{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.630MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.630MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.630MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451.630MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, Board Mount SMD Fuse, Fast Blow, 630 mA, 125 VAC, 50 A breaking capacity, 2-SMD Square End Block package, Tape & Reel.","salesMarkdown":"## 630 mA fast-blow SMD fuse for secondary-side protection The Littelfuse 0451.630MRSN is a 630 mA, 125 VAC fast-blow surface-mount fuse from the NANO²® 451 series. It clears overcurrents quickly on secondary-side DC or AC rails where the load is sensitive to prolonged fault energy — think control boards, I/O modules, or sensor power inputs inside an enclosure. Rated breaking capacity is 50 A at 125 VAC. That is the maximum fault current the fuse can safely interrupt without rupturing or arcing — if the available short-circuit current on the secondary rail exceeds 50 A, this fuse is not the right choice; step up to a higher-interrupting series. Melting I²t is 0.143. That figure governs how much energy passes through before the element opens — useful when sizing the fuse to ride through inrush from a capacitive input or a small motor start. A lower I²t means less let-through energy to the downstream components. DC cold resistance is 0.305 Ohms. ## Package, mounting, and temperature range Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm. The fuse element is sealed inside the ceramic body, so no outgassing or contamination risk in sealed enclosures. Supplied in Tape & Reel packaging, ready for automated pick-and-place assembly. ## Approvals and compliance Carries CSA and UR approval marks — accepted in North American and Canadian equipment listings. Production status is Active per Littelfuse.","metaTitle":"Littelfuse 0451.630MRSN NANO²® 451 SMD Fuse, 630 mA, 125 VAC","metaDescription":"Littelfuse 0451.630MRSN NANO²® 451 surface-mount fuse, 630 mA, 125 VAC, fast-blow, 50 A breaking capacity. Active production, sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"Littelfuse Inc.","Color":"-","Series":"NANO²® 451","Package":"Tape & Reel (TR)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.143","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Active","Approval Agency":"CSA, UR","lifecycle_stage":"unknown","Size / Dimension":"0.240\\\" L x 0.106\\\" W x 0.106\\\" H (6.10mm x 2.69mm x 2.69mm)","DC Cold Resistance":"0.305 Ohms","Voltage Rating - AC":"125 V","Current Rating (Amps)":"630 mA","Operating Temperature":"-55°C~125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4469","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of 0451.630MRSN?","answer":"It is rated 50 A at 125 VAC — the maximum fault current it can safely interrupt at that voltage."},{"question":"What approvals does 0451.630MRSN carry?","answer":"It carries CSA and UR approval marks for North American equipment listings."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.630MRSN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.630MRSN when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:49:49.435Z","lastPublished":"2026-08-11T15:49:49.435Z","indexable":true}}