{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SMAJ18CA-TR","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"SMAJ18CA-TR","canonicalUrl":"https://icboms.com/stmicroelectronics/SMAJ18CA-TR","factsUrl":"https://icboms.com/api/mcp/products/SMAJ18CA-TR","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics SMAJ18CA-TR, TRANSIL™ series, bidirectional TVS diode, 400W peak pulse power, 18V reverse standoff, 20V breakdown, 39.3V clamping, 59A (8/20µs), DO-214AC (SMA), surface mount, -55°C to 150°C.","salesMarkdown":"## 400W bidirectional TVS in the SMA footprint It is designed for general-purpose overvoltage protection, clamping transients on power rails and signal lines where the normal operating voltage is 18 V. The part is rated for a peak pulse power of 400 W, with a breakdown voltage range starting at 20 V and a maximum clamping voltage of 39.3 V at the peak pulse current of 59 A (8/20 µs waveform). The 39.3 V clamping voltage at 59 A (8/20 µs) tells you the maximum voltage the protected circuit will see during a surge. For a 12 V supply rail, the 18 V standoff provides headroom without leakage; the 20 V breakdown ensures the device starts conducting before the rail exceeds safe limits. The 400 W peak pulse power defines the energy the part can absorb in a single pulse — sufficient for ESD and inductive-load transients, but for higher-energy events (e.g., lightning surge on exposed cables) a larger package like the SMBJ series may be needed. ## Package and board-level integration The DO-214AC (SMA) package is a widely used footprint for TVS diodes, compatible with standard reflow soldering profiles. No power line protection is provided internally — this is a transient clamp, not a regulator. The bidirectional configuration means a single device protects both positive and negative transients on a line, simplifying BOM count for AC-coupled or bipolar signal paths.","metaTitle":"STMicroelectronics SMAJ18CA-TR Bidirectional TVS Diode, 400W","metaDescription":"STMicroelectronics SMAJ18CA-TR bidirectional TVS diode, 400W peak pulse power, 18V standoff, 39.3V clamping, DO-214AC (SMA) package, active lifecycle, sourced","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":"SMAJ18","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)":"20V","Voltage - Clamping (Max) @ Ipp":"39.3V","Voltage - Reverse Standoff (Typ)":"18V","Current - Peak Pulse (10/1000µs)":"59A (8/20µs)"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.4000","priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/cb45a0c551131e855efff64db719fd1e.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/SMAJ18CA-TR/alternatives.json"},"ai":{"faq":[{"question":"Is SMAJ18CA-TR a bidirectional TVS diode?","answer":"Yes, the SMAJ18CA-TR is a bidirectional Zener-type TVS diode, with one bidirectional channel. It clamps transients of both polarities, suitable for AC signal lines or bipolar supply rails where the normal operating voltage is 18 V."},{"question":"What is the peak pulse power of SMAJ18CA-TR?","answer":"The SMAJ18CA-TR is rated for a peak pulse power of 400 W, measured with the 8/20 µs waveform. This rating defines the maximum transient energy the device can handle in a single pulse before failure."},{"question":"What is the difference between SMAJ18CA-TR and SMAJ18A-TR?","answer":"The SMAJ18CA-TR is the bidirectional variant, clamping both positive and negative transients. The SMAJ18A-TR is the unidirectional version, which only clamps transients in one polarity and is typically used on DC rails where the polarity is fixed. Both share the same 18 V standoff, 400 W peak pulse power, and DO-214AC package."},{"question":"Can SMAJ18CA-TR be used for 12V power supply protection?","answer":"Yes, the 18 V reverse standoff voltage provides adequate margin above a 12 V rail, so the TVS will not leak during normal operation. The breakdown voltage starts at 20 V, and clamping occurs at 39.3 V, which protects downstream circuitry from transients. For a 12 V supply, this part is a common choice."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/SMAJ18CA-TR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/SMAJ18CA-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}}