{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451005.MR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451005.MR","canonicalUrl":"https://icboms.com/littelfuse-inc/0451005.MR","factsUrl":"https://icboms.com/api/mcp/products/0451005.MR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, board mount SMD fuse, 0451005.MR, 5 A, 125 V AC/DC, fast blow, 2-SMD square end block package, 50 A breaking capacity, CSA/PSE/UL approved.","salesMarkdown":"## 5 A fast-blow SMD fuse — obsolete, sourced to order The Littelfuse 0451005.MR is a 5 A fast-blow surface-mount fuse from the NANO²® 451 series, rated for 125 V on both AC and DC circuits. The 50 A breaking capacity at rated voltage means it safely interrupts faults up to that level without rupturing the package — adequate for secondary-side protection in power supplies and control boards where the available fault current stays under 50 A. The 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm) occupies a compact footprint on the PCB, and the surface-mount format suits automated assembly lines. ## Lifecycle reality: obsolete — no direct successor on record Littelfuse has marked the 0451005.MR as obsolete. No official successor order code is recorded in the lifecycle data, so there is no drop-in replacement from the manufacturer. For new designs, a parametric match (5 A fast-blow, 125 V, SMD, 50 A breaking capacity) from Littelfuse or a competitor like Bel Fuse / Eaton Bussmann should be qualified — the 2-SMD square end block footprint narrows the field, but no single pin-compatible alternative is guaranteed without board-level testing. ## Melting I²t and inrush handling The melting I²t of 5.566 A²s tells you how much energy the fuse element absorbs before opening. For a circuit that sees capacitive inrush (e.g., a DC-DC converter input), the inrush energy must stay well below this figure — typically a 20% derating margin — to avoid nuisance blowing on startup. The 0.0125 Ohm DC cold resistance means at 5 A the fuse dissipates about 0.31 W in steady state, which is negligible for most PCB thermal budgets but worth checking in a dense layout.","metaTitle":"0451005.MR Littelfuse NANO² 451 5A Fast-Blow SMD Fuse","metaDescription":"Littelfuse 0451005.MR NANO² 451 series SMD fuse, 5A fast-blow, 125V AC/DC, 50A breaking capacity. Obsolete — sourced to order against RFQ. CSA/PSE/UL approved.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","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":"5.566","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Obsolete","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":"0.0125 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"5 A","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":"Where can I buy the 0451005.MR and get a price?","answer":"Submit a quote request with your target quantity; we confirm current availability and pricing at quote time."},{"question":"What approvals does the 0451005.MR carry?","answer":"The fuse is approved by CSA, PSE, and UL — covering North American (UL/CSA) and Japanese (PSE) regulatory acceptance for equipment-level safety certification."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451005.MR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451005.MR when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-20T14:34:45.345Z","lastPublished":"2026-07-20T14:34:45.345Z","indexable":true}}