A board-mounted power supply module using a new low power dissipation control IC

The authors present a board-mounted power supply module for telecommunications systems. It uses a new control IC to achieve higher efficiency and compactness. The IC mainly consists of CMOSFETs to reduce dissipation. The output driver for the main switch has been improved by regulating the swing voltage and optimizing the output-MOSFET channel width. The newly designed internal regulator in the IC has an extra input from a third winding on the transformer and supplies the regulated voltage using either input. The IC consumes one-fourth of the power of a conventional control IC. To minimize the size of the power supply module, the IC integrates and perfectly isolates a primary circuit, a secondary circuit, a start-up, and an alarm-activator using dielectric isolation. Using the IC, a 3 W power supply module with 80% efficiency was developed