{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"04513.15MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"04513.15MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/04513.15MRSN","factsUrl":"https://icboms.com/api/mcp/products/04513.15MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 Series, Board Mount SMD Fuse, 04513.15MRSN, 3.15 A, 125 VAC, Fast Blow, 50 A Breaking Capacity, 2-SMD Square End Block, Tape & Reel.","salesMarkdown":"## SMD footprint and integration The 04513.15MRSN is a Littelfuse NANO²® 451 series SMD fuse in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm (0.240\" x 0.106\" x 0.106\"). The surface-mount footprint is a standard two-pad layout; the square end caps take reflow solder without a separate clip or holder. ## Rated current, voltage, and the so-what on interrupting capacity Rated 3.15 A at 125 VAC with a 50 A interrupting capacity at rated voltage. The 50 A breaking capacity is the maximum fault current the fuse can safely clear without rupturing the package — a figure that matters when the secondary-side fault current from a 150 VA transformer can exceed 10 A. The fast-blow response time means it opens quickly on overcurrents above roughly 200% of rating, which suits circuits where the inrush is low (logic supplies, sensor rails) and a slow-blow element would let a sustained fault damage the board trace. ## Melting I²t and cold resistance — the pre-arcing energy budget The melting I²t is 1.92 A²s, a figure the PCB designer uses to size the copper trace that feeds the fuse pad: a trace carrying 3.15 A for the fuse's pre-arcing time must not vaporise before the fuse element opens. The 0.0215 Ohm cold resistance is the starting value; resistance rises with temperature as the element heats toward the melting point, so the voltage drop under a sustained overload is higher than the 68 mV calc at rated current.","metaTitle":"04513.15MRSN Littelfuse NANO² 451 SMD Fuse, 3.15 A, 125 V","metaDescription":"04513.15MRSN Littelfuse NANO² 451 SMD fuse, 3.15 A, 125 VAC, fast blow, 50 A breaking capacity. Active production, sourced per RFQ. CSA, METI, UR approved.","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":"1.92","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":"0.0215 Ohms","Voltage Rating - AC":"125 V","Current Rating (Amps)":"3.15 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 closest pin-compatible alternative to 04513.15MRSN in the NANO² 451 family?","answer":"The NANO² 451 family includes multiple current ratings in the same 2-SMD square end block package and footprint. A direct pin-compatible alternative at a different current rating would be another 451 series fuse (e.g., 0451.xxxMRSN). There is no single 'closest' alternative; the right current rating for the protection target drives the selection."},{"question":"What compliance documentation does Littelfuse provide for 04513.15MRSN?","answer":"The fuse carries CSA, METI, and UR agency approvals. Littelfuse typically provides RoHS and REACH compliance declarations for the NANO² 451 series through its product documentation portal. The specific documentation set is confirmed at the time of order against the BOM line."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/04513.15MRSN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/04513.15MRSN 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}}