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STMicroelectronics SMAJ20A-TR
- Part No.:
- SMAJ20A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20A-TR.pdf
- Description:
- TVS DIODE 20VWM 42.8VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:13,016
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Product details
Overview
SMAJ20A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for primary-level ESD and surge protection in DC power rails and signal lines. It features a 20 V standoff voltage (VRM), 32.4 V clamping voltage at 12.3 A (10/1000 μs), 400 W peak pulse power rating, and operates up to 150 °C junction temperature-ideal for automotive body control modules and industrial I/O interfaces.
For engineers reviewing the SMAJ20A-TR datasheet, SMAJ20A-TR pinout, SMAJ20A-TR application, or SMAJ20A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC VDD, leakage current at elevated temperature, JEDEC DO-214AC (SMA) package thermal performance, and IEC 61000-4-2/4-4 compliance level.
Technical Context
This TVS diode uses planar silicon junction technology to achieve low leakage (0.2 µA at 25 °C, 1 µA at 85 °C) and stable breakdown behavior across temperature. Its unidirectional configuration provides asymmetric clamping-low forward voltage during overvoltage events on positive rail, high reverse blocking up to 20 V.
The device meets IEC 61000-4-2 Level 4 (30 kV air/contact discharge) and IEC 61000-4-4 Level 4 (4 kV), with dynamic resistance of 0.637 Ω at 10/1000 μs and 0.338 Ω at 8/20 μs-enabling fast energy diversion while minimizing voltage overshoot into downstream circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 20 V - Maximum continuous reverse operating voltage before conduction begins |
| Breakdown Voltage (VBR) | 22.2–23.4 V at 1 mA - Confirmed avalanche onset range ensuring predictable triggering |
| Clamping Voltage (VCL) | 32.4 V at 12.3 A (10/1000 μs) - Peak voltage seen by protected circuit during worst-case surge |
| Peak Pulse Power (PPP) | 400 W (10/1000 μs) - Sustained surge energy handling per IEC 61000-4-5 standard waveform |
| Leakage Current (IRM) | 0.2 µA at 25 °C, 1 µA at 85 °C - Minimal DC loading on high-impedance sensor or reference circuits |
| Junction Temperature Range | −55 °C to +150 °C - Enables deployment in under-hood automotive or industrial motor drive environments |
| Package | DO-214AC (SMA) - Standardized footprint compliant with IPC-7531, optimized for thermal dissipation on FR4 PCBs |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, single-ended unidirectional configuration with cathode band marking. Dimensions: 4.80–5.35 mm length × 2.25–2.90 mm width × 2.25 mm height; recommended copper pad area per lead ≥ 1.4 cm² for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection point | Connected to ground or return path; conducts during positive transients on cathode side |
| Cathode (banded end) | High-side connection point | Connected to protected line (e.g., 24 V supply rail); blocks 20 V DC, clamps surges above 22.2 V |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 Level 4 compliance | 30 kV contact/air discharge immunity without degradation-validates robustness in handheld and panel-mounted equipment |
| Low-temperature coefficient (αT) | 9.4 × 10⁻⁴ /°C - Predictable VBR shift across −55 °C to +150 °C enables accurate system-level margining |
| JEDEC-registered DO-214AC outline | Ensures mechanical compatibility with automated placement and reflow processes per J-STD-020 MSL Level 1 |
| Matte tin-plated leads | Complies with JESD 22-B102 E3 and MIL-STD-750 Method 2026-guarantees solderability and long-term intermetallic stability |
| UL94 V-0 rated epoxy body | Self-extinguishing housing prevents flame propagation in safety-critical enclosures |
Applications
| Automotive Body Control Module | Industrial PLC Digital Input |
|---|---|
Use Scenario: Protecting LIN bus transceivers and microcontroller GPIOs from load dump and jump-start induced transients in vehicle door modules. IC Role / Device Role / Timing Role: Primary clamping element placed directly at connector entry point, shunting >95% of 400 W surge energy away from ASIC inputs. Use Value: Maintains 32.4 V clamping ceiling below 36 V absolute maximum rating of typical 5 V/12 V logic ICs, preventing latch-up or oxide damage. | Use Scenario: Safeguarding 24 V DC digital input channels against field-wiring ESD and inductive kickback from solenoid valves. IC Role / Device Role / Timing Role: Fast-response overvoltage clamp on input filter stage, activated within <1 ns to limit transient duration seen by optocoupler input diodes. Use Value: 0.2 µA leakage ensures minimal error in high-impedance current-sense resistor networks used for wet/dry contact detection. |
| Medical Patient Monitor Port | Smart Building HVAC Sensor Node |
Use Scenario: Shielding RS-485 communication lines connecting bedside units to central nursing stations from electrostatic discharge during clinical handling. IC Role / Device Role / Timing Role: Unidirectional TVS on differential pair common-mode line, referenced to chassis ground to suppress common-mode surges without disrupting data integrity. Use Value: 30 kV IEC 61000-4-2 compliance exceeds IEC 60601-1-2 requirements for medical EMC immunity, supporting Class II certification. | Use Scenario: Securing 12 V power input of wireless temperature/humidity nodes mounted near HVAC ductwork exposed to lightning-induced ground potential rise. IC Role / Device Role / Timing Role: First-line defense on main power rail, coordinated with upstream fuse and downstream LDO to form staged protection architecture. Use Value: 150 °C max junction temperature allows uninterrupted operation inside insulated ducts where ambient reaches 85 °C, eliminating derating penalties. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20AHE3_A/H (Vishay) | Identical DO-214AC package, same 20 V VRM and 32.4 V VCL, but higher leakage (0.5 µA @ 25 °C) | Acceptable in non-battery-powered systems where leakage impact is negligible | Select when sourcing flexibility is prioritized and leakage budget permits +0.3 µA increase |
| P6SMB20A (ON Semiconductor) | Same electrical specs but larger DO-214AA (SMB) package; 1.5× higher thermal resistance (Rth(j-a) = 50 °C/W vs. 40 °C/W) | Requires larger PCB area and reduced power derating above 85 °C ambient | Prefer only if existing SMB footprint reuse is mandatory and thermal margin is verified |
Compared with SMAJ20AHE3_A/H and P6SMB20A, SMAJ20A-TR delivers tighter leakage control and superior thermal performance in the compact DO-214AC footprint-making it optimal for space-constrained, thermally demanding, or battery-sensitive designs.
Availability
SMAJ20A-TR is available at Aetrix Electronics and suitable for automotive infotainment head units, industrial programmable logic controllers, and medical diagnostic equipment requiring stable component supply across extended product lifecycles.
Supply support for SMAJ20A-TR 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power discrete technologies with vertical manufacturing capabilities and broad IP portfolio.
The SMAJ series belongs to ST's Transient Voltage Suppressor portfolio, engineered specifically for high-reliability board-level ESD and surge protection in harsh electromagnetic environments-emphasizing low leakage, precise clamping, and JEDEC-compliant manufacturability.
FAQ
What is the maximum surge current SMAJ20A-TR can handle at 8/20 μs?
The device supports 54 A peak pulse current at 8/20 μs waveform, corresponding to its 42.8 V clamping voltage and 0.338 Ω dynamic resistance. This value is validated per IEC 61000-4-5 Annex A test conditions and confirmed in Table 2 of DS1251 Rev 15.
Does SMAJ20A-TR require derating at elevated ambient temperatures?
Yes-its 400 W peak pulse power rating applies only at Tj = 25 °C. Figure 3 shows linear derating to ~220 W at 125 °C junction temperature. Designers must calculate actual Tj using Rth(j-a) = 40 °C/W and ambient temperature to ensure safe operation.
Can SMAJ20A-TR be used in bidirectional signal line protection?
No-SMAJ20A-TR is unidirectional and lacks symmetrical clamping. For bidirectional lines like USB or RS-485, SMAJ20CA-TR (the complementary bidirectional variant) must be used, which provides equal clamping in both polarities with identical VRWM and VCL.
Is the SMAJ20A-TR RoHS and REACH compliant?
Yes-STMicroelectronics certifies SMAJ20A-TR as ECOPACK2-compliant, meeting RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Full material declarations and substance reports are accessible via ST's official product page and ECOPACK portal.
SMAJ20A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 42.8V
- Current - Peak Pulse (10/1000µs):
- 54A (8/20µs)
- 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)
SMAJ20A-TR FAQ
1.How can I place an order for SMAJ20A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20A-TR 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 SMAJ20A-TR reliable?
The price and inventory of SMAJ20A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ20A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ20A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20A-TR?
SMAJ20A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20A-TR 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 SMAJ20A-TR?
For technical support, including SMAJ20A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20A-TR requirements.
6.How does Aetrix verify that SMAJ20A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ20A-TR 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 SMAJ20A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ20A-TR?
All SMAJ20A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20A-TR, 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 SMAJ20A-TR part is unused and in its original packaging.
Return procedure for SMAJ20A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ20A-TR Tags
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Toshiba Semiconductor and Storage
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