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Vishay General Semiconductor - Diodes Division SMAJ78CAHM3_A/I
- Part No.:
- SMAJ78CAHM3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CAHM3_A/I.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,406
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Product details
Overview
SMAJ78CAHM3_A/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on power and signal lines. It features a 78 V stand-off voltage (VWM), 86.7–95.8 V breakdown voltage (VBR) at 1 mA, 126 V maximum clamping voltage (VC) at 3.2 A peak pulse current (IPPM), and 400 W peak pulse power (10/1000 μs waveform) - suitable for protecting automotive sensor interfaces and industrial I/O circuits against ESD and load dump.
For engineers reviewing the SMAJ78CAHM3_A/I datasheet, SMAJ78CAHM3_A/I pinout, SMAJ78CAHM3_A/I application, or SMAJ78CAHM3_A/I equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification status, thermal resistance (RθJA = 120 °C/W), and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.
Technical Context
This device operates as a voltage-clamping protection element across two terminals, responding to both positive and negative polarity transients without polarity marking. Its glass-passivated junction enables fast response time (<1 ps), low incremental surge resistance, and stable clamping under repetitive 10/1000 μs surges at 0.01% duty cycle.
The SMAJ78CAHM3_A/I is rated for -55 °C to +150 °C operating junction temperature, meets MSL Level 1 per J-STD-020 (peak reflow 260 °C), and delivers 3.3 W steady-state power dissipation on infinite heatsink at 50 °C ambient - confirming suitability for high-reliability automotive and industrial environments where thermal margin and long-term stability are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse operating voltage before clamping initiates; defines safe operating window for 12 V/24 V automotive supply rails. |
| VBR (min/max) | 86.7 V / 95.8 V at IT = 1 mA - ensures consistent breakdown threshold across production lots; guarantees clamping activation within defined tolerance band. |
| VC @ IPPM | 126 V at 3.2 A - peak clamped voltage during 10/1000 μs surge; determines protected circuit's maximum overvoltage exposure. |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - peak pulse power handling per 10/1000 μs waveform; defines transient energy absorption capacity. |
| ID @ VWM | 1.0 μA - ultra-low reverse leakage at stand-off voltage; minimizes standby power loss and avoids false triggering in high-impedance nodes. |
| TJ max. | +150 °C - maximum junction temperature rating; supports operation in under-hood automotive and industrial control cabinet environments. |
| RθJA | 120 °C/W - thermal resistance junction-to-ambient on standard PCB pad layout; informs derating requirements for sustained power dissipation. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, AEC-Q101 qualified. Matte tin-plated leads, solderable per J-STD-002 and JESD 22-B102. No polarity marking for bidirectional configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient return path (bidirectional) | Provides symmetrical conduction path for both polarities; connects to protected line or ground reference depending on layout. |
| Cathode | Transient return path (bidirectional) | Functionally identical to Anode in CA-type devices; no cathode band marking; terminals interchangeable in circuit design. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - required for engine control, ADAS, and body electronics. |
| 400 W peak pulse power (10/1000 μs) | Enables robust protection against ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 surge events without degradation over lifetime. |
| Low profile SMA package | Height ≤1.98 mm - fits space-constrained layouts in automotive ECUs and industrial PLC modules while supporting automated pick-and-place. |
| MSL Level 1 moisture sensitivity | Allows unlimited floor life and standard reflow profile (peak 260 °C) without baking - reduces manufacturing overhead and yield risk. |
| Glass passivated junction | Ensures stable VBR and low leakage over 10+ years of field operation; resists humidity-induced parameter drift in harsh environments. |
Applications
| Automotive Sensor Protection | Industrial I/O Interface |
|---|---|
|
Use Scenario: Protecting CAN/LIN bus transceivers and analog sensor inputs (e.g., pressure, temperature) from load dump and ESD in vehicle subsystems. IC Role / Device Role / Timing Role: Bidirectional clamping TVS placed between signal line and chassis ground to limit transient voltage to <126 V. Use Value: Prevents latch-up or permanent damage to 5 V/3.3 V interface ICs during 12 V battery disconnect events or relay coil flyback. |
Use Scenario: Safeguarding digital input/output channels on programmable logic controllers (PLCs) exposed to motor switching noise and lightning-induced surges. IC Role / Device Role / Timing Role: Standoff-rated transient suppressor installed across terminal blocks or optocoupler inputs to absorb 1 kV/500 A surges. Use Value: Maintains functional safety integrity by limiting voltage excursion below 126 V during 10/1000 μs transients per IEC 61000-4-5 Level 3. |
| Consumer Power Adapter Input | Telecom Line Card Protection |
|
Use Scenario: Secondary-side overvoltage suppression in AC/DC adapters for USB-C PD and smart home hubs subjected to mains-borne transients. IC Role / Device Role / Timing Role: Clamping device connected across DC output rails (e.g., 12 V, 19 V) to prevent downstream regulator failure. Use Value: Limits output overvoltage to 126 V during surge events, preserving compliance with UL 62368-1 secondary circuit insulation requirements. |
Use Scenario: Front-end protection for Ethernet PHYs and PoE injectors in enterprise switches facing induced surges from nearby power cables. IC Role / Device Role / Timing Role: Bidirectional TVS placed on differential pairs (e.g., ETH_MDIO, ETH_MDC) referenced to local ground plane. Use Value: Ensures signal integrity by clamping common-mode transients to <126 V while maintaining <0.5 pF junction capacitance at 0 V bias. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78CAHE3_A/I | Same electrical specs, RoHS-compliant but not halogen-free; lacks AEC-Q101 qualification. | Restricted to commercial-grade industrial or consumer applications; not approved for automotive use. | Select when AEC-Q101 is not required and cost optimization is prioritized over halogen-free compliance. |
| SMBJ78CAHM3_A/I | Same VWM/VBR/VC ratings but in SMB (DO-214AA) package - 27% larger footprint and 10% higher RθJA (133 °C/W). | Better surge energy handling (600 W) but incompatible with SMA-optimized board space; requires layout revision. | Choose only if higher peak power (600 W) is mandatory and PCB real estate allows SMB footprint. |
Compared with SMAJ78CAHE3_A/I, the SMAJ78CAHM3_A/I adds halogen-free construction and AEC-Q101 qualification without sacrificing clamping performance; versus SMBJ78CAHM3_A/I, it trades 200 W peak power for 25% smaller board area and lower thermal resistance - optimizing for space-constrained automotive modules.
Availability
SMAJ78CAHM3_A/I is available at Aetrix Electronics and suitable for automotive sensor protection, industrial I/O interface hardening, and telecom line card surge suppression requiring stable component supply across multi-year production cycles.
Supply support for SMAJ78CAHM3_A/I includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific performance.
The SMAJ series is engineered for high-speed transient suppression in automotive, industrial, and communications systems - delivering precise clamping, AEC-Q101 validation, and robust SMT manufacturability in compact DO-214AC packages.
FAQ
What is the clamping voltage of SMAJ78CAHM3_A/I at its rated peak pulse current?
The SMAJ78CAHM3_A/I has a maximum clamping voltage (VC) of 126 V at its specified peak pulse current (IPPM) of 3.2 A, measured under the standardized 10/1000 μs double-exponential surge waveform. This value defines the upper voltage limit imposed on protected circuitry during transient events and is guaranteed across the full operating temperature range of -55 °C to +150 °C. The SMAJ78CAHM3_A/I maintains this clamping performance with minimal variation due to its glass-passivated junction and tight VBR tolerance.
Is SMAJ78CAHM3_A/I suitable for automotive applications?
Yes, the SMAJ78CAHM3_A/I is AEC-Q101 qualified and specifically designed for automotive use - validated for temperature cycling, highly accelerated life testing (HALT), and ESD robustness per automotive reliability standards. Its 78 V stand-off voltage aligns with 24 V system architectures, and its 126 V clamping voltage protects sensitive CAN transceivers, LIN drivers, and sensor signal conditioning ICs from load dump and inductive switching transients. The SMAJ78CAHM3_A/I carries the HM3 suffix indicating halogen-free, RoHS-compliant, and AEC-Q101-qualified construction.
What is the thermal resistance of SMAJ78CAHM3_A/I, and how does it affect PCB layout?
The SMAJ78CAHM3_A/I has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on the minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes standard FR-4 PCB with no internal copper planes. To maintain safe junction temperatures below 150 °C during repetitive surge events or elevated ambient conditions, designers must ensure adequate copper area and avoid excessive trace length between the SMAJ78CAHM3_A/I and ground/power planes. Derating curves in the Vishay datasheet (Fig. 2) guide power handling vs. ambient temperature.
How does SMAJ78CAHM3_A/I differ from unidirectional SMAJ78A variants?
The SMAJ78CAHM3_A/I is bidirectional, meaning it provides symmetrical clamping for both positive and negative transients without polarity marking - ideal for AC-coupled lines or differential signals. In contrast, the unidirectional SMAJ78A variant has a cathode band and conducts only in reverse bias, making it suitable for DC rail protection where polarity is fixed. Both share identical VWM (78 V), VBR (86.7–95.8 V), and VC (126 V) ratings, but the SMAJ78CAHM3_A/I eliminates orientation-dependent placement errors in automated assembly and supports floating-ground configurations.
What packaging and moisture sensitivity level applies to SMAJ78CAHM3_A/I?
The SMAJ78CAHM3_A/I is supplied in 13" diameter plastic tape and reel (package code "I"), with 7500 units per reel. It meets MSL Level 1 per J-STD-020, meaning it has unlimited floor life and can undergo standard lead-free reflow profiles with a maximum peak temperature of 260 °C without preconditioning or baking. This simplifies SMT manufacturing flow and eliminates moisture-related defects such as popcorning or delamination during assembly - a key advantage for high-volume automotive and industrial production using the SMAJ78CAHM3_A/I.
SMAJ78CAHM3_A/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AC, SMA
- Series:
- TransZorb®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ78CAHM3_A/I FAQ
1.How can I place an order for SMAJ78CAHM3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CAHM3_A/I on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SMAJ78CAHM3_A/I reliable?
The price and inventory of SMAJ78CAHM3_A/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CAHM3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ78CAHM3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CAHM3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CAHM3_A/I?
SMAJ78CAHM3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CAHM3_A/I order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SMAJ78CAHM3_A/I?
For technical support, including SMAJ78CAHM3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CAHM3_A/I requirements.
6.How does Aetrix verify that SMAJ78CAHM3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ78CAHM3_A/I products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SMAJ78CAHM3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ78CAHM3_A/I?
All SMAJ78CAHM3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CAHM3_A/I, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SMAJ78CAHM3_A/I part is unused and in its original packaging.
Return procedure for SMAJ78CAHM3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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