{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451004.NRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451004.NRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451004.NRL","factsUrl":"https://icboms.com/api/mcp/products/0451004.NRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board-mount SMD fuse, 0451004.NRL, 4 A, 125 V AC/DC, fast-blow, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 4 A fast-blow SMD fuse for secondary-side protection The 0451004.NRL is a Littelfuse NANO²® 451 series surface-mount fuse rated at 4 A with a fast-blow response time, designed for board-level overcurrent protection on 125 V AC or DC circuits. Its 50 A breaking capacity at rated voltage means it can safely interrupt fault currents up to that level without rupturing — a key parameter for secondary-side protection in power supplies and DC-DC converters where the available fault current is known. ## Parametric profile for the BOM engineer Melting I²t is 3.152 — this figure governs the fuse's ability to ride through inrush current without nuisance opening; compare it against the I²t of the downstream capacitance and load to confirm coordination. ## Agency approvals and compliance baseline The 0451004.NRL carries CSA, PSE, and UL approvals — meaning it is accepted for use in equipment destined for North American and Japanese markets without additional fuse re-qualification at the system level. ## Package and board-fit dimensions The 2-SMD square end block package measures 0.240\" x 0.106\" x 0.106\" (6.10 mm x 2.69 mm x 2.69 mm) — a common footprint that matches the NANO² 451 land pattern. The low profile keeps it clear of nearby components on a densely populated board.","metaTitle":"0451004.NRL Littelfuse NANO² 451 4A Fast-Blow SMD Fuse","metaDescription":"0451004.NRL Littelfuse NANO²® 451 surface-mount fuse, 4 A, 125 V AC/DC, 50 A breaking capacity, fast-blow response. Active production, quoted 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":"3.152","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Active","Approval Agency":"CSA, PSE, 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":"0.016 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"4 A","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 0451004.NRL carry?","answer":"The fuse is approved by CSA, PSE, and UL — covering North American and Japanese regulatory acceptance for equipment-level overcurrent protection."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451004.NRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451004.NRL 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}}