The LM25180 is a primary-side regulated (PSR) flyback converter with high efficiency over a wide input voltage range of 4.5 V to 42 V. The isolated output voltage is sampled from the primary-side flyback voltage, eliminating the need for an optocoupler, voltage reference, or third winding from the transformer for output voltage regulation. The high level of integration results is a simple, reliable and high-density design with only one component crossing the isolation barrier. Boundary conduction mode (BCM) switching enables a compact magnetic solution and better than ±1% load and line regulation performance. An integrated 65-V power MOSFET provides output power up to 7 W with enhanced headroom for line transients.