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Taiwan Semiconductor Corporation SMAJ45A
- Part No.:
- SMAJ45A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ45A.pdf
- Description:
- TVS DIODE 45VWM 72.7VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,363
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Product details
Overview
SMAJ45A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for robust overvoltage protection in DC power rails. It features a 45 V working stand-off voltage (VWM), 50.0–55.3 V breakdown voltage (VBR), and clamps to ≤72.7 V at 5.5 A peak impulse current (IPPM) under 10/1000 µs waveform, delivering 400 W peak pulse power.
For engineers reviewing the SMAJ45A datasheet, SMAJ45A pinout, SMAJ45A application, or SMAJ45A equivalent, key selection considerations include its unidirectional polarity, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, <1.0 ps response time, and suitability for automotive-grade DC/DC converters, SMPS input stages, and lighting driver protection where fast clamping and low leakage (<1 µA @ 45 V) are critical.
Technical Context
The SMAJ45A operates as a unidirectional avalanche diode with glass-passivated junction, optimized for transient suppression on positive-polarity DC lines. Its electrical behavior follows standard TVS I-V characteristics: high-impedance standby state below VWM (45 V), sharp transition into low-impedance clamping mode above VBR (min 50.0 V), and stable clamping voltage (VC ≤ 72.7 V) during 10/1000 µs surges.
Thermal performance is defined by a 150 °C maximum junction temperature and 1 W steady-state power dissipation, with pulse derating above 25 °C per Fig.2. The device meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements, supporting automated SMT placement in industrial and automotive environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 45 V - Maximum continuous reverse operating voltage before clamping begins; defines safe DC rail margin. |
| VBR @ IT=1 mA | 50.0–55.3 V - Breakdown threshold range; ensures reliable turn-on above nominal system voltage. |
| VC @ IPPM=5.5 A | ≤72.7 V - Clamped voltage during 10/1000 µs surge; determines protected circuit's maximum stress level. |
| PPPM | 400 W - Peak pulse power handling (10/1000 µs); supports high-energy transients like load dump or inductive kick. |
| IR @ VWM | ≤1 µA - Reverse leakage at 45 V; minimizes standby power loss in battery-powered systems. |
| Response Time | <1.0 ps - Time from 0 V to VBR min; enables protection against nanosecond-scale ESD and fast transients. |
| TJMAX | 150 °C - Maximum junction temperature; sets thermal design limits for PCB copper area and ambient conditions. |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Dimensions comply with JEDEC DO-214AC outline; matte tin-plated leads meet J-STD-002 solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Positive terminal for unidirectional operation | Connected to protected line (e.g., +12 V rail); conducts only during forward surge events. |
| Cathode | Negative terminal / clamping reference | Connected to ground or lower-potential return path; defines clamping voltage relative to this node. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR and low leakage across temperature and lifetime; eliminates passivation-related drift in harsh environments. |
| ISO 7637-2 compliance | Validated for automotive transients including Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching spikes), and Pulse 3a/3b (capacitive coupling), enabling direct use in vehicle ECUs. |
| Moisture sensitivity level 1 | Zero bake requirement before reflow; supports standard SMT assembly without dry-pack or floor-life constraints. |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS Directive; suitable for green manufacturing and export to regulated markets. |
Applications
| Automotive Body Control Module (BCM) | Industrial SMPS Input Stage |
|---|---|
Use Scenario: Protects microcontroller I/O and CAN transceiver power rails from load dump and jump-start transients in 12 V vehicle systems. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between +12 V supply and chassis ground, clamping surges within 1 ps to limit voltage seen by downstream regulators. Use Value: Withstands 400 W pulses and maintains VC ≤ 72.7 V, preventing latch-up or damage to 5 V LDOs and 3.3 V logic circuits. | Use Scenario: Shields primary-side controller ICs and MOSFET gates from switching noise and line surges in offline AC/DC adapters. IC Role / Device Role / Timing Role: Mounted across bulk capacitor terminals to clamp differential-mode transients induced by rectifier recovery or lightning-induced surges. Use Value: Low 1 µA leakage avoids capacitor discharge during standby; fast response ensures clamping occurs before controller ICs experience overvoltage stress. |
| LED Driver Power Input | On-Board DC/DC Converter Protection |
Use Scenario: Safeguards constant-current LED driver ICs from voltage spikes caused by hot-plug events or cable inductance in streetlight and signage applications. IC Role / Device Role / Timing Role: Placed at DC input (e.g., 24–48 V bus) to absorb energy from 10/1000 µs transients before reaching buck controller and gate drivers. Use Value: 45 V VWM provides 10 % margin over 48 V nominal rail; clamping at ≤72.7 V prevents overvoltage shutdown of integrated FETs. | Use Scenario: Protects point-of-load (POL) converters in telecom and server boards from back-fed transients originating from upstream modules or hot-swap events. IC Role / Device Role / Timing Role: Installed at POL input (e.g., 12 V to 3.3 V converter), shunting surge current away from synchronous rectifiers and PWM controllers. Use Value: DO-214AC footprint allows compact layout near connector; 72.7 V clamping ensures secondary-side components remain within absolute maximum ratings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ45 | Higher VBR range (50.0–61.1 V) and higher VC (80.3 V @ 5.0 A); same package and PPPM. | Less precise clamping control; higher let-through voltage may stress sensitive downstream ICs. | Select SMAJ45A when tighter VBR tolerance and lower clamping voltage are required for margin-critical designs. |
| SMBJ45A | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; 600 W PPPM rating. | Higher surge capacity and better thermal dissipation; requires larger PCB area and different pad layout. | Choose SMBJ45A for applications needing >400 W pulse handling or extended thermal margin in high-ambient environments. |
Compared with SMAJ45 and SMBJ45A, the SMAJ45A offers the tightest VBR tolerance (±5.3 V vs ±11.1 V) and lowest clamping voltage in the DO-214AC footprint, making it optimal for space-constrained, high-reliability 45 V rail protection where precise voltage limiting is essential.
Availability
SMAJ45A is available at Aetrix Electronics and suitable for automotive body electronics, industrial switch-mode power supplies, and LED lighting systems requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMAJ45A 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and protection devices since 1979.
The SMAJ series is part of TSC's high-reliability transient suppression portfolio, engineered specifically for automotive and industrial applications demanding ISO 7637-2 compliance, low leakage, and consistent clamping performance across temperature.
FAQ
What is the polarity configuration of the SMAJ45A?
The SMAJ45A is a unidirectional TVS diode, meaning it protects only against positive-going transients on the anode-to-cathode direction. Its cathode band marks the terminal that must be connected to ground or the lower-potential reference node. This configuration ensures low leakage during normal operation while providing fast clamping when the anode voltage exceeds VBR. The SMAJ45A does not conduct in reverse bias beyond its specified IR, unlike bidirectional variants such as SMAJ45CA.
Does the SMAJ45A meet automotive transient standards?
Yes, the SMAJ45A meets ISO 7637-2 requirements for Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling), as confirmed in the official Taiwan Semiconductor datasheet. Its 400 W peak pulse power rating and sub-1 ps response time enable reliable suppression of these standardized waveforms in 12 V automotive systems. The SMAJ45A is widely deployed in body control modules and infotainment power supplies where such compliance is mandatory.
What is the maximum clamping voltage of the SMAJ45A under standard test conditions?
The maximum clamping voltage (VC) of the SMAJ45A is 72.7 V, measured at a peak impulse current (IPPM) of 5.5 A using the 10/1000 µs double-exponential waveform. This value represents the upper limit of voltage imposed on the protected circuit during worst-case surge events. Designers use this parameter to verify that downstream components-such as LDOs, microcontrollers, or gate drivers-remain within their absolute maximum voltage ratings when the SMAJ45A is active.
Can the SMAJ45A be used in bidirectional protection applications?
No, the SMAJ45A is strictly unidirectional and unsuitable for bidirectional protection. For symmetrical transient suppression on AC lines or differential buses, a bidirectional variant such as SMAJ45CA must be selected. The SMAJ45CA has identical VWM, VBR, and VC ratings but conducts in both directions. Using the SMAJ45A in a bidirectional configuration would leave the circuit unprotected against negative transients, risking component failure. Always verify polarity alignment before placing the SMAJ45A in circuit.
What is the moisture sensitivity level (MSL) and reflow profile compatibility of the SMAJ45A?
The SMAJ45A is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and requires no baking prior to reflow soldering. It is compatible with standard lead-free reflow profiles, including peak temperatures up to 260 °C, and its matte tin-plated leads meet J-STD-002 solderability requirements. This makes the SMAJ45A ideal for high-volume automated assembly without special handling, reducing manufacturing risk and cost in consumer, industrial, and automotive production lines.
SMAJ45A 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):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.7V
- Current - Peak Pulse (10/1000µs):
- 5.5A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ45A FAQ
1.How can I place an order for SMAJ45A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ45A 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 SMAJ45A reliable?
The price and inventory of SMAJ45A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ45A is usually 5 days.
3.What payment methods are accepted for SMAJ45A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ45A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ45A?
SMAJ45A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ45A 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 SMAJ45A?
For technical support, including SMAJ45A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ45A requirements.
6.How does Aetrix verify that SMAJ45A is sourced from the original manufacturer or authorized distributors?
All SMAJ45A 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 SMAJ45A meets industry standards.
7.What is the process for return or replacement of SMAJ45A?
All SMAJ45A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ45A, 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 SMAJ45A part is unused and in its original packaging.
Return procedure for SMAJ45A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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