{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"045103.5MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"045103.5MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/045103.5MRSN","factsUrl":"https://icboms.com/api/mcp/products/045103.5MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, Board Mount Surface Mount Fuse, Fast Blow, 3.5 A, 125 VAC, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 3.5 A fast-blow SMD fuse for secondary-side protection The Littelfuse 045103.5MRSN is a 3.5 A, 125 VAC fast-blow fuse from the NANO²® 451 series, housed in a 2-SMD square end block package. It is designed for board-level overcurrent protection where a quick open time is needed to protect downstream semiconductors or sensitive loads. ## Breaking capacity and inrush handling Rated breaking capacity is 50 A at 125 VAC — sufficient for interrupting low-level fault currents typical of secondary-side DC/DC converter outputs and low-power AC rails without rupturing the package. Melting I²t is 2.469 A²s, which gives a measure of the energy needed to open the fuse. This value helps predict whether the fuse will hold during brief inrush events, such as charging a bulk capacitor bank on a 3.5 A rail. ## Operating temperature and approvals Approved by CSA, METI, and UR (UL Recognized), so it is accepted in North American and Japanese equipment without additional agency review of the fuse itself.","metaTitle":"Littelfuse 045103.5MRSN NANO² 451 Fuse, 3.5 A, 125 VAC","metaDescription":"Littelfuse 045103.5MRSN NANO² 451 surface-mount fuse, 3.5 A, 125 VAC, 50 A breaking capacity. Active production, CSA/METI/UR approved. 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)","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":"Active","Approval Agency":"CSA, METI, UR","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","Current Rating (Amps)":"3.5 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.6741","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 045103.5MRSN?","answer":"The breaking capacity is 50 A at the rated 125 VAC — sufficient for interrupting secondary-side fault currents in low-power AC and DC circuits."},{"question":"What approvals does the 045103.5MRSN carry?","answer":"It is approved by CSA, METI, and UR (UL Recognized), covering North American and Japanese equipment compliance."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/045103.5MRSN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/045103.5MRSN 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}}