The U.S. DOE predicts the potential of high-brightness LEDs to exceed the traditional technologies of today and the past. Efficacy has input power in the denominator of the metric, and the input power and the efficiency of delivering energy to the LED string are related to the LED driver solution. One single driver topology is not optimal across the full range of LED power load possibilities, but there is a minimal set of topology choices to consider that meet the entire spectrum of LED driver development needs.
The other common design constraint of a LED Driver is the cost. The DOE approximates today’s driver costs is 10%~20% of the total manufacturing cost. The total cost target is what the end user sees and becomes the most frequent impediment to the adoption of the LED light solutions, regardless of performance improvements. DOE suggested the need for cost targets almost a 50% reduction in cost every 4 years.
The operating life is related to the reliability of the LED Driver itself. Reliability is affected by component count, types of components used, and temperature or power dissipated in the LED driver. Reliability can be calculated using a part-count method with the goal to reduce the components used in the driver. Reliability is also affected by operating temperatures; so, while thermal design is important, it is equally important to reduce the power losses associated with LED driver components and topology control method. The trend is to eliminate components like electrolytic capacitors and opto-isolators and integrate features into the control silicon.