The FSL138MRT is a green-mode Fairchild power switch (FPS™) for high input voltage. It features an internal avalanched-rugged 800V SenseFET, advanced soft burst-mode operation for low standby power and low audible noise, under 40mW standby power consumption at 265VAC and no-load condition, random frequency fluctuation for low EMI, pulse-by-pulse current limit, various protection functions, low operating current in burst mode, internal startup circuit, built-in soft-start, and auto-restart mode.