by Eric Faraci, Texas Instruments, Santa Clara, Calif, How2Power Today, Jul 15 2015
Focus:
Converters for LED lighting must have a small form factor and operate in high-ambient temperatures due to the proximity of the LED light source. GaN overcomes these obstacles by decreasing the size of the switched-mode power supply with significantly higher switching frequencies and by improving power supply efficiency. Despite these improvements, using GaN imposes new challenges at the system-level design of the converter. By switching at high frequencies, key current loops and parasitics in the switching converter that could previously be neglected now become prominent. Unless measures are taken to minimize them, they can cause serious degradation in performance or even prevent circuit operation. This article discusses the design tradeoffs and shows how to properly apply GaN devices in a 20-W offline LED driver design example. Important details are explained such as the methodology behind the topology selection, the control technique, component selection, and layout design. By reading this article, the designer will learn how to take advantage of the benefits that GaN provides while avoiding the pitfalls.
What you’ll learn:
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