A Guide to Determining the Dimmability of LEDs

LED lights are increasingly prevalent in contemporary society. They serve as an appropriate substitute that provides significant energy savings for the replacement of outdated lights in both commercial and residential settings. LEDs have been integrated into standard bulb types, enabling swift retrofitting into conventional fittings, thereby facilitating the replacement of outdated lighting (incandescent, fluorescent, halogen, etc.) with superior LED bulbs while retaining traditional fixtures if preferred.
However, not all LEDs has dimmable capabilities.
You must evaluate your requirements prior to selecting your LED lights. This is particularly crucial when substituting outdated lighting with contemporary LED technology for the first time and anticipating dimming capabilities.

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This article will elucidate how to ascertain the dimmability of an LED and identify appropriate LED dimmers.

It is commonplace for rooms in our houses to have numerous functions. Contemporary kitchens serve as spaces for cooking, dining, and even functioning as an office throughout the day.
Dimmable lighting provides the adaptability to align the illumination in your environment with your activities. One could choose a strong light for chequebook tasks, yet a soft, soothing light for evening dining.
Dimming has increasingly being utilised in commercial and industrial settings. Incorporating dimmable lighting enhances the versatility of your workplace environment, accommodating the specific tastes and requirements of your staff. Extensive study has concentrated on both dimming and colour tuning in workspaces; for further information on adjustable white lighting, refer here.

Not all LED lights possess dimmable functionality; therefore, it is essential to verify some factors to ensure you select a dimmable bulb initially:
Verify that the package of the purchased LED fixture or bulb explicitly indicates that it is dimmable. This should be included in the description or the technical specs of the light. Utilising a non-dimmable LED with a dimmer may result in significant flickering and may harm the bulb, hence reducing its lifespan.
#2 – Is your dimmer compatible with LED lights? When replacing incandescent lights with LEDs, it is probable that you own a leading-edge dimmer. An earlier dimmer was likely engineered for higher wattage illumination and may be incompatible with low-wattage LED lights. In these instances, you must select an alternative dimmer; please refer to our recommendations at the conclusion of this essay.

The dimmability of an LED bulb relies on the LED driver that the light employs.
All LED bulbs have a driver that transforms power into a low-voltage constant current essential for LED operation.
When constructing your own setup with component LEDs, you have the advantage of selecting whatever LED driver you choose, along with your desired dimming settings. When purchasing a completed LED fixture or bulb, one is constrained by the dimming settings selected by the manufacturer.
Non-dimmable LED drivers include just two operational states: ON and OFF. When transitioning to an LED bulb, the non-dimmable driver will attempt to stabilise the current. This will ultimately overstrain the LED driver, leading to its failure.
Dimmable drivers, conversely, are designed to manage fluctuations in current. Dimmable drivers will adjust for current loss by dimming the LED using analogue or pulse width modulation (PWM) techniques.

LEDs have distinct dimming characteristics compared to traditional lighting sources, necessitating meticulous consideration of dimming throughout the planning of an LED conversion.
For instance, incandescent lights generate light by heating a filament wire to the point of incandescence. To reduce brightness, decrease the voltage, resulting in a cooler wire that emits less light.
LED bulbs generate illumination using a diode rather than a heated filament. A diode possesses just two states: it is either ON, emitting light, or OFF, resulting in darkness.
Dimming LEDs need an alternative approach to create a dimmable LED lighting solution. The two primary techniques for dimming LEDs are Pulse Width Modulation (PWM) and analogue dimming.

PWM provides comprehensive dimming capabilities by adjusting the duration of the signal's ON and OFF states. With PWM dimming, the light-emitting diode can only be in an ON or OFF state at any moment. This differs from analogue dimming, which modulates output power to reduce LED brightness.

Using pulse width modulation, to achieve 80% brightness in an LED, one would maintain the LED in an active state for 80% of the duration and inactive for the remaining 20%. It is logical that you would experience around 80% of the light output; yet, what accounts for our inability to see the LED's rapid on-off cycling?
PWM dimming capitalises on a limitation of human eyesight. The light flickers at a frequency above the human eye's perception, which ranges from around 50 to 90 Hz (around 60 frames per second). When the light flashes at a rapid frequency, our brains interpolate the intervals, creating a perception of smooth vision.
Exercise caution with PWM dimming, particularly when utilising lighting for film or videography. While human eyesight may not perceive PWM flickering, a high-quality camera will certainly detect a subtle strobe effect when the light is adjusted to a modest level. One should seek a superior dimming alternative to PWM when engaged in videography.

This dimming method gained significant popularity in commercial fluorescent lighting. This solution is effective for LED installations, making it a favoured option for retrofitting fluorescent lights. The illumination is regulated by a specific DC voltage signal that varies from zero to ten volts. Do you comprehend the name now? This enables the regulated light to function at 100% output with full voltage and 0% output with no voltage. The luminosity of your light varies in accordance with the voltage level of the control signal.

Leading edge dimming, also known as forward phase-cut, incandescent, or TRIAC dimming, is the predominant dimming technique.
The predominant type of these dimmers is TRIAC Dimmers, which employ leading-edge phase cutting to diminish the electrical current supplied to the bulb.
This dimmer is commonly placed in residences as it is suitable for high voltage applications required by most traditional lighting systems. The primary issue with TRIAC dimming is the occasional occurrence of buzzing or flickering in the light. This may occur due to the vibrations generated by the fragmented AC transmission.
Fortunately, many contemporary TRIAC dimmers have addressed this issue and implemented measures to prevent flickering. Numerous dimmable LED drivers or LED dimmers are marketed as having a flicker-free design.

A trailing edge dimmer is a rather uncommon type of dimming. This was identified subsequent to the adoption of leading-edge as the standard, which is more advantageous for low voltage illumination such as LEDs. Due to its rarity, this sort of dimming is not as frequently employed as one might assume.
Rather than truncating the waveform at the beginning, the trailing edge intersects the posterior edge of the AC sine wave. This restricts significant voltage fluctuations occurring during leading-edge dimming, as the waveform ceases when it is already in a consistent decline.
Restricting significant fluctuations mitigates the prevalent flickering problems associated with LEDs and TRIAC dimming. Nonetheless, as previously discussed, cutting-edge dimming has embraced advancements in science and technology that have effectively mitigated these concerns.