Cirrus Logic Digital Controller/Driver Delivers Near 100 Percent TRIAC Dimmer Compatibility

SSLDesign News Staff

March 28, 2012…Cirrus Logic has created an integrated driver, the CS161X, that the company says solves frequent compatibility problems when LED replacement lamps (LED "bulbs") or luminaires are used with standard TRIAC dimmers. The company, which is known for its analog and mixed signal components, filed over 40 patents in the process of developing their solution. During a recent visit to Cirrus Logic in Austin, Texas, Product Marketing Manager, Will Draper pointed out, "Despite the hundreds of dimmer switches on the market from around the world, no real standard exists that can accommodate the LED luminaires. Unlike an incandescent lamp, which appears as a resistive load to the dimmer, an LED will look more like a capacitive load, as will most electronics." A simple analogy would be wiring your stereo into a dimmer switch and attempting to use the dimmer to control the volume.

The company has applied smart adaptive signal processing technology running TRIAC interface algorithms to form the basis for Cirrus Logic's TruDim technology. Cirrus spent over 3 years and tested over 200 available dimmers during the development the company's new CS161 LED controller. In their testing, Cirrus found that that the closest competing technology was only able to be compatible with about 71 percent of the dimmer switches tested, with the industry average closer to 50% compatibility. As the team pointed out, the problem is not a trivial one, and it effects the perception that the public has of LED lighting as a whole.

"Several years ago Cirrus Logic identified the growing LED market as an area where we could leverage our signal processing expertise and solve meaningful engineering challenges," said Jason Rhode, Cirrus Logic president and CEO. "As it turns out, solving the challenges of dimmer compatibility was enormously complex, and we're pleased that one of the largest LED lamp manufacturers has showcased our first LED controller precisely because it provides near- perfect compatibility with every installed dimmer from around the world that we could find and test."

The company tested each of the dimmers with 1, 5, and 10 LED lamps running in parallel. For each of the dimmers, the company tested functionality, flicker free steady state, flicker free transient state, smoothness of dimming, and the minimum and maximum dimming range. When a consumer brings home a $20-$30 LED replacement lamp from the store, and plugs it into a light socket, the consumer expects it to work perfectly with every dimmer they could put it with. Failure to meet that expectation is having a growing impact on the industry more consumers willing to try the lamps at lowering price points. (See: Demonstration on YouTube).

The CS161X is the first family of products in Cirrus Logic's new line of LED controller solutions. According to the company, its unique adaptive dimmer compatibility algorithm controls the boost stage to enable flicker-free phase dimming across the light spectrum, including "deep dimming" down to zero percent light output. The CS161X integrates a variable conduction mode boost converter (CRM/CCM), providing power factor correction and dimmer compatibility with primary-side control, constant output current, and quasi-resonant flyback or buck output stage. It includes solutions for both 100-120 VAC and 220-240 VAC line voltages. The dimming solution is reportedly compliant with Energy Star, NEMA SSL6, and IEC 61000-3-2. Cirrus Logic says that the CS161X is now in volume production and is available in a 16-pin SOIC package priced at $0.81 (USD) in quantities of 100,000.  Commercial Lighting Tampa

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