Dimming compatibility and cost-effectiveness are key to the development of the LED lighting market

LED bulbs have excellent energy efficiency and long life, and are considered to be a replacement for incandescent lamps and compact fluorescent lamps. Research firm Datapoint Research estimates that the market for LED lamps in lighting applications will grow from about 200 million in 2011 to 1 billion in 2015. However, the main obstacles to large-scale adoption currently come from relatively expensive procurement costs and the same dimming compatibility issues as compact fluorescent lamps.

"For most consumers, buying an LED light bulb today is a frustrating experience because once you get home, most of them don't work," said David Biven, marketing director for Cirrus Logic's EXL division. "Solving the challenge of dimming compatibility is extremely complex. Fortunately, we have leveraged our signal processing expertise to design the CS161X family of digital LED controllers to be nearly 100% compatible with every dimmer that can be found and tested worldwide."

Cirrus Logic's first digital LED controller is designed to be nearly 100 percent compatible with every dimmer that can be found and tested worldwide.

Biven believes that today's LED bulbs are mainly based on analog drivers, and no product can provide broad dimming compatibility for consumers' dimmers installed in homes, retail stores and businesses. Dimming incompatibility issues, including bulb flickering, flashing or inability to switch on and off, are the main reasons for the high product return rate. Therefore, he analyzed that achieving LED bulb compatibility with all existing dimming systems in the world will be one of the biggest challenges facing LED bulb manufacturers in the future. In the next few years, solving dimming compatibility and maintaining cost-effectiveness will be the key to accelerating the widespread adoption of LED bulbs by consumers.

The CS161X is the result of a three-year investment by Cirrus Logic in TRIAC interface algorithms, LED driver topologies and system architectures, which are the core of its digital TruDim technology. The digital intelligence of the CS161X is said to allow the controller to identify the type of dimmer in use and adjust the compatibility algorithm, providing smooth dimming in the same way that consumers have expected for decades using incandescent bulbs. "This intelligent adaptive digital signal processing technology is not possible with today's analog controllers." Biven said.

The series integrates a variable conduction mode boost converter (CRM/CCM) that provides power factor correction and dimmer compatibility using side control, a constant output current, quasi-resonant flyback or buck output stage, and solutions for 100-120VAC and 220-240VAC line voltages. The adaptive dimming compatible algorithm used controls the boost stage to achieve optimal flicker-free phase dimming across the entire light spectrum, including "deep dimming" down to 0% light output using leading edge, trailing edge and digital dimmers.

Cirrus Logic has acquired more than 200 dimmers worldwide and developed a set of compatibility tests to measure the impact of CS161X products on the performance of existing solutions. The dimming compatibility test includes testing of 120V and 230V products, covering single and multi-lamp configurations of 5-10 bulbs in parallel, and mainly measures 4 key parameters to determine dimming compatibility performance:

1) Function;

2) Flicker-free and stable state;

3) Smooth dimming and;

4) Dimming range (maximum value - minimum value). Cirrus Logic said that compared with the industry average of 50% compatibility for LED controllers, its CS161X performed nearly perfectly throughout the test, reaching 98% compatibility, while even the closest competitor only achieved 71% compatibility.

The CS161X is the first product family in a new line of Cirrus Logic LED controller solutions designed to help leading LED luminaire manufacturers solve complex engineering challenges and drive growth in high-volume LED sales, with 5 million to 10 million LED controllers expected to be shipped to multiple customers in 2012. Subsequent products in the company's product roadmap will improve LED light color and reduce system costs to meet industry needs.