{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451002.MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451002.MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451002.MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451002.MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, Board Mount (Cartridge Style Excluded) fuse, 0451002.MRSN, 2 A, 125 VAC, Fast Blow, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 2 A fast-blow fuse for secondary-side protection The Littelfuse 0451002.MRSN is a 2 A, 125 VAC fast-blow fuse from the NANO²® 451 series, designed for board-level overcurrent protection where a quick open time on moderate overloads is required. Rated breaking capacity is 50 A at 125 VAC, meaning it can safely interrupt a fault current up to that level without rupturing — sufficient for secondary-side power supplies and low-power branch circuits where the prospective short-circuit current stays under that threshold. Melting I²t is 0.53, a figure used to coordinate with downstream semiconductor ratings and to estimate let-through energy during a fault event. ## Surface-mount package and thermal environment Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, this fuse is intended for reflow soldering onto a PCB — the small footprint suits dense layouts where a through-hole cartridge fuse would not fit. DC cold resistance is 0.0367 ohms, which translates to about 147 mW of self-heating at rated current — negligible in most designs, but worth checking if the fuse sits in a confined pocket with no airflow. ## Approvals and sourcing posture Carries CSA, METI, and UR approvals — accepted in North American and Japanese regulatory jurisdictions without additional agency review.","metaTitle":"Littelfuse 0451002.MRSN NANO² 451 Fuse, 2 A, 125 VAC","metaDescription":"Littelfuse 0451002.MRSN NANO² 451 surface-mount fuse, 2 A, 125 VAC, 50 A breaking capacity, fast blow. 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":"0.53","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":"0.0367 Ohms","Voltage Rating - AC":"125 V","Current Rating (Amps)":"2 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 0451002.MRSN at 125 VAC?","answer":"The 0451002.MRSN has a breaking capacity of 50 A at 125 VAC. This means it can safely interrupt a fault current up to 50 A without rupturing or causing a safety hazard."},{"question":"What approvals does the Littelfuse 0451002.MRSN carry?","answer":"The 0451002.MRSN is approved by CSA, METI, and UR, making it suitable for use in equipment destined for North American and Japanese markets without additional agency testing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451002.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/0451002.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}}