{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.400NRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.400NRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.400NRL","factsUrl":"https://icboms.com/api/mcp/products/0451.400NRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, Board Mount SMD Fuse, Fast Blow, 400 mA, 125 V AC/DC, 50 A breaking capacity, 2-SMD Square End Block package, Tape & Reel.","salesMarkdown":"## 400 mA fast-blow SMD fuse — NANO²® 451 series The Littelfuse 0451.400NRL is a 400 mA fast-blow surface-mount fuse from the NANO²® 451 series, designed to protect sensitive circuits where a quick open on overcurrent prevents damage to downstream silicon or trace work. Rated for 125 V AC and DC with a 50 A interrupting capacity at that voltage, it clears faults within its rating without rupturing the package — a key constraint when the available fault current from the supply exceeds the fuse's breaking capacity. ## Melting I²t and coordination The 0.0484 melting I²t value lets a designer verify that downstream components — like a regulator or FET — can survive the energy let-through before the fuse opens. Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451.400NRL sits flat on the board for reflow soldering and mates with standard pick-and-place equipment. ## Compliance and approvals Carries CSA and UL approvals, confirming the fuse meets North American safety standards for overcurrent protection in equipment.","metaTitle":"Littelfuse 0451.400NRL NANO² 451 SMD Fuse, 400 mA, Fast Blow","metaDescription":"Littelfuse 0451.400NRL NANO²® 451 SMD fuse, 400 mA fast-blow, 125 V AC/DC, 50 A breaking capacity. Active production. CSA/UL approved. Order via 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)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.0484","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":"0.4233 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"400 mA","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.5926","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What approvals does the 0451.400NRL carry?","answer":"The fuse is CSA and UL approved, suitable for equipment shipped into North American markets requiring those safety marks."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.400NRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.400NRL 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}}