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STMicroelectronics SMTPA120
- Part No.:
- SMTPA120
- Manufacturer:
- STMicroelectronics
- Category:
- Thyristors
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMTPA120.pdf
- Description:
- THYRISTOR 120V 150A DO-214AA
- Quantity:
- Payment:
- Shipping:
Inventory:4,420
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Product details
Overview
SMTPA120 from STMicroelectronics is a bidirectional Trisil™ thyristor surge protection device (SPD) designed for telecom line-level overvoltage clamping in analog/digital xDSL, T1/E1, and ISDN interfaces. It features 120 V standoff voltage (VRM), 160 V dynamic breakover voltage (VBO), 16 mA minimum holding current (IH), 30 pF capacitance at 50 V, and 50 A repetitive peak pulse current (10/1000 µs).
For engineers reviewing the SMTPA120 datasheet, SMTPA120 pinout, SMTPA120 application, or SMTPA120 equivalent, this device is selected for telecom-grade lightning surge protection where low capacitance, fail-safe short-circuit behavior, and compliance with GR-1089, ITU-T K20/K21, and FCC Part 68 are required.
Technical Context
SMTPA120 operates as a crowbar-type bidirectional thyristor that latches on when transient voltage exceeds its dynamic breakover threshold (~160 V), diverting surge current to ground until current falls below its holding threshold (≥16 mA). Its fail-safe mode ensures permanent short-circuit failure under overstress, enabling predictable system-level fault containment.
Designed specifically for telecom line cards and terminal equipment, it meets stringent IEC61000-4-5 (4 kV, 10/700 µs), ITU-T K20 (6 kV, 10/700 µs), and FCC Part 68 Type A (1.5 kV, 10/160 µs) surge immunity requirements without external triggering circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 120 V - Maximum continuous operating voltage before conduction begins |
| Dynamic Breakover Voltage (VBO) | 160 V @ 100 A/µs - Voltage at which device triggers into low-impedance state during fast transients |
| Holding Current (IH) | ≥16 mA - Minimum current required to maintain on-state; ensures reliable latch-off after surge decay |
| Capacitance (C) | 30 pF @ 50 V - Low signal-line loading for high-speed xDSL and T1/E1 data integrity |
| Repetitive Peak Pulse Current (IPP) | 50 A (10/1000 µs) - Sustained surge handling capability per GR-1089 Core Level 1 compliance |
| Leakage Current (IRM) | ≤2 µA @ 108 V - Negligible standby power loss and minimal impact on line bias stability |
| Package | SMB (DO-214AA) - JEDEC-registered surface-mount package with 100 °C/W junction-to-ambient thermal resistance |
Pinout & Package
SMT SMB package (DO-214AA), cathode-anode symmetrical bidirectional structure; no polarity marking required. Two-terminal device with identical electrical behavior in both directions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Current entry terminal during positive half-cycle surge | Connected to protected line; forms bidirectional conduction path with Cathode |
| Cathode (K) | Current exit terminal during positive half-cycle surge | Connected to ground or common reference; completes crowbar current path |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional crowbar action | Enables single-device protection of AC-coupled telecom lines without polarity constraints |
| Fail-safe short-circuit failure mode | Guarantees continued overvoltage clamping even after end-of-life stress events |
| UL497B and UL94 V0 certified | Validated for use in safety-critical telecom infrastructure meeting UL1950, IEC61000-4-5, and FCC Part 68 |
| Low 30 pF capacitance at 50 V | Maintains >1 MHz signal bandwidth for ADSL2+ and VDSL2 line cards without insertion loss degradation |
Applications
| DSL Line Card Protection | T1/E1 Interface Protection |
|---|---|
Use Scenario: Protecting copper-pair DSLAM line cards from lightning-induced surges on subscriber loops. IC Role / Device Role / Timing Role: Crowbar clamping device placed between tip/ring and ground, triggered within nanoseconds upon exceeding 160 V transient. Use Value: Prevents damage to upstream op-amps and line drivers while maintaining <30 pF signal path loading for full-bandwidth ADSL2+ operation. | Use Scenario: Safeguarding T1/E1 framer ICs and transformer-coupled receivers in central office equipment. IC Role / Device Role / Timing Role: Primary surge shunt on balanced differential pair, activated before 1.5 kV FCC Part 68 Type A surges reach sensitive PHY layers. Use Value: Enables compliance with GR-1089 Core Level 1 (2.5 kV, 10/1000 µs) without adding series impedance or degrading jitter performance. |
| ISDN Terminal Protection | Fax/Modem Analog Port Protection |
Use Scenario: Integrated surge suppression on BRI-U interface PCBs of ISDN terminal adapters and routers. IC Role / Device Role / Timing Role: Bidirectional overvoltage clamp across U-interface transformer secondary windings. Use Value: Survives repeated 1 kV/10/700 µs ITU-T K21 surges while preserving DC bias integrity for S/T bus signaling. | Use Scenario: Front-end protection of POTS-line-connected fax machines and dial-up modems. IC Role / Device Role / Timing Role: Fail-safe crowbar on telephone line input, shorting transients directly to chassis ground. Use Value: Eliminates need for backup fusing or resettable PTCs due to inherent self-holding behavior and UL497B certification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar telecom surge protection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMTPA100 | Lower VRM (100 V), lower VBO (135 V), higher capacitance (35 pF) | Better suited for 100 V nominal systems (e.g., legacy T1); less margin against 120 VAC line coupling | Select when system operating voltage is ≤100 V and higher capacitance is acceptable |
| SMTPA130 | Higher VRM (130 V), higher VBO (173 V), lower capacitance (30 pF) | Provides greater margin against 130 VAC-induced transients; tighter timing window for GR-1089 second-level compliance | Select for new designs targeting 130 V nominal telecom infrastructure or enhanced immunity headroom |
Compared with SMTPA100 and SMTPA130, SMTPA120 offers optimal balance of 120 V system compatibility, 160 V trigger threshold, and 30 pF capacitance-making it the preferred choice for modern xDSL line cards operating at standard ±60 V bias with strict bandwidth requirements.
Availability
SMTPA120 is available at Aetrix Electronics and suitable for DSL line card design, T1/E1 interface protection, and ISDN terminal equipment requiring stable component supply and long-term lifecycle support.
Supply support for SMTPA120 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 automotive ICs with broad industrial and communications portfolio coverage.
SMTPA120 belongs to ST's Trisil™ family of bidirectional thyristor surge protectors, engineered specifically for fail-safe, low-capacitance overvoltage clamping in telecom infrastructure meeting GR-1089, ITU-T, and FCC regulatory mandates.
FAQ
What is the fail-safe behavior of SMTPA120 under catastrophic surge conditions?
Under extreme overstress beyond its IFS rating (2.5 kA, 8/20 µs), SMTPA120 enters a permanent short-circuit state-maintaining low-impedance clamping without open-circuit failure. This behavior is certified per UL497B (file E136224) and ensures downstream circuit protection remains active even after end-of-life stress events.
Can SMTPA120 be used in AC mains-powered telecom equipment?
Yes-SMTPA120 is rated for continuous reverse voltage up to 120 V and withstands 50/60 Hz AC line coupling transients. Its 160 V dynamic breakover voltage provides sufficient margin above 120 VAC peaks (170 V), and its UL497B listing explicitly covers AC-powered telecom terminal applications per FCC Part 68.
How does SMTPA120 compare to TVS diodes for telecom surge protection?
Unlike unidirectional TVS diodes, SMTPA120 provides intrinsic bidirectional clamping without series DC blocking capacitors. Its thyristor-based crowbar action delivers lower clamping voltage under high-current surges (e.g., 50 A, 10/1000 µs) and eliminates leakage-dependent voltage drift-critical for stable bias in analog line interfaces.
Is SMTPA120 compliant with RoHS and REACH environmental standards?
Yes-SMTPA120 is supplied in ST's ECOPACK®-compliant SMB package with lead-free second-level interconnect, fully conforming to RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The inner box label and package marking indicate compliance per JEDEC JESD97.
SMTPA120 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SMP, TRISIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Breakover:
- 160V
- Voltage - Off State:
- 120V
- Voltage - On State:
- -
- Current - Peak Pulse (8/20µs):
- 150 A
- Current - Peak Pulse (10/1000µs):
- 50 A
- Current - Hold (Ih):
- 150 mA
- Number of Elements:
- 1
- Capacitance:
- 30pF
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
SMTPA120 FAQ
1.How can I place an order for SMTPA120 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMTPA120 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 SMTPA120 reliable?
The price and inventory of SMTPA120 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMTPA120 is usually 5 days.
3.What payment methods are accepted for SMTPA120?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMTPA120 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMTPA120?
SMTPA120 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMTPA120 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 SMTPA120?
For technical support, including SMTPA120 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMTPA120 requirements.
6.How does Aetrix verify that SMTPA120 is sourced from the original manufacturer or authorized distributors?
All SMTPA120 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 SMTPA120 meets industry standards.
7.What is the process for return or replacement of SMTPA120?
All SMTPA120 units undergo pre-shipment inspection (PSI). If there is an issue with SMTPA120, 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 SMTPA120 part is unused and in its original packaging.
Return procedure for SMTPA120:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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