{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451003.MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451003.MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451003.MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451003.MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 Series, Board Mount SMD Fuse, Fast Blow, 3 A, 125 VAC, 50 A Breaking Capacity, 2-SMD Square End Block Package, Tape & Reel.","salesMarkdown":"## 3 A fast-blow SMD fuse for secondary-side protection The Littelfuse 0451003.MRSN is a 3 A, 125 VAC rated fast-blow fuse in the NANO²® 451 series, housed in a 2-SMD square end block package. It is a board-mount fuse (cartridge style excluded) designed for surface-mount assembly on densely populated PCBs where a low-profile, high-reliability overcurrent protection element is needed. With a DC cold resistance of 0.0227 Ohms and a melting I²t of 1.65, this fuse provides predictable, repeatable clearing characteristics for protecting downstream semiconductors and power rails from short-circuit faults. The 50 A breaking capacity at 125 VAC means it can safely interrupt a fault current up to that level without rupturing or sustaining an arc. ## Package, approvals, and temperature range Its compact footprint — 0.240\" L x 0.106\" W x 0.106\" H (6.10 mm x 2.69 mm x 2.69 mm) — fits tight board layouts where space is at a premium. Safety approvals from CSA, METI, and UR confirm the fuse meets recognized standards for overcurrent protection in equipment destined for North American and Asian markets. ## Active production — sourcing posture It is a current-production part, sourced through authorized and independent distribution channels. Pricing and lead time are confirmed at quote against the BOM quantity.","metaTitle":"0451003.MRSN Littelfuse NANO² 451, 3A","metaDescription":"0451003.MRSN Littelfuse NANO² 451 surface-mount fuse, 3A, 125VAC, fast-blow, 50A breaking capacity, CSA/METI/UR approved, -55°C to 125°C.","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) Cut Tape (CT)","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":"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":"0.0227 Ohms","Voltage Rating - AC":"125 V","Current Rating (Amps)":"3 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4900","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 0451003.MRSN?","answer":"The 0451003.MRSN has a breaking capacity of 50 A at its rated voltage of 125 VAC. This means it can safely interrupt a fault current up to 50 A without catastrophic failure."},{"question":"What approvals does the 0451003.MRSN carry?","answer":"The fuse is approved by CSA (Canadian Standards Association), METI (Japanese electrical safety), and UR (UL Recognized Component), covering North American and Asian regulatory requirements."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451003.MRSN","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.MRSN 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}}