Dimming Profiles

Several E-Plex modules have the ability to dim their outputs. This means that in addition to being able to run a load at full power, the load can be run at fractions of the full power. This is particularly useful when controlling lighting circuits, as it allows the brightness of the lights to increased or decreased via the clock logic.

Digital circuits (like those used in the DC distribution modules) are only actually capable of producing two output levels (off and full power). Dimming is achieved by continuously switching the output on and off at high speed. By varying the ratio of on time to off time, the effective output level can be controlled. When the output is switched on for 100 % of the time, the effective output voltage will be 100 % of the module's operating voltage; when the output is switched on for 50 % of the time, the effective output voltage will be 50 % of the module's operating voltage. This technique is called PWM (Pulse Width Modulation).

With incandescent and halogen type lights, when you run the light at half voltage, the light appears to operate at half brightness. However, this is not usually the case for LED lights. LED lights react quite differently to small changes in voltage at low voltages than to small changes at higher voltage levels. In practice, what this means is that when turning off LED lighting controlled by a dimmed circuit, there will be a brief but noticeable period of time where there is no perceivable change in light level, then the LEDs will turn off rapidly. Ideally when a light is turned on or off it should fade evenly from one level to another, regardless of the lighting technology used. This problem is addressed by using dimming profiles.

A dimming profile describes how a particular lighting technology responds to changes in supply voltage. Once a dimmer module knows the dimming profile of the lights that it is controlling, it can compensate its PWM output so that the brightness of the connected lights more accurately represents the specified dimming level.

Each dimming profile describes the characteristic of a specific lighting technology. Once this characteristic is known, the module is able to adjust its PWM output levels accordingly so that the brightness of the light more accurately represents the specified dimming level.

The following profiles are currently supported by E-Logic. If you wish to use a lighting technology which does not work well with any of these profiles, please contact support@e-plex.co, and we will try to include a compatible profile in a future E-Logic release.

This is the default dimming profile, it performs no compensation. This profile is intended for use with incandescent and halogen type lights.

This dimming profile is intended for positively PWM'd LED lights (i.e. they are dim at low PWM levels, and bright at high PWM levels).

This dimming profile is intended for negatively PWM'd LED lights (i.e. they are bright at low PWM levels, and dim at high PWM levels).