{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451005.MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451005.MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451005.MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451005.MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board mount SMD fuse, 5 A, 125 V AC/DC, fast blow, 2-SMD square end block package, 50 A breaking capacity.","salesMarkdown":"## Active production, field-swappable SMD fuse The 0451005.MRSN: Breaking capacity is 50 A at the rated voltage — enough to safely clear a fault on most low-voltage DC rails or AC control circuits without the fuse casing rupturing. ## What the ratings mean for your board The 5 A current rating is the continuous current the fuse carries without opening at 25 °C ambient. The fast-blow response time means it clears quickly on overcurrent — useful for protecting sensitive downstream silicon where a slow-blow fuse would let the fault energy through. Melting I²t is 5.566 — this is the energy needed to melt the fuse element. If your circuit has a capacitor inrush or motor start surge, compare the pulse energy to this figure to avoid nuisance openings. DC cold resistance is 0.0125 ohms. At 5 A the voltage drop is about 62.5 mV, and power dissipation is roughly 0.31 W — negligible for most designs, but worth checking if the fuse sits in a tightly sealed enclosure with no airflow. ## Package and board-fit Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm. ## Temperature range and approvals Carries CSA, METI, and UR approvals, so it is accepted in North American and Japanese regulatory jurisdictions without additional testing.","metaTitle":"0451005.MRSN Littelfuse NANO² 451 5A Fast Blow SMD Fuse","metaDescription":"0451005.MRSN Littelfuse NANO² 451 5A fast blow SMD fuse, 125V AC/DC, 50A breaking capacity, -55 to +125°C. Active production. Quoted 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":"5.566","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":"0.0125 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"5 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 0451005.MRSN?","answer":"Breaking capacity is 50 A at the rated 125 V AC or DC. This means the fuse can safely interrupt a fault current up to 50 A without rupturing or sustaining an arc."},{"question":"What package does 0451005.MRSN come in?","answer":"It is a 2-SMD square end block package, 6.10 mm x 2.69 mm x 2.69 mm, surface-mount."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451005.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/0451005.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}}