LM1851N

The LM1851N from Texas Instruments is an integrated circuit designed to provide ground fault protection for AC power outlets in consumer and industrial environments. It triggers an external SCR-driven circuit breaker when ground fault currents exceed a presettable threshold, interrupting the AC line to remove the fault condition. This IC detects both conventional hot wire to ground faults and neutral fault conditions.

Key features include an internal power supply shunt regulator, externally programmable fault current threshold, and externally programmable fault current integration time. The LM1851N offers direct interface to SCR and operates under line reversal, detecting faults between load vs line and hot vs neutral. It also detects neutral line faults.

This component operates within a supply voltage range of 22V to 30V with a typical supply current of 19mA. The operating temperature range is -40°C to 70°C, and it is housed in an 8-PDIP package suitable for through-hole mounting.

The LM1851N is designed to ensure maximum immunity to false triggering due to line noise, with circuitry that rapidly resets the timing capacitor. It also features a memory circuit that allows firing even a sluggish breaker on either half-cycle of the line voltage when external full-wave rectification is used.