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Vishay General Semiconductor - Diodes Division SMAJ78CAHM3/H
- Part No.:
- SMAJ78CAHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CAHM3/H.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,890
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Product details
Overview
SMAJ78CAHM3/H from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of sensitive electronics. 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) - rated for automotive-grade applications per AEC-Q101.
For engineers reviewing the SMAJ78CAHM3/H datasheet, SMAJ78CAHM3/H pinout, SMAJ78CAHM3/H application, or SMAJ78CAHM3/H equivalent, this device is selected for high-reliability DC bus, sensor interface, and power rail protection where fast response (<1 ns), low clamping ratio (VC/VBR ≈ 1.33), and halogen-free RoHS compliance are critical design requirements.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, with identical VBR min/max (86.7 V / 95.8 V), VC (126 V), and IPPM (3.2 A) in either direction. Its glass-passivated junction ensures stable avalanche characteristics and low leakage (<1.0 μA at 78 V), while MSL Level 1 moisture sensitivity supports lead-free reflow up to 260 °C.
The device delivers 400 W peak pulse power below 78 V and derates to 300 W above 78 V per Fig. 2; thermal resistance is RθJA = 120 °C/W (on 0.2" × 0.2" copper pads) and RθJL = 30 °C/W, enabling reliable operation up to TJ = +150 °C with 3.3 W steady-state power dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins; defines safe DC/AC working margin. |
| VBR (min/max) | 86.7 V / 95.8 V at IT = 1 mA - Confirmed breakdown range ensures predictable turn-on threshold under surge conditions. |
| VC @ IPPM | 126 V at IPPM = 3.2 A - Clamping voltage limits downstream component stress during 10/1000 μs transients. |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - Peak surge energy handling capability per standard waveform; defines protection level. |
| ID @ VWM | <1.0 μA - Ultra-low reverse leakage preserves signal integrity and minimizes standby power loss. |
| TJ max. | +150 °C - Enables deployment in under-hood automotive, industrial motor drives, and high-ambient environments. |
| Package | SMA (DO-214AC) - Surface-mount outline with 5.28 mm length, 4.50 mm width, and 2.29 mm height; compatible with automated placement. |
Pinout & Package
Package: SMA (DO-214AC), bidirectional configuration with no polarity marking - terminals are symmetrical and interchangeable. Mounting requires 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal for rated power dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Transient conduction path | Both terminals function identically in bidirectional mode; no cathode band marking - enables flexible PCB layout without orientation constraints. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units and ADAS sensor interfaces requiring long-term reliability under thermal cycling and vibration. |
| Halogen-free & RoHS-compliant (HM3 suffix) | Meets IEC 61249-2-21 and JEDEC J-STD-203B; eliminates brominated flame retardants for safer end-of-life processing and regulatory compliance. |
| 400 W peak pulse power (10/1000 μs) | Withstands high-energy transients from inductive load switching (e.g., solenoid drivers, relay coils) without degradation. |
| Fast response time & low clamping ratio | Sub-nanosecond turn-on and VC/VBR ≈ 1.33 ensure minimal overvoltage exposure to protected ICs like microcontrollers or CAN transceivers. |
| MSL Level 1, 260 °C peak reflow | Supports single-pass lead-free assembly without preconditioning; eliminates moisture-related popcorning risk during manufacturing. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 12 V/24 V vehicle battery-fed ECUs against load dump (ISO 7637-2 Pulse 5a) and alternator transients. IC Role / Device Role / Timing Role: Bidirectional clamping element placed directly at power entry point to shunt surge energy before it reaches LDOs or MCU power pins. Use Value: Limits voltage excursion to ≤126 V during 3.2 A surges, preserving system uptime and meeting OEM EMC immunity requirements. |
Use Scenario: Safeguarding analog outputs (4–20 mA) and digital I/O (I²C, SPI) of pressure/temperature sensors in factory automation. IC Role / Device Role / Timing Role: Low-capacitance (≈100 pF at 0 V) TVS placed adjacent to connector pins to suppress ESD (IEC 61000-4-2 ±8 kV contact) and cable-induced surges. Use Value: Prevents latch-up or permanent damage to precision ADC front-ends while maintaining signal fidelity due to sub-μA leakage at 78 V. |
| Telecom DC Power Input Protection | Consumer Appliance Motor Drive Protection |
|
Use Scenario: Securing PoE-powered equipment (e.g., IP cameras, access points) against induced lightning surges on 48 V DC input lines. IC Role / Device Role / Timing Role: Primary overvoltage clamp upstream of DC/DC converter, coordinated with secondary TVS or MOV for staged protection. Use Value: Handles repetitive 400 W pulses without parameter drift, ensuring multi-year field reliability in outdoor deployments. |
Use Scenario: Shielding microcontroller GPIOs and gate drivers in washing machine motor control boards from commutation spikes. IC Role / Device Role / Timing Role: Fast-acting transient suppressor across H-bridge supply rails and feedback sensing nodes exposed to brushless motor back-EMF. Use Value: Withstands 40 A non-repetitive forward surge (IFSM), preventing failure during stall or startup events in high-inertia loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78CAHE3/H | Same electrical specs and AEC-Q101 qualification, but RoHS-compliant with standard tin plating (not halogen-free). | Acceptable for commercial/industrial use where halogen-free mandate does not apply; lower cost than HM3 variant. | Select when halogen-free requirement is absent and cost optimization is prioritized without sacrificing automotive qualification. |
| SMBJ78CAHM3 | Same VWM/VBR/VC ratings but in larger SMB (DO-214AA) package; higher PPPM (600 W) and IPPM (5.0 A), RθJA = 80 °C/W. | Better thermal performance and surge margin; requires larger PCB footprint and different pad layout. | Choose when higher surge endurance or improved thermal management is needed, and board space allows SMB footprint. |
Compared with SMAJ78CAHM3/H, SMAJ78CAHE3/H offers identical protection performance without halogen-free compliance, while SMBJ78CAHM3 provides greater surge headroom and thermal capability at the expense of size - enabling trade-offs between footprint, reliability, and regulatory scope.
Availability
SMAJ78CAHM3/H is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor systems, and telecom power input circuits requiring stable component supply, halogen-free compliance, and AEC-Q101 validation.
Supply support for SMAJ78CAHM3/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 performance.
The SMAJ series is engineered for high-speed transient suppression in harsh environments - targeting automotive, industrial, and communications systems where consistent clamping, low leakage, and AEC-Q101 validation are mandatory.
FAQ
What is the clamping voltage of SMAJ78CAHM3/H at its rated peak pulse current?
The SMAJ78CAHM3/H has a maximum clamping voltage (VC) of 126 V at its specified peak pulse current (IPPM) of 3.2 A under a 10/1000 μs waveform. This value is measured per ANSI/IEEE C62.35 standards and ensures predictable overvoltage limiting during surge events. The clamping performance is verified across temperature and production lots, making SMAJ78CAHM3/H suitable for safety-critical protection schemes where voltage overshoot must remain bounded.
Is SMAJ78CAHM3/H qualified for automotive applications?
Yes, SMAJ78CAHM3/H is AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HM3" and documentation in datasheet 88390 (Revision 09-Jan-2024). This qualification covers stress tests including high-temperature operating life, temperature cycling, and mechanical shock - validating its suitability for engine control modules, body electronics, and ADAS sensor units. The "HM3" designation also confirms halogen-free and RoHS-compliant construction required by Tier 1 automotive suppliers.
How does the bidirectional configuration of SMAJ78CAHM3/H affect circuit design?
The bidirectional configuration of SMAJ78CAHM3/H means it functions identically in both polarities - no cathode marking is present, and terminals are interchangeable. This simplifies PCB layout by eliminating orientation constraints and enables protection of AC-coupled signals or dual-rail supplies without additional components. Unlike unidirectional variants, SMAJ78CAHM3/H suppresses transients regardless of polarity, making it ideal for data lines, transformer-coupled interfaces, and floating power domains where voltage reversal may occur.
What is the maximum operating junction temperature for SMAJ78CAHM3/H?
The maximum operating junction temperature (TJ max.) for SMAJ78CAHM3/H is +150 °C, as specified in the Thermal Characteristics table of datasheet 88390. This rating allows sustained operation in high-ambient environments such as under-hood automotive locations or enclosed industrial enclosures. Derating curves (Fig. 2) confirm usable power dissipation down to ~1.5 W at +125 °C ambient, supporting robust thermal design when mounted on recommended 0.2" × 0.2" copper pads.
Does SMAJ78CAHM3/H meet moisture sensitivity level (MSL) requirements for lead-free reflow?
Yes, SMAJ78CAHM3/H meets MSL Level 1 per J-STD-020, with a maximum peak reflow temperature of 260 °C. This allows direct placement into lead-free soldering processes without baking or dry-pack handling. The device's matte tin-plated leads comply with J-STD-002 and JESD 22-B102 for solderability, and its molding compound satisfies UL 94 V-0 flammability - collectively ensuring manufacturability in high-volume SMT lines without process modifications.
SMAJ78CAHM3/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:
- Discontinued at Digi-Key
- 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/H FAQ
1.How can I place an order for SMAJ78CAHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CAHM3/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 SMAJ78CAHM3/H reliable?
The price and inventory of SMAJ78CAHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CAHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ78CAHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CAHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CAHM3/H?
SMAJ78CAHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CAHM3/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 SMAJ78CAHM3/H?
For technical support, including SMAJ78CAHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CAHM3/H requirements.
6.How does Aetrix verify that SMAJ78CAHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ78CAHM3/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 SMAJ78CAHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ78CAHM3/H?
All SMAJ78CAHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CAHM3/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 SMAJ78CAHM3/H part is unused and in its original packaging.
Return procedure for SMAJ78CAHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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