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Vishay General Semiconductor - Diodes Division SMAJ78CAHE3/61
- Part No.:
- SMAJ78CAHE3/61
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CAHE3/61.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,970
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Product details
Overview
SMAJ78CAHE3/61 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 standoff 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 (10/1000 μs waveform) - rated for automotive-grade reliability per AEC-Q101.
For engineers reviewing the SMAJ78CAHE3/61 datasheet, SMAJ78CAHE3/61 pinout, SMAJ78CAHE3/61 application, or SMAJ78CAHE3/61 equivalent, this device serves as a surface-mount solution for protecting power rails and signal lines against ESD, lightning-induced surges, and inductive switching transients in automotive ECUs, industrial sensor interfaces, and telecom power supplies.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, with identical electrical characteristics in forward and reverse directions. Its glass-passivated junction enables fast response time (<1 ns), low incremental surge resistance, and stable clamping performance under repetitive 10/1000 μs transients at 0.01% duty cycle.
The device is rated for operation from −55 °C to +150 °C junction temperature, with thermal resistance of 120 °C/W (junction-to-ambient) on standard 0.2" × 0.2" copper pads. It meets MSL Level 1 per J-STD-020 and is RoHS-compliant with matte tin-plated leads solderable per J-STD-002.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse operating voltage before clamping begins; defines safe operating margin for 72–80 V nominal DC rails. |
| VBR (min/max) | 86.7 V / 95.8 V at IT = 1 mA - ensures reliable triggering above system operating voltage while maintaining noise immunity. |
| VC @ IPPM | 126 V at 3.2 A - limits transient voltage seen by downstream ICs during 400 W surge events, protecting 100 V-rated components. |
| PPPM | 400 W (≤78 V); 300 W (>78 V) - peak pulse power rating for 10/1000 μs waveform, derated linearly above TA = 25 °C. |
| IFSM | 40 A - non-repetitive forward surge current rating (8.3 ms half-sine), supporting inrush and fault-current handling in unidirectional variants. |
| Junction Temp Range | −55 °C to +150 °C - enables deployment in under-hood automotive, industrial motor drives, and outdoor telecom equipment. |
| Package | SMA (DO-214AC) - surface-mount, low-profile package compatible with automated placement and reflow soldering (peak 260 °C). |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; polarity-unmarked for bidirectional operation (no cathode band).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry point (positive polarity) | Connects to protected line; conducts during positive transients to clamp voltage to VC. |
| Cathode | Transient current entry point (negative polarity) | Connects to protected line; conducts during negative transients to clamp voltage to VC - functionally symmetric to Anode in bidirectional mode. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Identical VBR, VC, and IPPM in both directions - eliminates polarity concerns in AC-coupled or floating signal lines. |
| AEC-Q101 qualification | Validated for automotive applications including engine control, body electronics, and ADAS sensors - supports PPAP and long-term reliability requirements. |
| 400 W peak pulse power | Withstands high-energy transients per ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 Level 3 without degradation. |
| Low clamping ratio (VC/VBR ≈ 1.34) | Minimizes let-through voltage during surge events - critical for safeguarding 80 V-tolerant microcontrollers and CAN transceivers. |
| MSL Level 1 moisture sensitivity | Enables standard SMT reflow without baking - reduces manufacturing overhead and avoids moisture-related popcorning. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Signal Line Protection |
|---|---|
|
Use Scenario: Protecting 12 V/24 V battery-fed ECUs against load dump and alternator transients per ISO 7637-2. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC-DC converters and microcontroller power inputs. Use Value: Limits transient voltage to ≤126 V, preventing latch-up or permanent damage to 100 V-rated power management ICs. |
Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loops) in factory automation sensors from ESD and cable discharge events. IC Role / Device Role / Timing Role: Bidirectional shunt protector mounted at connector interface to divert fast transients before reaching precision ADC front-end. Use Value: Sub-1 ns response ensures clamping occurs before 100 ns rise-time ESD pulses propagate into signal conditioning circuitry. |
| Telecom DC Power Input Protection | Consumer Device USB/Type-C Port Protection |
|
Use Scenario: Safeguarding −48 V telecom rectifier outputs against lightning-induced surges entering via distribution cabling. IC Role / Device Role / Timing Role: Secondary-level TVS placed after primary MOVs to handle residual fast-rising energy not absorbed upstream. Use Value: 300–400 W rating handles multiple 10/1000 μs surges without parameter drift, ensuring long service life in central office equipment. |
Use Scenario: Adding robustness to USB PD 3.0 power delivery paths in laptops and docking stations exposed to user-handling ESD. IC Role / Device Role / Timing Role: Low-capacitance bidirectional clamp across VBUS and GND to suppress ±15 kV contact ESD per IEC 61000-4-2. Use Value: 78 V VWM allows safe operation with 20 V PD profiles while clamping to 126 V - well below typical 16 V OVP thresholds of PD controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78CA-M3/61 | Same electrical specs; halogen-free, RoHS-compliant variant without AEC-Q101 qualification. | Suitable for commercial/industrial use where automotive qualification is not required. | Select when cost-sensitive designs prioritize halogen-free compliance over automotive reliability validation. |
| SMBJ78CAHE3/61 | Same VWM/VBR/VC; higher 600 W PPPM rating in larger SMB (DO-214AA) package. | Better suited for higher-energy surge environments (e.g., outdoor base stations) where PCB space permits larger footprint. | Choose when system-level surge testing exceeds 400 W and thermal dissipation margin is constrained by ambient conditions. |
Compared with SMAJ78CAHE3/61, the M3 variant trades AEC-Q101 qualification for halogen-free compliance, while the SMBJ78CAHE3/61 offers 50% higher surge power handling in a physically larger package - enabling design flexibility between automotive robustness, environmental compliance, and energy absorption capacity.
Availability
SMAJ78CAHE3/61 is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor interfaces, telecom power inputs, and consumer USB PD systems requiring stable component supply with full traceability and lifecycle support.
Supply support for SMAJ78CAHE3/61 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, efficiency, and application-specific optimization.
The SMAJ series targets high-reliability transient suppression in space-constrained, high-volume applications - engineered for automotive, industrial, and telecom markets where consistent clamping performance and AEC-Q101 validation are mandatory.
FAQ
What is the clamping voltage of SMAJ78CAHE3/61 at its rated peak pulse current?
The SMAJ78CAHE3/61 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 waveform. This value ensures downstream components rated for ≤130 V remain within safe operating limits during surge events. The clamping behavior is symmetric in both directions due to its bidirectional construction.
Is SMAJ78CAHE3/61 qualified for automotive applications?
Yes, SMAJ78CAHE3/61 is AEC-Q101 qualified, as indicated by the "HE3" suffix in its part number. This certification confirms it meets stress test requirements for temperature cycling, humidity bias, mechanical shock, and high-temperature operating life - making it suitable for under-hood and chassis-mounted automotive electronics such as body control modules and ADAS power supplies.
How does the bidirectional nature of SMAJ78CAHE3/61 affect its PCB layout?
The SMAJ78CAHE3/61 has no polarity marking (no cathode band), simplifying PCB layout by eliminating orientation constraints. Engineers can place it inline with any two-terminal path - such as across a DC rail or differential signal pair - without verifying anode/cathode alignment. This reduces assembly errors and supports automated optical inspection (AOI) compatibility in high-mix manufacturing.
What is the thermal resistance of SMAJ78CAHE3/61, and how does it impact power derating?
SMAJ78CAHE3/61 has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" copper pads. At ambient temperatures above 25 °C, its peak pulse power must be linearly derated per Figure 2 in the datasheet - e.g., at 75 °C ambient, maximum PPPM drops to ~280 W. Proper pad sizing and thermal vias improve heat dissipation and maintain clamping integrity during repetitive surges.
Can SMAJ78CAHE3/61 replace SMAJ78AHE3/61 in a design?
No - SMAJ78CAHE3/61 is bidirectional, while SMAJ78AHE3/61 is unidirectional. Replacing one with the other requires verifying circuit topology: unidirectional types require correct polarity placement relative to ground, whereas bidirectional types may introduce leakage paths in DC-biased rails. Always confirm VBR, VC, and application context before substitution; SMAJ78CAHE3/61 is not a drop-in replacement for SMAJ78AHE3/61.
SMAJ78CAHE3/61 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ78CAHE3/61 FAQ
1.How can I place an order for SMAJ78CAHE3/61 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CAHE3/61 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 SMAJ78CAHE3/61 reliable?
The price and inventory of SMAJ78CAHE3/61 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CAHE3/61 is usually 5 days.
3.What payment methods are accepted for SMAJ78CAHE3/61?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CAHE3/61 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CAHE3/61?
SMAJ78CAHE3/61 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CAHE3/61 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 SMAJ78CAHE3/61?
For technical support, including SMAJ78CAHE3/61 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CAHE3/61 requirements.
6.How does Aetrix verify that SMAJ78CAHE3/61 is sourced from the original manufacturer or authorized distributors?
All SMAJ78CAHE3/61 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 SMAJ78CAHE3/61 meets industry standards.
7.What is the process for return or replacement of SMAJ78CAHE3/61?
All SMAJ78CAHE3/61 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CAHE3/61, 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 SMAJ78CAHE3/61 part is unused and in its original packaging.
Return procedure for SMAJ78CAHE3/61:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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