{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"1206SFS400F/32-2","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"1206SFS400F-32-2","canonicalUrl":"https://icboms.com/littelfuse-inc/1206SFS400F-32-2","factsUrl":"https://icboms.com/api/mcp/products/1206SFS400F%2F32-2","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse SFS series, Board Mount Slow Blow Fuse, 1206 (3216 Metric), 4 A, 32 V DC, 50 A Breaking Capacity, Tape & Reel.","salesMarkdown":"## 4 A slow-blow in a 1206 footprint The 1206SFS400F/32-2: The slow-blow characteristic means it tolerates brief inrush current spikes without nuisance opening — a fit for circuits with capacitive or inductive loads that draw a short surge at power-up. ## Breaking capacity and I²t for the BOM Rated breaking capacity is 50 A at the rated 32 V DC — the fuse safely interrupts a fault current up to that level without rupturing the package. The melting I²t of 2.2 A²s gives the energy needed to open the element; this number is what you compare against the I²t of the upstream protection and the let-through energy the downstream components can survive. DC cold resistance is 0.024 Ω, which at 4 A continuous dissipates about 0.38 W — negligible in most designs but worth checking against the trace thermal budget on a dense board. ## Obsolete — sourcing through independent channels Littelfuse lists the 1206SFS400F/32-2 as obsolete. If you are stocking for a long-production-run BOM, consider qualifying a current-production 1206 slow-blow fuse with matching I²t and breaking capacity to avoid a last-time-buy scramble. ## UL recognition and storage note The fuse carries UL recognition, which simplifies acceptance in UL-listed end equipment. Supplied on Tape & Reel (TR) or Cut Tape (CT) — store the reels in a dry, temperature-stable environment; the 1206 ceramic body is not moisture-sensitive, but the plating on the terminations can tarnish in high-humidity storage.","metaTitle":"1206SFS400F/32-2 Littelfuse SFS 4A 32V Slow Blow Fuse","metaDescription":"1206SFS400F/32-2 Littelfuse SFS series 4A 32V DC slow-blow fuse, 1206 SMD, 50A breaking capacity. 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":"2.2","Mounting Type":"Surface Mount","Response Time":"Slow Blow","Package / Case":"1206 (3216 Metric)","Product Status":"Obsolete","Approval Agency":"UL","lifecycle_stage":"unknown","Size / Dimension":"0.126\\\" L x 0.063\\\" W x 0.038\\\" H (3.20mm x 1.60mm x 0.97mm)","DC Cold Resistance":"0.024 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":"$0.9000","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/8939cf38a5e3035b0d6c6bedcc1d525b.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Where can I buy 1206SFS400F/32-2?","answer":"The 1206SFS400F/32-2 is obsolete but available through independent distribution."},{"question":"What is the breaking capacity of 1206SFS400F/32-2?","answer":"The breaking capacity is 50 A at the rated 32 V DC. This is the maximum fault current the fuse can safely interrupt."},{"question":"What approvals does 1206SFS400F/32-2 carry?","answer":"The fuse is UL recognized."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/1206SFS400F-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/1206SFS400F-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}}