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Taiwan Semiconductor Corporation SMAJ51AH
- Part No.:
- SMAJ51AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51AH.pdf
- Description:
- TVS DIODE 51VWM 82.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,539
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Product details
Overview
SMAJ51AH 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), 56.7–62.7V breakdown voltage (VBR), and 82.4V maximum clamping voltage (VC) at 4.9A peak impulse 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 SMAJ51AH datasheet, SMAJ51AH pinout, SMAJ51AH application, or SMAJ51AH equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, lighting drivers, and automotive electronics where fast response (<1.0 ps), low leakage (<1 µA @ VWM), and stable clamping under 10/1000 µs transients are critical.
Technical Context
The SMAJ51AH operates as a unidirectional avalanche diode with glass-passivated junction, optimized for clamping induced transients on DC power rails. Its 150°C maximum junction temperature and -55°C to +150°C operating range support under-hood automotive environments and industrial power supplies.
It exhibits <1.0 ps response time from 0 V to VBR(min), 400W peak pulse power (10/1000 µs), and 1 W steady-state dissipation. The device complies with JESD201 Class 2 whisker resistance and moisture sensitivity level 1 per J-STD-020 - enabling high-reliability automated SMT assembly without baking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before significant leakage begins; defines safe DC rail margin. |
| VBR @ IT=1 mA | 56.7–62.7 V - Breakdown threshold range; ensures reliable triggering above nominal system voltage. |
| VC @ IPPM=4.9 A | 82.4 V - Clamped voltage during 10/1000 µs surge; limits downstream IC stress to ≤82.4 V. |
| PPPM | 400 W - Peak pulse power handling (10/1000 µs); supports high-energy load dump and inductive switching events. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage at rated stand-off; avoids parasitic drain in battery-backed or low-power systems. |
| Junction Temp Range | -55°C to +150°C - Enables deployment in engine control units, LED drivers, and industrial power modules. |
| AEC-Q101 Qualified | Yes - Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing. |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Matte tin-plated leads meet J-STD-002 solderability; weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or return path; defines polarity for unidirectional clamping. |
| Cathode | High-side transient input terminal | Connected to protected line (e.g., 48V rail); conducts surge current to ground when VIN exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics per stress test requirements - enables use in ADAS, body control, and infotainment power rails. |
| Glass passivated junction | Enhances long-term stability and humidity resistance vs. epoxy-passivated alternatives - critical for under-hood reliability. |
| <1.0 ps response time | Clamps transients before sensitive downstream logic or analog circuitry responds - prevents latch-up or data corruption. |
| ISO 7637-2 compliance | Withstands standardized automotive electrical disturbances (Pulse 1, 2a, 2b, 3a, 3b) without degradation - simplifies EMC validation. |
| Moisture sensitivity level 1 | Zero bake requirement prior to reflow - reduces manufacturing cost and process complexity in high-volume SMT lines. |
Applications
| Automotive Power Rail Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 48V battery-fed ECUs against load dump and alternator transients in passenger vehicles. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed at main power entry point to clamp surges to ≤82.4 V. Use Value: Prevents damage to buck controllers, CAN transceivers, and microcontrollers during ISO 7637-2 Pulse 5a events up to 400W. |
Use Scenario: Safeguarding isolated flyback or forward converter primary-side inputs in factory automation power supplies. IC Role / Device Role / Timing Role: Standoff protector absorbing inductive kickback from relay coils and motor drivers. Use Value: Limits voltage overshoot to 82.4 V during 10/1000 µs transients, preserving MOSFET gate oxide integrity and feedback optocoupler operation. |
| LED Driver Overvoltage Clamp | SMPS Secondary-Side Surge Suppression |
Use Scenario: Securing constant-current LED drivers in streetlight and tunnel lighting against lightning-induced surges on 24–48V DC distribution lines. IC Role / Device Role / Timing Role: Fast-clamping unidirectional TVS across output terminals to absorb line-to-ground transients. Use Value: Maintains LED string integrity by clamping to 82.4 V within <1.0 ps - avoiding thermal runaway in high-brightness arrays. |
Use Scenario: Adding secondary-side transient immunity to AC/DC adapters used in medical and test equipment. IC Role / Device Role / Timing Role: Low-leakage (≤1 µA) TVS on regulated 5V/12V outputs to suppress ESD and capacitive coupling spikes. Use Value: Ensures output voltage remains within ±5% of nominal during 8 kV contact ESD events - meeting IEC 61000-4-2 Level 4. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ51A | Identical VWM (51 V), VBR (56.7–62.7 V), and VC (82.4 V); same DO-214AC package and AEC-Q101 qualification. | No functional deviation; validated for identical automotive and industrial surge profiles. | Select when dual-sourcing or lead-time constraints require alternate supply chain. |
| ON Semiconductor SMAJ51A | VC = 85.0 V @ 4.9 A (vs. 82.4 V); otherwise matches VWM, VBR, PPPM, and package. | Higher clamping increases downstream component voltage stress marginally - verify tolerance in 51V rail designs. | Prefer for cost-sensitive non-automotive applications where 2.6 V higher clamping is acceptable. |
Compared with SMAJ51AH, Littelfuse SMAJ51A offers identical clamping and qualification for seamless second-source use, while ON Semiconductor SMAJ51A trades 2.6 V higher clamping for broader commercial availability - requiring verification of downstream voltage margins in precision 51V systems.
Availability
SMAJ51AH is available at Aetrix Electronics and suitable for automotive power rail protection, industrial DC/DC converter input stages, and LED driver overvoltage clamp circuits requiring stable component supply, AEC-Q101 compliance, and 400W transient handling.
Supply support for SMAJ51AH 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 Taiwanese semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for automotive, industrial, and consumer markets.
The SMAJ series was developed specifically for high-reliability transient suppression in harsh-environment applications - emphasizing AEC-Q101 qualification, fast response, and ISO 7637-2 compliance from initial design.
FAQ
What is the clamping voltage of the SMAJ51AH under standard 10/1000 µs surge conditions?
The SMAJ51AH has a maximum clamping voltage (VC) of 82.4 V at 4.9 A peak impulse current (IPPM) under the 10/1000 µs waveform. This value is measured per JEDEC standards and guarantees that protected circuitry sees no more than 82.4 V during defined transient events - critical for safeguarding 51V-rated components downstream of the SMAJ51AH.
Is the SMAJ51AH unidirectional or bidirectional, and how is polarity identified?
The SMAJ51AH is a unidirectional TVS diode, indicated by the absence of "C" or "CA" suffix (e.g., SMAJ51CH would be bidirectional). Polarity is marked by a cathode band on the DO-214AC package body - the banded end connects to the protected line, while the anode connects to ground. This configuration enables precise clamping only during positive transients relative to ground.
Does the SMAJ51AH meet automotive qualification standards?
Yes, the SMAJ51AH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements. Its construction - including glass-passivated junction, JESD201 Class 2 whisker resistance, and moisture sensitivity level 1 - satisfies full automotive component reliability criteria for under-hood and chassis-mounted applications.
What is the maximum steady-state power dissipation rating for the SMAJ51AH?
The SMAJ51AH has a steady-state power dissipation (PD) rating of 1 W at 25°C ambient. This defines its continuous thermal limit during leakage conduction or low-level bias conditions - not to be confused with its 400W peak pulse rating. Derating applies above 25°C per the published pulse derating curve (Fig.2), reaching ~0.5 W at 100°C ambient.
How does the SMAJ51AH differ from the non-A version (SMAJ51H)?
The SMAJ51AH features tighter breakdown voltage tolerance (56.7–62.7 V) versus SMAJ51H (56.7–69.3 V), resulting in lower maximum clamping voltage (82.4 V vs. 91.1 V) and improved consistency in surge response. Both share identical package, power rating, and qualification - but SMAJ51AH is preferred where precise clamping control and reduced voltage overshoot are required.
SMAJ51AH 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:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 4.9A
- 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)
SMAJ51AH FAQ
1.How can I place an order for SMAJ51AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51AH 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 SMAJ51AH reliable?
The price and inventory of SMAJ51AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51AH is usually 5 days.
3.What payment methods are accepted for SMAJ51AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51AH?
SMAJ51AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51AH 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 SMAJ51AH?
For technical support, including SMAJ51AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51AH requirements.
6.How does Aetrix verify that SMAJ51AH is sourced from the original manufacturer or authorized distributors?
All SMAJ51AH 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 SMAJ51AH meets industry standards.
7.What is the process for return or replacement of SMAJ51AH?
All SMAJ51AH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51AH, 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 SMAJ51AH part is unused and in its original packaging.
Return procedure for SMAJ51AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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