{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"04511.25NR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"04511.25NR","canonicalUrl":"https://icboms.com/littelfuse-inc/04511.25NR","factsUrl":"https://icboms.com/api/mcp/products/04511.25NR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 Series, Board Mount SMD Fast Blow Fuse, 04511.25NR, 1.25 A, 125 V AC/DC, 50 A breaking capacity, 2-SMD Square End Block package.","salesMarkdown":"## Obsolete — sourcing the 04511.25NR today The 04511.25NR is marked Obsolete by Littelfuse. ## 1.25 A fast-blow in a 125 V SMD package Rated 1.25 A continuous at 125 V AC and 125 V DC. The fast-blow response time means it opens quickly on overcurrent — suited for protecting sensitive semiconductor circuits where a slow-blow would let the fault energy through before clearing. Breaking capacity is 50 A at rated voltage. On a 125 V rail with a prospective short-circuit current up to 50 A, this fuse interrupts the fault without rupturing the package. Above 50 A available fault current, the fuse may not clear safely — check the fault level at the board input. ## Melting I²t and cold resistance — the so-what for the BOM Melting I²t is 0.664. This is the energy needed to melt the fuse element. For a capacitor inrush or a motor start, the I²t of the surge must stay below this value or the fuse opens on turn-on. DC cold resistance is 0.078 Ohms — the voltage drop at 1.25 A is under 100 mV, negligible for most 125 V rails. ## Board-mount SMD footprint and approvals Surface-mount in a 2-SMD, square end block package. Dimensions are 0.240\" x 0.106\" x 0.106\" (6.10 mm x 2.69 mm x 2.69 mm). The NANO² 451 series uses a ceramic body with silver-plated end caps — reflow soldering profile follows standard lead-free profiles. Approved by CSA, cULus, and PSE. cULus listing means it is recognized for use in UL-listed equipment in the US and Canada. PSE covers Japan's electrical appliance and material safety law.","metaTitle":"Littelfuse 04511.25NR NANO² 451 Fuse, 1.25A, 125V Fast Blow","metaDescription":"Littelfuse 04511.25NR NANO² 451 fast-blow SMD fuse, 1.25A, 125V AC/DC, 50A breaking capacity, CSA/cULus/PSE. Obsolete; sourced to order.","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)","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":"Obsolete","Approval Agency":"CSA, cULus, PSE","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":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/b741f1b0e0a9e21e6a76cce2b8d96e45.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What compliance documentation does Littelfuse provide for 04511.25NR?","answer":"The fuse carries CSA, cULus, and PSE approvals. The cULus mark covers UL 248-14 recognition for North America; PSE covers Japan's DENAN law."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/04511.25NR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/04511.25NR 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}}