Compatibility Issues

We mentioned in various sections that product compatibility between LED dimmers and dimmable drivers is the key to project success. Unfortunately, the only sure-fire approach for project success involves actual and detailed compatibility tests before project deployment.

In many system-related lighting applications, it’s not uncommon to encounter Contractors / Sub-Contractors that experience colossal difficulty in the installation stage. It would be very stressful to investigate on-site and revert installed devices. Thus, we strongly recommend detailed tests before installing a project involving DALI control devices from different manufacturers.

Dimmable LED Driver Compatibility

To keep the discussion relevant to our products, let’s classify compatibility tests in terms of dimmer-and-dimmable driver and dimmable driver-and-LED light. We know there are two types of phase-cut dimming: leading-edge and trailing-edge phase-cut dimming. Before we need to confirm that both the dimmer and dimmable drivers operate on the same phase-cut methodology before any meaningful tests. Naturally, a trailing-edge dimmer works with a trailing-edge or both leading / trailing-edge supportable dimmable drivers. It’s easy to understand why a trailing-edge dimmer doesn’t work with a leading-edge dimmable driver.

If customers find no sensible result when connecting a dimmer and a dimmable driver, we suggest them validating the phase-cut methodology first. And they can easily do that by cross-testing the same dimmable driver with a TRIAC light dimmer and a Trailing-edge LED dimmer. If dimming restores after the TRIAC dimmer replacement, we have reason to believe that the dimmable driver is TRIAC dimmable only. Due to cost constraints, not all dimmable LED drivers accept both leading-edge and trailing-edge phase-dimming methodologies. Some dimmable drivers only work with leading-edge dimmers.

In our experience, many dimmable LED drivers for LED strips are TRIAC dimmable only; thus, they are not suitable for trailing-edge dimmers. For LED strip dimming applications, we suggest our 1-10V dimming approach. Over time, the inrush surge and repetitive current spikes at each zero-crossing points (100Hz for a 50Hz AC source) can become problematic in consistency and lifespan.

Sometimes, it can be difficult to judge the dimmer-and-dimmable driver compatibility by the limited product description in the field. Therefore, to address the need for testing for compatibility, we offer our dimmable lights as kit-set solutions to reduce the time and effort for compatibility trials.

In practice, people often desire dimmable downlights in the reading room or children's room. To do this, customers can buy a new dimmable downlight or buy a dimmable driver to replace the existing light (LED downlights usually have an external driver). For the latter case, please refer to our application notes about DIY matching a dimmable driver with an LED downlight to get initial ideas.

In fact, to help explain about the product capability topics, we created several relevant LED dimming videos so interested prospects can understand further.

Compatibility with LED MR16 Lamps

We mentioned several times that product compatibility is one of the few technical issues to investigate in lighting applications. We like to point out that incompatibility can also occur even without the presence of a dimmer.

Somewhat unique to LED MR16 or PAR 30 lamps is that as a replacement of halogen lamps, these lighting fixtures require a transformer to convert the mains voltage to the 12Vac for the light with an integral driver.

Historically, the 12Vac transformers are heavy and bulky magnetic coils that light-weight electronic transformers had already replaced. Therefore, most people would be replacing the halogen lamp with an LED MR16 lamp with the same electronic transformer in a retrofit case. Interestingly, sometimes people find that a non-dimmable LED MR16 lamp shows flickering, even when no dimmer is present.

To understand these phenomena easily, we should point out that halogen lights are resistive load, whereas LED lamps are not. Therefore, if the timing required to charge the integral driver of the LED MR16 lamp does not meet that required by the 12Vac ELV transformer operating under 50 / 60Hz cycle, flickering would occur. Again, this phenomenon shows one of the incompatibilities found in LED lighting, even without any dimming functionality involved.

Previously, we spent some time testing the performance of different product combinations using our dimmer and SORAA® and other LED MR16 or PAR30 lamps. By holding the dimmer and light unchanged, we see clearly that the dimming performance varies significantly with different 12Vac transformers. Given the vast pool of other products in the market to try, the trial-and-error-based experience can be frustrating.

As SORAA® released its own brand 12Vac transformer (TCVW-P-12-600-70-01-S3), we're glad to put behind such a trial-and-error approach for compatibility issues among the products, at least partially. It's also great to see the excellent deep dimmable performance using our dimmers and the SORAA® lamps together. This product strategy inspires us to work on our kit-set towards an easier-to-use dimmable LED lighting solution.