{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SMAJ40A-TR","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SMAJ40A-TR","canonicalUrl":"https://icboms.com/stmicroelectronics/SMAJ40A-TR","factsUrl":"https://icboms.com/api/mcp/products/SMAJ40A-TR","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SMAJ40A-TR, TRANSIL™ series, TVS Zener diode, 400W peak pulse power, 40V reverse standoff, 44.4V breakdown, 84V clamping, 1 unidirectional channel, DO-214AC SMA package, surface mount, -55°C to 150°C.","salesMarkdown":"It is a Zener-type device in a surface-mount DO-214AC SMA package, rated for a peak pulse power of 400W. The 44.4V minimum breakdown voltage means the device starts conducting just above the normal operating voltage, and the 84V maximum clamping voltage tells you what the downstream circuitry must survive during a surge event. This part is a general-purpose protector, suited for industrial control, telecom, and power supply applications where a 40V rail needs transient protection across the -55°C to 150°C temperature range. ## Clamping voltage and peak current — sizing the protection margin The 84V clamping voltage at a peak pulse current of 27A (tested with an 8/20µs waveform) is the key parameter for design margin. If your 40V rail feeds a converter rated for 80V absolute maximum, this TVS provides a few volts of headroom before the downstream part sees stress. The 400W peak pulse power rating is the energy-handling envelope for a single pulse; for repetitive surges or longer-duration events, you need to check the derating curve in the datasheet. ## DO-214AC footprint — what to check on the board The part comes in a DO-214AC SMA package, a standard surface-mount footprint for TVS diodes in this power class. For rework, the SMA body is large enough to hand-solder with a fine-tip iron if needed, but a hot-air station is cleaner for removal.","metaTitle":"STMicroelectronics SMAJ40A-TR TVS Diode, 400W, 40V Standoff","metaDescription":"SMAJ40A-TR TVS diode from STMicroelectronics, 400W peak pulse power, 40V reverse standoff, 84V clamping, DO-214AC package. Active lifecycle.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"STMicroelectronics","Type":"Zener","Series":"SMAJ, TRANSIL™","Package":"Tape & Reel (TR); Cut Tape (CT)","Applications":"General Purpose","Mounting Type":"Surface Mount","Package / Case":"DO-214AC, SMA","Product Status":"Active","lifecycle_stage":"eol_hot","Power - Peak Pulse":"400W","Base Product Number":"SMAJ40","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)":"44.4V","Voltage - Clamping (Max) @ Ipp":"84V","Voltage - Reverse Standoff (Typ)":"40V","Current - Peak Pulse (10/1000µs)":"27A (8/20µs)"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.5300","priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/cb45a0c551131e855efff64db719fd1e.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/SMAJ40A-TR/alternatives.json"},"ai":{"faq":[{"question":"What is the difference between SMAJ40A and SMAJ40A-TR?","answer":"The SMAJ40A-TR is the Tape & Reel packaged variant of the base SMAJ40A device. The electrical specifications — 400W peak pulse power, 40V standoff, 44.4V breakdown, 84V clamping — are identical. The -TR suffix indicates the packaging format for automated assembly."},{"question":"Can I replace SMAJ40A-TR with a similar TVS diode from another brand?","answer":"Yes, there are pin-compatible alternatives from other manufacturers in the same DO-214AC SMA package with a 40V standoff and 400W rating. The key parameters to match are the 40V reverse standoff, 44.4V minimum breakdown, and 84V maximum clamping. Any TVS diode meeting those specs in the same footprint is a functional replacement, though surge capability and clamping characteristics should be verified against the application's transient profile."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SMAJ40A-TR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SMAJ40A-TR 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}}