DESIGN GUIDE 3‑Channel White Tunable 1000 lm 4” Downlight Reference Design Cree LED / 4001 E. Hwy. 54, Suite 2000 / Durham, NC 27709 USA / +1.919.313.5330 / www.cree-led.com © 2024 Cree LED. The information in this document is subject to change without notice. Cree®, the Cree logo, the Cree LED logo, J Series® and XLamp® are registered trademarks, and Pro9 is a trademark, of Cree LED. ENERGY STAR® is a registered trademark of the U.S. Environmental Protection Agency. This document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree-led.com.

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN DESCRIPTION OF REFERENCE DESIGN BUILD Two 3‑channel boards with an identical 35‑mm LES size were built into a basic wall‑mounted downlight. They are refered to as Board 1 and Board 2 below. 1. Using three discrete bins of J Series® Pro9™ 90 CRI White LEDs: 6500 K, 4000 K and 2700 K. a. Channel 1: 14x 2835 3‑V G Class Pro9 6500 K 90 CRI White b. Channel 2: 12x 2835 3‑V G Class Pro9 4000 K 90 CRI White c. Channel 3: 12x 2835 3‑V G Class Pro9 2700 K 90 CRI White 2. Using seven colors of J Series Color LEDs, split among the 3 channels...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN 3. A BrightView C-HE55-PE07-S-M01 secondary diffuser Bare Board Figure XXD: Build sequence (left to right) showing each optical diffusing element added. Figure 2: Build sequence (left to right) showing each optical diffusing element added. The reflector and first diffuser were necessary for good color-mixing. The secondary diffuser showed a further marginal improvement and was used during data collection. More details will be shared in a later used during data collection. More details will be shared in a later section. section. The...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN Figure 3: Comparison of color output near the black body line when using 2-channel vs. 3-channel White mixing solutions, as was done in this reference design. Note that the 2-channel approach falls well below the black body line at middle CCTs. Color LED Selection The J Series Color board (Board 2) went through several iterations of color LED selection until the widest CCT range of >90 CRI was achieved. The simplest 3‑channel build would be three desaturated colors surrounding the White color space like a 6500 K 90 CRI White, a PC...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN Figure 4: Comparison of LPW, CRI and CRI R9 across the CCT range of a single J Series Pro9 White downlight (with optics), operated in both 2‑channel and 3‑channel modes. The board’s channels were 2700 K, 4000 K and 6500 K White. Comparison Using All 3 Channels Simultaneously Efficiency, CRI and CRI R9 data are shown over the full CCT range in Figure 5 below. Overall, the Pro9 board (Board 1) achieved a higher LPW at all color temperatures. This was impacted slightly by the two additional 6500 K LEDs on the board, but removing those...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN Figure 6: Maximum lumen output and resulting LPW at each CCT of the Pro9 Board 1 and color-mixed Board 2. Light Intensity Distribution The two luminaires had identical emission profiles even though they had different LED counts and arrangements. The LES size, reflector, diffusers and housing were all consistent and were the driving factors in these similarities. The polar plot overlay from goniometer testing is shown in Figure 7. The resulting beam angles (FWHM) were 100° and field angles (FWTM) were 149°. Figure 7: Light intensity...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN Color over vertical angle of each luminaire Figure 8: Color uniformity comparison of both luminaires over vertical angle, tuned to 3000 K. The shape of the markers represents the horizontal angle sampled. The fit line is a spline with Lambda = 100 averaging all three horizontal angles. When the diffusers were removed (not shown), Board 2 had worse color uniformity compared to Board 1 due to the higher complexity of color mixing involved to generate white light. In most builds, only one diffuser may be necessary if only using Pro9 White...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN 3000 K Using 6500 K, 4000 K and 2700 K J Series Pro9 90 CRI White 3000 K Using J Series Color LEDs Figure 9: True‑color dark room comparison of the two modules tuned to 3000 K 90+ CRI in the wall-mounted downlight against a painted white background. Spectral Comparison at 3000 K A spectral comparison at 3000K 90+ CRI is shown in Figure 10 with basic color rendering metrics inset. Although the Pro9 Board 1 tends to have higher color rendering (CRI) and TM-30 Fidelity score (Rf), the Color board excels in gamut (Rg) and CRI R9 because...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN Spectral Comparison of Board 1 and Board 2 at 3000 K Figure 10: Spectral comparison of the Pro9 Board 1 and Color mixed Board 2, tuned to 3000 K at 90 CRI minimum. Important color rendering metrics are inset in the table. ENERGY STAR® DOWNLIGHT CONSIDERATIONS These luminaires would also qualify for the new ENERGY STAR® certification for downlights being released in 2024. The program requires, among other things: 1. A minimum of 82 LPW at all available operating conditions 2. A minimum of 80 CRI and 0 CRI R9 3. A maximum color shift...

3‑CHANNEL WHITE TUNABLE 1000 LM 4” DOWNLIGHT REFERENCE DESIGN When mixing to create white light, colors on opposite sides of the black body line (BBL) should be neighbors to avoid hue splotches. For example, Reds and Cyans or Blues and Greens should be paired. Follow these guidelines for physical spacing, regardless of color: • Asymmetric LEDs like the J Series 2835 can be rotated in any orientation for the best fit, like in the left side of Figure 1 where the inner circle is packed with long edges facing each other for the highest lumen density. Optically, these LEDs do not have emission asymmetry....