

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    I agree with Bob you can not try to make a chart when there is no standard set for these specifications. The information you already have may be considered "Common Values" but by no means would be reference material.

    i.e. Broadcom 3mm red LED HLMP-1700-B0002 is 1.7V 2mA 50° 626nm 2.1mcd and only the fact thatmatches your chart is that it is red.
    Best to reference the data sheet.
     
    Robert_fay, Mar 8, 2018
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  4. Vikrant Mohanty

    Sunnysky

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    I used to supply 100k 5mm custom LEDs to one customer for over 10 years and discovered the differences that make them special. Tolerances are a quality control factor on the epitaxial wafer.

    The Vf has a high tolerance on the high side solely due to the ESR which is inversely related to the chip bulk spreading resistance and power rating such that ESR ~ 1/Pd max rated. so a 65mW 5mm chip is ~ 16 Ohms and 50% more on poor quality sources. I only got single bin intensity and voltage in the range of 3~3.2V for all white , although client needed 4000~4500K only 16000~20000 mcd and 2.0 to 2.1V for all Red and Yellow.

    3mm being a small er chip and power rating has a higher ESR . Tolerances are typically +50%/-25% for Vf but mine were all +/-0.05V bin @20mA or +/- 2.5%. I still have boxes of excess stock with 200/bag in the garage. A 1W LED "may" have an ESR of 1 Ohm +/-50% and much less from excellent sources while 10W single chip will be 0.1 Ohm above 2.8V. Arrays will have ESR added in strings and divided in shunts.
     
    Sunnysky, Mar 14, 2018
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  5. Vikrant Mohanty

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I have seen the same approx 3.3V Vf on red, green, and yellow LEDs.

    I'm pretty sure if they were "white" LEDs with a filter.

    In any case, the colour didn't indicate the Vf.
     
    (*steve*), Mar 14, 2018
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  6. Vikrant Mohanty

    Sunnysky

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    The threshold voltage at 1mA is dependent on the wavelength . This is true for all clear case LEDs.
    Red/Yellow Vt~1.6 635nmD to 592nmD White/Blue/Green 415~525nmD 2.6V
    Any Vf measured at rated current again depends on Pd = ~1/ESR +/50% of the chip.
     
    Sunnysky, Mar 14, 2018
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  7. Vikrant Mohanty

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Yeah, as I said, I assumed these were white LEDs (i.e. blue + phosphor) in a coloured case.

    It's just an instance of the colour observed being misleading.

    As a side note, I also had some blue LEDs of the same type, and I bet these were blue LEDs with phosphor (to give white) and then placed in a blue package to give blue light!
     
    (*steve*), Mar 14, 2018
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  8. Vikrant Mohanty

    Sunnysky

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    3.3V Red's are pretty bad and colour of light without lens colour is vague.
     
    Sunnysky, Mar 15, 2018
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  9. Vikrant Mohanty

    Doug3004

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    You have already identified the one matter that can be assumed: among 5mm and 3mm visible LEDs, the maximum current rating is usually 20mA.

    leds_01.jpg

    I have usually seen red, yellow and green LEDs as having the same 2.1 volt drop but all of the other colors are different.

    The specific wavelengths is all over and generally not important anyway, unless you had the equipment around to check that matter... $$$

    SMD LEDs need less current, <10 mA. Or less, for the smaller ones.

    IR LEDs usually have a very low voltage drop (~1.6 v) but can run very high currents--50 mA is common and some can run over 100 mA. They actually get warm to the touch when running. For other LEDs getting warm is bad, but IR LEDs are supposed to do that.

    COB LEDs I have no idea, never played with them. You'd have to find a datasheet...

    Same goes for the high-power "lighting"-style LEDs that have big heatsinks....

    Most LEDs that you can buy cheaply are not made by just one company. The commodity market is split vertically, with different companies making different parts and processes:
    https://learn.sparkfun.com/tutorials/how-leds-are-made
     
    Doug3004, Mar 15, 2018
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