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Taiwan Semiconductor Corporation SMAJ51H
- Part No.:
- SMAJ51H
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51H.pdf
- Description:
- TVS DIODE 51VWM 91.1VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:5,118
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Product details
Overview
SMAJ51H from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 51V working stand-off voltage (VWM), 56.7–69.3V breakdown voltage (VBR), and 91.1V clamping voltage (VC) at 4.4A peak pulse current. It delivers AEC-Q101 qualification and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.
For engineers reviewing the SMAJ51H datasheet, SMAJ51H pinout, SMAJ51H application, or SMAJ51H equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, automotive ECUs, and industrial power rails where fast response (<1.0 ps), low leakage (<1 µA @ 51V), and stable clamping under 10/1000 µs transients are required.
Technical Context
The SMAJ51H operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its VBR range (56.7–69.3 V @ 1 mA). Its glass-passivated junction ensures stable breakdown behavior and low leakage (<1 µA @ VWM = 51 V), while its DO-214AC package supports automated placement and meets JESD201 Class 2 whisker resistance.
It sustains 400W peak pulse power per 10/1000 µs waveform up to TA = 25°C, derating linearly above that temperature, and clamps transients to ≤91.1 V at IPPM = 4.4 A - enabling reliable protection of 51V-rated downstream circuitry such as CAN transceivers, microcontroller I/O, and gate drivers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before conduction begins; sets system-level surge immunity threshold. |
| VBR @ IT = 1 mA | 56.7–69.3 V - Confirmed breakdown range ensuring consistent turn-on across production lots and temperature. |
| VC @ IPPM = 4.4 A | 91.1 V - Clamped voltage during 10/1000 µs transient; defines maximum stress on protected ICs. |
| PPPM | 400 W - Peak pulse power handling capability; validates suitability for ISO 7637-2 Pulse 1 and 2b waveforms. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks and battery-backed circuits. |
| TJ max | +150 °C - Junction temperature rating enabling operation in under-hood automotive environments and enclosed industrial enclosures. |
Pinout & Package
DO-214AC (SMA) surface-mount package with cathode band marking; matte tin-plated leads compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance. Polarity is unidirectional: anode and cathode terminals defined by molded cathode band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (non-banded end) | Reference node for reverse-biased operation | Connected to ground or low-impedance return path; establishes reference for clamping action. |
| Cathode (banded end) | Transient current sink terminal | Connected to protected line (e.g., 51V rail); conducts surge current to ground during overvoltage events. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - suitable for engine control units and ADAS power domains. |
| Glass passivated junction | Ensures stable VBR tolerance and long-term leakage stability across humidity and thermal stress conditions. |
| Fast response time <1.0 ps | Enables suppression of nanosecond-scale ESD and lightning-induced transients before sensitive logic is damaged. |
| Meets ISO 7637-2 Pulse 1/2a/2b/3a/3b | Guarantees compliance with automotive supply-line transient immunity standards without external filtering augmentation. |
| Moisture sensitivity level 1 (J-STD-020) | Allows unlimited floor life and standard reflow without baking - simplifies SMT manufacturing flow. |
Applications
| Automotive Engine Control Unit (ECU) Power Input | Industrial 48V DC/DC Converter Primary Side |
|---|---|
Use Scenario: Protecting 51V nominal supply input of engine control module against load dump (ISO 7637-2 Pulse 5a) and alternator switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp surges before they reach DC/DC controller IC. Use Value: Limits transient voltage to ≤91.1 V at 4.4 A, preventing latch-up or damage to 65V-rated buck controller and associated gate drivers. | Use Scenario: Safeguarding primary-side MOSFET gate driver and controller in isolated 48V-to-12V flyback converter subjected to line surges. IC Role / Device Role / Timing Role: Standoff-rated TVS connected across bulk capacitor input to absorb repetitive 10/1000 µs transients induced by nearby motor switching. Use Value: 400W peak power rating and <1 µA leakage ensure no standby power penalty while maintaining immunity to 300V/500ms pulses per IEC 61000-4-5. |
| Telecom Remote Radio Head (RRH) Power Interface | Medical Imaging Power Supply Input Stage |
Use Scenario: Securing 51V auxiliary power input of outdoor RRH unit exposed to induced lightning surges on long cable runs. IC Role / Device Role / Timing Role: First-stage transient protector upstream of DC-DC modules and FPGA power sequencing ICs. Use Value: 91.1 V clamping voltage ensures downstream 100V-rated input capacitors and controllers remain within safe operating area during Category C3 surges. | Use Scenario: Protecting diagnostic imaging equipment's internal 51V subsystem rail from mains-coupled transients during hospital-grade power switching. IC Role / Device Role / Timing Role: Secondary-side TVS on regulated 51V bus feeding detector bias supplies and analog front-end ASICs. Use Value: AEC-Q101 qualification and halogen-free construction meet medical safety and environmental compliance (IEC 60601-1, RoHS, IEC 61249-2-21) without compromising clamping performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51AH | Narrower VBR range (56.7–62.7 V vs. 56.7–69.3 V); tighter 5% tolerance on VWM. | Better suited for precision-clamp designs requiring minimal VC variation across temperature and lot. | Select SMAJ51AH when VBR consistency is prioritized over worst-case clamping margin. |
| SMBJ51A | Same VWM/VBR specs but in larger DO-214AA (SMB) package; 600W PPPM rating. | Higher power handling enables use in higher-energy surge environments (e.g., industrial AC/DC front ends). | Choose SMBJ51A only if board space allows larger footprint and 600W headroom is required beyond ISO 7637-2 compliance. |
Compared with SMAJ51AH and SMBJ51A, the SMAJ51H offers broader VBR tolerance for cost-sensitive automotive and industrial designs where clamping margin >40V is acceptable, while retaining identical DO-214AC footprint and AEC-Q101 qualification.
Availability
SMAJ51H is available at Aetrix Electronics and suitable for automotive ECU power inputs, industrial 48V DC/DC converters, telecom remote radio heads, and medical imaging subsystems requiring stable component supply and full AEC-Q101 traceability.
Supply support for SMAJ51H 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs, with global distribution and AEC-Q101 validation capabilities.
The SMAJ series is designed specifically for automotive and industrial transient suppression, emphasizing high-reliability packaging, tight process control for VBR, and compliance with ISO 7637-2 and J-STD-020 standards.
FAQ
What is the clamping voltage of SMAJ51H at its rated peak pulse current?
The SMAJ51H has a maximum clamping voltage (VC) of 91.1 V at IPPM = 4.4 A, measured using the standardized 10/1000 µs double-exponential transient waveform. This value is guaranteed across temperature and production lots, and defines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ51H maintains this clamping performance while delivering 400W peak pulse power dissipation.
Is SMAJ51H suitable for bidirectional transient protection?
No, SMAJ51H is a unidirectional TVS diode intended for DC line protection with defined polarity. For bidirectional applications (e.g., AC lines or data buses), Taiwan Semiconductor specifies parts with CH or CAH suffixes - such as SMAJ51CH - which feature symmetrical breakdown in both directions. Using SMAJ51H in reverse-biased AC configurations risks forward conduction and failure; always verify polarity alignment in schematic and layout for SMAJ51H.
Does SMAJ51H meet automotive qualification standards?
Yes, SMAJ51H is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b transient immunity requirements. Its DO-214AC package is rated for moisture sensitivity level 1 (J-STD-020), and it complies with RoHS and halogen-free standards (IEC 61249-2-21). These qualifications make SMAJ51H appropriate for under-hood and body-control module applications where reliability under thermal and mechanical stress is mandatory.
What is the maximum steady-state power dissipation of SMAJ51H?
The SMAJ51H has a steady-state power dissipation (PD) rating of 1 W at TA = 25°C. This value applies only to continuous DC or low-frequency reverse-bias conditions - not transient events. In normal operation, reverse leakage remains below 1 µA at 51 V, resulting in negligible static power loss (<51 µW). The 1 W rating primarily informs thermal design margins during abnormal sustained overvoltage conditions, not typical clamping duty cycles.
How does SMAJ51H differ from SMAJ51AH?
SMAJ51H and SMAJ51AH share identical VWM (51 V) and package (DO-214AC), but differ in VBR tolerance: SMAJ51H specifies 56.7–69.3 V (±11%), while SMAJ51AH narrows this to 56.7–62.7 V (±5%). This results in lower typical VC (82.4 V vs. 91.1 V) for SMAJ51AH at the same IPPM. Both parts are AEC-Q101 qualified and ISO 7637-2 compliant; selection depends on whether design priority is cost (SMAJ51H) or tighter clamping consistency (SMAJ51AH).
SMAJ51H Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 91.1V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- 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)
SMAJ51H FAQ
1.How can I place an order for SMAJ51H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51H 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 SMAJ51H reliable?
The price and inventory of SMAJ51H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51H is usually 5 days.
3.What payment methods are accepted for SMAJ51H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51H?
SMAJ51H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51H 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 SMAJ51H?
For technical support, including SMAJ51H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51H requirements.
6.How does Aetrix verify that SMAJ51H is sourced from the original manufacturer or authorized distributors?
All SMAJ51H 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 SMAJ51H meets industry standards.
7.What is the process for return or replacement of SMAJ51H?
All SMAJ51H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51H, 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 SMAJ51H part is unused and in its original packaging.
Return procedure for SMAJ51H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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