{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SM4T28AY","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SM4T28AY","canonicalUrl":"https://icboms.com/stmicroelectronics/SM4T28AY","factsUrl":"https://icboms.com/api/mcp/products/SM4T28AY","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SM4T28AY, Automotive AEC-Q101 TRANSIL™ TVS diode, 400W peak pulse power, 24V reverse standoff, 26.7V breakdown, 50V clamping, 46A (8/20µs), single unidirectional channel, DO-214AC SMA package, -55°C to 150°C.","salesMarkdown":"The STMicroelectronics SM4T28AY is a single-channel unidirectional Zener-type TVS diode from the automotive-grade SM4TY TRANSIL™ series. The 400W peak pulse power rating (10/1000µs waveform) and 46A peak pulse current (8/20µs) give it enough headroom for load-dump and inductive-load spikes common in automotive ECUs, body controllers, and sensor modules. ## AEC-Q101 and the temperature range The active lifecycle status means STMicroelectronics is still manufacturing it — no last-time-buy clock ticking, no need to hunt for obsolete-stock brokers yet. ## 24V system fit — the clamping numbers For a 24V automotive system (nominal 28V alternator float, transients up to 36V or more), the 24V reverse standoff means the diode stays out of conduction during normal operation. The 26.7V minimum breakdown gives a guard band before the part starts clamping. The maximum clamping voltage of 50V at the peak pulse current is what the downstream circuitry sees during a surge — make sure your 24V-rated ICs have at least that much margin, or add a second stage. The single unidirectional channel is polarity-sensitive; the cathode goes to the protected rail, anode to ground. ## Sourcing and field reality In the field, the SMA package is straightforward to replace — no hot-air station needed, just a standard iron and tweezers. The part marking is clear enough to read without magnification, which helps when you are swapping it on a customer site without a lab bench.","metaTitle":"STMicroelectronics SM4T28AY TVS Diode, AEC-Q101, 400W","metaDescription":"STMicroelectronics SM4T28AY automotive TVS diode, AEC-Q101 qualified, 400W peak pulse power, 24V standoff, DO-214AC SMA package.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"STMicroelectronics","Type":"Zener","Series":"Automotive, AEC-Q101, SM4TY, TRANSIL™","Package":"Tape & Reel (TR); Cut Tape (CT)","Applications":"Automotive","Mounting Type":"Surface Mount","Package / Case":"DO-214AC, SMA","Product Status":"Active","lifecycle_stage":"eol_hot","Power - Peak Pulse":"400W","Base Product Number":"SM4T28","Operating Temperature":"-55°C~150°C(TJ)","Power Line Protection":"No","Capacitance @ Frequency":"-","Supplier Device Package":"SMA (DO-214AC)","Unidirectional Channels":"1","Voltage - Breakdown (Min)":"26.7V","Voltage - Clamping (Max) @ Ipp":"50V","Voltage - Reverse Standoff (Typ)":"24V","Current - Peak Pulse (10/1000µs)":"46A (8/20µs)"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.8900","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/45721247f0377ca5ff3983c35eddc2fa.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Does SM4T28AY have AEC-Q101 qualification for automotive use?","answer":"Yes, the SM4T28AY is part of the Automotive, AEC-Q101 series, which means it has passed the automotive-grade discrete semiconductor qualification tests. It is suitable for under-hood and other harsh automotive environments."},{"question":"Can SM4T28AY be used in a 24V automotive system?","answer":"Yes. The reverse standoff voltage is 24V, so the diode does not conduct during normal 24V operation. The minimum breakdown voltage is 26.7V, providing margin before clamping begins."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SM4T28AY","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SM4T28AY 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}}