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Vishay General Semiconductor - Diodes Division SMAJ51AHM3/H
- Part No.:
- SMAJ51AHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51AHM3/H.pdf
- Description:
- TVS DIODE 51VWM 82.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:3,600
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Product details
Overview
SMAJ51AHM3/H from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for robust overvoltage protection in power and signal lines. It features a 51 V standoff voltage (VWM), 56.7–62.7 V breakdown range at 1 mA test current, 82.4 V maximum clamping voltage at 4.9 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform - deployed to safeguard MOSFETs, ICs, and sensor interfaces against inductive switching transients and ESD in automotive and industrial control systems.
For engineers reviewing the SMAJ51AHM3/H datasheet, SMAJ51AHM3/H pinout, SMAJ51AHM3/H application, or SMAJ51AHM3/H equivalent, key selection criteria include its AEC-Q101 qualification (HM3 suffix), halogen-free RoHS compliance, SMA (DO-214AC) package thermal performance (RθJA = 120 °C/W), and verified clamping behavior under repetitive surge conditions up to 150 °C junction temperature.
Technical Context
This TVS diode operates as a unidirectional avalanche clamp: reverse-biased during normal operation with ≤1.0 μA leakage at 51 V, then rapidly avalanches when transient voltage exceeds VBR (min 56.7 V), limiting downstream voltage to ≤82.4 V at 4.9 A. Its glass-passivated junction ensures stable breakdown and low incremental surge resistance.
Designed for surface-mount assembly on standard PCB copper pads (0.2" × 0.2"), it delivers 400 W peak pulse power below 78 V and derates linearly above that threshold per Fig. 2; polarity is marked by cathode band, and it meets MSL Level 1 per J-STD-020 with 260 °C reflow peak.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before conduction begins; defines safe operating margin for 48 V nominal systems. |
| VBR (min/max) | 56.7 V / 62.7 V at IT = 1 mA - Confirmed breakdown range ensures reliable triggering without premature clamping. |
| VC @ IPPM | 82.4 V at 4.9 A - Clamped voltage under 10/1000 μs surge; determines maximum stress imposed on protected IC or MOSFET. |
| PPPM | 400 W - Peak pulse power handling with 10/1000 μs waveform; validates protection capability against common load-switching transients. |
| IFSM | 40 A - Non-repetitive forward surge current rating (8.3 ms half-sine); supports unidirectional placement in DC power rail protection. |
| TJ max | +150 °C - Maximum junction temperature; enables use in under-hood automotive and high-ambient industrial environments. |
| RθJA | 120 °C/W - Thermal resistance junction-to-ambient on standard pad layout; informs derating requirements for sustained power dissipation. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile plastic case with matte tin-plated leads solderable per J-STD-002 and JESD 22-B102; cathode identified by molded band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry (unidirectional) | Connected to lower-potential side of protected circuit; conducts only during forward surge events (e.g., reverse polarity fault). |
| Cathode | Reverse-biased terminal (marked with band) | Connected to higher-potential rail (e.g., +VIN); initiates avalanche clamping when transient exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and surge endurance - required for engine control, body electronics, and ADAS power rails. |
| Halogen-free & RoHS-compliant (HM3) | Meets global environmental regulations without compromising thermal or electrical performance; supports green manufacturing and export compliance. |
| 400 W peak pulse power (10/1000 μs) | Provides proven immunity to ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 surge events in 12/24 V systems. |
| Low clamping ratio (VC/VBR ≈ 1.45) | Minimizes voltage overshoot during clamping - critical for protecting 5 V, 3.3 V, or 12 V logic interfaces adjacent to power stages. |
| MSL Level 1 moisture sensitivity | Enables standard SMT reflow without baking; reduces production risk and cost in high-volume automotive and industrial assembly. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 12 V supply inputs of engine control units (ECUs) and body control modules (BCMs) against load dump and inductive kickback. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp transients before they reach LDOs or microcontrollers. Use Value: Withstands 400 W surges and maintains VC ≤ 82.4 V, ensuring downstream 5 V regulators remain within absolute maximum ratings during ISO 7637-2 Pulse 5a events. |
Use Scenario: Shielding analog and digital signal lines (e.g., CAN, LIN, or ADC inputs) in factory automation sensors exposed to relay switching noise. IC Role / Device Role / Timing Role: Low-capacitance TVS mounted at connector entry point to divert fast transients (<1 ns rise time) away from precision front-end circuitry. Use Value: Sub-100 pF junction capacitance (typ.) avoids signal integrity degradation on 1 Mbps CAN buses while clamping EFT bursts per IEC 61000-4-4. |
| DC-DC Converter Input Protection | Consumer Power Adapter Output Protection |
|
Use Scenario: Safeguarding buck converter ICs and MOSFETs in telecom power supplies subjected to hot-swap and cable discharge events. IC Role / Device Role / Timing Role: Primary-side TVS placed across input bulk capacitor to absorb energy from 10/1000 μs surges before reaching controller IC gate drivers. Use Value: 40 A IFSM rating supports single-event fault clearing without bond wire fusing; RθJL = 30 °C/W enables effective heat transfer to PCB copper. |
Use Scenario: Adding secondary-side overvoltage protection to USB-C PD adapters and laptop chargers to meet UL 62368-1 transient immunity requirements. IC Role / Device Role / Timing Role: Final-stage TVS on regulated 20 V output rail to prevent damage to connected devices during open-circuit or feedback loop failure. Use Value: Halogen-free HM3 construction satisfies end-product sustainability mandates; 150 °C TJ max accommodates enclosed thermal environments without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51AHE3/H | Same electrical specs and package, but RoHS-compliant commercial grade (E3) without halogen-free certification or AEC-Q101 qualification. | Lacks automotive qualification and halogen-free status; suitable for non-automotive industrial or consumer designs where those attributes are not mandated. | Select SMAJ51AHE3/H only if AEC-Q101 and halogen-free compliance are unnecessary and cost optimization is prioritized. |
| SMAJ51A-M3/61 | Identical electrical parameters and halogen-free RoHS compliance, but packaged in 7" tape-and-reel (61 code) instead of H-code carrier; no AEC-Q101 validation. | Not qualified for automotive use; differs only in packaging format and qualification status - not functional or electrical replacement. | Choose SMAJ51A-M3/61 for high-volume commercial production requiring alternate reel configuration, provided AEC-Q101 is not required. |
Compared with SMAJ51AHM3/H, SMAJ51AHE3/H omits automotive qualification and halogen-free assurance, while SMAJ51A-M3/61 retains halogen-free compliance but lacks AEC-Q101 validation - making SMAJ51AHM3/H the sole option meeting full automotive-grade material and reliability requirements in the SMAJ51A family.
Availability
SMAJ51AHM3/H is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface hardening, and DC-DC converter input surge suppression requiring stable component supply across multi-year production cycles.
Supply support for SMAJ51AHM3/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, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific performance.
The SMAJ series was developed specifically for high-energy transient suppression in automotive, industrial, and telecom power systems - delivering standardized 400 W surge capability in compact DO-214AC packaging with rigorous qualification for harsh environments.
FAQ
What is the clamping voltage of SMAJ51AHM3/H under a 10/1000 μs surge?
The SMAJ51AHM3/H exhibits a maximum clamping voltage (VC) of 82.4 V when subjected to its rated peak pulse current of 4.9 A with a 10/1000 μs waveform. This value is measured per standard test conditions (TA = 25 °C) and defines the upper voltage limit imposed on protected circuitry during transient events. The SMAJ51AHM3/H maintains this clamping performance consistently due to its glass-passivated junction and low incremental surge resistance.
Is SMAJ51AHM3/H qualified for automotive applications?
Yes, SMAJ51AHM3/H is AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HM3" (halogen-free, RoHS-compliant, and AEC-Q101 qualified). This qualification covers stress tests including temperature cycling, high-temperature reverse bias, and surge endurance - validating its suitability for under-hood and chassis-mounted automotive electronics such as ECUs, ADAS modules, and body control units. The SMAJ51AHM3/H meets the reliability requirements for automotive-grade TVS deployment.
What does the "HM3" suffix indicate for SMAJ51AHM3/H?
The "HM3" suffix in SMAJ51AHM3/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification - distinguishing it from commercial variants like E3 (RoHS only) or M3 (halogen-free but not AEC-Q101 validated). This suffix confirms compliance with automotive material standards (e.g., JESD201 Class 2 whisker resistance) and environmental regulations, and is tied to specific manufacturing lots and traceability protocols. The SMAJ51AHM3/H must be specified with this exact suffix to guarantee full qualification.
Can SMAJ51AHM3/H be used in bidirectional configurations?
No, SMAJ51AHM3/H is a unidirectional TVS diode, as indicated by the "A" (not "CA") in its part number and the presence of a cathode band marking. Bidirectional operation requires the "CA" suffix (e.g., SMAJ51CA), which has symmetrical breakdown in both polarities. Using SMAJ51AHM3/H in reverse-biased AC or floating signal paths will result in forward conduction and potential failure. Always verify polarity alignment: cathode to higher potential for proper clamping. The SMAJ51AHM3/H is engineered exclusively for DC rail protection with defined polarity.
What is the thermal resistance of SMAJ51AHM3/H, and how does it affect layout?
The SMAJ51AHM3/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal - a standard reference layout defined in Vishay's datasheet. This value directly impacts power derating: at 50 °C ambient, its 3.3 W steady-state power dissipation limit drops significantly under surge duty cycles. To maintain reliability, PCB layout must replicate the recommended pad dimensions and avoid excessive trace length or isolation. The SMAJ51AHM3/H thermal performance is optimized for this specific footprint.
SMAJ51AHM3/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:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 4.9A
- 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)
SMAJ51AHM3/H FAQ
1.How can I place an order for SMAJ51AHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51AHM3/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 SMAJ51AHM3/H reliable?
The price and inventory of SMAJ51AHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51AHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ51AHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51AHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51AHM3/H?
SMAJ51AHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51AHM3/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 SMAJ51AHM3/H?
For technical support, including SMAJ51AHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51AHM3/H requirements.
6.How does Aetrix verify that SMAJ51AHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ51AHM3/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 SMAJ51AHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ51AHM3/H?
All SMAJ51AHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51AHM3/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 SMAJ51AHM3/H part is unused and in its original packaging.
Return procedure for SMAJ51AHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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