1 Scope 1.1 General
This Standard specifies a test method for calculating the energy efficiency of external power supplies (EPS) across a full range of load conditions. It covers single-voltage external ac-dc and ac-ac power supplies, which provide one ac or dc output that is at a fixed voltage or user selectable through a selector switch. Note: External power supplies are designed to convert line voltage ac into the low-voltage output (ac or dc) typically required by laptop computers, cordless and cellular phones, portable stereos, etc. EPS are contained in a separate housing from the product they are powering.