Referência Engenharia Fita de LED: IRC, SDCM, Lux | DENO

Correlated colour temperature (CCT) selection for linear lighting

Correlated colour temperature describes the chromaticity of white light on the blackbody locus, from 1800K candle-warm through 2700K residential warm white, 3000K hospitality, 4000K neutral commercial white and 5000K to 6500K daylight. For architectural coves and retail shelves, DENO recommends specifying both the nominal CCT and the allowed MacAdam ellipse so that adjacent runs cut from different reels visually match.

Tunable white and dim-to-warm tape adds a second variable: the mixing curve. A dim-to-warm strip follows the blackbody curve from about 3000K at full output to 1800K at low output, which mimics incandescent dimming, while a tunable white strip mixes two channels independently so the designer sets CCT and intensity separately.

Colour rendering: CRI, R9 and TM-30 fidelity

CRI Ra averages the first eight pastel test colours and says nothing about saturated red, which is why DENO always publishes R9 alongside Ra. A CRI 90 tape with R9 below 20 renders skin tones and red merchandise poorly; DENO high-CRI SKUs hold Ra 95 or above with R9 above 50, and full-spectrum SKUs hold R9 above 90.

TM-30-18 adds fidelity index Rf and gamut index Rg, which better predict how a full spectrum source will look in museums, food retail and studio applications. Higher colour rendering costs efficacy: moving from CRI 80 to CRI 95 typically reduces lm/W by 15 to 25 per cent on the same LED die and drive current.

SDCM, MacAdam ellipses and batch colour consistency

Standard deviation of colour matching (SDCM) expresses binning tightness in MacAdam ellipse steps. 5 SDCM differences are visible on a continuous cove, 3 SDCM is the general architectural standard, and 2 SDCM or 1 SDCM is required for museum, luxury retail and back-lit surface work where two runs sit side by side.

DENO offers 1 SDCM and 2 SDCM binning on request, with the bin recorded per production lot so a repeat order months later can be matched to the original installation.

Voltage drop, copper weight and maximum run length

Voltage drop on a constant-voltage strip scales with current, run length and the resistance of the copper trace. Doubling copper weight from 1 oz to 2 oz roughly halves the drop, and 35 plus 70 micron double-layer construction lowers it further. Feeding a run from both ends, or tapping the middle, halves the effective electrical distance and therefore quarters the drop.

For long runs, linear constant-current tape with a per-segment IC removes brightness fall-off entirely: each segment regulates its own current, so a 24V run stays uniform far beyond the point at which a plain constant-voltage strip visibly dims. DENO's ProCalc voltage-drop tool computes drop, end-of-run brightness and recommended feed strategy from real product data.

• Single-end feed: simplest wiring, shortest usable run
• Both-ends feed: halves electrical distance, quarters voltage drop
• Mid-strip tap: same benefit as both-ends on centre-fed layouts
• Linear constant current: uniform output regardless of position

Thermal management and lumen maintenance

LED strip lifetime is governed by junction temperature. Mounting tape on an aluminium profile instead of directly on plasterboard or timber typically drops solder-point temperature by 15 to 25 degrees Celsius and moves the product from an L70 of around 30,000 hours to 50,000 hours or more. High-power and wide-PCB builds above 20 W/m should always be profile-mounted, and enclosed diffusers require a derating allowance.

Dot-free uniformity: pitch, depth, transmittance and beam angle

Whether a strip looks dot-free behind a diffuser depends on four variables: LED pitch, the depth from tape surface to diffuser, diffuser transmittance and the beam angle of the light source. As a rule of thumb, the diffuser depth should be at least equal to the LED pitch for a smooth line; COB and SOB tape with continuous phosphor removes the requirement altogether and is the safest choice for shallow profiles and grazing views.

IP ratings, waterproofing methods and installation environment

IP20 tape suits dry interior coves. IP54 and IP65 silicone coating handles splash, kitchens and covered exteriors. IP67 and IP68 extruded or injected silicone with sealed end caps is required for submerged, in-ground and marine-adjacent work. Waterproofing lowers thermal dissipation, so DENO derates drive current on sealed variants to keep lumen maintenance targets intact.