{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"045106.3MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"045106.3MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/045106.3MRSN","factsUrl":"https://icboms.com/api/mcp/products/045106.3MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 Series, Board Mount Surface Mount Fuse, 045106.3MRSN, 6.3 A, 125 VAC, Fast Blow, 50 A Breaking Capacity, 2-SMD Square End Block Package.","salesMarkdown":"## 6.3 A fast-blow for tight board protection The Littelfuse 045106.3MRSN is a 6.3 A, 125 VAC rated fast-blow fuse from the NANO²® 451 series. Its 50 A breaking capacity at rated voltage means it can safely interrupt a short-circuit fault up to that current without rupturing — critical for protecting downstream traces and load components in a 125 VAC circuit. The 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm) is a standard surface-mount footprint. The 0.0096 ohm DC cold resistance keeps voltage drop low at rated current — about 60 mV at 6.3 A, which matters for low-voltage rails where every millivolt counts. Melting I²t of 9.17 tells you the energy needed to open the fuse. For inrush-limited loads like a capacitor bank on a DC-DC converter input, this number lets you check whether the fuse holds through the start-up surge without nuisance trips. ## Active production with CSA, METI, UR approvals Approvals from CSA, METI, and UR cover North American and Japanese regulatory acceptance. Available in Tape & Reel (TR) or Cut Tape (CT) packaging — the TR option is the standard production reel for pick-and-place assembly; CT is for prototyping or small-batch builds. ## What the ratings mean for your BOM The 6.3 A rating at 125 VAC is the continuous current the fuse carries without opening. For a 125 VAC line feeding a 6 A load, this fuse sits right at the nominal current — factor in ambient temperature derating if the board runs above 25°C, since the fuse element's thermal response shifts with the environment. Fast-blow response means it clears quickly on overcurrent — no intentional delay for motor-start or capacitive inrush. If your load has a high surge-to-steady-state ratio, compare the surge I²t against the fuse's 9.17 melting I²t to confirm margin. The 50 A breaking capacity at 125 VAC is the maximum fault current the fuse can safely interrupt. In a branch circuit with a prospective short-circuit current above 50 A, this fuse would not be the right choice — you would need a higher-interrupting rating or an upstream current-limiting device.","metaTitle":"Littelfuse 045106.3MRSN NANO²® 451 Fuse, 6.3A, 125V","metaDescription":"Littelfuse 045106.3MRSN NANO²® 451 surface-mount fuse, 6.3A at 125VAC, fast blow, 50A breaking capacity. Active production, sourced per RFQ.","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":"9.17","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":"0.0096 Ohms","Voltage Rating - AC":"125 V","Current Rating (Amps)":"6.3 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 045106.3MRSN?","answer":"The breaking capacity is 50 A at the rated 125 VAC. This is the maximum fault current the fuse can safely clear without rupturing or causing a fire hazard."},{"question":"What approvals does the 045106.3MRSN carry?","answer":"The fuse is approved by CSA (Canadian Standards Association), METI (Japanese electrical safety), and UR (UL Recognized component). These cover North American and Japanese regulatory compliance for board-level overcurrent protection."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/045106.3MRSN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/045106.3MRSN 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}}