Triac-output optoisolator for AC load control
The onsemi MOC3012TVM is a 1-channel optoisolator with a triac output, designed to switch AC loads from a low-voltage logic or microcontroller signal while maintaining galvanic isolation. The 4170Vrms isolation rating provides a safety barrier between the control side and the line-voltage load, meeting the creepage and clearance requirements for equipment that interfaces directly with mains circuits. With a 250 V off-state voltage rating, this part can directly drive loads up to that peak voltage — suitable for 120 VAC or 240 VAC applications with adequate margin. The absence of a zero-crossing circuit means the triac fires at whatever phase angle the LED is triggered, which is useful for phase-angle control or when the load itself manages the turn-on transient.
Trigger current and drive requirements
The LED trigger current (Ift) is 5 mA maximum — a standard logic output or GPIO pin can drive it directly through a current-limiting resistor. Forward voltage is 1.15 V typical at the LED, so a 5 V supply with a 680 Ω resistor delivers roughly 5.6 mA, comfortably above the threshold. The maximum continuous LED forward current is 60 mA, giving headroom for pulsed or high-duty-cycle drive. Once triggered, the triac holds conduction until the load current drops below the 100 µA typical hold current (Ih). This is a very low threshold — the triac will stay on through most of the AC cycle until the load current crosses zero naturally, which is the expected behaviour for a non-zero-crossing part.
Housed in a 6-DIP package with 0.400-inch (10.16 mm) body width, the MOC3012TVM is a through-hole part supplied in bulk tubes. The 6-DIP footprint is a standard 0.100-inch pitch layout — it drops into any existing DIP-6 socket or solder pads without layout changes. The through-hole package is well suited for prototyping, low-volume production, or environments where vibration resistance from a soldered lead is preferred over a surface-mount joint.
Compliance and approvals
The MOC3012TVM carries IEC/EN/DIN and UL approvals — the key safety certifications for optoisolators used in mains-connected equipment. UL recognition covers the 4170Vrms isolation rating, and the IEC/EN/DIN marks satisfy European and international standards for reinforced insulation in industrial and consumer products.