78M6613 Safety Precautions

Abstract

This application note discusses the Teridian 78M3301, a single-phase power-measurement IC. Safety precautions for test equipment, evaluation (EV) boards, in-circuit emulators, and communications interfaces are described. The article explains that when a shunt is used as a current sensor with the 78M6613, then V3P3 must be directly connected to the NEUTRAL wiring for precise energy-measurement accuracy. This topology presents two potential safety issues: the 78M6613 ground pin is normally -3.3V below earth ground; and in the event of a LINE wiring reversal, the 78M6613 ground pin becomes 120/240 VAC. The article thus explains that any external test equipment attached to the 78M6613 is subject to this -3.3V ground reference disparity. Read full article.