{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0603SFS400F/32-2","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0603SFS400F-32-2","canonicalUrl":"https://icboms.com/littelfuse-inc/0603SFS400F-32-2","factsUrl":"https://icboms.com/api/mcp/products/0603SFS400F%2F32-2","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. SFS series board-mount fuse, 0603 (1608 metric), 4 A, 32 VDC, slow-blow, 50 A breaking capacity, UL recognized, surface mount.","salesMarkdown":"## Obsolete — last-time-buy sourcing Littelfuse has marked the 0603SFS400F/32-2 as Obsolete. No pin-compatible replacement is listed; a board spin may be required if a functional equivalent is needed. ## Overcurrent protection envelope Rated 4 A continuous at 32 VDC, the fuse opens within its slow-blow time-current characteristic when the current exceeds the rating. The 50 A breaking capacity at rated voltage means it safely interrupts faults up to that level without rupturing — adequate for secondary-side protection in low-voltage DC rails where the available fault current stays under 50 A. The melting I²t of 2.3 quantifies the energy needed to open the element. A slow-blow response allows brief inrush pulses (from capacitive input filters or motor start) to pass without nuisance opening — the element absorbs the pulse energy as long as the I²t of the pulse stays below the fuse's rated I²t. ## Board-fit and environmental range Housed in the standard 0603 (1608 metric) surface-mount package, the fuse shares the same footprint as a chip resistor or capacitor — no special pad geometry beyond the usual 0603 land pattern. DC cold resistance is 0.017 Ohms, so the voltage drop at 4 A is under 70 mV, negligible for most low-voltage rails. No derating is specified by the datasheet at the high end, but the element's time-current curve shifts with temperature — expect faster opening at elevated ambient. ## Approvals and compliance UL recognized — the fuse is accepted for use in UL-listed equipment without additional component-level testing. The 0603SFS400F/32-2 is supplied in Tape & Reel (TR) and Cut Tape (CT) packaging, suitable for pick-and-place assembly.","metaTitle":"Littelfuse 0603SFS400F/32-2 Fuse, 4A 32V Slow-Blow, Obsolete","metaDescription":"Littelfuse 0603SFS400F/32-2 SFS series fuse, 4 A, 32 VDC, slow-blow, 50 A breaking capacity, UL recognized. Obsolete — sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"Littelfuse Inc.","Color":"-","Series":"SFS","Package":"Tape & Reel (TR) Cut Tape (CT)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"2.3","Mounting Type":"Surface Mount","Response Time":"Slow Blow","Package / Case":"0603 (1608 Metric)","Product Status":"Obsolete","Approval Agency":"UL","lifecycle_stage":"unknown","Size / Dimension":"0.063\\\" L x 0.031\\\" W x 0.031\\\" H (1.60mm x 0.80mm x 0.80mm)","DC Cold Resistance":"0.017 Ohms","Voltage Rating - DC":"32 V","Current Rating (Amps)":"4 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.6900","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/8939cf38a5e3035b0d6c6bedcc1d525b.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of 0603SFS400F/32-2?","answer":"50 A at the rated 32 VDC. This is the maximum fault current the fuse can safely interrupt without rupturing. For applications where the available short-circuit current exceeds 50 A, a higher-breaking-capacity fuse or an upstream current-limiting device is required."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0603SFS400F-32-2","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0603SFS400F-32-2 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}}