5000Vrms isolation for line-voltage switching
The FOD4208V is a single-channel optoisolator from onsemi with a triac output, rated for 5000Vrms isolation and 800V off-state voltage. This combination makes it suitable for switching 240V AC loads in industrial motor drives, HVAC contactors, and solid-state relay applications where galvanic isolation between the low-voltage control side and the high-voltage load side is mandatory. With a static dV/dt of 10kV/µs minimum, the output triac resists false turn-on from fast voltage transients — a common failure mode when switching inductive loads such as motors or solenoids. The non-zero-crossing output enables phase-angle control for dimming or soft-start, unlike zero-crossing optotriacs that only trigger at the AC zero point.
Trigger current and thermal margin
The LED trigger current (Ift) is 2mA maximum, which is low enough to be driven directly from a 3.3V or 5V GPIO through a series resistor. Forward voltage is 1.28V typical at If=30mA, so the control-side power budget stays modest even in multi-channel designs. The 500µA hold current means the triac stays latched once triggered until the load current drops below that threshold — relevant for minimum-load scenarios like small fans or LED lamps that might not draw enough current to keep the triac conducting.
Active production, through-hole package
It is in a 6-DIP through-hole package, which is a standard footprint for optoisolators and easy to hand-assemble or wave-solder. The supplier device package is 6-DIP. Approvals include cUL, FIMKO, UL, and VDE, which streamlines safety certification for end equipment sold into North American and European markets. ROHS3 compliance is confirmed.