{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SM30T21CAY","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SM30T21CAY","canonicalUrl":"https://icboms.com/stmicroelectronics/SM30T21CAY","factsUrl":"https://icboms.com/api/mcp/products/SM30T21CAY","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SM30T21CAY, Automotive AEC-Q101 TRANSIL™ TVS, Bidirectional, 18V Standoff, 29.2V Clamp, 3kW Peak Pulse, DO-214AB SMC, -55°C to 175°C.","salesMarkdown":"## Automotive transient suppressor for 18 V rails The STMicroelectronics SM30T21CAY is a bidirectional Zener TVS diode from the TRANSIL™ family, designed to clamp voltage transients on automotive power and signal lines. It is rated for a peak pulse power of 3000 W (10/1000 µs waveform), with a reverse standoff voltage of 18 V and a maximum clamping voltage of 29.2 V at a peak pulse current of 102.7 A. The device is AEC-Q101 qualified, making it suitable for under-hood and chassis-mounted electronic modules that must survive load-dump, inductive kickback, and ISO 7637 transients. ## 3 kW clamping — what it buys the BOM The 3000 W peak pulse power (10/1000 µs) is the headline rating that determines how much transient energy the diode can shunt before the junction overheats. For an 18 V nominal rail, the 29.2 V clamp means downstream DC-DC converters and ASICs see a peak voltage well within their 30–36 V absolute maximum ratings, even during a severe load-dump event. The 102.7 A peak pulse current handling is sized for direct battery-line protection in 12 V automotive systems where alternator field decay or a jumped battery can inject hundreds of amps for a few milliseconds. A lower-rated TVS would either fail short or let the clamp voltage rise above the downstream silicon's breakdown threshold. ## Package and footprint The SM30T21CAY is housed in a DO-214AB (SMC) package, a surface-mount footprint common for medium-power TVS diodes. The SMC body handles the thermal dissipation of a 3 kW pulse without requiring a heatsink, relying on the PCB copper pad and solder joint to sink the transient heat. The bidirectional configuration means a single device protects both polarities on a line, saving board space compared to a back-to-back unipolar pair. The package is compatible with standard reflow soldering profiles;. ## Lifecycle and compliance The AEC-Q101 qualification provides the PPAP and change-control traceability that tier-1 automotive suppliers require for safety and reliability audits. The device is also part of the SM30TY series, which includes multiple voltage variants in the same SMC footprint, simplifying second-source qualification across the same board layout.","metaTitle":"SM30T21CAY TVS Diode, 3 kW, Bidirectional, AEC-Q101, SMC","metaDescription":"STMicroelectronics SM30T21CAY bidirectional TVS diode, 3 kW peak pulse power, 18 V standoff, 29.2 V clamp, AEC-Q101 qualified, -55°C to 175°C, SMC 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, SM30TY, TRANSIL™","Package":"Tape & Reel (TR); Cut Tape (CT)","Applications":"Automotive","Mounting Type":"Surface Mount","Package / Case":"DO-214AB, SMC","Product Status":"Active","lifecycle_stage":"eol_hot","Power - Peak Pulse":"3000W (3kW)","Base Product Number":"SM30T21","Operating Temperature":"-55°C~175°C(TJ)","Power Line Protection":"No","Bidirectional Channels":"1","Capacitance @ Frequency":"-","Supplier Device Package":"SMC","Voltage - Breakdown (Min)":"20V","Voltage - Clamping (Max) @ Ipp":"29.2V","Voltage - Reverse Standoff (Typ)":"18V","Current - Peak Pulse (10/1000µs)":"102.7A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4100","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/c1da1532b421560a6148be51fb30338a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Is SM30T21CAY AEC-Q101 qualified?","answer":"Yes, the SM30T21CAY is AEC-Q101 qualified, as indicated by its Automotive series designation. This qualification covers the rigorous stress tests required for automotive-grade discrete semiconductors, including high-temperature reverse bias, temperature cycling, and humidity testing."},{"question":"Is SM30T21CAY unidirectional or bidirectional?","answer":"The SM30T21CAY is a bidirectional TVS diode with a single bidirectional channel. This configuration protects both positive and negative transients on a single line, simplifying board layout for AC-coupled or bipolar signal paths."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SM30T21CAY","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SM30T21CAY when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-16T15:42:54.869Z","lastPublished":"2026-07-16T15:42:54.869Z","indexable":true}}