{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.630MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.630MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.630MRL","factsUrl":"https://icboms.com/api/mcp/products/0451.630MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board-mount fast-blow fuse, 630 mA, 125 VAC/DC, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel / Cut Tape.","salesMarkdown":"## 630 mA fast-blow in a compact SMD footprint The 0451.630MRL is a 630 mA fast-blow fuse from Littelfuse's NANO²® 451 series, rated for 125 VAC and 125 VDC. The fast-blow response means it opens quickly on overcurrents above the rating — designed for protecting sensitive downstream components that cannot tolerate sustained fault current. Breaking capacity is 50 A at the rated voltage — the fuse safely interrupts a fault current up to that level without arcing or rupturing the package. For a 630 mA rail, 50 A clearance covers most secondary-side faults in telecom and industrial control supplies. ## Package, approvals, and temperature grade Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm (0.240\" x 0.106\" x 0.106\"). The end-block termination pattern mates with standard SMD pads — no through-hole keep-out zone, so the fuse sits alongside passives on the same side of the board. ## Melting I²t and cold resistance — inrush sizing Melting I²t is 0.143, and DC cold resistance is 0.305 Ohms. The I²t value tells you how much energy the fuse absorbs before opening — useful for checking whether the inrush of a downstream capacitor bank or motor start will hold. The 0.305 Ohm resistance means a voltage drop of roughly 0.19 V at rated current, negligible on a 125 V rail.","metaTitle":"0451.630MRL Littelfuse NANO² 451 Fuse, 630 mA, Fast Blow","metaDescription":"0451.630MRL Littelfuse NANO² 451 board-mount fuse, 630 mA, fast-blow, 125 VAC/DC, 50 A breaking capacity. Active production, CSA/UL. Sourced per RFQ.","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) Cut Tape (CT)","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, UL","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","Voltage Rating - DC":"125 V","Current Rating (Amps)":"630 mA","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4600","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What approvals does the 0451.630MRL carry?","answer":"CSA and UL approval agency listings are confirmed. These cover North American regulatory acceptance for equipment-level circuit protection without separate agency review."},{"question":"What package and packaging options are available for 0451.630MRL?","answer":"The fuse comes in a 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm)."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.630MRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.630MRL 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}}