{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SM4T68CAY","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SM4T68CAY","canonicalUrl":"https://icboms.com/stmicroelectronics/SM4T68CAY","factsUrl":"https://icboms.com/api/mcp/products/SM4T68CAY","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SM4T68CAY, SM4TY series, Automotive AEC-Q101 TRANSIL™ bidirectional TVS diode, 400W peak pulse power, 58V reverse standoff, 64.4V breakdown min, 121V clamping max, 19A peak pulse current, DO-214AC SMA package, -55°C to 150°C.","salesMarkdown":"## Automotive-grade bidirectional TVS in a compact SMA package The STMicroelectronics SM4T68CAY is a bidirectional TRANSIL™ TVS diode from the SM4TY series, designed for automotive applications and qualified to AEC-Q101. It provides 400W peak pulse power protection with a 58V reverse standoff voltage, making it suited for 48V automotive bus protection, sensor lines, and general-purpose surge clamping on power rails in engine control units, body controllers, and infotainment modules. The DO-214AC SMA surface-mount package fits standard pick-and-place assembly and reflow profiles used in high-volume automotive PCB production. ## Voltage thresholds and clamping performance With a minimum breakdown voltage of 64.4V and a maximum clamping voltage of 121V at the peak pulse current, this part protects downstream circuitry from transients up to 19A (8/20µs waveform). The 58V reverse standoff voltage means it does not conduct at normal operating levels up to that DC voltage, avoiding unnecessary leakage in steady-state conditions. For a 48V nominal automotive rail that sees load-dump or alternator-field decay events, the 64.4V breakdown threshold provides margin above the normal operating range before the device starts to clamp. ## Temperature range and thermal reliability The 400W peak pulse power rating is derated with temperature per the TRANSIL datasheet curves — at 150°C junction, derate to approximately 50% of the room-temperature rating. For high-energy pulses or elevated ambient temperatures, consider the pulse-width derating factors for the specific waveform. ## Package and mounting for automotive production The DO-214AC SMA package (also designated SMA) is a standard JEDEC outline with a small footprint — roughly 4.6 mm by 2.8 mm body — suitable for dense PCB layouts. The surface-mount design supports reflow soldering with typical lead-free profiles. The bidirectional configuration uses a single die, so no polarity marking is needed, simplifying pick-and-place orientation. For production builds requiring AEC-Q101 qualified TVS protection, this part is a stable BOM line item. No immediate LTB risk, and the TRANSIL series has broad automotive market adoption with multiple package variants for design flexibility.","metaTitle":"SM4T68CAY STMicroelectronics TVS Diode, AEC-Q101, 400W","metaDescription":"SM4T68CAY STMicroelectronics TRANSIL™ bidirectional TVS diode. AEC-Q101 qualified, 400W peak pulse power, 58V standoff, 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":"SM4T68","Operating Temperature":"-55°C~150°C(TJ)","Power Line Protection":"No","Bidirectional Channels":"1","Capacitance @ Frequency":"-","Supplier Device Package":"SMA (DO-214AC)","Voltage - Breakdown (Min)":"64.4V","Voltage - Clamping (Max) @ Ipp":"121V","Voltage - Reverse Standoff (Typ)":"58V","Current - Peak Pulse (10/1000µs)":"19A (8/20µs)"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.9300","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/45721247f0377ca5ff3983c35eddc2fa.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is SM4T68CAY used for?","answer":"The SM4T68CAY is a bidirectional TVS diode used for transient voltage suppression in automotive electronics. It protects 48V power rails, sensor interfaces, and communication lines from surges such as load dump, inductive kickback, and electrostatic discharge. Its AEC-Q101 qualification makes it suitable for under-hood and cabin-mounted ECUs, battery management systems, and motor drive modules."},{"question":"Is there a replacement or equivalent for SM4T68CAY?","answer":"Within the same SM4TY TRANSIL series, STMicroelectronics offers other bidirectional TVS diodes in the DO-214AC SMA package at different voltage ratings. For a pin-compatible alternative at the same voltage, the SM4T68CAY is the specific AEC-Q101 qualified variant; the non-automotive SM4T68C (without the 'AY' suffix) shares the same electrical characteristics but lacks the automotive qualification. For dual-sourcing, verify the clamping voltage and peak pulse power requirements against other manufacturers' SMA-packaged bidirectional TVS diodes rated for 58V standoff and 400W peak pulse power."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SM4T68CAY","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SM4T68CAY 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}}