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STMicroelectronics SMAJ188A-TR
- Part No.:
- SMAJ188A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ188A-TR.pdf
- Description:
- TVS DIODE 188VWM 388VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:9,880
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Product details
Overview
SMAJ188A-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 188 V stand-off voltage (VRM), 328 V clamping voltage at 1.4 A (10/1000 µs), 400 W peak pulse power rating, and operates up to 150 °C junction temperature-ideal for industrial power supplies and telecom interface protection.
For engineers reviewing the SMAJ188A-TR datasheet, SMAJ188A-TR pinout, SMAJ188A-TR application, or SMAJ188A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, 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) and stable breakdown behavior across -55 °C to +150 °C operating range. Its unidirectional configuration provides asymmetric clamping-forward conduction only during reverse overvoltage events-making it suitable for DC-biased lines where polarity is fixed.
The device complies with IEC 61000-4-2 (30 kV air/contact discharge) and IEC 61000-4-4 Level 4 (4 kV), with dynamic resistance of 26.2 Ω at 8/20 µs pulse. Its DO-214AC package supports IPC 7531-compliant footprint and meets J-STD-020 MSL Level 1 for moisture sensitivity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 188 V - Maximum continuous reverse operating voltage before significant leakage or clamping begins. |
| Breakdown Voltage (VBR min) | 209 V at 1 mA - Ensures reliable triggering above normal rail voltage with margin against false triggering. |
| Clamping Voltage (VCL) | 328 V at 1.4 A (10/1000 µs) - Limits transient voltage seen by downstream circuitry to safe levels. |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - Sustains short-duration surges typical of lightning-induced or inductive-switching transients. |
| Leakage Current (IRM) | 0.2 µA at 25 °C - Minimizes standby power loss and avoids interference in high-impedance sensing circuits. |
| Junction Temperature Range | -55 °C to +150 °C - Enables deployment in under-hood automotive, industrial motor drives, and outdoor telecom equipment. |
| Dynamic Resistance (RD) | 26.2 Ω - Determines voltage rise per unit surge current; critical for predicting clamping behavior under varying IPP. |
Pinout & Package
The SMAJ188A-TR is housed in a JEDEC DO-214AC (SMA) surface-mount package with cathode band marking. The package measures 4.80–5.35 mm (E) × 2.25–2.90 mm (D) × 0.75–1.50 mm (L), optimized for thermal dissipation on standard FR4 PCBs with 70 µm copper.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or lowest potential node; defines forward conduction path during clamping. |
| Cathode | Protected line input | Connected to the line being protected (e.g., 24 V rail); reverse-biased during normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 Level 4 ESD robustness | 30 kV contact/air discharge - Eliminates need for external ESD protection in front-end interfaces. |
| Low temperature coefficient (αT) | 10⁻⁴ /°C - Ensures predictable VBR and VCL shift across operating temperature range. |
| UL94 V0 flammability rating | Self-extinguishing epoxy molding compound - Meets safety requirements for enclosed industrial enclosures. |
| MSL Level 1 moisture sensitivity | No floor life limitation - Simplifies manufacturing handling without baking or dry-pack requirements. |
| Matte tin-plated leads | J-STD-002 compliant solderability - Ensures reliable reflow joint formation with lead-free processes. |
Applications
| Industrial Power Supply Input | Telecom Line Interface |
|---|---|
|
Use Scenario: 24 V DC input stage of programmable logic controller (PLC) power module exposed to load dump and field wiring surges. IC Role / Device Role / Timing Role: Primary surge clamp on main DC input rail, placed upstream of DC-DC converter and EMI filter. Use Value: Clamps 400 W transients to ≤328 V, preventing damage to 40 V-rated input capacitors and MOSFETs while maintaining <0.2 µA leakage at ambient temperature. |
Use Scenario: RS-485 data line termination in outdoor base station remote radio units subject to induced lightning surges. IC Role / Device Role / Timing Role: Unidirectional TVS on VCC-supplied bias rail of isolated RS-485 transceiver, referenced to local ground. Use Value: Withstands 4 kV IEC 61000-4-4 bursts and 30 kV ESD without degradation, preserving signal integrity due to low 26.2 Ω RD and minimal capacitance (<100 pF at 100 V). |
| Automotive Body Control Module | Smart Energy Meter Interface |
|
Use Scenario: 12 V battery-connected microcontroller supply rail in BCM exposed to ISO 7637-2 pulse 1/2a/5a transients. IC Role / Device Role / Timing Role: Secondary overvoltage protector after LC filter, guarding MCU LDO input against residual spikes. Use Value: Operates reliably at 150 °C junction temperature and delivers consistent 328 V clamping across -40 °C to +125 °C ambient, meeting AEC-Q200 stress screening expectations. |
Use Scenario: AC mains-derived 12 V auxiliary supply in smart meter, subjected to fast transient bursts from grid switching events. IC Role / Device Role / Timing Role: Standoff-rated TVS on rectified DC bus feeding metering SoC and real-time clock backup circuit. Use Value: 188 V VRM provides 50% margin above nominal 12 V rail (after rectification and filtering), enabling robust protection without false triggering during brownout conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ188CA-TR | Bidirectional version; symmetric clamping in both polarities; same VRM/VBR/VCL ratings. | Required for AC-coupled or floating signal lines (e.g., Ethernet PHY differential pairs) where polarity reversal occurs. | Select SMAJ188CA-TR only when protecting bidirectional signals; SMAJ188A-TR is preferred for DC rails with defined polarity. |
| SMBJ188A-TR | Same electrical specs but in larger SMB (DO-214AA) package; 600 W PPP rating; higher thermal mass. | Used where board space allows and higher surge energy handling (e.g., 600 W 10/1000 µs) is required. | Choose SMBJ188A-TR if system-level testing reveals insufficient margin with 400 W rating; otherwise SMAJ188A-TR offers optimal size-to-performance ratio. |
Compared with SMAJ188CA-TR and SMBJ188A-TR, the SMAJ188A-TR delivers best-in-class power density for unidirectional DC protection-its DO-214AC footprint saves 30% board area versus SMB while maintaining full IEC 61000-4-2/4-4 compliance and thermal reliability up to 150 °C.
Availability
SMAJ188A-TR is available at Aetrix Electronics and suitable for industrial power supplies, telecom line interfaces, automotive body control modules, and smart energy meter designs requiring stable component supply and long-term obsolescence management.
Supply support for SMAJ188A-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 power management, analog, MEMS, and microcontrollers for industrial, automotive, and consumer markets.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for high-reliability, low-leakage DC rail protection in harsh environments-emphasizing thermal stability, ESD immunity, and JEDEC-compliant manufacturability.
FAQ
What is the maximum clamping voltage of SMAJ188A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 328 V at 1.4 A for a 10/1000 µs waveform, measured at Tj = 25 °C. This value increases with junction temperature at a rate of 10⁻⁴ /°C, reaching approximately 342 V at 125 °C junction temperature per the αT coefficient provided in the datasheet.
Is SMAJ188A-TR suitable for bidirectional signal lines like RS-485?
No-SMAJ188A-TR is unidirectional and conducts only when reverse-biased beyond its breakdown voltage. For bidirectional lines such as RS-485 differential pairs, the SMAJ188CA-TR variant must be used, as it provides symmetrical clamping in both polarities and matches the same electrical ratings.
How does the DO-214AC (SMA) package affect thermal performance?
The DO-214AC package has a thermal resistance (Rth j-a) of ~140 °C/W on a standard 1 cm² copper pad, rising to ~4.5 °C/W with 5 cm² total copper area per lead. Its low profile and matte tin plating ensure compatibility with lead-free reflow profiles and deliver adequate heat dissipation for 400 W pulses when mounted per IPC 7531 footprint recommendations.
Does SMAJ188A-TR meet automotive qualification standards?
While not AEC-Q200 qualified out-of-the-box, SMAJ188A-TR meets key automotive stress requirements: 150 °C operating junction temperature, MSL Level 1, UL94 V0, and IEC 61000-4-2/4-4 compliance. Customers may qualify it for specific automotive applications via internal stress testing per AEC-Q200 guidelines.
SMAJ188A-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):
- 188V
- Voltage - Breakdown (Min):
- 209V
- Voltage - Clamping (Max) @ Ipp:
- 388V
- Current - Peak Pulse (10/1000µs):
- 6A (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)
SMAJ188A-TR FAQ
1.How can I place an order for SMAJ188A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ188A-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 SMAJ188A-TR reliable?
The price and inventory of SMAJ188A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ188A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ188A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ188A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ188A-TR?
SMAJ188A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ188A-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 SMAJ188A-TR?
For technical support, including SMAJ188A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ188A-TR requirements.
6.How does Aetrix verify that SMAJ188A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ188A-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 SMAJ188A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ188A-TR?
All SMAJ188A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ188A-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 SMAJ188A-TR part is unused and in its original packaging.
Return procedure for SMAJ188A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ188A-TR Tags
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