{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451004.MR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451004.MR","canonicalUrl":"https://icboms.com/littelfuse-inc/0451004.MR","factsUrl":"https://icboms.com/api/mcp/products/0451004.MR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, 0451004.MR, 4 A, 125 V AC/DC, fast-blow, surface-mount fuse, 2-SMD square end block package, CSA, PSE, UL approved.","salesMarkdown":"## Obsolete — sourcing reality for the 0451004.MR Littelfuse has marked the 0451004.MR as obsolete. Availability is lot-specific; quantities and traceability are confirmed at the time of an RFQ. ## 4 A fast-blow — what the ratings mean for the board Rated 4 A continuous at 125 V AC or DC, this is a fast-blow fuse — it clears on sustained overcurrents faster than a time-delay type, which matters when the downstream circuit has no significant inrush or start-up surge. The 50 A interrupting rating at rated voltage means it safely opens a fault up to that prospective current without rupturing the package. The melting I²t is 3.152, a figure that governs how much energy the fuse passes before it opens. A downstream semiconductor with a lower I²t withstand rating may fail before the fuse clears — this is the key co-ordination number for the protection engineer. Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451004.MR is a surface-mount device intended for reflow assembly. ## Approvals and compliance The 0451004.MR carries CSA, PSE, and UL approvals — accepted in North American and Japanese regulatory jurisdictions without additional testing.","metaTitle":"0451004.MR Littelfuse NANO² 451 4A Fast Blow SMD Fuse","metaDescription":"0451004.MR Littelfuse NANO² 451 4A 125V fast-blow SMD fuse, 50A breaking capacity. Obsolete — sourced to order against RFQ through independent distribution.","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":"3.152","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":"0.016 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":"$2.9500","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What compliance documentation does Littelfuse provide for the 0451004.MR?","answer":"The fuse carries CSA, PSE, and UL approvals. The manufacturer's datasheet and compliance certificates are the authoritative source for RoHS and REACH status."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451004.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/0451004.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}}