FAN1851A

The FAN1851A is a controller for AC outlet ground fault interrupters. These devices detect hazardous grounding conditions (example: a pool of water or an electrical equipment connected to opposite phases of the AC line) in consumer and industrial environments. The output of the IC triggers an external SCR, which in turn opens a relay circuit breaker to prevent a harmful or lethal shock.

Full advantage of the U.S. UL943 timing specification is taken to ensure maximum immunity to false triggering due to line noise. A special feature in the circuitry rapidly resets the integrating timing capacitor in the event that noise pulses introduce unwanted charging currents. Also, a flip-flop is included that ensures firing of even a slow circuit breaker relay on either of the two half-cycles of the line voltage when external full wave rectification is used.

The application circuit can be configured to detect both normal faults (hot wire to ground) and grounded neutral faults.