{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.375MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.375MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.375MRL","factsUrl":"https://icboms.com/api/mcp/products/0451.375MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 series, board mount surface mount fuse, 0451.375MRL, 375 mA, 125 V AC/DC, fast blow, 50 A breaking capacity, 2-SMD square end block package.","salesMarkdown":"## 375 mA fast-blow fuse for secondary-side protection The 0451.375MRL is a 375 mA fast-blow surface-mount fuse from Littelfuse's NANO² 451 series, rated for 125 V AC and DC with a 50 A interrupting capacity at rated voltage. The 0.0425 melting I²t means it clears quickly on a hard short — the energy let-through stays low enough to protect downstream silicon before the junction overheats. ## What the ratings mean for your BOM Rated 375 mA continuous at 125 V AC or DC — this fuse sits on a secondary-side rail where the steady-state load stays under 300 mA and the fault current can reach 50 A. The fast-blow characteristic means it opens within milliseconds on a dead short, but tolerates brief inrush from a capacitive input filter. The 0.61 Ω cold resistance produces about 86 mW of self-heating at rated current — negligible for the 2-SMD square end block package, but worth factoring into the thermal budget if the fuse is enclosed without airflow. Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm — the same footprint as the rest of the NANO² 451 series, so a single PCB layout serves multiple current ratings across the family. Surface-mount with tape-and-reel or cut-tape packaging — the reel quantity suits automated pick-and-place for production runs; cut tape works for prototype or low-volume builds. ## Approvals and compliance CSA and UL approved — the fuse meets North American safety agency requirements for branch-circuit and supplementary protection in equipment listed to UL 248-14.","metaTitle":"0451.375MRL Littelfuse NANO² 451 Fuse, 375 mA, 125 V","metaDescription":"0451.375MRL Littelfuse NANO² 451 surface-mount fuse, 375 mA, 125 V AC/DC, fast blow, 50 A breaking capacity. Active production, sourced 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":"0.0425","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Active","Approval Agency":"CSA, UL","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":"0.61 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"375 mA","Operating Temperature":"-55°C~125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4600","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 0451.375MRL?","answer":"50 A at the rated 125 V AC or DC — sufficient for secondary-side power supplies and control circuits where the available fault current stays below that threshold. For higher fault-current environments, a fuse with a higher interrupting rating would be needed."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.375MRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.375MRL 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}}