The NCS37021 is a UL943 compliant signal processor for GFCI

applications with self−test. The device integrates a flexible power

supply (including a 12 V shunt, two 3.3 V internal series

regulators and a 1.8 V internal regulator), differential fault,

and grounded−neutral detection circuits. Self−test is monitored at start

up and then every minute.

Features

• Meets UL943 Self−test GFCI Requirements

• 4.0 – 12 V Operation

(120−480 V AC Mains with the Appropriate Series Impedance)

• Wide Operating Temperature Range from 40°C to 95°C

• Low Quiescent Current

• Optimized Solenoid Deployment

(Coil is not Energized Near the AC Mains Zero Crossings)

• Power Supply Monitor that Verifies Full Diode Bridge Operation

• Tiered GF Trip Times that Increase Immunity to Noise

• Under−voltage Detection that Allows for Increased Operation at

Lower AC Input Voltages

• Intelligent Sensing Differentiating Ground Fault versus Ground

Neutral Fault (Prevent Nuisance Tripping)

• 16 Pin QFN Package

• This is a Pb−Free Device

Typical Applications

• GFCI Receptacles

• Load Panel GFCI Breakers

• In−line GFCI Circuits (Power Cords)