{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.315MR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.315MR","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.315MR","factsUrl":"https://icboms.com/api/mcp/products/0451.315MR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse NANO²® 451 Series, Board Mount Surface Mount Fuse, 315 mA, 125 VAC/DC, Fast Blow, 2-SMD Square End Block, Tape & Reel.","salesMarkdown":"## Ratings: what the 315 mA and 50 A breaking capacity mean for the board The 0451.315MR: Rated 315 mA at 125 VAC and 125 VDC, this is a fast-blow fuse — it clears quickly on overcurrent, protecting sensitive downstream components. The 50 A interrupting rating at rated voltage means it safely opens the circuit under a fault up to that current without rupturing or arcing across the package. In a 125 VDC rail, a short-circuit current below 50 A is within the fuse's safe clearing envelope. ## Package and board-fit: 2-SMD square end block, 6.10 mm length Housed in a 2-SMD square end block package, measuring 0.240\" x 0.106\" x 0.106\" (6.10 mm x 2.69 mm x 2.69 mm). The surface-mount footprint suits high-density PCB layouts where a through-hole cartridge fuse would consume too much board area. The 0.3918 Ohms DC cold resistance is the steady-state resistance before a fault — useful for estimating voltage drop at the rated 315 mA load (0.124 V drop at rated current). ## Approvals and temperature range CSA and UL approved — the fuse carries North American safety agency marks, which simplifies acceptance in UL-listed equipment.","metaTitle":"0451.315MR Littelfuse NANO² 451 Fuse, 315 mA, 125 V","metaDescription":"0451.315MR is obsolete. Littelfuse NANO² 451 surface-mount fuse, 315 mA, 125 VAC/DC, fast blow. Sourced to order against RFQ through independent channels.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"Littelfuse Inc.","Color":"-","Series":"NANO²® 451","Package":"Tape & Reel (TR)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.0311","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Obsolete","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":"0.3918 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"315 mA","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$2.7000","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Where can I buy 0451.315MR and get a price?","answer":"Submit a request through the storefront for a quote on the exact quantity needed."},{"question":"What is the melting I²t of 0451.315MR?","answer":"The melting I²t is 0.0311. This value is used to coordinate fuse selection with downstream components — a lower I²t means the fuse clears faster under a given overcurrent, reducing let-through energy to the protected circuit."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.315MR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.315MR when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-20T14:34:45.345Z","lastPublished":"2026-07-20T14:34:45.345Z","indexable":true}}