Triac Dimmable LED Driver Technology

How Triac mains dimmable constant current drivers let LED luminaires be dimmed from standard phase-cut wall dimmers, and how to get smooth, flicker-free results.

Triac mains dimmable constant current LED drivers

Overview

What is a Triac dimmable LED driver?

A Triac dimmable LED driver is a constant current LED power supply designed to work with a standard mains phase-cut dimmer. The dimmer is wired in the live feed in place of a light switch, and cuts away part of each mains half-cycle. The driver measures how much of the waveform remains and reduces its LED current to match, so luminaires can be dimmed with no extra control wiring.

Our Triac CC range from Lifud, Snappy and LTECH covers 3W to 50W, with output currents from 100mA to 1050mA and output voltages up to 42V. The drivers work with most leading edge and trailing edge dimmers, giving smooth, flicker-free dimming, and some models add mains push dimming or deep dimming down to 0.1%.

Dims from standard leading or trailing edge wall dimmers
No extra control wiring: ideal for retrofit and residential projects
Smooth, flicker-free 0–100% dimming
Output current fixed, selectable or set by DIP switch
Compact models for downlights and small luminaires

Triac CC range at a glance

Brands: Lifud, Snappy, LTECH
Power: 3W – 50W
Output current: 100mA – 1050mA
Output voltage: Up to 42VDC
Input: 220-240VAC mains
Dimmers: Leading and trailing edge
Dimming: 0–100%, flicker free
Current setting: Fixed, selectable or DIP

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The technology

How Triac dimming works

A Triac (phase-cut) dimmer switches the mains supply on and off within every half-cycle, 100 times a second on a 50Hz supply. Turning the dimmer down removes a larger part of each half-cycle, reducing the power delivered.

A leading edge dimmer cuts the start of each half-cycle; a trailing edge dimmer cuts the end. The Triac LED driver detects this conduction angle and converts it into a steady, reduced constant current for the LEDs.

Because the driver smooths the output, the LEDs dim without visible flicker, while the dimmer and wiring stay the same as for a traditional lamp.

Simplified illustration: the dimmer removes part of each mains half-cycle (dashed grey shows the full waveform). The driver reads what remains and sets a steady LED current.

Dimmer types

Leading edge vs trailing edge dimmers

Our Triac drivers work with both types. Choosing the right dimmer is the key to smooth, quiet, flicker-free dimming.

Feature	Leading edge (RL)	Trailing edge (RC / ELV)
Part of half-cycle removed	The start	The end
Designed for	Incandescent and wire-wound transformer loads	Electronic transformers and LED drivers
Switching	Abrupt switch-on, can cause buzz and inrush	Gentle switch-on, usually quieter
Minimum load	Often higher	Often lower, better for small LED loads
With our Triac drivers	Compatible: check the dimmer's LED rating	Compatible: usually the smoothest results

Our range

Triac CC drivers compared

Choose the power and current to suit the LEDs, then the size and features you need.

Series	Power	Output	Current setting	Features
Snappy SP3	3 – 10W	350 / 500 / 700mA, 2.5–29V	Model choice	Miniature size
Lifud LF-GD	3 – 30W	Constant current	DIP switch	Leading / trailing edge
LTECH TD-9 / TD-10	9W, 10W	100 – 700mA, 9–42V	Adjustable	Compact
LTECH SE-9 to SE-15	9W, 12W, 15W	100 – 700mA, 2–42V	Adjustable	Wide voltage window
Snappy SP	10 – 36W	Constant current	Fixed	Short circuit, overload, over temperature protection
Lifud LF-AAT	8 – 40W	100 – 1050mA, 9–42V	DIP switch	Smart MCU, 0.1% dimming depth
LTECH SE-30 / SE-40	30W, 40W	150 – 1050mA, 9–42V	DIP switch	Triac / ELV, soft-on, 0.1% depth
PSU-SEA TD	30 – 50W	Constant current	Choice of fixed values	Triac and mains push dimming

Benefits

Advantages of Triac dimmable LED drivers

Why Triac dimming is a popular choice for retrofit, residential and hospitality lighting.

No extra wiring

The dimmer replaces the light switch in the existing live feed, with no separate control cables.

Ideal for retrofit

Upgrade existing dimmed circuits to LED without rewiring walls or ceilings.

Smooth dimming

Flicker-free 0–100% dimming, down to 0.1% on selected models.

Wide dimmer choice

Works with most leading and trailing edge dimmers from the major wiring-accessory brands.

Familiar control

Users keep the rotary or push dimmers they know, with no app or programming needed.

Cost effective

The simplest, lowest-cost way to add dimming to small LED installations.

Selection & set-up

Choosing and installing a Triac driver

Match the current: set or choose the output current to match the LED module's rated current.
Check the voltage window: the LED forward voltage must sit within the driver's output voltage range.
Use an LED-rated dimmer: trailing edge dimmers usually give the smoothest, quietest results.
Respect the dimmer load: keep the total driver load between the dimmer's minimum and maximum LED rating.
Set the minimum level: if the dimmer has a minimum-level adjustment, set it so the LEDs stay stable at the bottom of the range.
Avoid mixing loads: keep different driver types off the same dimmer where possible.

Related technology and products

Compare other dimming methods and driver types:

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0–100%

Flicker-free dimming

3–50W

Power range

1050mA

Maximum output current

Extra control wires

Where Triac drivers are used

Wherever LED lighting needs to be dimmed from a standard wall dimmer.

Residential

Downlights and pendants on existing living-room and bedroom dimmers.

Hospitality

Restaurant, bar and hotel room lighting with simple mood control.

Retail

Spot and accent lighting in smaller shops and showrooms.

Retrofit

LED upgrades on circuits that already have phase-cut dimmers.

Meeting rooms

Presentation dimming without a separate control system.

Luminaires

Compact drivers built into dimmable downlights and decorative fittings.

FAQ

Triac driver questions

A Triac dimmable LED driver works with a standard mains phase-cut wall dimmer. The dimmer cuts away part of each half-cycle of the mains supply, and the driver measures how much is left and reduces its LED output current to match. No extra control wires are needed.

A leading edge dimmer cuts the start of each mains half-cycle and was designed for incandescent and wire-wound transformer loads. A trailing edge dimmer cuts the end of each half-cycle, switches more gently and is usually quieter and better suited to electronic LED drivers. Our Triac drivers work with both types, but trailing edge dimmers often give the smoothest results.

Flicker usually comes from a mismatch between the dimmer and the load: the total LED load may be below the dimmer's minimum load, the dimmer may not be designed for LEDs, or the dimmer's minimum setting may be too low. Use an LED-rated dimmer, keep the load within its LED rating and minimum load, and adjust its minimum level if it has one.

It depends on the dimmer's LED load rating, not its incandescent rating. Add up the input power of all the drivers, make sure the total sits between the dimmer's minimum and maximum LED load, and allow for the inrush current of several drivers switching on together.

Depending on the model, the output current is fixed, chosen from several values, or set by DIP switch. Set it to match the LED module's rated current before connecting the LEDs, and check that the LED forward voltage sits within the driver's output voltage range.

Triac Dimmable LED Driver Technology