They have several advantages over leading edge dimmers including smoother control, soft start and silent running when in operation. Conclusion Bleeder and damper circuits can be tuned to accommodate almost all leading-edge phase-cut dimmers. In contrast, buck-boost, tapped-buck and flyback converters can draw current for the entire switching cycle. Trailing edge dimmers are now the more popular of the two types. There are other types of dimming such as Dali, DMX, and Zigbee but these are more commonly used in larger buildings with more complex lighting needs. Buck converters are very popular for LED lamp drivers due to their high efficiency and low component count.

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Practical designs usually accommodate trailing-edge dimmers. The designer trades off efficiency in order to achieve ljghtech possible dimmer compatibility but is not able to guarantee performance due to the variability of dimmer component values.

Compatibility is not a problem with old incandescent or halogen light bulbs. A simple RC bleeder is used across the input line or after the bridge rectifier. The installed base of domestic dimmers supports the almost ideal resistance exhibited by the impedance of an incandescent bulb.

After the input edye rises following the zero crossing, leading edge dimmers inhibit for a period of time, controlling energy transferred to the lamp load and hence output brightness. In order to insure that I L is achieved, a bleeder circuit is typically added to the LED driver input stage.

Simplified schematic of a leading-edge phase-cut dimmer Including transient and surge suppression elements LS and CS.

If this is the case then you are using standard mains dimming.

Dimming LEDs – The difference between leading and trailing edge

If you wish to dim your LED Light source you will need to make sure that your LED is dimmable, this will be clearly stated on the box and will look something like this: Aug 18, 8: Trailing edge switches work best with LEDs. Buck diimming are very popular for LED lamp drivers due to their high efficiency and low component count. Phase-cut dimmers, either leading-edge or trailing-edge, make up the bulk of the dimmer market. There are two types of dimmer switch for mains dimming in your home; leading edeg and trailing edge.

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The national grid lghtech AC alternating current Electricity to our homes, offices, restaurants, pubs and clubs. Compact fluorescent bulbs also known as CFL or stick shape should be taken as non-dimmable unless stated on the bulbs packaging. These devices are increasingly called upon to support LED replacement lamps, which offer challenges unanticipated by the designers of the dimmer systems, such as low current draw and very fast luminous response to minor power fluctuations.

The designer must allow sufficient margin give up efficiency in the damper circuit to work with as many dimmers as practicable. You can browse the range here. This blog highlights how dimmer type determines both the selection of damper and bleeder circuits in LED drivers, and the switching topology needed to optimize operation.

So to summarise mains dimmers that are LED compatible have two separate min — max ranges; one for LEDs and the other for incandescent or halogen lamps. To further enhance damping, a bleeder is needed to compensate for, or mask the ringing below, dim,ing holding current.

The dimmer manufacturer will provide the min-max levels of load and the lamp manufacturer will provide a list of all the compatible dimmers they have tested their bulbs with. Can it be dimmed?

Often this can be found on their websites to download. May 22, at 1: In addition we also stock a range of Varilight dimmers which are recommended for dimming LED. You must have JavaScript enabled in your browser to utilize the functionality of this website. An LED lamp load does not exhibit incandescent-like pure resistance, and so, when presented with a step voltage the EMI filter and the bulk capacitance of the switching stage will cause an oscillation in the input current I F see lightecy 3.

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Dimming LEDs – The difference between leading and trailing edge

These two types of phase edte dimmer get their names from the part of the AC wave that they cut off. Trailing-edge dimmers require the input voltage of the LED driver to fall to zero each half-cycle to enable the dimmer controller to energize its own supply rails. Traiing this reason, buck-boost converters and tapped-buck drivers with ICs, which switch through the whole line cycle as the LYTSwitch-4 from Power Integrations, can pull down the dimmer voltage after it turns off and are therefore better able to support trailing-edge dimmers.

For lower power LED lamps higher bleed is required. Input filtering and topology selection for LED replacement bulbs By Andrew Smith Power Integrations The installed base of domestic dimmers supports the almost ideal resistance exhibited by the impedance of an incandescent bulb. Why shimmering trailijg flickering occurs in leading-edge dimmers and why leading-edge and trailing-edge dimmers respond differently In leading-edge phase-cut dimmers, the switching element is typically a TRIAC.