January 2015

DocID3572 Rev 4

1/17

AN390

Application note

AVS kit guidelines

Introduction

The AC line voltage around the world varies widely. Power supply designers may overcome

this problem by using a doubler / bridge switch to double the 120 V nominal AC line voltage,

in case the application is plugged on 120 V AC mains. In case of operation on the 230 V AC

line voltage, the doubler switch is non-active. Thus, the input voltage of the application

power supply after the rectifier bridge is always close to the peak line voltage of 230 V AC

line whatever is the real line voltage.

The AVS kit is used to regulate the input voltage of power supplies which are mainly

switched mode power supplies (SMPS). AVS kit still allows EMC standard compliance

(inrush current limitation, conducted noise, noise immunity) as soon as a proper circuit is

designed.

AVS8, AVS10 and AVS12 are automatic AC line voltage selectors used in full range switch

mode power supply (SMPS). These automatic line voltage selectors are made of two

devices, an integrated circuit (IC) and a customized Triac. The Triac automatically modifies

the structure of the input diode bridge to keep the same DC voltage range thanks to the IC

control.

The purpose of this document is to describe the AVS kit features and explain how to adapt

the power supply to various nominal line voltages. This document also provides technical

recommendations in terms of how to implement the AVS kit in the application.

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