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News and links! UPDATE 10/2/2019
General Notes and Disclaimers
Pure Red / Deep Red LEDs
- 14 to 39-42 lumens/watt, 51 - 73.5% efficient
Orangish Red LEDs -
46-96-100-109-110 lumens/watt
Red-Orange LEDs - 66-123-148
lumens/watt
Truly Orange LEDs - 54-102
lumens/watt
Yellow and amber LEDs -
34-161 lumens/watt, with a way for 50-110-plus for less-amberish yellow.
Non-Phosphor Yellow-Green LEDs
- 14 lumens/watt.
Non-Phosphored Green LEDs
- 70-143-152 lumens/watt.
Better InGaN green LEDs achieve
120-160-165-235 lumens/watt at reduced currents
Phosphored Green, Light Green and
Yellow-Green LEDs - 191-215-219-237 lumens/watt.
Blue-Green LEDs - 57-93
lumens/watt
Blue LEDs - 25-45
lumens/watt (and up to 59 lm/w at decreased current)
Royal Blue LEDs - 50-plus
- 56 - 74 maybe 76 % efficient, 22-27 maybe 30 lumens/watt
Broadband / Multiband Blue
LEDs - 50-51 lumens/watt
White LEDs - 100-192-230
lumens/watt
Warm White LEDs - up to 211
lumens/watt
Increased Efficiency of InGaN LEDs at lower currents
Important Notes on Gallium Nitride and InGaN LEDs!
LED Light Bulbs (for North America)
LEDs with high candela "beam candlepower" figures
Notes on Where To Get Efficient LEDs
Converting / comparing lumens, candelas, millicandelas
UPDATE 2/27/2016 this 3/26/2014 Cree
press release:
Cree announced 303 lumens/watt at 350 mA. I did not see mention of die size in
this press release, as in whether it was a roughly 1 mm square or larger.
Correlated color temperature was mentioned - 5150 K.
UPDATE 3/18/2013 this 2/27/2013 Cree
press release:
Cree announced 276 lumens/watt at 350 mA. I did not see mention in this
press release of die size, as in whether it was a roughly 1 mm square or
larger. Correlated color temperature was mentioned - 4401 K.
UPDATE 9/15/2010 - Nichia is mentioned by this LEDs Magazine 9/6/2010 news
item to have achieved:
* 135 lumens/watt at 1 amp through an LED lamp having four 1x1 mm dice
in series, 1,913 lumens from approx. 14.2 watts. The color temp. was
mentioned as 4700 K.
* 183 lumens/watt at 350 mA in a lamp with a 1 x 1 mm chip. (added 8/11/2011)
* A 4600 K LED lamp with a .45 x .45 mm die (larger than the usual
generally roughly .3 x .3 mm die in most low power LED lamps) achieving
250 lumens/watt at 20 mA.
The above article mentions that manufacturing techniques necessary to achieve
such efficiency are costly, and that Nichia is not prioritizing getting
such efficient LEDs onto the market if they are dispropotionately
expensive for their light output.
UPDATE 11/2/2004 - WITH THANKS TO FANS OF THIS WEBSITE:
In August 2004, Osram announced a prototype of an orange-red LED that
achieved 108 lumens/watt, producing over 2 lumens at 10 mA with a voltage
drop presumably of about 2 volts.
IMPORTANT NOTE: Some laboratory prototypes mentioned above are not yet in
production even if years old! Barriers apparently include but may not be limited
to patents held by competitors, also cost of production with materials and
processes used to achieve higher efficiency. Also, gallium nitride based LED
chips just may not be cheap (substrate material is generally about 9 on the
Moh's hardness scale where diamond is 10). Production of chips of size favoring
a more optimum lower current density may price such things out of the market or
increase the size of optics needed to control where the light goes.
Luminous efficacies were largely determined by one or more of several methods,
mostly almost laughably crude. I give NO warranty as to accuracy. I have at
times slightly changed my estimates for some models. Your mileage may vary.
Red, orange, yellow, and yellow-green models (other than high power /
heatsinkable ones) mentioned here generally have maximum efficiency at
currents around 15-25 milliamps. Efficiency of these is typically less at low
currents of a few milliamps or less. The decrease is not as bad with GaAlAsP
and "T.S." AlGaAs and the most efficient InGaAsP red ones as it is with most
other InGaAsP (orangish red through yellow-green).
Some of these LEDs radiate light of slightly different colors in different
directions. This is most apparent with some white models and some non-phosphor
yellow and yellow-green models.
PLEASE NOTE that the lumen per watt figures in this document are lumens of light
produced per watt of electricity delivered to the LED. Some LED manufacturers
state much higher figures, of lumens per watt of radiated light. This "high
figure" is typically around 60-100 for red, 130-180 for orange-red, 220-265 for
red-orange, 440-500 for yellow, 400-660 for green (656 for HLMP-C615 by
Broadcom, formerly by Avago, Agilent and HP, 650-656 for Broadcom LEDs with peak
and dominant wavelengths 555-560 nm), and around 50-90 for blue. The purpose of
this "high" figure is for conversion between radiometric and photometric units
for the emitted light. If the conversion efficiency and the "high" lumen/watt
figures are both known, multiply them to get the lumens out per watt in.
Beam brightness and width figures below are mostly ones claimed by manufacturers
or sellers.
UPDATE 8/1/2017 The LEDEngin LZ1-00R202 at 1000 mA and 25 C is claimed to
have typical "wall plug efficiency" of 51%, with a typical peak wavelength of
663 nm, which indicates typically 26 lumens/watt.
Spectral analysis of a discontinued older LedEngin model indicates dominant
wavelength of 643-644 nm and luminous efficacy of the emitted light to be about
60 lumens per emitted watt.
Update 8/1/2017 Osram GH CSHPM1.24-4T2U-1 and GH CSSPM1.24-4T2U-1 appear
to me to be good for typically 42 lumens/watt at 350 mA at 25 degrees C, 39
lumens/watt at 80 degrees C. Their radiometric efficiency is typically 70% at
25 C. The GH CS8PM1.24-4T2U-1 has these same ratings, but a narrower beam angle
where internal reflection losses are typically slightly greater.
UPDATE 7/30/2018 Cree XPEEPR-L1-0000-00C01 produces 425 mW minimum, 437
mW typically at 350 mA with a typical voltage drop of 2.1 volts at 25 degrees C.
This is typically 59% conversion efficiency and means typically 35 lumens/watt
assuming a typical spectrum with peak wavelength of 660 nm.
UPDATE 10/12/2020 Cree XPGDPR-L1-0000-00F01 produces 500 mW minimum, 512
mW typically at 350 mA with a typical voltage of 1.99 volts at 25 degrees C.
This is typically 73.5% conversion efficiency and means typically 25-30
lumens/watt assuming an extrapolated typical spectrum with peak wavelength
of 670 nm. I plan to do spectral analysis of this LED in late October 2020
to refine my estimate of lumens/watt.
Update 7/23/2011 Philips-Lumileds LXM3-PD01 is now available. My guess
is that it's LXML-PD03-0260, rated to produce typically 290 mW at 350 mA with a
typical voltage drop of 2.2 volts, for typical radiometric efficiency of 37%, at
a junction temperature of 25 C. This indicates overall luminous efficacy around
20-22 lumens/watt. The DS68 datasheet indicates achieving around or a little
over 92% of this when the heatsinkable surface is at 50 degrees C. Peak
wavelength is typically 660 nm, dominant wavelength is not specified. The
active material is said to be AlInGaP.
Low power red LEDs with GaAlAsP and Avago's similar AlGaAs in my experience,
when doing well, tend to achieve 7-8 lumens per watt. But unlike the more
efficient orangish red ones below, they are truly fairly pure red in color,
with dominant wavelength (color specification roughly meaning hue) of 637-645
nm, and peak wavelength of 654-665, usually 660 nm.
Some favorites of mine as of 10/21/2020 are Lumex SSL-LX5093SRC/E, Lumex
SSL-LX5093XRC/4, and Broadcom (previously Avago) HLMP-D150. A favorite of mine
with especially deep red color and good usefulness as an indicator lamp at low
current is Kingbright WP7113LSRD (temporarily having a significant lead
time at Digi-Key as of 10/21/2020). All of these bright truly red LEDs are
available at Digi-Key.
UPDATE 7/24/2017: Cree's XPEBRD-L1-0000-00901 and XPEBRD-L1-0000-00902 at
350 mA are rated to produce a minimum of 80.6 lumens and typically 84 lumens,
with a typical voltage drop of 2.2 volts. This works out to 104-109 lumens/watt
when the voltage drop is typical. This is with junction temperature of 25 C.
With junction temperature of 50 C, expect 89-94 lm/W.
UPDATE 3/22/2011: Lumileds LXM2-PD01-0050, according to its DS-68
datasheet, achieves minimum 50, typically 53 lumens at 350 mA when junction
temperature is 25 degrees C, with typical voltage drop of 2.1 volts. This
amounts to 68-73 lumens/watt.
UPDATE 12/25/2018: Lumileds LXM5-PD01, according to its DS-68 datasheet,
achieves minimum 50, typically 64 lumens at 350 mA when junction temperature is
25 degrees C, with typical voltage drop of 2.1 volts. This works out to 68-87
lumens/watt. This LED was not yet in stock but had an 8-week lead time at
Digi-Key as of 12/25/2018.
UPDATE 12/25/2018: Lumileds LXM2-PD01-0060, according to its DS-68
datasheet, achieves minimum 60, typically 62 lumens at 350 mA when junction
temperature is 25 degrees C, with typical voltage drop of 2.1 volts. This
works out to 81-84 lumens/watt. Although the datasheet gives specifications for
this LED, Digi-Key is not yet mentioning it as available as of 12/25/2018.
Expect these LEDs to produce 10-11% less light than mentioned here with
more realistic thermal conditions, namely heatsinking that cools their
thermal pads to 35 degrees C.
UPDATE 7/21/2021: Osram LJ CKBP-JZKZ-25-1 (mentioned as
LJ CKBP-JZKZ-25-1-350-R18-Z by Digi-Key) is claimed by Digi-Key to typically
produce 87 lumens (61-112 lumens) and 116 lumens/watt at 350 mA with a typical
forward voltage drop of 2.15 volts. The square root of the product of the upper
and lower limits of light output is 83 lumens, which corresponds with 110
lumens/watt. This is with junction temperature of 25 degrees C, or with a brief
pulse with heatsinking surface temperature of 25 degrees C. Expect about 10%
less output and efficiency with sustained operation and temperature of the
heatsinkable surface being 35 degrees C.
UPDATE 10/16/2020 (date previously typo-ed): The most efficient low power
red LEDs I tested so far are 7 samples of Cree C503B-RCN-CXAYCAA2-030 ones. This
batch achieved conservatively an average of 68 lumens/watt at 20 mA according to
my tests. Forward voltage drop averages 1.955 volts and light output averages
2.66 lumens according to my testing. This is at calculated junction temperature
of 25-26 degrees C, expect this 68 lumens/watt figure to decrease to 62-63
lumens/watt at a more realistic junction temperature of 40 degrees C. Dominant
wavelength of these 7 samples averaged about 620.5 nm, if this was the 624 nm
stated as typical by this LED's datasheet then lumens and lumens/watt would be
about 9% less or about 2.2-2.23 lumens (added 3/25/2021) and 57 lumens/watt at a
junction temperature of 40 degrees C.
UPDATE 8/3 and 10/13 2020: Some efficient low power red LEDs currently
available at Digi-Key that I planned to test in autumn 2020 (and have not yet
tested as of 3/25/2021):
Cree CLM1B-RKW-CUbVbAA3: Square root of product of upper and lower limits of its
millicandela at 20 mA is 792, which works out to 2.49 lumens if the radiation
pattern graph in its datasheet is correct in indicating a lambertian radiation
pattern. With typical voltage drop of 2.1 volts at 20 mA, this means typically
59 lumens er watt.
Cree CLM3C-RKW-CUBVAAA3: Square root of product of upper and lower limits of its
millicandela at 20 mA is 710, which works out to 2.23 lumens if the radiation
pattern graph in its datasheet is correct in indicating a lambertian radiation
pattern. With typical voltage drop of 2.1 volts at 20 mA, this means typically
53 lumens er watt.
These Cree red LEDs have their performance specified for junction temperature of
25 degrees C. Light output and efficiency will be a few percent less in a
25 degree C ambient according to thermal resistance and performance of similar
LEDs at elevated temperatures.
UPDATE 4/14/2012: Philips-Lumileds LXM2-PH01-0070 produces minimum
of 70 lumens, typically 72 lumens at 350 mA with voltage drop of typically
2.1 volts, maximum of 2.8 volts. This works out to typically 97.9 lumens/watt,
minimum of 71.4 lumens/watt. This is with junction temperature of 25 C.
Expect about 13% less typically when the thermal pad temperature is at
35 degrees C in continuous operation, which means about 62 lumens/watt
minimum, 85 lumens/watt typical.
UPDATE 12/25/2018: Lumileds LXM5-PD01, according to its DS-68 datasheet,
achieves minimum 50, typically 90 lumens at 350 mA when junction temperature is
25 degrees C, with typical voltage drop of 2.1 volts. This works out to 68-122
lumens/watt. This LED was not yet in stock but had an 8-week lead time at
Digi-Key as of 12/25/2018.
UPDATE 8/2/2017: Osram GA CSHPM1.23-KTLP-W3 and GA CSSPM1.23-KTLP-W3, in
stock at Digi-Key, typically achieves 148 lumens/watt at 25 degrees C and 133
lumens/watt at 50 degrees C according to its datasheet. Osram refers to their
reddish orange LEDs as amber, while other LED manufacturers refer to their
orangish yellow and occaisionally yellowish orange LEDs as amber.
As for low power ones:
UPDATE 10/31/2009: Nichia NSPRR70AS, version with nominally 615 nm
dominant wavelength (NSPRR70AS is nominally red): Dominant wavelength of 615
nm has a color that sometimes appears orangish red and usually appears reddish
orange. At 50 mA, typical voltage drop is supposed to be 2.4 volts and typical
light output is supposed to be 9 lumens. This works out to 75 lumens/watt.
UPDATE 10/12/2009: Osram LA E65F-CBEA-24-1-Z, in stock at Digi-Key,
typically achieves 66.7 lumens/watt according to its datasheet. The
datasheet states that typical performance at 50 mA is 7.17 lumens and a
typical forward voltage drop of 2.15 volts.
UPDATE 8/14/2017: Osram LO E67F-BADA-24-1-Z is rated to typically
produce typically 11 lumens at 50 mA with a typical voltage drop of 2.15 volts,
which works out to typically 102 lumens/watt.
UPDATE 8/14/2017: SunLED XSM2MOK983W is a 4-lead "piranha" LED that is
rated to produce typically 9 lumens at 70 mA with a typical voltage drop of 2.4
volts. This works out to 54 lumens/watt.
UPDATE 9/23/2019: Nichia NFSY757G typically produces 30.2 lumens at 65
mA with a typical voltage drop of 2.88 volts. This works out to 161 lumens/watt.
This LED has a typical dominant wavelength of about 578-579 nm, which is a
non-orangish yellow as opposed to the usual orangish yellow with dominant
wavelength around 590 nm.
Nichia NVSA119B-V1 and NVSA219B-V1 typically produce 240 lumens at 700 mA with a
typical voltage drop of 2.98 volts. This works out to 115 lumens/watt. These
LEDs are phosphored ones with the usual amber-yellow color with a dominant
wavelength of about 590 nm.
UPDATE 6/20/2020: Osram LCY CLBP-KZLY-5F5G-8E8G-350-S is stated to
typically produce 124 lumens at 350 mA with a typical voltage drop of 2.95
volts when the junction temperature is 25 degrees C, which works out to 120
lumens/watt. The square root of the product of its lower and upper limits of
light output is 120.6 lumemns, which indicates 117 lumens/watt. This LED uses a
phosphor.
UPDATE 6/20/2020: Osram GY CSHPM1.23-KQKS-36-0-350-R18 is stated as
producing 76.3-97 lumens, square root of product of these is 86 lumens, at
350 mA with a typical voltage drop of 2.2 volts when the junction temperature
is 25 degrees C. This works out to typically 111.7 lumens/watt. Please note
that light output and efficiency of non-phosphored yellow LEDs including
this one is significantly less with real-world junction temperatures.
UPDATE 10/7/2015: Cree XPEAMB-L1-0000-00901 typically produces 81 lumens
minimum, 84 lumens typical with a typical voltage drop of 2.1 volts at 350 mA
and junction temperature of 25 C, which works out to 110 low-side, 114 typical
lumens/watt. Expect significantly less, often at least 25% less with even
generous-side real-world heatsinking due to high temperature sensitivity shown
for this amber LED (like non-phosphor amber LEDs in general) in
this datasheet.
UPDATE 8/14/2018: Cree XPEBPA-L1-0000-00D01 is a phosphor amber LED
that produces 107 lumens minimum, 114 lumens maximum, I figure 110.4 lumens
typical, at 350 mA with a typical voltage drop of 3.05 volts at 25 degrees C.
This works out to typically 103 lumens/watt.
UPDATE 3/12/2016: Lumileds L1C1-PCA1000000000, a phosphor "amber" LED,
typically produces 94 lumens at 350 mA with a voltage drop of 2.75 volts, which
works out to 98 lumens/watt, at a junction temperature of 85 degrees C. At 25 C,
the DS144 datasheet indicates light output is 1.15 times higher or typically 108
lumens, and the typical voltage drop is 2.85 volts, which works out to typically
108 lumens/watt. At 100 mA and 25 C, the datasheet indicates light output about
31% of that at 350 mA or 33.5 lumens and typical voltage drop of 2.78 volts,
which works out to typically 120 lumens/watt.
UPDATE 12/25/2018: Lumileds LXM2-PL01-0000 produces minimum of 80
lumens, typically 110 lumens at 350 mA with a typical voltage drop of
3.05, maximum 3.51 volts. This works out to minimum of 65, typically 103
lumens per watt. This is with junction temperature of 25 C. Expect about
2% less with thermal pad temperature of 35 C.
UPDATE 12/25/2018: Lumileds LXM5-PL01 produces minimum of 50 typically
74 lumens at 350 mA with a voltage drop of 2.1 volts typical, 2.6 volts maximum.
This works out to lumens/watt being 55 minimum, 68 low side, 100 typical when
the junction temperature is 25 degrees C. Expect about 18% less when the
thermal pad temperature is 35 C.
UPDATE 10/7/2015: White LEDs can be filtered to yellow with yellow
filters or "lenses". Typically 60-75% of the luminous/photometric output of
a white LED gets through as reasonably yellow light. 60-165 lumens/watt
(from 100-220 lumens/watt as of mid 2018) is possible by filtering the most
efficient white LEDs. The downside is that white LEDs often have worse
aging characteristics than yellow LEDs unless they are underpowered.
The loss is greater if filtering to an orangish or "amber" shade of yellow
suitable for traffic signals. Phosphor yellow/amber LEDs may be better here.
As for low power yellow LEDs:
UPDATE 10/12/2009: Osram LY E65F-CADA-46-1-Z, in stock at Digi-Key,
typically achieves 44.6 lumens/watt according to its datasheet. Typical
performance at 50 mA is output of 4.8 lumens and forward voltage drop of
2.15 volts.
As for low power yellow LEDs in my testing:
UPDATE 10/16/2020 Cree C503B-ACN-CY0Z0341-030, 7 samples tested, produces
2.19 lumens at 20 mA with a voltage drop of 1.99 volts, meaning 55 lumens/watt.
This is with calculated juncion temperature of approx. 28 degrees C. At a more
realistic junction temperature of 40 degrees C, expect 47 lumens/watt.
I expect that others have fair chance of achieving similar luminous efficacy
with low power non-phosphor yellow / amber LEDs.
UPDATE 9/23/2019: Nichia's NCSG119B-V1 and NCSG219B-V1 typically produce
139 lumens at 350 mA with a typical voltage drop of 3.38 volts. This works out
to 105 lumens/watt.
UPDATE 9/25/2019: The above Nichia NCSG119B-V1 and NCSG219B-V1, at a
decreased current of 75 mA as extrapolated using graphs in their datasheets,
typically produce 37 lumens with a typical voltage drop of 3.04 volts, which
works out to 162 lumens/watt.
UPDATE 3/12/2016: Cree XPEBGR-L1-R250-00F02, XPEBGR-L1-0000-00F02, and
XPEBGR-L1-0000-00F01 typically produce 126 lumens at 350 mA with a typical
voltage drop of 3.2 volts. This works out to typically 113 lumens/watt.
At 150 mA, the datasheet for these LEDs indicates light output being 51% of that
at 350 mA with typical voltage drop of 2.9 volts, which indicates 147 lm/W. I
expect even greater efficiency at 50-100 mA, typically about or over 160
lumens/watt at 50-65 mA as of 9/25/2019.
UPDATE 12/25/2018: Lumileds L1C1-GRN1000000000 produces minimum of 90
lumens, typically 115 lumens at 350 mA with a typical voltage drop of 3.05,
maximum 3.5 volts. This works out to minimum of 73, typically 107 lumens per
watt. This is with junction temperature of 85 C. Expect about 1% more with
thermal pad temperature of 35 C.
UPDATE 6/22/2020: the above Lumileds L1C1-GRN1000000000, at decreased
current of 100 mA, typically produces about 36% as much light as at 350 mA
according to the Figure 3e graph in its datasheet (DS144), which means
typically 38.5 lumens. Its voltage drop at 100 mA is typically 2.85 volts
according to the Figure 4d graph in its datasheet. This means it typically
achieves 135 lumens/watt at 100 mA. This is with junction temperature of
85 degrees C.
UPDATE 4/14/2012: Lumileds Luxeon "Rebel" LXML-PM01-0100 is a top
brightness rank green one with worst case performance of 100 lumens at 350
mA and worst case forward voltage drop of 3.51 volts. This works out to
81.4 lumens/watt worst case minimum. According to the DS68-1 datasheet,
typical overall luminous efficacy at junction temperature of 25 degrees C
is 100 lumens/watt at 350 mA (102 lumens, 2.9 volt voltage drop). At 100
mA, the datasheet indicates light output being 38% of that at 350 mA or
38.7 lumens typically and a forward voltage drop of typically 2.65 volts,
which works out to typically 146 lumens/watt. I expect even higher overall
luminous efficacy around 160 lumens/watt at 50 mA.
Now for low power green LEDs, 70 - 87 - 125 lumens/watt,
UPDATE 8/5/2020: Cree C503B-GCS-CB0C0781, 10 samples received and tested
at 20 mA. Average voltage drop was 2.72 volts. Quantum efficiency, conservative
measurement: Antilog-mean-log for the lowest 8 of these 10 and 4th-lowest were
both 31%. Average photon energy of the spectrum with median dominant wavelength
(of 524 nm, noted 8/8/2020) is 2.37 eV based on centroid wavelength of 523 nm.
4th-lowest lumens per emitted watt is 466.3. This works out to conservative-side
typical figures of 6.8 lumens and 125 lumens/watt.
UPDATE 8/26/2015: Nichia NSPG510BS (which I have yet to test) has
claimed beam candela 45-60% greater than that of the below NSPG510AS as I
remember data mentioned in Nichia's website. This means overall luminous
efficacy can be anywhere from 87 to 115 lumens/watt at 20 mA.
UPDATE 1/1/2008: I tested several units of Nichia NSPG510AS
and NSPG520AS. My tests indicate at 20 mA average forward voltage drop of
3.05 volts and light output ranging from 3.9 to 4.4 lumens. The datasheet
says typical forward voltage drop is 3.2 volts. This indicates 61 to 72
lumens per watt overall luminous efficacy.
UPDATE 8/6/2020: A lowish median performing sample of one of 10 samples
of Cree C503B-GCS-CB0C0781 received 8/5/2020 was tested at 2 mA. Voltage is 2.33
volts. A conservative figure of quantum efficiency is 43%. Dominant wavelength
is 531 nm. Centroid wavelength is 529.2 nm, which indicates average energy of
emitted photons being 2.34 eV. Lumens per emitted watt is 518. This indicates
1.04 lumen and 223 lumens/watt.
UPDATE 8/9/2020: This same sample of Cree C503B-GCS-CB0C0781 was tested
at 1 milliamp. Voltage is 2.27 volts. A conservative measure of quantum
efficiency, rounded down, is 44%. Dominant wavelength is 532 nm. Centroid
wavelength, longer of determinations from two spectrometer recordings, is 533.4
nm, which indicates rounded-down average photon energy of 2.32 eV. Lumens per
radiated watt, lower of determinations from two spectrometer recordings, is 528.
This works out to .539 lumen and 237 lumens/watt. A curve fitting method using
data I have at other currents indicates 235-236 lumens/watt, so I'm calling this
as 235 lumens/watt in order to avoid error in favor of overreporting the
overall luminous efficacy of this LED.
UPDATE 8/26/2015: Nichia NSPG510BS is (untested by me) 45%-plus more
efficient than the NSPG510AS and 40%-plus more efficient than the NSPG520AS,
as I remember and understand data from Nichia's website. This means 165
lumens/watt is somewhat likely and 200 lumens/watt is possible at favorable
low currents.
UPDATE 12/25/2007: I just got a batch of NSPG510AS units that average
72 lumens/watt at 20 mA. At 3 mA, they had a forward voltage drop averaging
2.6 volts and produced on average .94 lumen according to my testing, for an
overall luminous efficacy of 120 lumens/watt.
UPDATE 2/16/2014: On 7/28/2009, I tested a NSPG520AS at 1.69 mA, and
found forward voltage drop of 2.45 volts and quantum efficiency of 29.5%. The
color matched that of a Nichia green LED whose spectrum was analyzed with
results indicating average photon energy of 2.339 eV and luminous efficacy of
the emitted light being 512 lumens/watt. This indicates .597 lumen, conversion
efficiency of 28.15% and overall luminous efficacy being 144 lumens/watt.
As for high power LEDs: As mentioned above, the Lumileds LXML-PM01-0100 and
some Cree XPEBGR-L1-* LEDs are likely to achieve 160 lumens/watt at 50 mA.
UPDATE 9/25/2019: The above Nichia NCSGE17A, at a decreased current of
100 mA, as extrapolated using graphs in its datasheet, typically produces 65
lumens with a voltage drop of 2.81 volts, which works out to 231 lumens/watt.
UPDATE 3/31/2021: Nichia NCSGE17A (G)14) is a version of NCSGE17A with a
very yellowish shade of green with dominant wavelength ~ 567-568 nm and about 2%
more photometric output than the less yellowish version of NCSGE17A has.
UPDATE 9/28/2019: Osram GT PSLR31.13, more specifically
GT PSLR31.13-LUMQ-T1T2-1 typically producves 187 lumens at 150 mA with a typical
voltage drop of 6.25 volts. This works out to 199 lumens/watt. This is a
phosphored LED with two blue dice/chips. Its color is a slightly whitish, very
slightly yellowish shade of green with a typical dominant wavelength of 540 nm.
At 60 mA, this LED typically produces 82 lumens with a typical forward voltage
.5 volt less than at 150 mA, or typically 5.75 volts. This works out to 237
lumens per watt. This is extrapolated using graphs in this LED's datasheet.
Now for lime green phosphored yellow-green LEDs:
UPDATED 8/14/2018: Lumileds LXML-PX02, AKA LXML-PX02-0000, is a
high power "lime" phosphored LED with dominant wavelength of 566-569 nm and its
lowest brightness bin achieves luminous efficacy of 140 lumens/watt minimum at
350 mA when its junction temperature is 85 degrees C. Its datasheet says that
it typically produces 184 lumens at 350 mA with typical voltage drop of 2.75
volts, which works out to 191 lumens/watt.
The datasheet indicates that at 25 degrees C, the light output is 1.1 times that
at 85 C. The voltage drop is probably the same as with royal blue, or 2.9 volts
at 25 C. This indicates typically 202 lumens and 199 lumens/watt at a junction
temperature of 25 C.
At 200 mA and a junction temperature of 25 C, the DS68-1 datasheet indicates a
typical typical light output at least 58% of that at 350 mA and a typical
voltage drop of 2.74 volts, which works out to 117 lumens and 213 lumens/watt.
At 100 mA and a junction temperature of 25 C, the datasheet indicates a typical
voltage drop of 2.65 volts and a typical light output at least 28% of that
at 350 mA, which works out to 56.5 lumens and 213 lumens/watt. I think that the
overall luminous efficacy is typically 215 lumens/watt at 120-150 mA.
Update 8/5/2020: Lumileds L128-LME1003500000 is a lime green LED that
typically produces 77 lumens according to Future Electronics, 79 lumens
according to its DS236 datasheet at 120 mA with a typical voltage drop of 3
volts. This works out to typically 214 or 219 respectively lumens/watt.
As of 8/5/2020 this LED was mentioned as orderable by the reel from
Future Electronics with none yet in stock, and not yet being mentioned
by Digi-Key.
Update 8/5/2020: Lumileds has related "mint" LEDs with a less yellowish
or non-yellowish and noticeably whitish shade of green. An example is
L128-MNT1003500000, which typically produces 77 lumens with a typical forward
voltage of 3 volts at 120mA according to its DS236 datasheet, which works out
to 114 lumens/watt.
Update 8/14/2018: Lime LEDs that consist of a royal blue LED chip and
yellow-green-emitting phosphor are not on the market with the most efficient
royal blue LED chips used in royal blue LEDs that are on the market as of
8/14/2018. If such lime green LEDs were to exist, they would typically achieve
about 250-275 lumens/watt at 350 mA.
LEDs of similar color and overall luminous efficacy similar to, maybe slightly
higher than that of white ones can be made by suitably adding a suitable
fluorescent dye to suitable white or blue ones. That means about 120-220-plus
lumens/watt! If you put a white or blue LED into a piece of green-fluorescing
yellow acrylic this will probably work! Go Here for
LED Hacking for Fun and Danger.
UPDATE 3/29/2016: Nichia NCSE119B-V1 and NCSE219B-V1 typically produce
108 lumens at 350 mA with a typical voltage drop of 3.32 volts, which works out
to 93 lumens/watt.
UPDATE 6/20/2020: Lumileds L1C1-CYN1000000000 typically produces
100 lumens at 350 mA with a typical voltage drop of 3.05 volts when the
junction temperature is 85 degrees C, which works out to 93.7 lumens/watt.
UPDATE 6/22/2020: the above Lumileds L1C1-CYN1000000000, at decreased
current of 100 mA, typically produces about 38% as much light as at 350 mA
according to the Figure 3e graph in its datasheet (DS144), which means
typically 38 lumens. Its voltage drop at 100 mA is typically 2.85 volts
according to the Figure 4d graph in its datasheet. This means it typically
achieves 133 lumens/watt at 100 mA. This is with junction temperature of
85 degrees C.
UPDATE 5/29/2016: Lumileds Luxeon "Rebel" LXML-PE01-0080 is a top
brightness rank "cyan" sometimes-in-stock one with worst case performance
of 80 lumens at 350 mA and worst case forward voltage drop of 3.51 volts.
This works out to 65 lumens/watt worst case minimum. Typical is 81 lumens/watt.
In "real world" heatsinking, these figures can be a couple percent less.
Lumileds LXML-PE01-0070 is more reliably available and has luminous efficiency
of 57 lumens/watt worst-case and 74 lumens/watt typical when the junction
temperature is 25 C.
High power LEDs:
UPDATE 7/30/2018: Lumileds Luxeon "Rebel" LXML-PB01-0040 is
a top brightness rank blue one with worst case performance of 40 lumens at
350 mA and worst case forward voltage drop of 3.51 volts. This works out to 32.5
lumens/watt worst case minimum. Typical is 40 lumens/watt according to the
"DS68" datasheet. This is at junction temperature of 25 C; expect a percent or
two less with good heatsinking.
UPDATE 6/20/2020: Lumileds L1C1-BLU1000000000 produces minimum of 25
lumens, typically 43 lumens at 350 mA with a typical voltage drop of 2.84,
maximum 3.5 volts. This works out to minimum of 20, typically 43 lumens per
watt. This is with junction temperature of 85 C. Expect strangely about 6% less
with thermal pad temperature of 35 C, assuming the unusual blue curve in
Figure 2e of the DS144 datasgeet is correct.
UPDATE 6/22/2020: the above Lumileds L1C1-CYN1000000000, at decreased
current of 100 mA, typically produces about 36% as much light as at 350 mA
according to the Figure 3e graph in its datasheet (DS144), which means
typically 15.5 lumens. Its voltage drop at 100 mA is typically 2.63 volts
according to the Figure 4d graph in its datasheet. This means it typically
achieves 58.8 lumens/watt at 100 mA. This is with junction temperature of
85 degrees C.
UPDATE 7/29/2018: Cree XPEBBL-L1-0000-00301 produces typically 49
lumens at 350 mA with a typical voltage drop of 3.1 volts. This works out to
typically 45 lumens per watt at 25 C junction temperature. Worst case minimum at
25 C and 350 mA is 45.7 lumens with a voltage drop of 3.5 volts, which means
37 lumens/watt.
UPDATE 3/31/2021: Nichia NCSBE17A produces typ. 42 lumens at 350 mA with
a typical voltage drop of 3.0 volts, which works out to typ. 40 lumens/watt.
Now for low power blue LEDs:
UPDATE 8/26/2015: UNTESTED, SIGHT UNSEEN: Nichia has new blue LEDs
recently becoming available. One is NSPB510BS, which achieves 25-34 lumens/watt
according to my extrapolation from Nichia published data and results of my
testing on older models. Expect optical output at 20 mA to be about 22-30 mW,
which means conversion efficiency around 34-46 percent.
UPDATE 10/15/2020: Cree C503B-BCN-CX0Y0451, in my testing of 7 samples,
had conservative determination of typical overall luminous efficacy/efficiency
of 31 lumens/watt at 20 mA. UPDATE 10/16/2020: These 7 samples have dominant
wavelength averaging at least 472.5 nm. If their dominant wavelength was 470 nm
that their datasheet says is typical, they would achieve 28-29 lumens/watt
instead of 31.
I have yet to do testing at lower currents. I suspect my samples of Cree
C503B-BCN-CX0Y0451 will achieve about 37 lumens/watt at a current close to 8 mA,
and about 40 possibly 41 lumens/watt at 2-3 mA.
Update 7/30 - 8/1 2018: Cree XQEROY-00-0000-000000Q01 and
XQEROY-00-0000-000000Q02 produce 600 mW minimum, 612 mW typical at 350 mA with
a tyypical voltage drop of 3.1 volts at 350 mA at 25 degrees C. This means
conversion efficiency is typically 56%. Spectrum analysis of a different LED
with similar spectrum indicates 48 lumens per emitted watt, so overall luminous
efficiency is probably about 27 lumens per watt.
Update 7/30/2018: Cree XPGDRY-L1-0000-00601 produces 730 mW minimum
at 350 mA with a voltage drop of 2.82 volts typical 3.1 volts maximum at 25
degrees C. This means conversion efficiency is 67% minimum, 74% low side. If its
typical radiant flux at 350 mA is 750 mW, then its typical efficiency is 76%.
This is a horticultural royal blue LED with a short peak wavelength of typically
448 nm, and I believe its light has about 40 lumens per emitted watt. This means
overall luminous efficiency is typically somewhere around 30 lumens/watt, but it
could be less.
This LED is designed for use with much higher current, and its efficiency is
less with higher current. Its efficiency at 1500 mA is about .78 times its
efficiency at 350 mA, so I think typically about 59% or typically about 23
lumens per watt at 1500 mA. Its lumens/watt at 1500 mA could be less due to its
peak wavelength probably being slightly shorter at higher current.
UPDATE 8/1/2018: Cree XQEAPB-H0-0000-000000401, not cataloged at
Digi-Key as of this date, is a "PC blue" LED with luminous flux of 51.7 lumens
minimum, 56.8 lumens maximum, at 350 mA with a typical voltage drop of 3.1
volts. This indicates a luminous efficiency of typically 50 lumens/watt.
UPDATE 8/1/2018: Osram LB CL7P-HZJZ-3B6B-Z, listed as obsolete by
Digi-Key, produces typically 55 lumens (with a wide range of 39-71 lumens)
at 350 mA with a typical voltage drop of 3.1 volts. This means typically 51
lumens/watt.
UPDATE 7/21/2021: Luminus Devices MP-3030-120H-50-80 and
MP-3030-120H-40-80 are claimed to typically produce 40 lumens at 65 mA with a
typical voltage drop of 2.68 volts at junction temperature of 25 degrees C.
This works out to 229.6 lumens/watt, which has been stated as 230.
UPDATE 7/21/2021: Cree JB2835BWT-G-B50GA0000-N0000001 and three others in
the same series but not yet in stock at Digi-Key as of this date are claimed on
its datasheet to typically produce 33.5 lumens at 55 mA with a typical voltage
drop of 2.67 volts at junction temperature of 25 degrees C. This works out to
228 lumens/watt. Digi-Key states 34 lumens rounded up from 33.5.
UPDATE 11/18/2019: Seoul Semiconductor S1W0-3030508003-0000003S-00001
is claimed to typically produce 39 lumens at 65 mA with claimed typical voltage
of 2.7 volts at 65 mA at 25 C. This works out to typically 222 lumens/watt.
UPDATE 8/2/2018: Everlight 62-227ET/KK7D-3M5050X6Y62629U6/2T/EU of
middle brightness bin of T3 produces typically 41 lumens at 65 mA with a
voltage drop of 2.84 volts according to the Figure 2 graph of its datasheet.
This works out to 222 lumens/watt. Using the 2.75 volt midpoint of its 2.6-2.9
volt range of voltage drop at 65 mA, overall luminous efficiacy works out to
229 lumens/watt.
UPDATE 8/7/2018: The Nichia NF2W757G-V3F1 version with CRI rank of
R70 (CRI of 70 min.) and color temperature 5000K typically produces 38.8 lumens
at 65 mA with a typical forward voltage drop of 2.73 volts, when its solder pad
is at 25 degrees C. This works out to 218 lumens/watt.
UPDATE 5/21/2016: Lumileds L135-4080CA35000P1 typically produces 53
lumens from 100 mA of current with a typical voltage drop of 2.8 volts which
works out to luminous efficacy of 189 lumens/watt, although its datasheet says
186 lumens/watt. At 65 mA it typically produces 34 lumens with a voltage drop
of 2.72 volts which works out to 192 lumens/watt, although its datasheet says
194 lumens/watt.
UPDATE 8/5/2018: Lumileds L135-4080SA35000P1, L135-5080SA35000P1 and
L135-5780SA35000P1, not mentioned at Digi-Key as of this date through 12/6/2020,
typically produce (or will produce) 36 lumens at 65 mA with a typical voltage
drop of 2.8 volts, which works out to typically 198 lumens/watt, although the
DS203 datasheet says 203 lumens/watt.
As of 12/6/2020, the most efficient Lumileds L135 LED being mentioned at
Digi-Key is L135-4080CA35000P1, mentioned above.
UPDATE 3/10/2019: Samsung SPMWHD32AMD3XAR0S0 and SPMWHD32AMD3XAT0S0 are
rated to typically produce 39 lumens at 65 mA with a typical voltage drop
of 2.75 volts. This works out to 218 lumens per watt.
As for high power white LEDs:
UPDATED 1/28/2017: Cree XPLAWT-00-0000-0000V5051 and four other XLPAWT
series cool white LEDs produce 513 lumens minimum, (extrapolated) 524 lumens
typical, at 1050 mA with junction temoperature of 25 C. With junction of 85 C,
minimum luminous flux output is 460 lumens, and typical is 470 lumens. Typical
voltage drop at 1050 mA is 2.95 volts at 85 C, most likely 3.07 volts at 25 C.
This works out to typically 162 lumens/watt at junction temperature of 25 C,
152 lumens/watt at junction temperature of 85 C.
This is a very high power LED, comfortably producing 776-794 or more lumens at
2 amps when its junction temperature is 85 C, and its absolute maximum current
rating is 3 amps.
When significantly underpowered with 350 mA, this LED appears to typically
produce (conservatively) 36% of 511 lumens with a forward voltage drop of
typically 2.76 volts at 25 C, based on its datasheet. This works out to
extrapolated as typically 190 lumens/watt.
Cree claimed in this
5/22/2014 press release that this series of LEDs is to achieve up to 200
lumens/watt at 350 mA.
The datasheet for Cree XP-L LEDs is here.
UPDATE 5/30/2016: Cree XPGDWT-01-0000-00ME3 and XPGDWT-01-0000-00ME2
typically produce 177 lumens at 350 mA with a typical voltage drop of 2.73
volts at 350 mA and junction temperature of 85 C. This works out to 185
lumens/watt. When the junction temperature is 25 C, the voltage drop increases
by .1 volt and the light output increases by 11-12% according to the datasheet,
so this indicates luminous efficiency of about 190 lumens/watt.
The datasheet indicates that when current is 125 mA, light output is typically
about 36% of that at 350 mA, and voltage drop is about .08 volt less than at
350 mA. At junction temperature of 25 C, this appears to be about 70.5-71 lumens
with a voltage drop of 2.75 volts when current is 125 mA, which works out to
about 205 lumens/watt. According to how I see the graph of relative luminous
flux vs. current in the datasheet, I expect about 205 lumens/watt at 25 C to be
achieved with current from 125 to 150 maybe 160 mA.
UPDATE 12/22/2018: Lumileds "Luxeon V2" L1V2-5770000000000,
L1V2-5070000000000 and L1V2-4070000000000 typically produce 315 lumens at 700 mA
with a typical voltage drop of 2.83 volts when the junction temperature is 85 C.
This works out to 159 lumens/watt. Worst case extrapolated using datasheets for
related parts is 298 lumens with a voltage drop of 3.04 volts, which is 140
lumens/watt. At 350 mA, typical luminous efficiency extrapolated using
datasheets for related LEDs is 180 lumens/watt when the junction temperature is
85 C. At junction temperature of 25 C, light output is 6% more and voltage drop
is not stated, but other recent datasheets for similar LEDs indicate 4% more,
meaning luminous efficiency is 2% more or 183 lumens/watt. Luminous efficiency
increases from that as current is decreased to 100 milliamps, maybe even less.
UPDATE 2/27/2016 - As for a Nichia high power LED: The NVSW119B-V1
version with color temp. of 5000 K and the lowest color rendering index rating
(none specified) typically achieves 305 lumens at 700 mA with a typical voltage
drop of 2.98 volts, which works out to typically 146 lumens/watt. The version
with second-lowest CRI (70 minimum) typically produces 302 lumens and achieves
144.5 lumens/watt.
At 350 mA, the typical forward voltage drop is 2.83 volts. Light output is
typically 168 and 164 lumens for the lowest and second-lowest CRI versions
respectively. This works out to 169 and 165 lumens/watt respectively.
NOTE: All high power white LED data above is from datasheets and
datasheet interpretations and not personally experienced actual test results.
UPDATE 5/11/2009 Cecol / Citizen
Electronics produces their CL-L233-C13N with nominal light output of 1335
lumens at 720 milliamps with a typical voltage drop of 18.6 volts, which
works out to 100 lumens/watt.
Now for low power white LEDs:
UPDATE 6/30/2012: Nichia announced on 5/10/2012 their NSPW510HS-K1,
which has a claimed typical luminous efficacy of 170 lumens per watt at 20 mA.
Typical light output is 10 lumens and typical voltage drop is 2.8 volts at
20 mA. Nominal beam width is 30 degrees. This LED may have a chip similar to
that of NSPWR70CS-K1, which is larger than usual for low power LEDs. The beam
may have different characteristics from those of other Nichia NSPW-510 series
LEDs.
Update 5/11/2009: Nichia has an extremely efficient 4-lead LED,
NSPWR70CS-K1, A.K.A. NSPWR70CSS-K1. At 20 mA, it is said to typically produce
8.7 lumens with a typical voltage drop of 2.9 volts, which works out to 150
lumens per watt. At 50 mA, typical luminous flux is stated as 20 lumens and
typical voltage drop is stated as 3.1 volts, which works out to 129
lumens/watt.
I have tested this LED. My testing indicates 140-145 lumens/watt at 20 mA
for a few that I have tested.
Update 8/3/2014: This LED may now be discontinued.
UPDATE 10/15/2020: Seven Cree C535A-WJN-CU0W0231 LEDs tested (at 20 mA),
results are in, with a conservative typical figure of overall luminous
efficacy/efficiency of 100 lumens/watt. Typical voltage drop in my testing of
these 7 samples was 3.00 volts, typical light output was determined
conservatively as being 6.0 lumens. The dimmest of these 7 samples produced a
little over 5.6 lumens and achieved almost 94 lumens out per watt in.
(Part number found typo-ed, corrected 11/4/2020.)
UPDATE 10/23/2020: Cree C535A-WJN-CU0W0231 actual conservative test
results at various currents less than 20 mA: 115 lumens/watt at 10 mA, 119
lumens/watt at 8 mA, 125 lumens/watt at 5 mA, 127 lumens/watt at 4 mA, 129
lumens/watt at 3 mA, 130 lumens/watt at 2.5 mA (2.5-2.7 milliamps maximizes
lumens out per mA), 130-131 lumens/watt at 2 mA with this figure peaking at
about 2 - 2.2 mA.
UPDATE 11/2/20202020: Cree C535A-WJN-CV0W0231 is brighter still,
typically 10.7 % brighter than C535A-WJN-CU0W0231 according to their datasheet.
My test results are only about 3% brighter with about 1% more voltage drop, with
conservative average of 102 lumens out per watt in at 20 mA. Note 11/4/2020:
I found increased consistency of results with the newer part number.
UPDATE 11/4/2020: Results from testing at currents 2-10 mA are in.
Efficiency of C535A-WJN-CV0W0231 improved better than I expected from quick
preliminary testing at very low currents as current was decreased from 20 to 2
mA, by a hardly measurably smaller percentage than was the case with
C535A-WJN-CU0W0231. My figures for lumens out per watt in, conservatively
determined like I did with C535A-WJN-CU0W0231, at all currents from 2 to 20 mA
are 2 lumens/watt grerater for C535A-WJN-CV0W0231 than for C535A-WJN-CU0W0231.
I figure ratio of light output to current for C535A-WJN-CV0W0231 is maximized
at about 2.7 mA, based on my testing of 10 of these. My figures for lumens
out per watt in for C535A-WJN-CV0W0231 are 117 lumens/watt at 10 mA (typo
correction from 20 mA 4/26/2022), 121 lumens/watt at 8 mA, 127 lumens/watt at 5
mA, 129 lumens/watt at 4 mA, 131 lumens/watt at 3 mA, 132 lumens/watt at 2.5 mA
and 132-133 lumens/watt at 2 mA with this figure peaking at about 2-2.3 mA.
Update 11/4/2020: Mouser Electronics had 497 C535A-WJN-CV0W0231 in stock
and stated a factory lead time of 3 weeks for units after these 497.
The above white LED lamps have blue chips plus a phosphor to convert some of
the blue light to yellowish light of broadband spectral content from mid-green
to mid-red. The color is usually a cool white to "daylight" slightly bluish or
sometimes violetish-bluish white, usually of about 5000-6500 K. Color rendering
index of the most efficient ones as well as most other white LEDs is usually
stated as 65 to 70 or 70-plus when stated. There are white LEDs with improved
color rendering index, but their overall luminous efficacy is compromised,
although not much when the color rendering index is 80 or minimum of 80. Higher
color rendering index of 90 or more involves significant reduction of luminous
efficiency, although a few white LEDs of such premium color rendering index are
now getting slightly more efficient than even T8 and T5 fluorescent lamps.
UPDATE 3/24/2013 This
3/19/2013 LEDs Magazine article mentions a 2700K Samsung LM561B-family LED
achieving 130 lumens/watt at 150 mA, and 150 lumens/watt at a lower current,
with 65 mA mentioned as a lower current for higher efficiency in another LED
in this series.
Overall luminous efficacy typically peaks at 1.5 to 3.5 mA and remains above
that of 20mA usually at least down to .5-1 mA. Efficiency and light output
become less predictable below .4-.5 mA.
White LEDs have most of their photometric output from a phosphor, and so the
luminous efficacy of emitted light does not improve with decreasing current as
much as with colored InGaN LEDs. In fact, spectral shifting of the LED chip's
output away from wavelengths best-utilized by the phosphor can impair overall
luminous efficacy at low currents. However, photometric output per milliamp
seems to usually improve with decreasing current down to about 6 milliamps,
sometimes as low as 2.5-3 milliamps. I have tested three (as of 11/4/2020)
low power white LED models by Cree at various currents, and found ratio of
photometric output to current to be maximized at 2.5-5 mA, achieving about
1.135-1.175 times that achieved at 20 mA. These LEDs had efficiency maximized
at 2-3 mA, with efficiency about 1.26-1.3 times that at 20 mA.
Important Note on Gallium-Nitride LEDs!
The 40 watt incandescent equivalent member of this series that has a clear bulb
and an E26 base is claimed to produce 450 lumens from 2.8 watts, 160 lumens/watt.
Highest millicandela green LEDs that I am aware of as of 6/22/2020: Cree
C503B-GAS-CB0F0791, C503B-GAN-CB0F0791, C503B-GAS-CB0F0792, and
C503B-GAN-CB0F0792 typically produce 53.65 candela at 20 mA. I expect these to
typically produce 6-7 candela at 2 mA. Two of these have been available at least
since 5/14/2012. Also Broadcom HLMP-CM1A-560DD, claimed 60.5 candela at 20 mA.
Highest MCD red 5 mm LED lamp at 20 mA that I am aware of as of 6/22/2020:
Cree C503B-RAN-CA0C0 and C503B-RAS-CA0C0, claimed 22.45 candela.
Brightest white 5 mm LED lamp at 20 mA that I am aware of as of 5/11/2009 -
3/20/2013: Nichia NSPW500DS (15 degree beamwidth, 27 candela) and Nichia
NSPW500GS-K1 (same beam angle, 30-33 candela, but has compromised life
expectancy).
Brightest white LED at 20 mA that I am aware of as of 8/2/2020: Cree
C503D-WAN-CCBEB151, square root of product of lower and upper limits of
intensity is 42.7 candela.
General Notes and Disclaimers:
I don't know everything, and I only mention LED brands and models that I know
of. Better LEDs than the ones I mention here may exist, and may be manufactured
by companies that I don't name here.
Unless otherwise noted, luminous efficacy is stated for a 25 degree Celsius
(77 degree F.) ambient with a current of 20 milliamps (350 mA for heatsinkable
models) in an environment that does not build up heat around the LED, unless
otherwise is stated. Heatsinkable models are generally stated to achieve their
claimed performance when cooling is sufficient to cool either the heatsinkable
surface or the junction temperature to 25 degrees C.
Most ultrabright blue, blue-green, non-yellowish green, and white LEDs have
luminous efficiency that increases with decreasing current, although the
increase will reverse as current decreases below the current at which efficiency
is maximized. This current is usually 1-3.5 mA for most blue and green low power
LEDs and 2.5-7 mA for most white low power LEDs. For high power LEDs with 1 mm
square dice, the current that results in maximum efficiency is typically 25-80
mA for white, and 15-45 mA for blue and green ones with dominant wavelength of
465 to 535 nm.
Please beware that performance of many LED models at currents below a few tenths
of a milliamp or a percent or so of maximum rated current may be unreliable.
There may be significant tolerance in light output. Your mileage may vary.Most Efficient Deep Red / Pure Red LEDs - 14-39-42
lumens/watt, 51 - 73.5 % efficient
InGaAlP low power LEDs with dominant wavelength at least 631 nm are sometimes
called "royal red". They may achieve 12-16 lumens/watt.Most Efficient Orangish Red LEDs - 46-96-100-109-110
lumens/watt
The following orangish-red LEDs have typical dominant wavelength stated to
be 623 to 627 nm, which often appears to be an orangish red but sometimes
appears "plain red", especially when the background illumination is white
light with color temperature at least 4000 K.Most Efficient Red-Orange LEDs - 66-123-148 lumens/watt
UPDATE 8/2/2017: Cree XPEBRO-L1-0000-00D01 and XPEBRO-L1-0000-00D02,
available at Digi-Key, typically produce 111 lumens at 350 mA with a typical
voltage drop of 2.2 volts, when the junction temp. is 25 degrees C. This works
out to 144 lumens/watt. The datasheet indicates 123 lumens/watt when the
junction temp. is 50 degrees C.Most Efficient Truly Orange LEDs - 54-102 lumens/watt.
NOTE that rated typical performance is with a lead temperature of 25 degrees C.
Real world performance can be significantly less.Most Efficient Yellow / Amber LEDs - 34-161 lumens/watt
Note: Amber on this page refers to an orangish shade of yellow with dominant
wavelength around 590 nm, which most yellow LEDs have. Some LED manufacturers
such as Cree and Lumileds mean this color when they say amber. A few LED
manufacturers such as Osram use the word amber as meaning a reddish shade of
orange, with dominant wavelength around 611-617 nm.Most Efficient Non-Phosphor Yellow-Green LEDs - 14
lumens/watt
UPDATE 10/3/2019: Osram LG T67F-R1T1-24 typically produces .6 lumen
(square root of the product of the minimum of .38 lumen and the maximum of .95
lumen), at 20 mA with a typical voltage drop of 2.1 volts, which works out to
typically 14 lumens/watt. This is +58.3, -36.7 %, in addition to +/- of the
voltage drop. This is at 25 degrees C, light output is down to half its 25
degree C amount at 75 degrees C.Most Efficient Non-Phosphor Green LEDs -
70-143-152 lumens/watt
UPDATE 12/25/2019: Osram GT CSHPM1.13 produces 130-140 lumens at 350 mA
with a typical voltage drop of 2.7 volts according to Digi-Key (for specifically
GT CSHPM1.13-LRLT-26-1-350-B-R18). This works out to typically 143 lumens/watt.
The datasheet (V. 2.0) for CSHPM1.13, which mentions specifically GT
CSHPM1.13-LRLT-26-1-B, says 130-164 lumens with a typical figure of 144 lumens,
and typically 152 lumens/watt.
even more when underpowered:Better InGaN Green LEDs get 120-160-165-235 lumens/watt
at reduced currents
See my note below on efficiency of indium gallium nitride
LEDs at reduced current.
UPDATE 9/25/2019: As mentioned above, I expect Nichia NCSG119B-V1 and
NCSG219B-V1 to typically achieve 162 lumens/watt at 75 mA. I expect even
greater efficiency of at least typically 165 lumens/watt at 50 mA.Most Efficient Phosphored Green, Light Green and Yellow-Green
LEDs - 191-215-219-237 lumens/watt
UPDATE 9/23-25/2019: Nichia NCSGE17A typically produces 208 lumens at
350 mA with a voltage drop of 3.0 volts. This works out to 198 lumens/watt.
This LED has a slightly whitish, very slightly yellowish green color with a
dominant wavelength of about 540 nm. It uses a phosphor to produce green light
from a blue die / chip.Most Efficient Blue-Green LEDs - 57-93 lumens/watt
(And even more at decreased currents)Most Efficient Blue LEDs - 25-45 lumens/watt
(and even more up to 59 lumens/watt at decreased currents)
As I see data characteristeric curves published by Nichia, NCSBE17A at 100 mA
typically produces 15.6 - 15.75 lumens with typical voltage drop of 2.61-2.62
volts. Assuming typicvally 15.6 lumens with typical voltage drop of 2.62 volts
at 100 mA, this works out to typically 59.5 lumens/watt at 100 mA.Most Efficient Royal Blue LEDs - 50-plus - 74 maybe 76 %
efficient, 22-27 maybe 30 lumens/watt
Note that the flux (output) of royal blue LEDs is usually specified in
radiometric terms, not photometric terms. Even when this deep blue light is used
for miximg with other colors of light, it is generally prefered to consider
radiometric quantities of this light. Changing the peak wavelength of narrowband
blue light whose peak wavelength is around 450 nm significantly affects the
photometric/radiometric ratio, in terms of lumens of blue light per watt of blue
light, without much change in other characteristics. Characteristics that are
not changed much by change of peak wavelength (within the 440-458 nm range)
include the radiometric amount of blue light to add to a quantity of
yellow/yellowish light to achieve a specified shade of white, and the luminous
efficiency of the resulting white light.Most Efficient Broadband / Multiband Blue LEDs - 50 - 51
lumens/watt
These are generally phosphored blue LEDs, which have a royal blue die (chip)
with a phosphor that absorbs a minority of the royal blue light and converts it
(by fluorescence) to green or greenish light that mixes with the unabsorbed
majority of the royal blue light. The result is a shade of blue that is not
saturated, along with high luminous efficiency. It is possible to make such LEDs
with overall luminous efficacy exceeding 80 lumens/watt and with a noticeably
unsaturated shade of blue, but closer in color to a spectral blue than to the
color of infinite color temperature (1931 CIE chromaticity coordinates
x=.2399, y=.2342).Most Efficient White LEDs - 100-192-230 lumens/watt
The following LEDs that achieve typically 189-222 lumens/watt when used as
directed are mid power LEDs.
Update 12/20/2020 and 4/26/2022:Digi-Key had none in stock and a minimum
order of 500 and a standard lead time of 4 weeks.Most Efficient Warm White LEDs - up to 211 lumens/watt
UPDATE 8/7/2018: Nichia NF2W757G-V3F1, version R70 with color
temperature 3000K typically produces 37.5 lumens at 65 mA with a typical voltage
drop of 2.73 volts when its solder pad temperature is 25 degrees C, which works
out to 211 lumens/watt.Increased Efficiency of InGaN LEDs at lower currents
UPDATE 8/26/2015: InGaN green, blue-green and blue LEDs have about
30-34 percent as much optical output at 5 mA as at 20 mA if they are
characterized primarily at 20 mA. Better ones have even greater improvement to
about 14-16% as much optical output at 2 mA as at 20 mA. In addition, there is
usually a spectral shift towards longer wavelengths closer to the visibility
peak of 555 nm when current is decreased, which results in more lumens per
milliwatt of optical output. The voltage drop is also .1-.2 volt less at 5 mA
than at 20 mA. Overall luminous efficacy is generally about 30-50 percent more
at 5 mA than at 20 mA for green and blue InGaN LEDs characterized primarily
at 20 mA, and usually 35-60% more at 3 mA than at 20 mA.
Gallium nitride and indium gallium nitride LEDs are fussy, and do not
like their ratings to be exceeded. Exceeding 5 volts reverse voltage even with
low current is supposedly damaging to them. I suspect that destructive
electrolysis is what goes wrong. Peak forward currents in excess of 100 mA
may also be bad for low power ones. Many of these LEDs are also supposed to
be considered static sensitive.LED Light Bulbs (for North America)
Update 5/11/2022: Ikea's Solhetta series of LED light bulbs are more
efficient than most others. As a result, they produce less heat than most others
of the same light output. They also have higher color rendering index than most
others, despite higher CRI generally disfavoring higher efficiency.High candela (beam candlepower) LEDs
Brightest 5 mm LED lamp that I am aware of as of 5/11/2009 - the green Nichia
NSPG-500DS, typical beam width 15 degrees, typical candela 37.7 at 20 mA.
Update 6/22/2020: I expect typically 4.5-5 candela at 2 mA.Notes on Where To Get Efficient LEDs
UPDATE 9/28/2019: I have mostly looked at Digi-Key in 2016-2020 for good LEDs,
especially good non-Nichia ones such as ones by Cree, Lumileds and Osram.
Mouser Electronics is also a good source of good LEDs.
Some good LEDs are available from Newark Electronics. Visit http:/www.newark.com. Duplicate shipping charges may apply if you order more than one type of item not all in stock in the same warehouse.
Future Electronics is the original distributor of Lumileds products and is a distributor of other LEDs.
Nichia LEDs are best obtained from their sales offices. In North America, check out Nichia America. Some Nichia LEDs are available from Future Electronics, sometimes with large minimum orders.
A lumen is defined as the "luminous flux" of 1/683 of a watt of monochromatic
light that has a frequency of 540 terahertz, or a wavelength of approx. 555.5
nm.
One thing worth noting is that a lumen is defined secondarily, in terms of
the candela (which is 1 lumen per steradian), and the candela is defined
primarily (it's the "beam candlepower" of 1/683 watt per steradian of 540 THz
monochromatic light.)
Light of wavelengths other than 555.5 nm have a different amount of lumens
per watt of radiation. The number of lumens in a watt of wavelength other
than 555.5 nm is 683 times the photopic function of
the wavelength in question, divided by the photopic function of 555.5 nm
(which I believe is very close to but maybe not exactly 1).
A recently banned "USA-usual" 100 watt, 120 volt, 750 hour "regular" (A19) lightbulb usually produces 1710 lumens.
Lumens per watt is a measure of efficiency in converting electrical energy to light. Multiply this by the watts dissipated in the LED to get lumens. A typical red, orange, or yellow or yellow-green LED has a voltage drop around 2 volts and is getting around .04 watt at the typical "standard" current of 20 milliamps. A blue, white, or non-yellowish-green one typically has a voltage drop of 3.25 volts at 20 mA and gets .065 watt at 20 mA.
A candela is a lumen per steradian, or "beam candlepower". (Actualy, as
mentioned above, the candela is a primarily defined metric unit, while the
lumen is defined in terms of the candela.)
So lumens are candelas times the beam coverage in steradians. Candelas are
lumens divided by the beam coverage in steradians. Ideally, that is -
assuming that all light is within the beam and the "candlepower" is
constant within this beam.
So you may now be wondering what a steradian is. It is 1 / (4 * pi) of a whole sphere or 1 / (2 * pi) of a hemisphere or about 3283 "square degrees", to the extent there is such a thing as a "square degree". To get steradians from the beam angle:
Steradians = 2 * pi * (1 - cos (.5 * (beam angle)))
(NOTE: There are a few other expressions equal to this. Proving that is homework for 12th graders taking trig / "elementary functions".)
So if you determine the steradian beam coverage and multiply that by the candela figure (or 1/1000 of the millicandela figure), you get the lumen light output - very roughly! The beam is not uniform and it does not contain all of the light. Obtaining lumens from beam angle and candela can easily be in the +100 / - 50 percent range. Actual lumens are generally higher than predicted by this formula with smaller beam angles of 8 degrees or less since the nominal beam does not include a secondary "ring-shaped" "beam" that usually surrounds the main one. Also note that some beam angle figures are optimistic and could lead one to expect a lot more lumen light output than actually occurs.
Please read my disclaimer.