Why Dimming Matters

DOE's 2010 Lighting Market Characterization study found that 12 percent of the 3.3 billion sockets in the United States are controlled by dimmers, and that percentage is over 30% in newer constructions. The Building Energy Efficiency Standards 2013 now require most screw‐base A19 sockets in residential newly constructed buildings to be on dimmer switches, and even non-residential lighting to change from one intermediate level of control to three-levels or continuous dimming.

"If LED lamps fail to meet this high standard of dimming performance, consumers are likely to be dissatisfied." – CEC Staff Report on LED Lights, Dec 2012"

Why are Dimmers Hard?

Dimmers, occupancy or energy management sensors are non-standard parts. OEMs have had differing design approaches – the only constant being the Edison incandescent bulb in the socket being a simple analog resistive component with linear behavior and no state storage. And now with LEDs, that has totally changed. LEDs require complex active circuits that use a switched-mode power supply topology and various inductive and capacitive elements that together present an active and non-linear load for dimmers/sensors. So, when those dimmers that are designed for a simple resistive load are now faced with an LED driver characteristic defined by complexity, it is no wonder that so many hiccups result.

Current state of LED driver solutions

Most available products in the market behave poorly, as the currently available LED driver electronics have not solved this compatibility at the root-cause level. Most solutions face one or multiple issues related to: compatibility with a limited subset of dimmers, early cutoff and limited dimming range, non-monotonic light output, lighting imperfections like flicker, shimmer, strobing effects, etc.

Instead of solving the issue at root-cause level, some semiconductor vendors have created solutions with digital intelligence that try to recognize dimmer/sensor type and adjust LED driver circuit to compensate for that. This helps broaden dimmer compatibility, without being a universal dimmer solution, and at a significantly higher die-size cost and complexity, leading to increased consumer pricing.

Impact to OEMs and Consumers

Given these limitations of silicon IC / LED driver solutions, OEMs had to resort to publishing dimmer compatibility charts on bulb packages and dealing with the burden of testing the product a against large number of dimmers. With 40-50 years of deployment history of dimmers in the markets, it is impossible to solve this problem with brute force.

And from the consumer's perspective, it creates confusion at the time of purchase, poor experience after installation, and significant return rates given expensive initial cost of the LED bulbs. Even 5-10% return rates of the bulbs can lead to a significant impact on OEM margins, and create a snowball effect of reduced consumer adoption of the LED lights.

A bulb that does not work in retrofit application with an installed base of dimmers is a total anti-thesis of what the consumer lighting experience needs to be for rapid migration from incandescent/CFL to Solid-State lighting.

Can the LED Lighting industry afford dimmer incompatibility dimming the market potential of LED lighting?