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Vishay General Semiconductor - Diodes Division SMAJ78AHE3_A/I
- Part No.:
- SMAJ78AHE3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78AHE3_A/I.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,690
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Product details
Overview
SMAJ78AHE3_A/I 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, and 400 W peak pulse power rating with 10/1000 μs waveform - suitable for automotive power supply line protection per ISO 7637-2.
For engineers reviewing the SMAJ78AHE3_A/I datasheet, SMAJ78AHE3_A/I pinout, SMAJ78AHE3_A/I application, or SMAJ78AHE3_A/I equivalent, key selection criteria include clamping performance under 3.2 A surge, AEC-Q101 qualification status, unidirectional polarity marking, and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.
Technical Context
This TVS diode operates as a fast-acting shunt clamp, activating when reverse voltage exceeds its VBR threshold to divert transient energy away from protected circuitry. Its glass-passivated junction ensures stable leakage (<1.0 μA at 78 V) and low incremental surge resistance, enabling consistent clamping across repetitive transients.
Designed for surface-mount use in high-reliability environments, SMAJ78AHE3_A/I meets MSL level 1 per J-STD-020, supports peak forward surge current up to 40 A (8.3 ms half-sine), and maintains operation from −55 °C to +150 °C junction temperature - critical for under-hood automotive electronics and industrial power interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse operating voltage before clamping initiates |
| VBR min/max | 86.7 V / 95.8 V at 1 mA - guaranteed breakdown range defining turn-on threshold tolerance |
| VC @ IPPM | 126 V at 3.2 A - clamped voltage during 10/1000 μs surge, limiting stress on downstream ICs |
| PPPM | 400 W - peak pulse power handling capability with standard 10/1000 μs waveform |
| ID @ VWM | <1.0 μA - ultra-low reverse leakage preserves efficiency in always-on power rails |
| TJ max. | +150 °C - enables deployment in high-temperature engine control units and motor drives |
| AEC-Q101 | Qualified - certified for automotive-grade reliability per stress test requirements |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, molded plastic case with matte tin-plated leads; cathode indicated by band on body; compliant with UL 94 V-0 flammability rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path) in unidirectional configuration |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 78 V rail); band-marked end absorbs positive transients |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power | Handles ISO 7637-2 Pulse 1/2a/5a transients without degradation when mounted on 5 mm × 5 mm copper pads |
| Glass-passivated junction | Ensures stable VBR and low leakage over temperature and lifetime, critical for long-term automotive deployments |
| AEC-Q101 qualified | Validated for automotive applications including engine control modules, body control units, and ADAS power supplies |
| MSL Level 1 | Reflow-compatible up to 260 °C peak, supporting standard lead-free assembly without moisture sensitivity concerns |
| Low profile SMA package | 0.208" × 0.157" footprint enables dense PCB layouts while maintaining thermal dissipation via lead-frame conduction |
Applications
| Automotive Power Rail Protection | Industrial DC Power Input |
|---|---|
Use Scenario: Protecting 72–80 V battery-fed ECUs against load dump and alternator transients per ISO 7637-2. IC Role / Device Role / Timing Role: Unidirectional shunt TVS clamping positive surges on main power input before DC-DC converters. Use Value: Limits voltage to ≤126 V during 3.2 A transients, preventing damage to 100 V-rated MOSFETs and regulators. |
Use Scenario: Safeguarding programmable logic controller (PLC) 24–80 V DC inputs from inductive switching spikes. IC Role / Device Role / Timing Role: Standoff-clamp protector placed directly at connector entry point to absorb field-induced surges. Use Value: Sub-1 μA leakage avoids loading sensitive analog monitoring circuits; 150 °C rating supports enclosed cabinet operation. |
| Telecom Power Interface | Motor Drive Control Board |
Use Scenario: Shielding PoE-powered base station RF modules from lightning-induced surges on 48–78 V bias lines. IC Role / Device Role / Timing Role: Primary overvoltage clamp on DC feed line upstream of DC-DC isolation stage. Use Value: 400 W rating handles multi-event surges; AEC-Q101 qualification adds confidence in harsh outdoor deployments. |
Use Scenario: Protecting gate drivers and current sense amplifiers on 78 V bus in BLDC motor inverters. IC Role / Device Role / Timing Role: Localized TVS at power stage input to suppress commutation-induced voltage spikes. Use Value: Fast response time and low clamping voltage preserve timing integrity of PWM signals and prevent false fault triggering. |
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 without AEC-Q101 qualification | Lacks automotive qualification; suitable for industrial/commercial designs not requiring AEC validation | Select when cost sensitivity outweighs automotive compliance requirements |
| SMAJ78AHM3_A/I | Halogen-free, RoHS-compliant, AEC-Q101 qualified; identical VWM/VBR/VC/PPPM ratings | Same automotive use cases; preferred where halogen-free material content is mandated | Choose for automotive programs requiring halogen-free BOM compliance |
Compared with SMAJ78AHE3_A/I, SMAJ78A-E3/61 omits AEC-Q101 validation but matches all electrical parameters, while SMAJ78AHM3_A/I provides identical automotive qualification plus halogen-free construction - enabling direct substitution where material compliance is specified.
Availability
SMAJ78AHE3_A/I is available at Aetrix Electronics and suitable for automotive ECU protection, industrial PLC power inputs, telecom DC bias line safeguarding, and motor drive control board surge suppression requiring stable component supply and full AEC-Q101 traceability.
Supply support for SMAJ78AHE3_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, rectifiers, TVS devices, and optoelectronics with emphasis on reliability and application-specific performance.
The SMAJ series was developed specifically for high-energy transient suppression in automotive, industrial, and telecom systems - delivering standardized 400 W pulse capability, AEC-Q101 qualification, and robust DO-214AC packaging for demanding environments.
FAQ
What is the clamping voltage of SMAJ78AHE3_A/I at its rated peak pulse current?
The SMAJ78AHE3_A/I has a maximum clamping voltage (VC) of 126 V when subjected to its rated peak pulse current of 3.2 A using the standard 10/1000 μs waveform. This value is measured under defined test conditions per JEDEC standards and ensures predictable overvoltage limiting for downstream components in the protected circuit - a key parameter verified in the Vishay datasheet revision 09-Jan-2024 for SMAJ78AHE3_A/I.
Is SMAJ78AHE3_A/I qualified to AEC-Q101, and what does that mean for automotive use?
Yes, SMAJ78AHE3_A/I is explicitly AEC-Q101 qualified, as confirmed in Vishay's ordering information table and mechanical data section. This qualification validates its reliability under automotive-grade stress tests including temperature cycling, humidity bias HAST, and accelerated life testing - making SMAJ78AHE3_A/I suitable for engine control units, body electronics, and ADAS power domains where failure is not acceptable.
What is the polarity configuration of SMAJ78AHE3_A/I, and how is it marked on the device?
SMAJ78AHE3_A/I is a unidirectional TVS diode, with polarity indicated by a cathode band on the SMA (DO-214AC) package body. The banded end connects to the protected line (e.g., 78 V rail), while the unbanded end connects to ground or return. This configuration allows it to clamp only positive-going transients - a design choice confirmed in Vishay's "Polarity" note and primary characteristics table for SMAJ78AHE3_A/I.
What is the maximum operating junction temperature for SMAJ78AHE3_A/I, and why does it matter?
The maximum operating junction temperature (TJ max.) for SMAJ78AHE3_A/I is +150 °C, as specified in the "Maximum Ratings" table of the Vishay datasheet. This rating enables reliable operation in high-ambient environments such as under-hood automotive locations or sealed industrial enclosures - ensuring sustained clamping performance without thermal runaway, which is essential for safety-critical power protection functions performed by SMAJ78AHE3_A/I.
How does the 400 W peak pulse power rating of SMAJ78AHE3_A/I relate to real-world surge events?
The 400 W peak pulse power rating of SMAJ78AHE3_A/I applies to the standardized 10/1000 μs double-exponential waveform and is validated with 0.2" × 0.2" copper pads per JEDEC test conditions. It corresponds to real-world threats like ISO 7637-2 Pulse 5a (load dump) and IEC 61000-4-5 surges - meaning SMAJ78AHE3_A/I can safely absorb and dissipate these transients without failure, provided layout guidelines (pad size, trace width, grounding) are followed as specified for SMAJ78AHE3_A/I.
SMAJ78AHE3_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:
- 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/I FAQ
1.How can I place an order for SMAJ78AHE3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78AHE3_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 SMAJ78AHE3_A/I reliable?
The price and inventory of SMAJ78AHE3_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 SMAJ78AHE3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ78AHE3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78AHE3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78AHE3_A/I?
SMAJ78AHE3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78AHE3_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 SMAJ78AHE3_A/I?
For technical support, including SMAJ78AHE3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78AHE3_A/I requirements.
6.How does Aetrix verify that SMAJ78AHE3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ78AHE3_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 SMAJ78AHE3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ78AHE3_A/I?
All SMAJ78AHE3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78AHE3_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 SMAJ78AHE3_A/I part is unused and in its original packaging.
Return procedure for SMAJ78AHE3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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