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Vishay General Semiconductor - Diodes Division SMAJ78AHE3_A/H
- Part No.:
- SMAJ78AHE3_A/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78AHE3_A/H.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,069
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Product details
Overview
SMAJ78AHE3_A/H from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of DC power rails 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 rating with 10/1000 μs waveform - suitable for automotive power supply line protection against load dump and ISO 7637-2 transients.
For engineers reviewing the SMAJ78AHE3_A/H datasheet, SMAJ78AHE3_A/H pinout, SMAJ78AHE3_A/H application, or SMAJ78AHE3_A/H equivalent, key selection criteria include clamping performance under 3.2 A surge, unidirectional polarity marking (cathode band), AEC-Q101 qualification status, and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.
Technical Context
This TVS diode operates as a voltage-clamped shunt protector: under normal conditions it presents high impedance (>1 μA leakage at 78 V), but triggers into low-impedance conduction when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable VBR tolerance and long-term reliability under repetitive surge stress.
The device is rated for 40 A non-repetitive forward surge current (IFSM, 8.3 ms half-sine), supports operating junction temperatures from –55 °C to +150 °C, and meets MSL Level 1 per J-STD-020 with 260 °C reflow peak temperature - confirming suitability for standard lead-free PCB assembly processes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 78 V - maximum continuous reverse working voltage before significant leakage; defines safe operating margin below clamping threshold |
| VBR (Breakdown Voltage) | 86.7–95.8 V at 1 mA - precise triggering range ensuring reliable activation above nominal rail voltage |
| VC (Clamping Voltage) | 126 V at IPPM = 3.2 A - limits downstream voltage stress during worst-case 10/1000 μs surge |
| PPPM (Peak Pulse Power) | 400 W (≤78 V), 300 W (>78 V) - sustains standardized lightning/surge energy without failure |
| ID (Reverse Leakage) | 1.0 μA max at 78 V - negligible standby power loss and minimal impact on high-impedance circuits |
| TJ Max | +150 °C - enables deployment in under-hood automotive environments and industrial enclosures |
| AEC-Q101 Qualified | Yes - validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile case with matte tin-plated leads solderable per J-STD-002 and JESD 22-B102. Cathode indicated by molded band; anode is unmarked end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Protected circuit side (anode connected to ground or lower potential) | Defines unidirectional conduction path: clamps positive transients to cathode rail; blocks reverse current |
| Anode (unbanded end) | Reference/return path (typically system ground) | Provides low-impedance discharge path for surge current into ground plane or chassis |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Withstands IEC 61000-4-5 Combination Wave (1.2/50 μs + 8/20 μs) surges up to 3.2 A without degradation |
| Glass passivated chip junction | Ensures ±5 % VBR tolerance stability across temperature and lifetime; eliminates moisture-induced parameter drift |
| AEC-Q101 qualified (HE3 suffix) | Validated for automotive applications including engine control units, body electronics, and ADAS power domains |
| MSL Level 1, 260 °C peak reflow | Compatible with standard lead-free SMT reflow profiles without pre-baking or special handling |
| Low incremental surge resistance | Minimizes VC overshoot during fast-rising transients (<1 ns response time), improving protection margin |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: 12 V battery-fed ECUs exposed to ISO 7637-2 Pulse 5a (load dump) up to 60 V/100 ms. IC Role / Device Role / Timing Role: Unidirectional shunt clamp placed between battery rail and regulator input. Use Value: Limits voltage to ≤126 V during 3.2 A surge, preventing LDO or MCU damage while maintaining <1 μA leakage at 78 V. |
Use Scenario: 24 V industrial PLC analog input channel subjected to field-wiring induced transients. IC Role / Device Role / Timing Role: Primary overvoltage clamp ahead of precision op-amp front-end and ADC driver. Use Value: Clamps 10/1000 μs surges to 126 V with sub-nanosecond response, preserving signal integrity and avoiding saturation of downstream amplifiers. |
| Telecom DC Power Feeds | Consumer Power Adapter Output Protection |
|
Use Scenario: -48 V telecom rectifier output lines vulnerable to lightning-induced surges on long cable runs. IC Role / Device Role / Timing Role: Secondary protection stage after primary MOV, placed directly at equipment input connector. Use Value: Provides precise 78 V clamping with 126 V VC to safeguard PoE controllers and Ethernet PHYs without false triggering during normal operation. |
Use Scenario: USB-C PD adapter 20 V output rail subject to hot-plug and capacitive coupling transients. IC Role / Device Role / Timing Role: Final-stage TVS between DC-DC converter output and USB-C port VBUS line. Use Value: Delivers 400 W surge handling with 1.0 μA leakage at 78 V, enabling compact layout and zero standby power penalty. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-E3/61 | Same electrical specs and SMA package; RoHS-compliant commercial grade (non-AEC-Q101) | Lacks automotive qualification; not approved for under-hood or safety-critical modules | Select when cost-sensitive industrial or consumer designs do not require AEC-Q101 validation |
| SMAJ78AHE3_A/I | Identical electrical and mechanical specs; differs only in packaging format (7500 pcs/reel vs. 1800 pcs/reel) | No functional difference; same AEC-Q101 qualification and thermal performance | Choose based on production volume and SMT line reel capacity requirements |
Compared with SMAJ78AHE3_A/H, the SMAJ78A-E3/61 offers identical protection performance but lacks automotive qualification, while SMAJ78AHE3_A/I provides identical functionality in higher-volume tape-and-reel format - enabling optimized procurement without design or layout changes.
Availability
SMAJ78AHE3_A/H is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor interfaces, and telecom DC power feeds requiring stable component supply with AEC-Q101 assurance and full traceability.
Supply support for SMAJ78AHE3_A/H 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 optimization.
The SMAJ series is engineered for high-energy transient suppression in harsh environments, targeting automotive, industrial, and telecom systems where precise clamping, low leakage, and AEC-Q101 compliance are mandatory.
FAQ
What is the clamping voltage of SMAJ78AHE3_A/H at its rated peak pulse current?
The SMAJ78AHE3_A/H has a maximum clamping voltage (VC) of 126 V at its specified peak pulse current (IPPM) of 3.2 A, measured using the standard 10/1000 μs double-exponential waveform. This value ensures protected circuits remain within safe voltage limits during surge events, and is confirmed in the Vishay datasheet Document Number 88390, page 2, Electrical Characteristics table.
Is SMAJ78AHE3_A/H qualified for automotive applications?
Yes, SMAJ78AHE3_A/H is AEC-Q101 qualified, as indicated by the "HE3" suffix in its part number and explicitly stated in the Vishay datasheet revision 09-Jan-2024. This qualification covers stress tests including temperature cycling, high-temperature reverse bias, and ESD, making SMAJ78AHE3_A/H suitable for use in engine control units, body control modules, and ADAS power domains.
What does the "A/H" suffix in SMAJ78AHE3_A/H signify?
The "A/H" suffix in SMAJ78AHE3_A/H denotes the packaging configuration: "H" indicates a 7-inch diameter plastic tape-and-reel format containing 1800 units per reel, while "A" refers to the revision code (document revision level A). This matches the ordering information shown in the Vishay datasheet, page 3, under "ORDERING INFORMATION (Example)".
How does SMAJ78AHE3_A/H differ from bidirectional variants like SMAJ78CA?
SMAJ78AHE3_A/H is unidirectional, with a cathode band marking and clamping action only for positive transients relative to ground; SMAJ78CA is bidirectional and clamps both polarities symmetrically. The SMAJ78AHE3_A/H has VWM = 78 V and VBR = 86.7–95.8 V, whereas SMAJ78CA shares the same VWM but exhibits matched breakdown in both directions - making SMAJ78AHE3_A/H appropriate for DC rail protection and SMAJ78CA for AC or differential signal lines.
What is the thermal resistance of SMAJ78AHE3_A/H, and how does it affect PCB layout?
SMAJ78AHE3_A/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on minimum recommended pad layout, and 30 °C/W junction-to-lead (RθJL). To maintain TJ ≤ 150 °C under 3.3 W steady-state dissipation, designers must use ≥0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal - as specified in the Vishay datasheet, page 1, "MAXIMUM RATINGS" note (2).
SMAJ78AHE3_A/H 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:
- 1
- Bidirectional Channels:
- -
- 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ78AHE3_A/H FAQ
1.How can I place an order for SMAJ78AHE3_A/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78AHE3_A/H 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 SMAJ78AHE3_A/H reliable?
The price and inventory of SMAJ78AHE3_A/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78AHE3_A/H is usually 5 days.
3.What payment methods are accepted for SMAJ78AHE3_A/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78AHE3_A/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78AHE3_A/H?
SMAJ78AHE3_A/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78AHE3_A/H 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 SMAJ78AHE3_A/H?
For technical support, including SMAJ78AHE3_A/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78AHE3_A/H requirements.
6.How does Aetrix verify that SMAJ78AHE3_A/H is sourced from the original manufacturer or authorized distributors?
All SMAJ78AHE3_A/H 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 SMAJ78AHE3_A/H meets industry standards.
7.What is the process for return or replacement of SMAJ78AHE3_A/H?
All SMAJ78AHE3_A/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78AHE3_A/H, 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 SMAJ78AHE3_A/H part is unused and in its original packaging.
Return procedure for SMAJ78AHE3_A/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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