Zero-crossing triac output for clean AC switching
The onsemi MOC3042SVM is a single-channel triac-output optoisolator with a built-in zero-crossing detection circuit, rated for 4170Vrms isolation between the LED input and the triac output. The zero-crossing feature gates the triac on only when the AC line voltage is near zero, minimising the inrush current spike that occurs when switching inductive or capacitive loads — a common cause of relay contact welding and EMI bursts in solid-state relay designs. With a 400 V off-state voltage rating and a minimum static dV/dt of 1 kV/µs, this part is sized for 120 VAC or 240 VAC line switching where the triac must stay off through fast-rising transients without false triggering.
Package and board-fit for surface-mount assembly
Housed in a 6-SMD gull-wing package (supplier device package 6-SMD), the MOC3042SVM sits on the board with a standard 0.100-inch (2.54 mm) pin pitch that matches common optoisolator footprints. The tube packaging (not tape-and-reel) means this part ships in anti-static tubes for manual or low-volume pick-and-place. For high-volume reflow, confirm the tube-to-tray transfer with your assembler; the gull-wing profile is compatible with standard lead-free solder profiles per J-STD-020.