{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.800MRL","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.800MRL","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.800MRL","factsUrl":"https://icboms.com/api/mcp/products/0451.800MRL","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, Board Mount (Cartridge Style Excluded) fuse, 0451.800MRL, 800 mA, 125 V AC/DC, Fast Blow, 50 A breaking capacity, 2-SMD square end block, surface mount.","salesMarkdown":"## 800 mA fast-blow fuse for low-voltage DC and AC rails The Littelfuse 0451.800MRL is an 800 mA fast-blow surface-mount fuse from the NANO² 451 series, rated for 125 V AC and 125 V DC circuits. Its fast-blow response means it opens quickly on overcurrent — useful for protecting sensitive electronics where a slow-blow part would let through damaging energy before clearing. With a breaking capacity of 50 A at the rated voltage, it can safely interrupt fault currents up to that level without rupturing or sustaining an arc. The 0.271 melting I²t figure is the energy required to melt the fuse element — a key number for coordination studies when sizing upstream protection or predicting let-through energy to downstream components. ## Package, approvals, and temperature range Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, this fuse mounts directly to the PCB surface — no through-hole leads. The DC cold resistance of 0.212 Ohms is the initial resistance before any current flows; it rises with temperature and after repeated surges, so the voltage drop at rated current stays under 200 mV in a cold circuit. CSA and UL approvals mean the fuse is accepted for use in equipment sold into North American markets without additional agency testing.","metaTitle":"Littelfuse 0451.800MRL NANO² 451 Fuse, 800 mA, 125 V","metaDescription":"Littelfuse 0451.800MRL NANO² 451 surface-mount fuse, 800 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":"0.271","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":"0.212 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"800 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 0451.800MRL?","answer":"The breaking capacity is 50 A at the rated voltage of 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 — important for ensuring the fuse clears the fault before upstream breakers see the energy."},{"question":"What approvals does the 0451.800MRL carry?","answer":"The fuse is CSA and UL approved. These certifications confirm it meets North American safety standards for overcurrent protection — equipment using this fuse can pass UL 248-14 or CSA C22.2 No. 248.14 without additional fuse-level testing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.800MRL","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.800MRL 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}}