{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SM4T18AY","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SM4T18AY","canonicalUrl":"https://icboms.com/stmicroelectronics/SM4T18AY","factsUrl":"https://icboms.com/api/mcp/products/SM4T18AY","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SM4T18AY, Automotive AEC-Q101 TRANSIL™ Zener, 400W peak pulse, 15V reverse standoff, 32.5V clamp, 16.7V min breakdown, unidirectional, DO-214AC SMA, -55°C to 150°C.","salesMarkdown":"## Automotive-grade Zener for 15 V rail clamping It is designed to clamp transients on a 15 V nominal rail, with a minimum breakdown voltage of 16.7 V and a maximum clamping voltage of 32.5 V at the peak pulse current. The 400 W peak pulse power rating (8/20 µs waveform) gives it headroom for load-dump and inductive kickback events common in automotive ECUs, body controllers, and sensor modules. ## 400 W peak pulse — sizing the protection for the BOM For a 15 V rail, the 32.5 V clamp voltage means the diode will hold the line well below the typical 40 V absolute maximum of downstream 12 V-rated ICs. The 71 A peak pulse current rating (8/20 µs) confirms it can handle direct strikes from inductive loads like relays, solenoids, or small motors without secondary protection. Power line protection is not integrated — this is a standalone Zener clamp, not a TVS array with series elements, so the PCB trace impedance and any upstream fuse or PTC should be considered in the overall protection scheme. ## Active lifecycle and automotive qualification This makes it suitable for production programs that require a documented reliability pedigree and a stable supply commitment. The base product number is SM4T18, so the 'Y' suffix denotes the specific AEC-Q101 variant — verify the exact ordering code against your BOM to avoid substituting the commercial-grade SM4T18A.","metaTitle":"STMicroelectronics SM4T18AY Zener, 400W, AEC-Q101, DO-214AC","metaDescription":"STMicroelectronics SM4T18AY automotive AEC-Q101 Zener diode, 400W peak pulse, 15V standoff, 32.5V clamp, DO-214AC SMA. Active lifecycle.","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":"SM4T18","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)":"16.7V","Voltage - Clamping (Max) @ Ipp":"32.5V","Voltage - Reverse Standoff (Typ)":"15V","Current - Peak Pulse (10/1000µs)":"71A (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":"Is SM4T18AY automotive qualified?","answer":"Yes, it is qualified to AEC-Q101 and is part of the Automotive series."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SM4T18AY","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SM4T18AY 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}}