{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"04511.25MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"04511.25MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/04511.25MRL","factsUrl":"https://icboms.com/api/mcp/products/04511.25MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board mount SMD fuse, 1.25 A, 125 V AC/DC, fast blow, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 1.25 A fast-blow SMD fuse for dense PCB protection The 04511.25MRL is a Littelfuse NANO²® 451 series surface-mount fuse rated 1.25 A at 125 V AC and 125 V DC. Its fast-blow response clears quickly on high overcurrents, making it a fit for protecting power rails, input stages, and branch circuits where the downstream components can't ride through a sustained fault. The 2-SMD square end block package (6.10 x 2.69 x 2.69 mm) is a compact footprint for space-constrained boards — common in telecom line cards, battery management systems, and portable equipment where every mm² counts. ## Breaking capacity and coordination Breaking capacity is 50 A at the rated voltage — the fuse can safely interrupt a fault current up to 50 A without rupturing or sustaining an arc. For circuits with available fault current above 50 A, an upstream current-limiting device (e.g., a higher-rated fuse or breaker) is needed to keep the let-through energy within this fuse's interrupt rating. Melting I²t is 0.664 A²s — this is the energy required to melt the fuse element. It matters for inrush coordination: if the downstream load's inrush energy exceeds this value, the fuse may nuisance-open. ## Approvals and temperature range The 04511.25MRL carries CSA, PSE, and UL approvals — accepted in North American and Japanese regulatory environments.","metaTitle":"04511.25MRL Littelfuse NANO² 451 SMD Fuse, 1.25 A, 125 V","metaDescription":"04511.25MRL Littelfuse NANO² 451 SMD fuse, 1.25 A, 125 V AC/DC, fast blow, 50 A breaking capacity, UL/CSA/PSE approved, 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) Cut Tape (CT)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.664","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":"0.078 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"1.25 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":"What approvals does 04511.25MRL carry?","answer":"The fuse is approved by CSA, PSE, and UL. These certifications cover North American and Japanese safety standards for overcurrent protection devices."},{"question":"What is the breaking capacity of 04511.25MRL at 125 V?","answer":"The breaking capacity is 50 A at both 125 V AC and 125 V DC. The fuse can safely interrupt fault currents up to 50 A at the rated voltage."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/04511.25MRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/04511.25MRL 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}}