Middle Power LEDs are those that usually use less than 0.3 Watt of energy, are fairly small and require minimal or no cooling. Small as they are, they play a key role in the ever larger penetration of LED into the lighting market. This comes from the possibility to build arrays of middle power LEDs that deliver the required light output for a given form factor.
Thus, many of the popular applications of LED technology use modules with middle power LEDs. Among them: fluorescent LED replacements, LED lamps, LED linear modules for cove lighting, linear luminaries, LED panels, back-light modules for illuminated ceilings or signs.
With a wide application base, the number of manufacturers offering is equally large. So are the variations and package, with 3030, 5630, 5050, 3528 being only some examples.
It comes at no surprise than choosing the LED for a luminaire, lamp or cove light light solution is a real challenge. A manufacturer can offer dozens of pages of LED technical data without following a common presentation template. Deciding which of the data is actually relevant to a project is one of the challenges. Another is comparing LEDs from different manufactures when the data from one's has no direct equivalent to the other`s.
To help with this matter we will compare the best versions of Middle Power LEDs that exist today on the market, from the top LED manufacturers: Nichia, Osram Opto Semiconductors, Samsung, Philips Lumileds, LG Innotek, Seoul Semiconductor, Cree, Everlight.
For a meaningful comparison we selected LEDs that function at 65 mA with a voltage between 2.75 and 3.2 V, classified in three groups:
- Cold White (5000-6500K), CRI 80+, for linear fluorescent replacements (LED tubes) or lighting fixtures for the office or industry.
- Warm White (2700K-3900K) , CRI 80+, usually used in LED lamps, linear lighting fixtures, cove lights, desk lamps, usually for residential and hospitality sectors.
- Warm White (2700K-3900K) , CRI 90+, with applications in luxury lighting, professional linear lighting fixtures, cove lights for commercial and hospitality sectors.
For each category we compare the luminous flux and luminous efficacy at the usual junction "lab temperature" of 25ºC and at a more realistic 100ºC. The comparison data is that from the manufacturers datasheet.
As detailed in a previous article, such a method of comparison is not the best. A real world comparison testing based on a standard product design would be better. However, for this to happen the support of many in the industry is needed.
To get an idea on how far LED technology progressed in the recent years, we added the performance data of 5050 and 3528 LED packages that where introduced on the market almost a decade ago. The comparison is not for historical purposes because such LEDs are still used by many lighting manufacturers today, with applications including linear led modules, fluorescent tubes, lamps, panels or even luxury lighting fixtures.
Cold White (5000-6500K), CRI 80+, for linear fluorescent replacements (LED tubes) or lighting fixtures for the office or industry.
Nichia has the highest performance and efficacy at 25ºC and 100ºC, with 37.5 lumen and 210 lumen / watt and 33.75 lm and 189 lumen / watt respectively. It also has the lowest performance difference between "lab" and "reality" operating temperatures, at only 10%.
Lumileds has the second highest performance and efficacy at 25ºC and 100ºC, with 34.5 lumen and 187 lumen / watt and 29.5 lm and 163 lumen / watt respectively. Followed close by Seoul Semiconductor with 32.9 lumen and 181 lumen / watt and 28.62 lm and 157 lumen / watt respectively.
Samsung and LG have equal good performance at 25ºC but cannot be included in the top because data for the relationship between temperature and luminous flux does not exist beyond 85ºC. If this temperature is a mechanical limit it can be problematic to use the LEDs at the specified current of 65 mA.
At some distance behind Osram, Everlight and Cree can be found.
Most striking is the difference between all the latest generation LEDs and the 5050 and 3528 respectively. The performance gap is so high that we can wonder why someone would still use these LEDs for lighting applications. Except a higher freedom of design, a fixture with these LEDs will have such low performance that integration in a project makes little or no sense. It might have been ok a decade ago but today it just seems a waste of resources...
Warm White (2700K-3900K) , CRI 80+, for LED lamps, linear lighting fixtures, cove lights, desk lamps for residential and hospitality sectors.
Besides the expected lower luminous flux for all warm white LEDs compared to cold white the situation is the same as 6500K. Nichia has the highest performance, followed by Lumileds and Seoul Semiconductor, with Osram, Everlight and Cree at some distance behind. LG and Samsung could not be included at the 100ºC comparsion. 5050 and 3528 LEDs are as inferior at 2700K as they are at 6500K.
Warm White (2700K-3900K) , CRI 90+, for luxury lighting, professional linear lighting fixtures, cove lights.
To obtain high light quality is technologically challenging and it also impacts LEDs performance. Not all the manufacturers seem to be able to offer CRI 90+ versions of the middle power LEDs we compared. The performance picture is also different from CRI 80+. The performance difference between Nichia and Lumileds is slightly bigger, 19% at 100ºC, and almost 35% from the third in line, Osram.
We could not find clear specifications for Samsung, Seoul Semiconductor and Everlight while LG does not provide performance data for 100ºC.
Articles like this should become common place and be an important factor in the decision by a lighting manufacturer of what LEDs to use for a fixture. Equally, it should be used for differentiating one LED fixture from another as the quality and performance of a fixture cannot be better than of the LEDs used.
The comparison could be more comprehensive, including such factors like LM-80 and TM-21 data, bin sorting system and availability of specific high performance bins and even reference price for a certain quantity.
As mentioned above, the presentation of the LED data is not standardized and can be incomplete or confusing at times. Therefore if mistakes exist, feedback is welcome. LM-80 and TM-21 data for the above LEDs would be very interesting to include in the article but unfortunately it seems difficult to obtain. Send me a message if you have such or other useful data.