The onsemi MOC3051SR2M is a single-channel optoisolator with a Triac output, designed to drive AC loads from a logic-level input while providing galvanic isolation. The output is rated for 600 V off-state blocking voltage, making it suitable for switching 120 VAC or 240 VAC loads with adequate margin for line transients. Isolation is specified at 4170 Vrms, which meets the reinforced insulation requirements for equipment connected to mains circuits. The minimum static dV/dt of 1 kV/µs means the output Triac will not falsely trigger on fast-rising voltage edges from inductive load switching or line noise — a critical parameter for reliable commutation in motor or solenoid drives.
Input drive and output ratings
Maximum continuous forward current is 60 mA, so the input side is robust for pulsed or DC drive schemes. Hold current (Ih) is 220 µA typical. Once triggered, the Triac stays latched until the load current drops below this threshold at the AC zero-crossing. Since this part has no zero-crossing circuit, it can be triggered at any point in the AC cycle, which is useful for phase-angle control or when the load current waveform is non-sinusoidal.
Package, mounting, and environmental range
The MOC3051SR2M comes in a 6-SMD Gull Wing package, surface-mount for automated pick-and-place assembly. The UR approval from Underwriters Laboratories indicates the part has been evaluated for safety in end-use equipment sold in North America.
It is RoHS3 compliant, meaning it meets the latest EU restriction on hazardous substances, and no exemption expiry is flagged. The part carries UR recognition, which simplifies UL 508A panel certification for industrial control equipment.