What this triac-output optoisolator does for your AC load control
The MOC3022VM is a single-channel optoisolator from onsemi that switches a triac output when the internal LED is triggered — no zero-crossing circuit, so it fires immediately on the LED current. That makes it a fit for phase-angle dimming and AC load switching where you need turn-on at any point in the mains cycle, not just the zero-cross. Rated for 4170Vrms isolation between the logic side and the AC line, it handles 400 V off-state voltage — enough for 240 VAC peak (340 V) with margin, so you can run it on universal mains without derating the off-state spec.
Key ratings that matter for your BOM and layout
4170Vrms isolation is the figure that drives creepage and clearance on the PCB — the 6-DIP package (0.300" lead spacing) gives you the physical separation to meet IEC/EN/DIN reinforced insulation requirements when the load side is mains-referenced. The non-zero-crossing output (no internal zero-cross circuit) means the triac turns on as soon as the LED current exceeds the 10 mA trigger threshold. For resistive or inductive AC loads, this lets you phase-control the power, but it also means the triac can switch at high dV/dt points — budget a snubber across the output if the load is inductive or the line has ringing. The 100 µA typical hold current (Ih) means the triac stays latched once triggered as long as the load current stays above that level — below it the output turns off. That is standard for this class, but worth checking if your load current dips near zero at the end of the AC half-cycle.
The base product number is MOC302, so the VM suffix indicates the tube-packaged, through-hole variant. Supplied in tubes (the listed package form) — the 6-DIP body is 0.300" wide, 7.62 mm pitch, through-hole.