{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.315MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.315MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.315MRL","factsUrl":"https://icboms.com/api/mcp/products/0451.315MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, Board Mount (Cartridge Style Excluded) fast-blow fuse, 315 mA, 125 VAC/DC, 50 A breaking capacity, 2-SMD square end block package, Tape & Reel.","salesMarkdown":"## 315 mA at 125 V — the protection envelope for this NANO² 451 fuse The Littelfuse 0451.315MRL is a 315 mA fast-blow fuse in the NANO² 451 series, rated for 125 V both AC and DC. The 50 A breaking capacity at rated voltage means it can safely interrupt a short-circuit fault up to that current without rupturing — a critical spec for clearing faults in low-impedance DC rails where the prospective fault current can be high. The fast-blow response time opens quickly on overcurrent, making this fuse a natural fit for protecting semiconductor circuits — diodes, MOSFETs, or DC-DC converter inputs — where a slow-blow delay would let the fault energy destroy the device before the fuse clears. ## Melting I²t and cold resistance — the inrush and voltage-drop numbers A melting I²t of 0.0311 A²s tells you the energy needed to blow the fuse element. For a capacitive input circuit, the inrush current pulse must stay below this energy level or the fuse will nuisance-blow at power-up. The 0.3918 Ω cold resistance means at 315 mA the voltage drop across the fuse is about 124 mV — negligible in a 5 V rail but worth checking in a 1.8 V supply where every millivolt of headroom matters. ## Surface-mount footprint and board integration The 2-SMD square end block package, 6.10 mm x 2.69 mm x 2.69 mm, is a standard surface-mount fuse footprint that reflows on a standard lead-free profile. CSA and UL approvals are on file — the safety agency marks confirm the fuse is listed for overcurrent protection in equipment sold in North American and Canadian markets.","metaTitle":"Littelfuse 0451.315MRL NANO² 451 Fuse, 315 mA, 125 V","metaDescription":"Littelfuse 0451.315MRL NANO² 451 surface-mount fast-blow fuse, 315 mA at 125 VAC/DC, 50 A breaking capacity, CSA/UL approved.","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":"0.0311","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":"0.3918 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":"$1.4600","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 0451.315MRL?","answer":"The breaking capacity is 50 A at the rated 125 VAC or 125 VDC. This means the fuse can safely interrupt a short-circuit fault up to 50 A without rupturing, which is adequate for most low-power board-level circuits where the prospective fault current stays below that level."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.315MRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.315MRL 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}}