My Inquiry
My Account
STMicroelectronics SMAJ28A-TR
- Part No.:
- SMAJ28A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28A-TR.pdf
- Description:
- TVS DIODE 28VWM 59VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:10,320
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SMAJ28A-TR from STMicroelectronics is a unidirectional 400 W transient voltage suppression (TVS) diode in SMA package, designed for IEC 61000-4-2 ESD protection (30 kV air/contact) and IEC 61000-4-4 surge immunity (4 kV), with 28 V standoff voltage (VRM), 31.1 V minimum breakdown (VBR), and 45.4 V clamping voltage (VCL) at 8.8 A peak pulse current.
For engineers reviewing the SMAJ28A-TR datasheet, SMAJ28A-TR pinout, SMAJ28A-TR application, or SMAJ28A-TR equivalent, key selection factors include clamping performance under 10/1000 µs surges, low leakage (<0.2 µA @ 25 °C), junction temperature capability up to +150 °C, and compatibility with IPC7531-compliant SMA footprints for high-reliability industrial and automotive PCB layouts.
Technical Context
This TVS diode operates as a unidirectional clamping device, triggered when reverse voltage exceeds its 31.1 V minimum breakdown threshold (IBR = 1 mA), limiting transient energy via avalanche conduction. Its planar silicon construction ensures stable VBR temperature coefficient (αT = 9.8 × 10⁻⁴ /°C) and low dynamic resistance (RD = 0.632 Ω).
It complies with JEDEC DO-214AC (SMA) mechanical outline and meets J-STD-020 MSL Level 1, UL94 V0 flammability, and IEC 61000-4-2/4-4 immunity standards-enabling direct integration into power rail and signal line protection circuits without derating for soldering thermal stress.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 28 V - Maximum continuous reverse operating voltage before leakage exceeds 0.2 µA |
| Breakdown Voltage (VBR) | 31.1–32.7 V @ 1 mA - Ensures reliable triggering above normal system voltage with margin |
| Clamping Voltage (VCL) | 45.4 V @ 8.8 A (10/1000 µs) - Limits downstream IC voltage stress during surge events |
| Peak Pulse Power | 400 W @ 10/1000 µs - Sustains typical lightning-induced transients per IEC 61000-4-4 |
| Leakage Current (IRM) | 0.2 µA @ 25 °C - Minimizes standby power loss in battery-backed or low-power systems |
| Junction Temp Range | −55 to +150 °C - Supports operation in under-hood automotive or industrial enclosures |
| Package | SMA (DO-214AC) - Standardized footprint compatible with automated SMT assembly and IPC7531 layout |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, single-ended unidirectional configuration with cathode band marking. Dimensions per JEDEC MS-013AA: length 4.80–5.35 mm, width 2.25–2.90 mm, height 2.26–2.46 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference node | Connected to ground or lowest potential rail; defines unidirectional clamping direction |
| Cathode | Protected line input | Connected to signal/power line requiring overvoltage protection; carries full surge current during clamping |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 ESD robustness | 30 kV contact & air discharge - Eliminates need for external ESD filters on USB, CAN, or sensor interfaces |
| Low junction capacitance | ~200 pF @ 0 V (typ.) - Preserves signal integrity on data lines up to ~100 Mbps without distortion |
| High-temperature reliability | 150 °C max Tj - Enables placement near heat sources (e.g., power converters) without derating |
| Matte tin lead finish | JESD 22-B102 E3 compliant - Ensures solder joint integrity and whisker resistance in long-life deployments |
| Planar silicon process | Stable VBR drift <±5% over lifetime - Guarantees consistent clamping behavior across product lifecycle |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Digital Input |
|---|---|
Use Scenario: Protecting LIN bus transceivers and microcontroller GPIOs from load dump and ESD in door modules. IC Role / Device Role / Timing Role: Unidirectional TVS placed between LIN line and ground, clamping transients within 1 ns response time. Use Value: Maintains 28 V VRM margin above 12 V nominal supply while limiting VCL to 45.4 V, preventing MCU latch-up. | Use Scenario: Safeguarding 24 V DC digital input channels against field-wiring surges and relay coil flyback. IC Role / Device Role / Timing Role: Primary overvoltage clamp on input front-end, mounted directly at connector entry point. Use Value: Withstands 400 W (10/1000 µs) surges per IEC 61000-4-4 Level 4, enabling Class I industrial certification. |
| USB 2.0 Port Protection | DC-DC Converter Input Rail |
Use Scenario: ESD protection for D+/D− lines in embedded host controllers with limited board space. IC Role / Device Role / Timing Role: Low-capacitance unidirectional TVS tied to VBUS and ground, preserving signal rise/fall times. Use Value: 200 pF capacitance avoids USB 2.0 eye diagram degradation; 30 kV ESD rating exceeds USB-IF compliance requirements. | Use Scenario: Secondary surge suppression on 24–48 V input rails of isolated DC-DC modules in telecom equipment. IC Role / Device Role / Timing Role: Parallel clamping device downstream of primary MOV or GDT, handling residual fast transients. Use Value: 45.4 V clamping ensures downstream regulator input remains below absolute maximum ratings during 8/20 µs surges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ28A-TR | Same VRM/VBR/VCL specs but SMB package (higher Ppp = 600 W, larger footprint) | Better suited for higher-energy surges; requires 20% more PCB area | Select when 600 W surge rating is required and board space permits SMB layout |
| P6SMB28A | Identical electrical specs; same SMB package; manufactured by Vishay | No functional difference; alternate sourcing option with identical thermal and clamping behavior | Choose for dual-sourcing strategy where ST part availability is constrained |
Compared with SMBJ28A-TR and P6SMB28A, SMAJ28A-TR offers optimal balance of 400 W surge handling, minimal 5.35 mm × 2.90 mm footprint, and ST's qualified automotive-grade process-making it preferred for space-constrained industrial and automotive ECUs where MSL-1 reflow compatibility and long-term leakage stability are critical.
Availability
SMAJ28A-TR is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC input protection, USB interface hardening, and DC-DC converter input rail safeguarding requiring stable component supply across multi-year production cycles.
Supply support for SMAJ28A-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, delivering intelligent power, analog, MEMS, and microcontroller solutions for automotive, industrial, and consumer markets.
The SMAJ series belongs to ST's Transient Voltage Suppression portfolio, engineered specifically for high-reliability, low-leakage ESD and surge protection in harsh environments-targeting applications demanding long-term parametric stability and JEDEC-compliant manufacturability.
FAQ
What is the maximum clamping voltage of SMAJ28A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 45.4 V at 8.8 A peak pulse current for a 10/1000 µs waveform, measured at 25 °C ambient. This value increases linearly with junction temperature due to the 9.8 × 10⁻⁴ /°C temperature coefficient, reaching approximately 47.2 V at 125 °C junction temperature.
Is SMAJ28A-TR suitable for bidirectional signal line protection?
No - SMAJ28A-TR is a unidirectional TVS diode, intended only for DC-biased lines like power rails or grounded signal paths. For bidirectional protection (e.g., RS-485, CAN), the SMAJ28CA-TR variant must be used, which features symmetrical breakdown in both polarities and identical clamping performance.
Does SMAJ28A-TR meet automotive qualification standards?
While not AEC-Q200 certified as a standalone component, SMAJ28A-TR uses ST's qualified automotive-grade silicon process, supports 150 °C junction operation, and meets J-STD-020 MSL Level 1 - enabling use in automotive applications where system-level qualification (e.g., ISO 16750-2 pulse testing) is performed, such as body control modules and infotainment power supplies.
How does the leakage current change with temperature?
Leakage current (IRM) rises exponentially with junction temperature: it is ≤0.2 µA at 25 °C, ≤1 µA at 85 °C, and reaches ~10 µA at 125 °C per Figure 9 in DS1251. This behavior is inherent to silicon PN junctions and is fully characterized in the datasheet for accurate system-level power budgeting.
SMAJ28A-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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 59V
- Current - Peak Pulse (10/1000µs):
- 39A (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)
SMAJ28A-TR FAQ
1.How can I place an order for SMAJ28A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28A-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 SMAJ28A-TR reliable?
The price and inventory of SMAJ28A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ28A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28A-TR?
SMAJ28A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28A-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 SMAJ28A-TR?
For technical support, including SMAJ28A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28A-TR requirements.
6.How does Aetrix verify that SMAJ28A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ28A-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 SMAJ28A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ28A-TR?
All SMAJ28A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28A-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 SMAJ28A-TR part is unused and in its original packaging.
Return procedure for SMAJ28A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ28A-TR Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
