AC/DC converters need to provide a defined and safe supply voltage from AC mains, varying from 90 to 264 V AC. Key requirements are efficiency, no-load power consumption and size. A new requirement for wall chargers is communication to the mobile, enabling faster charging by changing voltage or current. Most common AC/DC topologies are flyback and resonant. A flyback converter features lowest cost, but magnetics size becomes larger at higher output power. In that case, resonant converters are preferred, although efficiency is lower at low loads. NXP has invented a resonant concept that overcomes this issue. The presentation will introduce the mentioned AC/DC technologies and NXP’s product advantages.