{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"045103.5MR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"045103.5MR","canonicalUrl":"https://icboms.com/littelfuse-inc/045103.5MR","factsUrl":"https://icboms.com/api/mcp/products/045103.5MR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board mount SMD fuse, 045103.5MR, 3.5 A, 125 VAC/DC, fast-blow, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## Obsolete — last-time-buy sourcing for BOM continuity Littelfuse lists the 045103.5MR as Obsolete. ## 3.5 A fast-blow — what the ratings mean for fit Rated 3.5 A continuous at 125 VAC or 125 VDC. The fast-blow response means it clears on sustained overcurrents faster than a time-delay fuse — suited for circuits where inrush is minimal and the protected load does not draw a start-up surge. Breaking capacity is 50 A at rated voltage — this is the maximum fault current the fuse can safely interrupt without rupturing. In a 125 V rail with a prospective short-circuit current above 50 A, the fuse may not clear the fault; upstream coordination or a higher-interrupting device is needed. Melting I²t is 2.469 — the energy let-through before the element opens. This number drives the downstream component sizing: a semiconductor or PCB trace must survive the I²t pulse without damage. ## SMD package and temperature grade Housed in a 2-SMD square end block package, 6.10 mm x 2.69 mm x 2.69 mm, surface-mount. The compact footprint fits dense PCB layouts where a through-hole cartridge fuse would consume too much real estate. Supplied on Tape & Reel — pick-and-place ready for automated assembly. ## Approvals and compliance Approved by CSA, PSE, and UL — the fuse carries acceptance for North American (CSA, UL) and Japanese (PSE) markets.","metaTitle":"045103.5MR Littelfuse NANO² 451, 3.5A Fast-Blow SMD Fuse","metaDescription":"Littelfuse 045103.5MR NANO² 451 SMD fuse, 3.5A, 125VAC/DC, fast-blow, 50A 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":"2.469","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":"0.02 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"3.5 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.5300","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"How do I get current pricing and availability for 045103.5MR?","answer":"Sourced through independent distribution channels against an RFQ."},{"question":"What is the closest pin-compatible alternative to 045103.5MR in this Circuit Protection family?","answer":"The NANO² 451 series contains other current ratings in the same package, but a direct parametric substitute would require verifying the 3.5 A fast-blow characteristic, 125 V rating, and 50 A interrupting capacity against another manufacturer's offering."},{"question":"What compliance documentation does Littelfuse provide for 045103.5MR?","answer":"The listing confirms approvals from CSA, PSE, and UL."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/045103.5MR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/045103.5MR 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}}