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Taiwan Semiconductor Corporation SMAJ12AH
- Part No.:
- SMAJ12AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ12AH.pdf
- Description:
- TVS DIODE 12VWM 19.9VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,432
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Product details
Overview
SMAJ12AH from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 12 V working stand-off voltage (VWM), 13.3–14.7 V breakdown voltage (VBR), 19.9 V maximum clamping voltage (VC) at 20.1 A peak pulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - deployed in automotive-grade SMPS, on-board DC/DC converters, and lighting drivers.
For engineers reviewing the SMAJ12AH datasheet, SMAJ12AH pinout, SMAJ12AH application, or SMAJ12AH equivalent, key selection criteria include its AEC-Q101 qualification, DO-214AC (SMA) package compatibility with automated placement, sub-1 ps response time, <1 µA reverse leakage at 12 V, and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance for automotive transients.
Technical Context
The SMAJ12AH operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve fast transient suppression with minimal capacitance. Its clamping behavior is defined by a 10/1000 µs standard test waveform, delivering 19.9 V clamping at 20.1 A while maintaining thermal stability up to 150 °C junction temperature.
It is rated for 1 W steady-state power dissipation and supports 40 A non-repetitive forward surge current (8.3 ms half-sine), making it suitable for high-energy transient events in 12 V automotive and industrial power systems without requiring series impedance limiting in many implementations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 12 V - Maximum continuous DC or RMS voltage the device blocks without conduction. |
| VBR @ IT = 1 mA | 13.3–14.7 V - Breakdown threshold where avalanche conduction begins; ensures reliable triggering above system nominal voltage. |
| VC @ IPPM = 20.1 A | 19.9 V - Clamped voltage during 10/1000 µs transient; limits downstream IC stress to safe levels in 12 V systems. |
| PPPM | 400 W - Peak pulse power handling per 10/1000 µs waveform; supports high-energy load dump and inductive switching events. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves efficiency in battery-powered or low-quiescent circuits. |
| TJ max | 150 °C - Enables operation in under-hood automotive environments and thermally constrained PCB layouts. |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Matte tin-plated leads meet J-STD-002 solderability requirements and JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input/Line side (non-marked end) | Connected to protected line; conducts during reverse-biased transient events when cathode is held at higher potential. |
| Cathode | Ground/Reference side (marked with band) | Typically tied to system ground or low-impedance return path; defines polarity and clamping reference point. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including temperature cycling, humidity, and mechanical shock per stress test requirements. |
| Glass-passivated junction | Enhances long-term reliability and moisture resistance versus epoxy-passivated alternatives; critical for harsh-environment deployment. |
| Fast response time <1 ps | Clamps transients before sensitive downstream logic or analog circuitry can be damaged - essential for protecting CAN, LIN, or sensor interfaces. |
| ISO 7637-2 compliance | Meets Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) test profiles for 12 V vehicle networks. |
Applications
| Automotive Power Rail Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between battery rail and input filter capacitor. Use Value: Limits transient voltage to ≤19.9 V during 400 W pulses, preventing damage to upstream regulators and microcontrollers. | Use Scenario: Safeguarding isolated DC/DC converter primary-side inputs in factory automation controllers. IC Role / Device Role / Timing Role: Standoff protector on 24 V input stage exposed to relay coil kickback and ESD. Use Value: Sub-1 µA leakage avoids standby current penalty; 150 °C rating supports sealed enclosure operation. |
| LED Driver Overvoltage Suppression | USB-C Power Delivery Line Clamp |
Use Scenario: Shielding constant-current LED driver ICs from supply surges in streetlight ballasts. IC Role / Device Role / Timing Role: Parallel-connected TVS across input terminals of buck controller ICs. Use Value: 400 W rating handles repeated lightning-induced surges; DO-214AC footprint enables compact layout near connector entry. | Use Scenario: Adding secondary-level surge immunity to USB-C PD port VBUS lines in portable medical devices. IC Role / Device Role / Timing Role: Low-capacitance unidirectional clamp between VBUS and chassis ground. Use Value: 19.9 V clamping aligns with USB PD 3.0 20 V profile; AEC-Q101 grade assures reliability in field-deployed equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ12H | Higher VBR range (13.3–16.3 V); higher VC = 22.0 V at 18.2 A; same 400 W rating. | Less precise clamping in 12 V systems; marginally higher let-through voltage during transients. | Select SMAJ12H only if tighter VBR tolerance is not required and higher clamping voltage is acceptable. |
| SMBJ12AH | Different package (DO-214AA/SMB); 600 W rating; identical VWM/VBR/VC specs; higher IPPM = 30.2 A. | Larger footprint; suited for higher-power designs where board space permits larger package. | Choose SMBJ12AH when higher surge margin is needed and DO-214AA layout is available. |
Compared with SMAJ12H and SMBJ12AH, the SMAJ12AH delivers optimal balance of precision clamping (19.9 V), compact DO-214AC packaging, and AEC-Q101 reliability - making it preferred for space-constrained automotive and industrial 12 V rail protection where consistent low-VC performance is critical.
Availability
SMAJ12AH is available at Aetrix Electronics and suitable for automotive power management, industrial DC/DC converter input stages, and LED driver overvoltage protection requiring stable component supply across production lifecycles.
Supply support for SMAJ12AH 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 capability.
The SMAJ series is engineered for high-reliability transient suppression in automotive and industrial power systems - emphasizing fast response, low clamping, and robust package integrity under thermal and mechanical stress.
FAQ
What is the clamping voltage of the SMAJ12AH under standard 10/1000 µs surge conditions?
The SMAJ12AH exhibits a maximum clamping voltage (VC) of 19.9 V when subjected to its rated peak pulse current of 20.1 A using the 10/1000 µs waveform. This value is guaranteed per the manufacturer's electrical specifications table and reflects worst-case performance at TA = 25°C - critical for ensuring downstream components remain within safe operating voltage limits during transient events.
Is the SMAJ12AH suitable for automotive applications?
Yes, the SMAJ12AH is AEC-Q101 qualified and meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements - confirming its suitability for 12 V automotive power networks. Its DO-214AC package, 150 °C junction rating, and glass-passivated junction further support deployment in engine control units, body electronics, and infotainment power supplies where reliability under thermal and electrical stress is mandatory. The SMAJ12AH is explicitly designed for this environment.
How does the SMAJ12AH differ from the SMAJ12H variant?
The SMAJ12AH has a tighter breakdown voltage range (13.3–14.7 V) versus SMAJ12H (13.3–16.3 V), resulting in lower and more consistent clamping voltage (19.9 V vs. 22.0 V). Both share the same VWM (12 V), package (DO-214AC), and 400 W rating. The SMAJ12AH's tighter VBR tolerance improves predictability in 12 V rail protection, making it preferable where precise clamping is required - a distinction clearly documented in Taiwan Semiconductor's datasheet revision A2102.
What is the reverse leakage current specification for the SMAJ12AH at its working voltage?
The SMAJ12AH specifies a maximum reverse leakage current (IR) of 1 µA when biased at its working stand-off voltage (VWM) of 12 V and measured at TA = 25°C. This ultra-low leakage minimizes quiescent power loss in battery-backed or energy-sensitive systems - a confirmed parameter from the Electrical Specifications table in the official datasheet, directly supporting use in always-on automotive modules and IoT edge nodes.
Does the SMAJ12AH have polarity markings, and how is it oriented on the PCB?
Yes, the SMAJ12AH uses a cathode band marking on the DO-214AC (SMA) package to indicate polarity - the banded end is the cathode and must be connected toward the system ground or lower-potential reference node. This unidirectional configuration ensures proper clamping action during positive transients on the anode side. The marking diagram and mechanical outline in the datasheet confirm this orientation, and the band is visible under standard optical inspection.
SMAJ12AH 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):
- 12V
- Voltage - Breakdown (Min):
- 13.3V
- Voltage - Clamping (Max) @ Ipp:
- 19.9V
- Current - Peak Pulse (10/1000µs):
- 20.1A
- 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)
SMAJ12AH FAQ
1.How can I place an order for SMAJ12AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ12AH 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 SMAJ12AH reliable?
The price and inventory of SMAJ12AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ12AH is usually 5 days.
3.What payment methods are accepted for SMAJ12AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ12AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ12AH?
SMAJ12AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ12AH 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 SMAJ12AH?
For technical support, including SMAJ12AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ12AH requirements.
6.How does Aetrix verify that SMAJ12AH is sourced from the original manufacturer or authorized distributors?
All SMAJ12AH 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 SMAJ12AH meets industry standards.
7.What is the process for return or replacement of SMAJ12AH?
All SMAJ12AH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ12AH, 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 SMAJ12AH part is unused and in its original packaging.
Return procedure for SMAJ12AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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