{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"MOC3042SR2M","brand":"onsemi","brandSlug":"onsemi","productSlug":"MOC3042SR2M","canonicalUrl":"https://icboms.com/onsemi/MOC3042SR2M","factsUrl":"https://icboms.com/api/mcp/products/MOC3042SR2M","rawCanonicalId":null},"summary":{"shortDescription":"onsemi MOC3042SR2M, 1-channel optoisolator with triac output, zero-crossing circuit, 4170Vrms isolation, 400 V off-state voltage, surface-mount 6-SMD gull wing package, UL approved.","salesMarkdown":"## Triac-output optoisolator with zero-crossing for AC load switching The MOC3042SR2M is an onsemi optoisolator that integrates a triac output with a zero-crossing detection circuit, designed to switch AC loads such as solenoids, relays, motors, and lamps from a low-voltage control side. The zero-crossing circuit ensures the triac turns on only when the AC line voltage is near zero, which limits inrush current and reduces conducted EMI at the switching instant. This is a single-channel device in a 6-SMD gull wing package rated for surface-mount assembly. ## Isolation and off-state voltage rating for mains applications With a 4170Vrms isolation voltage and a 400 V off-state voltage rating, this part can reliably switch 240VAC loads with a healthy margin above the peak line voltage. The minimum static dV/dt of 1kV/µs provides immunity against false turn-on from fast line transients — a common concern when driving inductive loads like contactor coils or small motors. The typical LED trigger current (Ift) is 10 mA max, and the forward voltage is 1.25V typ, so a standard 5V or 3.3V logic output with a series resistor can drive the input LED. ## Active production status and sourcing The MOC3042SR2M carries an Active product status from onsemi. The package option is Bulk, which is typical for engineering samples or small-run production.","metaTitle":"MOC3042SR2M onsemi Optoisolator, Triac Output, 4170Vrms","metaDescription":"MOC3042SR2M onsemi optoisolator with triac output, 4170Vrms isolation, zero-crossing circuit, 400V off-state voltage.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Optoisolators"],"specifications":{"Package":"Bulk","Output Type":"Triac","Mounting Type":"Surface Mount","Package / Case":"6-SMD, Gull Wing","Approval Agency":"UL","lifecycle_stage":"eol_hot","Number of Channels":"1","Static dV/dt (Min)":"1kV/µs","Current - Hold (Ih)":"400µA (Typ)","Voltage - Isolation":"4170Vrms","Voltage - Off State":"400 V","Operating Temperature":"-40°C ~ 85°C","Zero Crossing Circuit":"Yes","Supplier Device Package":"6-SMD","Voltage - Forward (Vf) (Typ)":"1.25V","Current - DC Forward (If) (Max)":"60 mA","Current - LED Trigger (Ift) (Max)":"10mA"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.22","stockQuantity":0,"priceTiers":[{"qty":703,"price":"$0.43000","currency":"USD"}]},"links":{"datasheetUrl":"https://rocelec.widen.net/view/pdf/rf0pcmnkv6/FAIR-S-A0002364056-1.pdf?t.download=true&u=5oefqw","sourceUrl":null},"ai":{"faq":[{"question":"Does MOC3042SR2M have zero-crossing detection?","answer":"Yes. The datasheet specifies a zero-crossing circuit, meaning the internal triac triggers only when the AC line voltage is near zero. This reduces inrush current and EMI compared to random-phase optoisolators."},{"question":"Can MOC3042SR2M be used to drive a 240VAC load?","answer":"Yes. The off-state voltage rating is 400 V, which exceeds the peak of a 240VAC line (approximately 340 V peak). The 4170Vrms isolation provides reinforced insulation between the control and load sides. For inductive loads, an external snubber (RC network) across the triac is recommended to suppress dV/dt transients beyond the 1kV/µs minimum rating."},{"question":"What is the closest pin-compatible alternative to MOC3042SR2M in this Optoisolators family?","answer":"The MOC3041 is a common peer in the same family, but it has a higher LED trigger current (15 mA max vs 10 mA max for the MOC3042). Both are 6-pin DIP/gull wing packages with the same pinout and 400 V off-state rating. The MOC3042 offers a lower trigger threshold, which can simplify the drive circuit with lower-current logic outputs. Confirm the trigger current requirement for your specific design before substituting."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/onsemi/MOC3042SR2M","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/onsemi/MOC3042SR2M when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-17T20:09:02.643Z","lastPublished":"2026-07-17T20:09:02.643Z","indexable":true}}