Dimming LEDs is unlike dimming halogen. An LED is a semiconductor — it reacts instantly with no thermal inertia. That is why poor dimming shows up to the eye and the camera as flicker, hum or colour shift.

Methods in use: phase TRIAC (leading-edge), phase ELV (trailing-edge), 0/1–10 V, DALI / DALI-2 and PWM. TRIAC is cheapest but produces noise and usually flickers below 30 %. Trailing-edge is quieter and more LED-friendly. 1–10 V is analogue control for pro applications. DALI is today's standard. PWM is used with constant-voltage LED strips.

Flicker is the modulation of light output in time. It is rated by Percent Flicker, Flicker Index and the modern SVM (Stroboscopic Visibility Measure). IEEE 1789 advises SVM < 1 for offices and < 0.4 for demanding video work — value missing from cheap datasheets.

The dim curve maps a digital value to perceived brightness. A logarithmic / square-law curve reads as linear to the eye — 50 % on the controller is ~25 % perceived.

Warm Dim (dim-to-warm) mimics halogen: as intensity drops, CCT also falls from 2700 K toward 1800 K, recreating the candle effect for evenings.

Minimum dim level matters. Premium drivers reach 1 % or 0.1 % flicker-free; cheap ones bottom out around 10 % or flicker earlier.

Practical applications

Bedroom & bathroom

Very low dim levels (≤ 5 %) for night mode, Warm Dim for evening — minimises melatonin suppression.

Living & dining

Full 1–100 % range with precise low end for movie scenes; DALI accent on dining surface.

Hospitality (hotels, Fine dining)

Hotel rooms dim smoothly from 100 % down to ~2 % orientation; restaurants switch lunch / dinner scenes with Warm Dim.

Offices & Smart home

DALI-2 plus daylight sensor holds constant desk illuminance and saves energy.

Architectural lighting

Linear profiles and art accents must dim without CCT shift; premium drivers keep colour constant across the range.

Advantages

Smooth intensity matched to daily rhythm
Energy and lifetime savings
Warm Dim atmosphere without changing fittings
DALI / 1–10 V remove flicker across the full range

Limitations

Cheap drivers bottom out around 10 % with visible flicker
TRIAC can hum and disturb audio / mains
Warm Dim needs a dedicated driver — not every fitting supports it
PWM at low frequency creates strobe under motion / camera

Recommendations

Specify drivers with a logarithmic / square-law curve
Use Warm Dim in bedrooms, bathrooms and Fine dining
DALI-2 or 1–10 V where precision matters
PWM frequency ≥ 1 kHz, ideally 2–4 kHz
Insist on an SVM value in the datasheet, not just 'flicker-free'

Common mistakes

Cheap TRIAC drivers flickering below 30 % and disturbing mains
Dimming LED strip without a compatible controller
No dimming at all in bedroom or bathroom
Trusting a 'dimmable' label without checking the method
Mixing drivers from different brands on one circuit (curve mismatch)

In summary

Dimming is the interplay of driver, curve and method. The premium floor today is quality trailing-edge or 1–10 V, ideally DALI-2 with Warm Dim. The SVM value in the datasheet is a quick test of whether the fitting belongs in a demanding space.