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STMicroelectronics SMTPA320
- Part No.:
- SMTPA320
- Manufacturer:
- STMicroelectronics
- Category:
- Thyristors
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMTPA320.pdf
- Description:
- THYRISTOR 320V 150A DO-214AA
- Quantity:
- Payment:
- Shipping:
Inventory:6,511
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Product details
Overview
SMTPA320 from STMicroelectronics is a bidirectional Trisil™ thyristor surge protection device designed for primary overvoltage crowbar clamping in telecom line interfaces. It features a 320 V stand-off voltage (VRM), 400 V dynamic breakover voltage (VBO), 12 mA minimum holding current (IH), 25 pF capacitance at 50 V, and 50 A repetitive peak pulse current (10/1000 µs). It is used in xDSL line cards and central office equipment to meet GR-1089 Core Level 1 and ITU-T K20/K21 lightning immunity requirements.
For engineers reviewing the SMTPA320 datasheet, SMTPA320 pinout, SMTPA320 application, or SMTPA320 equivalent, this page delivers verified electrical parameters, JEDEC DO-214AA (SMB) package details, telecom-specific surge test compliance data, and functional alternatives validated for analog/digital line card protection.
Technical Context
The SMTPA320 operates as a voltage-triggered bidirectional thyristor with fail-safe short-circuit behavior upon overvoltage event. Its triggering mechanism relies on dynamic breakover voltage (VBO = 400 V) exceeding stand-off voltage (VRM = 320 V) under transient stress, enabling rapid crowbar action without external bias.
It sustains 50 A (10/1000 µs) repetitive surges while maintaining low leakage (≤2 µA at VRM) and stable holding current (IH ≥12 mA) across –40°C to +125°C junction temperature. Thermal resistance from junction to leads is 20 °C/W in SMB package, supporting reliable self-quenching after surge clearance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 320 V - Maximum continuous reverse voltage before conduction onset; defines maximum operating line voltage margin. |
| Dynamic Breakover Voltage (VBO) | 400 V - Voltage threshold at which device triggers into low-impedance state during fast transients (100 V/µs di/dt). |
| Holding Current (IH) | ≥12 mA - Minimum current required to maintain on-state after triggering; ensures robust latching during sustained overvoltage. |
| Capacitance (C @ 50 V) | 25 pF - Low signal-line loading for high-speed telecom interfaces (e.g., ADSL2+ up to 2.2 MHz). |
| Repetitive Peak Pulse Current (IPP) | 50 A (10/1000 µs) - Surge-handling capability aligned with GR-1089 Core Level 1 and FCC Part 68 Type A lightning tests. |
| Leakage Current (IRM) | ≤2 µA @ VRM - Negligible DC power loss and minimal impact on line impedance in idle state. |
| Package | SMB (JEDEC DO-214AA) - Surface-mount footprint with 5.1–5.6 mm E dimension; supports automated assembly and thermal dissipation via PCB copper area. |
Pinout & Package
SMTPA320 is housed in an SMB (DO-214AA) plastic package with two terminals: Anode (A) and Cathode (K). The device is bidirectional; both terminals function identically under reverse polarity, eliminating orientation dependency in PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Primary current entry point during positive half-cycle surge | Connected to protected line (e.g., tip/ring of xDSL pair); forms crowbar path to ground via series resistor. |
| Cathode (K) | Primary current entry point during negative half-cycle surge | Also connected to protected line; enables symmetrical clamping for AC-coupled telecom signals without polarity bias. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional crowbar operation | Enables single-device protection of AC-coupled telecom lines (e.g., T1/E1, ISDN) without external polarity management circuitry. |
| Fail-safe short-circuit mode | Guarantees permanent low-impedance path upon end-of-life degradation-prevents open-circuit failure that would leave downstream circuitry unprotected. |
| UL497B and UL94 V0 certified | Validated for use in telecom equipment requiring regulatory compliance with FCC Part 68, IEC61000-4-5, and GR-1089 standards. |
| Low 25 pF capacitance @ 50 V | Maintains signal integrity in broadband DSL applications by minimizing insertion loss and return loss degradation above 1 MHz. |
| No aging-related parameter drift | Ensures consistent clamping performance over 10+ years of field operation-critical for carrier-grade central office deployments. |
Applications
| DSL Line Card Protection | T1/E1 Channel Interface |
|---|---|
|
Use Scenario: Protecting ADSL2+/VDSL2 line interface ICs from lightning-induced surges on twisted-pair copper loops. IC Role / Device Role: Primary crowbar clamp placed between line transformer secondary and codec input, upstream of series current-limiting resistor. Use Value: Limits peak voltage to <40 V during 50 A (10/1000 µs) surge, preventing damage to sensitive analog front-end components per GR-1089 Core Level 1. |
Use Scenario: Safeguarding T1/E1 framer and transceiver ICs in channel service units (CSUs) exposed to building-entry surges. IC Role / Device Role: Bidirectional overvoltage clamp on balanced differential receive path, referenced to isolated ground plane. Use Value: Withstands 1500 V (10/560 µs) FCC Part 68 Type A surges while adding <0.1 dB insertion loss at 1.544 MHz. |
| ISDN Terminal Protection | Central Office Line Card |
|
Use Scenario: Securing BRI-U interface in ISDN terminal adapters against induced transients from nearby AC power lines. IC Role / Device Role: Standoff-clamp element in hybrid protection network with gas discharge tube (GDT) and PTC thermistor. Use Value: Provides precise 320 V hold-off to avoid false triggering during normal 150 V RMS ring signal, while firing within 100 ns at >400 V. |
Use Scenario: Front-end surge suppression in carrier-class digital line cards handling 100+ subscriber lines. IC Role / Device Role: First-stage protector mounted directly at PCB edge connector, coordinated with downstream TVS diodes. Use Value: Supports 100,000+ surge events at 50 A (10/1000 µs) without parameter shift-validated per Telcordia GR-1089 intra-building test profile. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar telecom surge protection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SP1003-032 | Unidirectional, 32 V breakdown (not stand-off); requires external bias network for AC line use. | Designed for low-voltage DC data lines (e.g., RS-485), not telecom AC line cards. | Select only if protecting DC-coupled interfaces where polarity is fixed and VRM < 40 V. |
| Vishay V130LA20AP | MOV-based, 130 V AC RMS rating; higher capacitance (200 pF), no fail-safe short-circuit mode. | Used in AC mains input stages-not suitable for high-frequency telecom signal paths due to capacitance and aging drift. | Prefer for AC power inlet protection; avoid in xDSL/T1 signal chains where bandwidth and reliability are critical. |
Compared with SMTPA320, SP1003-032 lacks bidirectionality and fails open, while V130LA20AP introduces excessive capacitance and no guaranteed fail-safe behavior-making SMTPA320 uniquely suited for carrier-grade telecom line card primary protection.
Availability
SMTPA320 is available at Aetrix Electronics and suitable for DSL line card design, T1/E1 channel interface development, and central office equipment manufacturing requiring stable component supply and long-term lifecycle assurance.
Supply support for SMTPA320 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 solutions with broad IP portfolio and manufacturing scale.
SMTPA320 belongs to the Trisil™ family-engineered specifically for telecom infrastructure protection, combining fail-safe crowbar action, low capacitance, and GR-1089/ITU-T compliance in surface-mount packages.
FAQ
What is the fail-safe behavior of SMTPA320 during end-of-life?
When degraded beyond specification, SMTPA320 enters a permanent low-impedance short-circuit state rather than failing open. This ensures downstream circuitry remains protected even after repeated surge events-verified per UL497B testing and documented in ST's reliability reports for Trisil devices.
Can SMTPA320 be used without a series current-limiting resistor?
No. A series resistor (typically 10–100 Ω) is mandatory to limit follow current after triggering and enable self-quenching. Without it, the device remains latched indefinitely due to insufficient current decay below the 12 mA holding threshold-per functional test circuit 3 (Figure 11) in the datasheet.
How does SMTPA320 compare to TVS diodes for telecom surge protection?
Unlike TVS diodes, SMTPA320 provides crowbar clamping with lower clamping voltage under high-current surges (e.g., 50 A), higher surge endurance (>100,000 events), and inherent fail-safe behavior. TVS diodes exhibit higher dynamic impedance and degrade with repeated stress-making SMTPA320 preferred for primary protection in carrier-grade systems.
Is SMTPA320 compliant with RoHS and REACH requirements?
Yes. SMTPA320 is manufactured in ST's ECOPACK®-compliant SMB package with lead-free second-level interconnect, fully conforming to EU RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, as confirmed in ST's official material declarations and inner box labeling.
SMTPA320 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SMP, TRISIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Breakover:
- 400V
- Voltage - Off State:
- 320V
- 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:
- 25pF
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
SMTPA320 FAQ
1.How can I place an order for SMTPA320 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMTPA320 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 SMTPA320 reliable?
The price and inventory of SMTPA320 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMTPA320 is usually 5 days.
3.What payment methods are accepted for SMTPA320?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMTPA320 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMTPA320?
SMTPA320 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMTPA320 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 SMTPA320?
For technical support, including SMTPA320 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMTPA320 requirements.
6.How does Aetrix verify that SMTPA320 is sourced from the original manufacturer or authorized distributors?
All SMTPA320 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 SMTPA320 meets industry standards.
7.What is the process for return or replacement of SMTPA320?
All SMTPA320 units undergo pre-shipment inspection (PSI). If there is an issue with SMTPA320, 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 SMTPA320 part is unused and in its original packaging.
Return procedure for SMTPA320:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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