{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451003.MR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451003.MR","canonicalUrl":"https://icboms.com/littelfuse-inc/0451003.MR","factsUrl":"https://icboms.com/api/mcp/products/0451003.MR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, board mount surface mount fuse, 0451003.MR, 3 A, 125 V AC/DC, fast blow, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 3 A fast-blow fuse for secondary-side protection The Littelfuse 0451003.MR is a 3 A surface-mount fuse from the NANO²® 451 series, rated for 125 V AC and DC circuits with a fast-blow response time. The 50 A breaking capacity at rated voltage means it can safely interrupt a fault current up to that level without rupturing — sufficient for secondary-side protection in power supplies, battery packs, and DC rail applications where the prospective short-circuit current stays under 50 A. ## Melting I²t and inrush coordination With a melting I²t of 1.65, this fuse opens quickly on overcurrent but will tolerate brief inrush pulses below that energy threshold. ## Package and board-fit The 2-SMD square end block package measures 6.10 mm x 2.69 mm x 2.69 mm — a compact footprint for dense PCB layouts. The surface-mount terminations are compatible with standard reflow profiles. ## Temperature range and approvals Approvals from CSA, PSE, and UL cover North American and Japanese regulatory acceptance — a signal that the part has passed the relevant safety and performance testing for those jurisdictions. ## Obsolete — sourcing through independent channels Littelfuse has marked the 0451003.MR as obsolete. The NANO²® 451 series is the product family; a buyer cross-referencing a BOM line should verify the 3 A, 125 V, fast-blow parameters against any proposed replacement.","metaTitle":"0451003.MR Littelfuse NANO² 451 Fuse, 3 A, 125 V, Fast Blow","metaDescription":"Littelfuse 0451003.MR NANO² 451 surface-mount fuse, 3 A, 125 V AC/DC, fast blow, 50 A breaking capacity. Obsolete — sourced to order against RFQ.","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":"1.65","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":"0.0227 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"3 A","Operating Temperature":"-55°C~125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$3.3100","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What approvals does 0451003.MR carry?","answer":"The fuse is approved by CSA, PSE, and UL — covering safety certification for North America and Japan."},{"question":"What is the melting I²t of 0451003.MR?","answer":"The melting I²t is 1.65. This value is used to coordinate fuse selection with downstream component inrush energy — the fuse should not open on normal startup surges below this threshold."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451003.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/0451003.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}}