Reference Design Description This engineering report describes a 5 W constant voltage/constant current (CV/CC) universal-input power supply for cell phone or similar charger applications. This reference design is based on the LinkSwitch-II family product LNK616PG. The LNK616PG was developed to cost effectively replace all existing solutions in low power charger and adapter applications. Its core controller is optimized for CV/CC charging applications with minimal external parts count and very tight control of both the output voltage and current, without the use of an optocoupler. The LNK616PG has an integrated 700 V switching MOSFET and ON/OFF control function which together deliver high efficiency under all load conditions and low no-load energy consumption. Both the operating efficiency and no-load performance exceed all current international energy efficiency standards. The LNK616PG monolithically integrates the 700 V power MOSFET switch and controller. A unique ON/OFF control scheme provides CV regulation. The IC also incorporates both output cable voltage-drop compensation and tight regulation over a wide temperature range for enhanced CV control. The switching frequency is modulated to regulate the output current for a linear CC characteristic.