FAN4149: Ground Fault Interrupter

The FAN4149 is a low-power controller for detecting hazardous current paths to ground and ground-to-neutral faults. The FAN4149 application circuit opens the load contacts before a harmful shock occurs.

The FAN4149, in combination with the FAN41501 auto-monitoring digital controller, meets the 2015 UL943 self-test requirements for permanently connected GFCI products. The FAN4149 detects and protects against a hot-wire-to-ground fault and a neutral-to-line/load short. The FAN41501 periodically monitors the FAN4149 and critical GFI components to comply with the 2015 UL943 requirements. The minimum number of components and the small 6-pin package allow for a dense, flexible, application solution.

The FAN4149 contains a precision bandgap 14 V shunt regulator, precision low-VOS sense amplifier, time-delay noise filter, window-detection comparators, and an SCR driver. The shunt regulator operates with a low quiescent current, which allows for a high value, low-wattage series supply resistor. The internal temperature compensated shunt regulator, sense amplifier, and bias circuitry provide for precision ground-fault detection. This enables the use of larger component variations so that binning or trimming external components is not required. The typical ±50 µV VOS sense amplifier offset allows for direct DC coupling of the sense coil. This eliminates the large AC-coupling capacitor. The internal delay filter rejects high-frequency noise spikes common with inductive loads. This decreases false nuisance tripping. The SCR driver provides increased current and temperature compensation to allow for a wider selection of external SCRs.

The minimum number of external components and the 6-pin SOT23 package allow a low-cost, compact design and layout.

Features

• Meets 2015 UL943 Self-Test Requirements (in combination with FAN41501)
• Precision Sense Amplifier and Bandgap Reference
• Low-V_OS Offset for Direct DC Coupling of Sense Coil
• Built-in Noise Filter
• High-Current SCR Gate Driver
• Adjustable Sensitivity
• 500 µA Quiescent Current
• Minimum External Components
• Ideal for 120 V or 220 V Systems
• Space-Saving, SOT23, 6-Pin Package