Application Note

Light Emitting Diode

Design Considerations
for COB Series LED-based Spotlights

Table of Contents
1. Overview ........................................................... 2
2. Advantages of COB LEDs over SMD LEDs .... 3
3. Structure of a COB LED-based Spotlight andKey Components .............................................. 4
4. Advantages of COB LEDs with Small Light
Emitting Surfaces (LES) .................................. 5
5. Thermal Design Considerations to Ensure Safe
Operating Junction Temperatures (TJ) .............11
6. Special Color Rendering COB LEDs.............. 16
7. Summary ......................................................... 22

The Nichia part numbers NTCWS024B-V2, NFDWJ130B-V2, NFCLL036B, NFCLL036B-M2,
NFCLL036B-M3, and NFCLL036B-M7 within this document are merely Nichia’s part numbers for
those Nichia products and are not related nor bear resemblance to any other company’s product thatmight bear a trademark.

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Application Note
1. Overview

Light Emitting DiodeIn recent years, as the number of LED-based products has increased, so too has the level of
popularity that LEDs have gained as the chosen light source in a wider range of applications due totheir advantages (e.g. low power consumption, long lifetime, etc.). This has encouraged manyluminaire designers/manufacturers to use LEDs instead of conventional light sources (e.g.
incandescent and fluorescent lamps) and enabled LED luminaires to be used everywhere in homes
and offices. Spotlights are one of these luminaires facing this transition: from high-intensity
discharge (HID) or halogen spotlights to LED spotlights. There is another noticeable shift in the
LED spotlight industry: from SMD LED array modules to assemblies populated with a COB LED.
When used in spotlights, LEDs have specific advantages: most LEDs only emit light in the visible
range. This makes them ideal for illuminating perishable, heat/UV sensitive commodities andartwork (e.g. fresh foods, frozen processed foods, clothing, drawings/paintings, photographs, etc.).
Additionally, since it does not contain infrared radiation, which would cause the surface temperatureof the spotlight to increase, LED spotlights may reduce the cooling load on the air conditioning
system leading to cost savings.
Although SMD LEDs offered economic and environmental advantages to spotlights, SMD LEDbased spotlights had challenges related to certain qualities of the light. Spotlights may be expected
to play an important role in situations that require accurate color rendering, manipulation of visualappearance/texture, and event/home staging. Nichia COB LEDs will offer solutions to theseissues/requirements and enable the spotlight to provide an even color and brightness without casting
multiple shadows in the projected image. Additionally, they can compete with conventional lightsources in terms of the quality of light as some COB LEDs feature specific color rendering indices(CRI, i.e. high CRI and special color rendering COB LEDs).
This application note details the design advantages of COB LEDs with a small light emitting surface(LES), which is a key feature of Nichia’s COB LEDs, and cautions/suggestions when designingthem into spotlights while also covering the basic advantages of COB LEDs and the structure of atypical LED spotlight. This application note also features Nichia’s special color rendering COB
LEDs intended for their respective applications showing some examples of their performances whencompared to Nichia’s high-efficient COB LEDs or high CRI COB LEDs.

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Application Note
2. Advantages of COB LEDs over SMD LEDs
Unlike SMD LEDs (i.e. generally low/middle power LEDs with a single or a few LED die in a
package), COB LEDs are high power LEDs with multiple LED die on a substrate and there arefunctional/design-related advantages that encourage the use of COB LEDs in spotlights as detailedin Table 1 below.

Table 1. Advantages of COB LEDs vs. SMD LEDs

Light Emitting Diode

Advantage of COB LEDs

Note

Ease of assembly

COB LEDs are designed to be directly attached to a
housing/heatsink while SMD LEDs require a PCB andsoldering process in advance.

Better heat dissipation

As mentioned above, COB LEDs do not require either PCBsor soldering, resulting in a shorter thermal path and lower
thermal resistance from junction to ambient.

Simplifying/reducing thesize of the system design

If the chosen spotlight requires a high luminous flux, there will
be more advantages to using a 10W COB LED than using
multiple SMD LEDs with much lower wattages (i.e. reducing
the number of components and the size of the spotlight)

Eliminating multiple
shadows (i.e. similar to whenilluminated by natural light)

Spotlights using multiple SMD LEDs as the light source create
multiple shadows and illumination variation. This can be
avoided by replacing them with a single COB LED.

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Application Note
3. Structure of a COB LED-based Spotlight and Key Components
Figure 1 below shows an example of the structure of a typical COB LED-based spotlight and Table
2 shows the key components and their functions.

Light Emitting Diode

Power Supply Circuit(i.e. AC-DC LED)
Driver)Housing (i.e. Heatsink)

Light Source (i.e. COB LED)

Reflector
Lens (i.e. Secondary Lens)

Figure 1. Structure of a typical COB-based spotlight

Table 2. Key components and their functions
Component

FunctionLens (i.e. Secondary Lens)

Refracts the light and causes it to converge/diverge to control
the light distribution pattern.

Reflector

Reflects the light and directs it in an intended/designed
direction for effective illumination.

Light Source (i.e. COB LED)

Determines the optical characteristics of the spotlight (i.e.
luminous flux, emission color, and color rendering index)

Housing (i.e. Heatsink)

Transfers the heat generated by the COB LED to air tomitigate a reduction in the luminous flux and/or prevent a
premature failure.

Power Supply Circuit (i.e.
AC-DC LED Driver)

Converts the general-purpose alternating current (AC) to
direct current (DC) to drive the COB LED.

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Application Note
4. Advantages of COB LEDs with Small Light Emitting Surfaces (LES)The LES sizes for Nichia’s COB LEDs are smaller than those of other competitors’ COB LEDs andthis offers the following design advantages for spotlights with narrow beam angles: If two spotlights have reflectors with the same size and shape, the spotlight using a COB LED
with a smaller LES can produce light with a narrower beam angle.

This section provides a summary of the evaluation results for the directivity/optical characteristicsof the evaluation modules, and the conclusion drawn. For comparison purposes, multiple COB LEDs
with different LES sizes and narrow beam reflectors with different sizes and shapes were used in
the evaluation.

4.1 Test Method/Conditions
Table 3 shows the details of the four different types of COB LEDs and Table 4 shows the details of
the two different types of reflectors used in the eight modules that were evaluated. The four types of
COB LEDs can be divided into two sets based on the optical/electrical characteristics (i.e.
“Comparison Group 1” and “Comparison Group 2” as shown in Table 3 below); the two COB LEDs
from the same comparison group are designed to be operated at almost the same input power (i.e.
same wattage class COB LEDs) just different sizes of LESs.

Table 3. Details of the COB LEDs used in the Evaluated Modules
Comparison Group 1

Comparison Group 2

COB LED

①-S

①-L

②-S

②-L

Part Number

NTCWS024B-V2

Sample L1NFDWJ130B-V2

Sample L2

Correlated Color Temperature,
Color Rendering Index

5000K, Ra≧80

12

φ18 .5

φ14 .628

24

19

Outline Dimensions (mm)5000K, Ra≧80

φ9

φ6 .7

15

Light Emitting Diode If the beam angle is specified, using a COB with a small LES can reduce the size of the reflector;
this will be an advantage when designing a compact spotlight.

16

19

28

LES Diameter (mm)

⌀6.7

⌀9.0

⌀14.6

⌀18.5

LES Size (mm2)

35.3

63.6

167

269

Relative Size of the LES (a.u.)

0.55

1.00

0.62

1.00

Directivity 2θ ½ (°)

118

121

116

120

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Application Note
Table 4. Details of the Reflectors Used in the Evaluated Modules
Reflector
Manufacturer
Part Number
Outline Dimensions

A

B

Nata Lighting Co., Ltd.
2-1120-E

Reflector

4-1761-E

Refer to Figure 3

3mm

Adapter
COB LED

Appearance

Structure of the evaluated module

43 .0

φ100 .0

φ71 .4

φ25 .0Light Emitting Diode

Figure 2.

65 .0Overview

Heatsink

1

A
A

B
B

［Unit: mm］
COB LED ②-S (For size comparison)

Figure 3. Outline Dimensions of the Reflectors

4.2 Comparisons between modules with the same luminous flux values
Nichia operated the evaluation modules in a manner that ensures that regardless of whether thereflector size is small (i.e. Reflector A) or large (i.e. Reflector B), their luminous flux values are thesame when the COB LEDs are from the same comparison group (i.e. COB LEDs with the ID number① or ② ). The evaluation results are shown in Table 5. An important finding is that whencomparing any two modules that had COB LEDs from the same comparison group and the samereflector, the module using the COB LED with a smaller LES had a higher center luminous intensity
and a narrower beam angle. Using a COB LED with a small LES will improve the light collection
efficacy of the spotlight and enable the spotlight to produce light with a narrow beam.

Note:
1 The reflectors are attached to a heatsink with an adapter (See Figure 2).
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Application Note
Table 5. Optical measurement results of the evaluation modules
when operated so that the luminous flux values are the same
Reflector

A

B

Light Emitting Diode

Module Appearance Overview

COB LED

①-S

①-L

①-S

①-L

LES Diameter (mm)

⌀6.7

⌀9.0

⌀6.7

⌀9.0

Luminous Flux (lm)

1000

1000

1000

1000

Center Luminous Intensity (cd)

18763

13428

23818

20060

Center Luminous Intensity/
Luminous Flux (cd/lm)

18.8

13.4

23.8

20.1

Directivity 2θ ½ (°)

8.3

10.0

7.4

8.3

COB LED

②-S

②-L

②-S

②-L

LES Diameter (mm)

⌀14.6

⌀18.5

⌀14.6

⌀18.5

Luminous Flux (lm)

6000

6000

6000

6000

Center Luminous Intensity (cd)

40498

24708

69804

45585

Center Luminous Intensity/
Luminous Flux (cd/lm)

6.7

4.1

11.6

7.6

Directivity 2θ ½ (°)

15.1

21.1

10.7

14.9

Directivity

Directivity

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Application Note
4.3 Comparisons between modules with the same center luminous intensity
Nichia performed another similar evaluation; in this evaluation, the modules were operated in amanner that ensures that regardless of whether the reflector size is small or large, their center
luminous intensity values are the same when the COB LEDs are from the same comparison group.
The evaluation results are shown in Table 6. An examination of these results with a focus on the
directivity values shows that:

Light Emitting Diode Comparison group 1: the module using COB LED ①-S (small LES) and Reflector A (small) andthe module using COB LED ①-L (large LES) and Reflector B (large) have almost identicaldirectivity values.
 Comparison group 2: the module using COB LED ②-S (small LES) and Reflector A (small) andthe module using COB LED ②-L (large LES) and Reflector B (large) have almost identicaldirectivity values.
These results show that when designing a spotlight, if the center luminous intensity and the
directivity are specified, using a COB LED with a small LES can reduce the reflector size.

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Application Note
Table 6. Optical measurement results of the evaluation modules
when operated so that the center luminous intensity values are the same
Reflector

A

B

Light Emitting Diode

Module Appearance Overview

COB LED

①-S

①-L

①-S

①-L

LES Diameter (mm)

⌀6.7

⌀9.0

⌀6.7

⌀9.0

Luminous Flux (lm)

853

1192

672

797

Center Luminous Intensity (cd)

16000

16000

16000

16000

Center Luminous Intensity/
Luminous Flux (cd/lm)

18.8

13.4

23.8

20.1

Directivity 2θ ½ (°)

8.2

10.1

7.4

8.3

COB LED

②-S

②-L

②-S

②-L

LES Diameter (mm)

⌀14.6

⌀18.5

⌀14.6

⌀18.5

Luminous Flux (lm)

5926

9746

3443

5262

Center Luminous Intensity (cd)

40000

40000

40000

40000

Center Luminous Intensity/
Luminous Flux (cd/lm)

6.8

4.1

11.6

7.6

Directivity 2θ ½ (°)

15.1

21.2

10.8

14.9

Directivity

Directivity

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Application Note
Another examination of the results in Table 6 with a focus on the luminous flux values shows that: Both comparison groups: when the reflector sizes and shapes are the same, the COB with a smaller
LES requires less luminous flux to deliver the same center luminous intensity.
This indicates that using COB LEDs with small LESs will improve the luminous efficacy of the
spotlight by reducing the required luminous flux.
Figure 4 below shows the difference in the luminous efficacy between the two COB LEDs withdifferent sizes of LESs (i.e. ①-S vs. ①-L or ②-S vs. ②-L) when assuming that the COB LEDs
have the same characteristics for both the luminous flux and luminous efficacy.
Reflector B
190
LES_⌀6.7mm
LES_⌀9.0mm

170

LES_⌀6.7mm

180
Luminous Efficacy (lm/W)

Luminous Efficacy (lm/W)

180

160
150

140
130

LES_⌀9.0mm

170
160
150

140
130

200

400

600 800 1000 1200 1400 1600
Luminous Flux (lm)

200

400

600 800 1000 1200 1400 1600
Luminous Flux (lm)

Reflector A

Reflector B

190

190
LES_⌀14.6mm

180

LES_⌀18.5mm

170

160
150
140
130
1000

3000

5000

7000

Luminous Flux (lm)

9000

LES_⌀14.6mm

180
Luminous Efficacy (lm/W)

Luminous Efficacy (lm/W)

Light Emitting Diode

Reflector A
190

11000

LES_⌀18.5mm

170

160
150
140
130
1000

3000

5000
7000
9000
Luminous Flux (lm)11000

Figure 4. Advantages of COB LEDs with a small LES in increasing the luminous efficacy (lm/W)of the modules when operated so that the center luminous intensity values are the same (TJ=85°C)

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Application Note
5. Thermal Design Considerations to Ensure Safe Operating Junction
Temperatures (TJ)
Many factors determine the actual lifetime of a COB LED; the most critical of these is the junction
temperature (TJ) of the COB LED during operation. To ensure that the junction temperature (TJ) issufficiently low, it is very important to optimize the thermal management of the COB LED.
Additionally, when determining the dielectric strength between the COB LED live parts andhousing/heatsink, it should be considered how the chosen design may affect the COB LED junction
temperature (TJ).

Light Emitting Diode

This section provides precautions when designing/manufacturing an LED spotlight using Nichia’s
COB LEDs to prevent failures due to an increase in the COB LED junction temperature (TJ).
5.1 Attaching a COB LED to a housing/heatsink
To increase the adhesion strength between the COB LED and housing/heatsink for better heatdissipation, Nichia recommends using a specially designed COB LED holder with a thermalinterface material (TIM), especially thermal grease. However, there are two important points to beaware of when using holders: Depending on the TIM (e.g. thermal conductivity, thickness, etc.), the heat dissipation varies;
sufficient verification should be performed to determine the proper TIM for the chosen application.
 Typically, COB LED holders are designed to be attached to housings/heatsinks with screws. The
adhesion strength between the COB LED holder and housing/heatsink (i.e. heat dissipation) cangreatly vary depending on the tightening torque. However, if the tightening torque is too high, it
may cause the COB LED ceramic substrate to be damaged. Refer to the product documentationof the selected COB LED holder for the torque specifications and use a torque wrench or anequivalent tool to ensure that the specified limits are not exceeded.
When selecting a part/material surrounding the COB LED in an LED spotlight (e.g. COB LED
holder, TIM, etc.), it is important to consider its adverse effect on the COB LED. There may begases released from parts/materials when exposed to heat/light and some of those gases may cause
Nichia’s COB LEDs to fail to illuminate or to degrade in performance. Examples of typical chemicalcompounds that could affect the COB LEDs and possible issues for each chemical compound group
include:Corrosive gases: Electrical connection failure resulting from chemical reactions in the COB LED
electrode areas due to exposure to a corrosive environment.
Volatile organic compounds (VOC): Reduction in the luminous flux and/or color shift when
VOCs penetrate the resin components (e.g. lens, encapsulating resin, dam wall, etc.) and discolor.
Halogen/phosphorus compounds: Adverse effect on the optical characteristics resulting fromcracks in the resin components (e.g. lens, encapsulating resin, dam wall, etc.) due to exposure to
halogen/phosphorus compounds.
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Application Note
Other important concerns are:
 If a COB LED holder/TIM is used, their characteristics/outline dimensions may change due toexposure to the heat/light, which may reduce the adhesion strength between the COB LED and
COB LED holder, or the COB LED holder and housing/heatsink and result in the COB LED
degrading in performance or failing to illuminate. Sufficient verification should be performed toensure that there are no issues with the reliability of each component in the chosen application.

Light Emitting Diode If an electric connection is established by soldering electrical leads to the COB LED electrodes
with hands, ensure that the leads are not pulled once soldered. Otherwise, this may cause theelectrodes to become delaminated.
 Additionally, some solder pastes contain chemicals (e.g. halogens, etc.) that may reduce theadhesion strength between the COB LED electrodes and COB LED ceramic substrate. Take this
into consideration when selecting a solder paste.

5.2 Housing/Heatsink Contact Surfaces
The condition of the housing/heatsink contact surface can affect the adhesion strength of the COB
LED to it. If there are issues with the contact surface (e.g. uneven surface, burr/flash, hole/recess,foreign material, etc.), it may: significantly reduce the heat dissipation.
 damage the COB LED ceramic substrate when attaching to the housing/heatsink, even if thetightening torque is appropriate.
For further details on information provided in sections 5.1 and 5.2, refer to the following Nichia
application notes:
1. Assembly and Handling Precautions for COB LEDs
2. Heat Dissipation Performance according to the Adhesion Strength of COB and Housing
3. How to Hand Solder an Electric Wire to a COB LED

5.3 COB LED Junction Temperature (TJ)
5.3.1 How to Calculate the Junction Temperature (TJ)
Using the suggestions above for effective heat dissipation, ensure that the junction temperature (TJ)
does not exceed the absolute maximum junction temperature (TJMax) detailed in the specification for
the COB LEDs. The junction temperature (TJ) can be estimated from equation 1 below. For thethermal resistance (RθJC), refer to the specification for each COB LED part number. Note that theRθJC may vary depending on each individual COB LED; to calculate the junction temperature (TJ)
use the maximum RθJC, instead of the typical RθJC.
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Application Note
Equation 1:

TJ = TC + RθJC x W

TJ = Junction Temperature [°C]
TC = Case Temperature [°C]
RθJC = Thermal Resistance from Junction to TC
Measurement Point [°C/W]2
W = Input Power (IF x VF) [W]IF = Forward Current [A]VF = Forward Voltage [V]TC Measurement Point
Figure 5.

Position of the TC measurement point

Light Emitting Diode5.3.2 Cautions/Suggestions for Using a Thermal Imaging Camera
Nichia recommends using a non-contact temperature measuring instrument (e.g. thermal imaging
camera) to measure the temperature of its COB LEDs for the thermal management design of thechosen application. Since the RθJC value can vary depending on the parts/material adjacent to the
COB LED (i.e. the thermal conductivity of the TIM, the material properties/surface condition of the
housing/heatsink), this method is very useful when: determining the surface temperature of the COB LED emission area
 verifying the evenness of the temperature distribution for the chosen design.
However, the temperature of the emission area obtained by thermal imaging is not an actual junction
temperature (TJ). It should be used as a reference value to assess the validity of the calculated
junction temperature (TJ).
Refer to Table 7 for an example of a calculated junction temperature (TJ) vs. thermal imaging camera
measured COB LED temperature. A NFCLL036B COB LED was used for the temperaturecomparison. The calculated junction temperature (TJ) was obtained by measuring the TC of this COB
LED and then calculating from equation 1 above. The thermal imaging camera measured
temperature was the maximum temperature when measuring the emission area of the same COB
LED using a thermal imaging camera. As shown in Table 7 below, the results provide evidence forthe validity of the calculated junction temperature (TJ) since it is very similar to the thermal imaging
camera measured value. If there is a large gap between these values, it may indicate that there areissues with the assembly; examine to ensure that the COB LED is properly attached to the
housing/heatsink.

Note:
2 Use the maximum R
θJC detailed in the specification as RθJC may vary depending on each individual COB LED.
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Application Note

Table 7. Example of a TJ validity assessment using a thermal imaging camera
NFCLL036B

COB LED Attached to Heatsink

Thermal Imaging Camera

FLIR T620

Light Emitting Diode

Appearance

P/N

CCT

4000K

CRI Rank

R8000

RθJC
(Max.)

2.1 °C/W

OperatingConditions
TC
TJ

Attached the COB LED to the heatsink
center with holders. Used thermal grease
between the COB LED and heatsink.

Input Power

10 W

Duration

60 minEmission Area Surface
Temperature3

38.7 °C
TJ ＝ 38.7 + 2.1 x 10 ＝59.7 [°C]Max.

58.9 °C

Min.

42.4 °C

Avg.

51.7 °C

These two values are similar enough to conclude that the calculated TJ is valid.

5.3.3 Thermal Evaluation Precautions
When performing a thermal evaluation, ensure that: the estimated maximum ambient temperature is used
 the COB LED is placed and oriented in a manner as similar as possible to the COB LED in thechosen spotlight (e.g. projecting the light upwards, downwards, or horizontally, etc.)
 the COB LED is properly attached to the housing/heatsink in a manner that takes into
consideration the conditions/environments in which the spotlight will actually be used.
Additionally, the junction temperature (TJ) may vary depending on each individual COB LED and/or
other components being used with the COB LED (e.g. power supply, etc.) due to manufacturing
variations. Ensure that the chosen design has sufficient margins/tolerances.

Note:
3 The level of the temperature is indicated by the colors (High temp.= ▲ Low temp.= ▼)This document contains tentative information, Nichia may change the contents without notice.
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Application Note
5.4 Forward Current (IF)Light Emitting Diode

The COB LED driver IC must be designed to ensure that the absolute maximum rating current is
not exceeded under any circumstances. Otherwise, it may cause the COB LED to degrade inperformance or to fail to illuminate. If the LED driver IC produces a current waveform with
noticeable periodic variation (i.e. ripple), the average value of the current flowing through the circuit
may be lower than the absolute maximum rating current for the COB LEDs and yet the peak current
may not. To ensure that this does not occur in the circuit of the chosen application, use an
oscilloscope to verify that any part of the current waveform does not exceed the absolute maximum
rating current.
Additionally, the chosen current should be determined taking into consideration its effect on the
COB LED lifetime. Note that if more IF is used, it increases the luminous flux; however, as follows
from equation 1 above it results in an increase in the junction temperature (TJ) that may adversely
affect the reliability/lifetime.

5.5 Dielectric Strength between the COB LED Live Parts and Housing/Heatsink
Electrical and electronic devices must provide sufficient dielectric strength according to the type of
power supply (i.e. single-, three- or split-phase system) and the nominal voltage (i.e. the standard
voltage of the region/country). E.g. A voltage of 2.5kV will be required for indoor commercial
spotlights designed for a rated voltage of 100V AC.
A COB LED with a ceramic substrate will be effective in ensuring the dielectric strength between
the COB live parts and housing/heatsink since ceramics are insulators. If the chosen design requires
an additional solution to extend the creepage distance (e.g. using an insulation sheet for the interface),
it may adversely affect the heat dissipation; perform sufficient verification to ensure that there are
no issues with the dielectric strength and heat dissipation.

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Application Note
6. Special Color Rendering COB LEDs

Light Emitting Diode

Depending on the intended use, spotlights may be required to provide a special lighting effect tomake the target object appear more attractive than it actually is. Nichia’s special color rendering
COB LEDs have been developed to focus on the qualitative aspects of light and designed for
applications that require enhanced the color saturation (see Table 8).
This section provides basic information about the special color rendering COB LEDs andperformance data comparing the color rendering of various objects between special color rendering
COB LEDs and standard high-efficiency R8000 CRI rank NFCLL036B COB LEDs and high-CRI
R9050 CRI rank COB LEDs. Note that the comparison data shown in Tables 9, 10, and 11 below
are results obtained by measuring random samples; COB LEDs with the same part number/color
rank as those used in the comparisons may vary in the emission spectrum/other values, and theresults will not be guaranteed. Use the data for reference purposes only. For the special rendering
COB LED product portfolio, refer to Nichia’s website.
Table 8. Options for Nichia’s Special Color Rendering COB LEDs

Rs020

Part Number Suffix(No longer used)
M2

Rs030

M3

Produce (e.g. vegetables, fruits, flowers, etc.)

Rｓ075

M7

White Fabrics

CRI Rank

Intended Application
Meat

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Application Note
6.1 Color Ranks for the Special Color Rendering COB LEDs
Figure 6 below shows the 3-step color ranks4 for the special color rendering COB LEDs (i.e.
Rs020/M2, Rs030/M3, and Rs075/M7) on the CIE chromaticity diagram.

CIE Chromaticity Diagram
0.44

sm273

0.42

sm303
sm353
0.40

Light Emitting Diode

sm403
0.38

sm303

sm453

y

sm323
sm353

sm503
0.36

sm403
Rs020/M2
Rs030/M3
Rs075/M7

BBL

0.34

0.32

smc53

sm353

0.30

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0.48

x

Figure 6. Color Ranks for the Special Color Rendering COB LEDs

6.2 Rs020 CRI Rank (Obsolete CRI P/N Suffix: M2) Special Color Rendering COB LEDs
The Rs020 CRI Rank COB LEDs are designed to produce light that has more emphasis in the red
wavelengths while reducing emission with yellow wavelengths; they enhance the redness in objects(e.g. meat) while making the white portions appear less yellow.
Table 9 shows an example of a comparison between the special color rendering NFCLL036B-M2
COB LED (equivalent CRI rank: Rs020, color rank: sm353g) and the high-efficiency NFCLL036B
COB LED (CRI rank: R8000, color rank: sm353) or the high CRI NFCLL036B COB LED (CRI
rank: R9050, color rank: sm353).

Note:
4 Some Nichia COB LEDs have 2-step color ranks (i.e. smaller eclipses with the same center chromaticity
coordinate as their corresponding 3-step eclipses).
This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
17/23
Dec. 13, 2021

Application Note
Table 9. Color Appearance Comparison between a COB LEDs from Different CRI Ranks(Rs020/M2 vs. R8000 vs. R9050)
Part Number

NFCLL036B

NFCLL036B

NFCLL036B-M2

Color Rank

sm353

sm353

sm353gCRI Rank

R8000

R9050

Equivalent CRI Rank: Rs020

Forward Current (mA)

260

260

260

Forward Voltage (V)

36.0

36.0

36.0

Luminous Flux (lm)

1350

1130

635

Luminous Efficiency (lm/W)

144

121

68

x

0.413

0.409

0.388

y

0.395

0.391

0.331

Chromaticity
Coordinates

Color Appearance of the
Object
TA＝25°C
IF=260mA

Relative Emission Intensity [a.u.]Light Emitting DiodeCOB LED
Appearance Overview

Emission Spectrum

Light optimized for red
portions while making white
portions appear less yellow

1.2

1.0

Spectrum weighted with red
wavelengths

0.8

R8000
R9050
M2/Rs020

0.6
0.4
0.2
0.0
400

450

500

Spectrum with reduced yellow wavelengths

CRI

550

600

650

700

750

800

Wavelength [nm]

Ra

R1

R2

R3

R4

R5

R6

R7

R8

R9

R10

R11

R12

R13

R14

R15

R8000

83

82

89

96

83

82

86

85

64

12

75

83

71

83

98

75

R9050

92

95

93

90

92

94

91

93

87

66

83

92

75

95

93

92

M2/Rs020

57

47

74

85

46

49

68

72

18

-75

48

35

53

51

88

32

Note that the Rs020/M2 CRI rank COB LEDs do not faithfully
reproduce the strong red test color (i.e. R9 value).
This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
18/23
Dec. 13, 2021

Application Note
6.3 Rs030 CRI Rank (Obsolete CRI P/N Suffix: M3) Special Color Rendering COB LEDs
The Rs030 CRI Rank COB LEDs are designed to produce light with improved color saturation, withemphasis in the blue (i.e. LED die), green, and red wavelengths (phosphor); they enhance the freshand healthy appearance of fruits and vegetables.

Light Emitting Diode

Table 10 shows an example of a comparison between the special color rendering NFCLL036B-M3
COB LED (equivalent CRI rank: Rs030, color rank: sm353) and the high-efficiency NFCLL036B
COB LED (CRI rank: R8000, color rank: sm353) or the high CRI NFCLL036B COB LED (CRI
rank: R9050, color rank: sm353).

Table 10. Color Appearance Comparison between a COB LEDs from Different CRI Ranks(Rs030/M3 vs. R8000 vs. R9050)
Part Number

NFCLL036B

NFCLL036B

NFCLL036B-M3

Color Rank

sm353

sm353

sm353

CRI Rank

R8000

R9050

Equivalent CRI Rank: Rs030

Forward Current (mA)

260

260

260

Forward Voltage (V)

36.0

36.0

36.0

Luminous Flux (lm)

1350

1130

815

Luminous Efficiency (lm/W)

144

121

87

x

0.413

0.409

0.408

y

0.395

0.391

0.392

COB LED
Appearance Overview

Chromaticity
Coordinates

Color Appearance of the
Object
TA＝25°C
IF=260mA

Light with improved color
saturation

This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
19/23
Dec. 13, 2021

Relative Emission Intensity [a.u.]

Application Note

Emission Spectrum

1.2

1.0
0.8
R8000
R9050
M3/Rs030

0.6

0.4
0.2
0.0

400

450

500

Light Emitting Diode

Spectrum weighted with blue, green, and red wavelengths

550

600

650

700

750

800

Wavelength [nm]

Ra

R1

R2

R3

R4

R5

R6

R7

R8

R9

R10

R11

R12

R13

R14

R15

R8000

83

82

89

96

83

82

86

85

64

12

75

83

71

83

98

75

R9050

92

95

93

90

92

94

91

93

87

66

83

92

75

95

93

92

M3/Rs030

78

75

94

82

68

78

92

80

57

15

90

60

95

79

88

71

CRI

6.4 Rs075 CRI Rank (Obsolete CRI P/N Suffix: M7) Special Color Rendering COB LEDs
The Rs075 CRI Rank COB LEDs are designed to produce light that enhances the whiteness ofobjects with a special combination of phosphors while maintaining the high efficiency of standard
high-efficiency COB LEDs; they are ideal light sources for clothing stores.
Table 11 shows an example of a comparison between the special color rendering NFCLL036B-M7
COB LED (equivalent CRI rank: Rs075, color rank: sm303j) and the high-efficiency NFCLL036B
COB LED (CRI rank: R8000, color rank: sm303) or the high CRI NFCLL036B COB LED (CRI
rank: R9050, color rank: sm303).

This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
20/23
Dec. 13, 2021

Application Note
Table 11. Color Appearance Comparison between a COB LEDs from Different CRI Ranks(Rs075/M7 vs. R8000 vs. R9050)
Part
Part Number
NumberColor Rank
Color
Rank

NFCLL036B
NFCLL036B
sm303
sm303

NFCLL036B
NFCLL036B
sm303
sm303

NFCLL036B-M7
NFCLL036B-M7
sm303jsm303j

CRI Rank
CRI
Rank

R8000
R8000

R9050
R9050

Equivalent CRI
Equivalent
CRI Rank:
Rank: Rs075
Rs075

Forward
Forward Current
Current (mA)(mA)
ForwardVoltage
Forward Voltage (V)
(V)

260
260
36.0
36.0

260
260
36.0
36.0

260
260
36.0
36.0

Luminous Flux
Luminous
Flux (lm)(lm)
Luminous
Luminous Efficiency
Efficiency (lm/W)(lm/W)

1310
1310
140
140

1090
1090
116
116

1155
1155
123
123

0.435
0.435
0.405
0.405

0.436
0.436
0.404
0.404

0.428
0.428
0.392
0.392

Light Emitting DiodeCOB
LED
COB LED
Appearance
Appearance Overview
Overview

Chromaticity
Chromaticity
Coordinates
Coordinates

xx
yy

R8000

Color
Appearance of
the Object
R9050
TA＝25°C
IF=260mA

M7/Rs075

The COB LEDs produce
light enhancing the whitenessof the target object while
ensuring high efficiency.

This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
21/23
Dec. 13, 2021

Application Note

Relative Emision Intensity [a.u.]

1.2

Emission Spectrum

1.0

0.8
R8000
R9050
M7/Rs075

0.6
0.4

0.2
0.0
400

450

500

550

600

650

700

750

800

Light Emitting Diode

Wavelength [nm]

CRI

Ra

R1

R2

R3

R4

R5

R6

R7

R8

R9

R10

R11

R12

R13

R14

R15

R8000

83

81

90

97

82

81

88

84

61

8

77

82

73

83

99

73

R9050

91

93

93

92

93

92

92

92

83

57

83

93

77

93

95

88

M7/Rs075

93

99

98

96

95

98

91

88

78

53

96

88

90

98

99

92

7. Summary
Nichia offers a wide variety of COB LEDs that are ideally suited in applications requiring thequalitative aspects of light in addition to the general requirements for high quality lighting grade
COB LEDs (e.g. high luminous flux, low power consumption, long lifetime, high reliability, etc.).
Along with ensuring proper thermal design and installation practices, Nichia’s COB LEDs will makeideal light sources for spotlights in various places and situations – from commercial establishments
to art galleries and museums, especially for heat/UV sensitive commodities (e.g. fresh foods, frozen
processed foods, clothes, etc.) and artwork (e.g. paintings, photographs, etc.), which may require
accurate color rendering, improved appearance of surface textures, and/or specific lighting effects.
This application note is intended to provide useful information and general cautions/suggestions
when designing an LED spotlight using a Nichia COB LED. It is strongly recommended that all theinformation and precautions detailed in this application note are incorporated into the design andassembly practices to prevent premature failures of the COB LED.

This document contains tentative information, Nichia may change the contents without notice.
SP-QR-C2-210310-1
22/23
Dec. 13, 2021

Application Note
Disclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide
technical information/data for reference purposes only. By using this application note, the user
agrees to the following:・ This application note has been prepared solely for reference on the subject matters incorporated
within it and Nichia makes no guarantee that customers will see the same results for their chosen
application.

Light Emitting Diode・ The information/data contained herein are only typical examples of performances and/or
applications for the product. Nichia does not provide any guarantees or grant any license underor immunity from any intellectual property rights or other rights held by Nichia or third parties.
・ Nichia makes no representation or warranty, express or implied, as to the accuracy, completenessor usefulness of any information contained herein. In addition, Nichia shall not be liable for any
damages or losses arising out of exploiting, using, or downloading or otherwise this document,or any other acts associated with this document.
・ The content of this application note may be changed without any prior or subsequent notice.
・ Copyrights and all other rights regarding the content of this document are reserved by Nichia or
the right holders who have permitted Nichia to use the content. Without prior written consent of
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NICHIA CORPORATION
http://www.nichia.co.jp

This document contains tentative information, Nichia may change the contents without notice.
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