{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451020.MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451020.MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451020.MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451020.MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, board-mount fuse, 0451020.MRSN, 20 A, 65 V AC/DC, fast blow, surface mount, 2-SMD square end block, cURus approved.","salesMarkdown":"## 20 A fast-blow fuse in a compact SMD footprint The Littelfuse 0451020.MRSN is a 20 A fast-blow fuse from the NANO²® 451 series, rated for 65 V AC and 65 V DC. It sits in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, making it a compact overcurrent protection choice for dense PCB layouts. With a breaking capacity of 100 A at 65 V AC and 150 A at 65 V DC, this fuse can safely interrupt fault currents up to those levels without rupturing — critical for protecting downstream components in power supply or motor drive circuits. ## Parametric fit and coordination The melting I²t of 154 gives the energy needed to open the fuse under surge conditions. This value is used to coordinate with upstream breakers or fuses — the I²t of the 0451020.MRSN should be lower than the let-through energy of the upstream device to ensure selective coordination. DC cold resistance is 0.00244 ohms, so at 20 A the voltage drop across the fuse is under 50 mV — negligible in a 65 V rail and keeps power dissipation low in the enclosure. The fast-blow response time means it clears on short-duration overcurrents, suited for protecting semiconductor rectifiers or DC-DC converter inputs that cannot tolerate sustained overloads. ## Lifecycle and supply posture Approved under cURus, the fuse is accepted for use in equipment sold into North American and Canadian markets without additional agency review.","metaTitle":"Littelfuse 0451020.MRSN NANO² 451 Fuse, 20 A, 65 V","metaDescription":"Littelfuse 0451020.MRSN NANO² 451 board-mount fuse, 20 A, 65 V AC/DC, fast blow, surface mount. Active production, cURus approved. Sourced to order against 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":"154","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Active","Approval Agency":"cURus","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":"0.00244 Ohms","Voltage Rating - AC":"65 V","Voltage Rating - DC":"65 V","Current Rating (Amps)":"20 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"100A AC, 150A DC"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4900","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 0451020.MRSN?","answer":"The fuse can interrupt 100 A at 65 V AC and 150 A at 65 V DC. This rating defines the maximum fault current the fuse can safely clear without rupturing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451020.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/0451020.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}}