LED driver platform designed to deliver the ultimate in dimmer performance

Designed to deliver the ultimate in dimmer performance and compatibility with an ultra-low bill of materials (BOM) cost for next-generation LED bulbs, Dialog Semiconductor has debuted its innovative solid state lighting (SSL) LED driver platform. The first LED driver from this new platform - the iW3688 - delivers smooth, flicker and shimmer-free dimming supporting the widest range of phase-cut dimmers. It also enables manufacturers to drive down the manufacturing cost of LED bulbs by using Dialog’s patented integrated digital control technology to eliminate more than 20 components, including the external bleeder circuit. The iW3688 single-stage LED driver is designed for applications up to 20W, including A-style, BR, candle, GU10 and PAR bulbs and T8 LED tubes, as well as external lighting ballast drivers. It uses Dialog’s patented intelligent digital dimming control technology to provide exceptional compatibility and performance with the most challenging TRIAC and digital dimmers, while Dialog’s patented sophisticated digital algorithms enable integrated active biasing for high performance dimming at a lower cost compared to conventional external bleeder circuits, says the company. “Dialog invented digital adaptive control LED driver ICs to optimise SSL luminaire performance and to drive the cost of LED lighting down to an affordable price point for mass consumer adoption,” said Davin Lee, senior vice president and general manager of the Power Conversion Business Group, Dialog Semiconductor. “Our innovative iW3688 LED driver platform once again raises the bar and extends our lead in wide dimmer compatibility, exceptional dimming performance and ultra-low BOM cost – sophistication and performance that can only be achieved with digital control.” TRIAC dimmers require a minimum load current to maintain forward conduction. This is a problem for highly efficient, low-power LED bulbs since they may fail to draw enough current through the TRIAC to clear the holding current threshold, resulting in flicker and shimmer in dimmable LED bulbs. Many low-power bulb designs address this issue by using an external bleeder circuit to draw extra current through the TRIAC while it is conducting. However, the disadvantage is these bleeder circuits require additional external components and dissipate additional power inside the bulb, significantly raising the internal temperature and shortening the LED bulb operating lifetime. The iW3688 eliminates the cost of up to 20 external components in the bulb design, including as many as 10 required for the external bleeder circuit, and instead uses Dialog’s integrated digital algorithms that modulate primary FET switching to draw extra current during dimming. This ensures the input current continuously stays above TRIAC biasing thresholds during forward conduction, eliminating the need for an external bleeder circuit. The iW3688 further reduces BOM costs by simplifying the EMI filter circuit and integrating the current sink, switching and VCC charging circuits. Additional savings come from the iW3688’s advanced IC power management and voltage sensing, which allow the use of low-cost, off-the-shelf inductors. The iW3688 integrates Dialog’s patented over-temperature protection (OTP) de-rating technology to address LED bulb lifetime issues caused by excessive heat. OTP technology monitors the temperature inside the sealed SSL bulb and seamlessly dims light output if the temperature rises above a safe operating threshold, then restores brightness as temperature falls. This results in cooler operation, avoids exceeding the temperature rating of the electrolytic capacitors, and helps ensure a predictable and safer bulb operating life, says the company.