{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451020.MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451020.MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451020.MRL","factsUrl":"https://icboms.com/api/mcp/products/0451020.MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, 0451020.MRL, 20 A fast-blow surface-mount fuse, 65 V AC/DC, 100 A AC / 150 A DC breaking capacity, 2-SMD square end block package, cURus approved.","salesMarkdown":"## Board-level protection for 20 A rails The 0451020.MRL is a 20 A fast-blow surface-mount fuse from the Littelfuse NANO² 451 series, designed for overcurrent protection on high-current board-level power rails. Its 65 V AC/DC rating covers common 48 V telecom and 24 V industrial buses with headroom. Breaking capacity of 100 A AC and 150 A DC at rated voltage means the fuse safely interrupts fault currents up to those levels without rupturing — critical for DC bus protection where arcs sustain longer than AC zero-crossings. Fast-blow response clears overcurrents quickly, suited for circuits without large inrush loads. The 154 A²s melting I²t helps coordinate with downstream semiconductors so the fuse opens before the trace or FET does. ## Package and thermal budget Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451020.MRL fits standard pick-and-place assembly. The 0.00244 Ω cold resistance at 20 A produces about 1 W self-heating at rated current — account for derating per the series curve in the datasheet when ambient exceeds 25 °C. ## Sourcing and lifecycle posture Available on tape and reel or cut tape for prototyping.","metaTitle":"0451020.MRL Littelfuse NANO² 451 SMD Fuse, 20 A Fast Blow","metaDescription":"0451020.MRL Littelfuse NANO² 451 series surface-mount fuse, 20 A fast-blow, 65 V AC/DC, 100 A AC / 150 A DC breaking capacity. Active, available to order.","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":"$2.2800","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the melting I²t of 0451020.MRL and why does it matter?","answer":"The melting I²t is 154 A²s. This value is used to coordinate fuse operation with downstream components — a lower I²t means the fuse opens faster, protecting sensitive semiconductors from thermal damage during a fault."},{"question":"What approvals does the 0451020.MRL carry?","answer":"The 0451020.MRL is cURus approved, which qualifies it for North American equipment certification under UL and CSA standards."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451020.MRL","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.MRL 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}}