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onsemi 1SMC20AT3
- Part No.:
- 1SMC20AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
1SMC20AT3.pdf
- Description:
- TVS DIODE 20VWM 32.4VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:5,921
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Product details
Overview
1SMC20AT3 from ON Semiconductor is a unidirectional 1500 W transient voltage suppressor (TVS) diode designed for parallel protection of sensitive electronics against ESD, lightning surges, and inductive switching transients. It features a 20 V working peak reverse voltage (VRWM), 22.1 V nominal breakdown voltage (VBR) at 1 A test current, 29.2 V maximum clamping voltage (VC) at 64.7 A peak pulse current, and sub-1 ns response time - deployed in power supplies, industrial controls, and automotive ECUs.
For engineers reviewing the 1SMC20AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, VRWM alignment with DC bus voltage, surge current capability under 8.3 ms waveform, UL 497B recognition for isolated loop protection, and SMC package thermal performance on FR-4 PCBs.
Technical Context
The 1SMC20AT3 operates as a Zener-based unidirectional TVS diode, entering avalanche conduction when reverse voltage exceeds its 22.1 V nominal breakdown threshold. Its low dynamic impedance ensures stable clamping during 1500 W, 1 ms pulses per IEC 61000-4-5 waveform.
It exhibits <5 µA leakage above 10 V, -65 °C to +150 °C operating range, and UL 497B certification for isolated loop circuit protection - confirming compliance with strike voltage, endurance, dielectric withstand, and discharge testing requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 1500 W @ 1 ms - sustains single high-energy surges without failure |
| Working Peak Reverse Voltage | 20 V - sets maximum continuous DC/peak AC voltage before clamping activates |
| Breakdown Voltage | 22.1 V (nominal) @ 1 A - precise Zener threshold triggering avalanche conduction |
| Clamping Voltage | 29.2 V @ 64.7 A - maximum voltage seen by protected load during full-rated surge |
| Response Time | <1 ns - limits voltage overshoot before suppression engages |
| ESD Rating | Class 3 (>16 kV HBM) - meets IEC 61000-4-2 Level 4 immunity requirements |
| Thermal Resistance | 165 °C/W (Junction-to-Ambient) - defines derating needed for sustained ambient temperatures >25 °C |
Pinout & Package
1SMC20AT3 uses the SMC (DO-214AB) surface-mount plastic package (Case 403), measuring 5.59–6.10 mm × 6.60–7.11 mm × 1.90–2.41 mm, with cathode indicated by molded notch and modified L-bend leads for enhanced solder joint reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current path / Surge return path | Connected to ground or low-impedance reference plane in unidirectional clamp configuration |
| Cathode | Protected line connection / Clamping node | Connected to the signal or power rail requiring overvoltage protection; polarity notch identifies this terminal |
Key Features
| Feature | Design Value |
|---|---|
| UL 497B Recognition | Validated for isolated loop protector classification - passes strike voltage, endurance, and discharge tests beyond basic flammability |
| Low Clamping Ratio | VC/VBR = 29.2/22.1 ≈ 1.32 - tight voltage margin enables robust protection of 24 V systems with 30 V tolerant ICs |
| Pb-Free Surmetic Package | Void-free thermosetting plastic with corrosion-resistant finish - supports lead-free reflow (260 °C/10 s) and long-term field reliability |
| High Surge Current Capacity | 64.7 A peak pulse current - handles IEC 61000-4-5 Combination Wave (1.2/50 µs voltage, 8/20 µs current) |
| Low Leakage Current | <5 µA @ 20 V - minimizes standby power loss and avoids false triggering in high-impedance circuits |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: 24 V DC input stage of programmable logic controller (PLC) power supply exposed to load dump and ISO 7637-2 transients. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed across input terminals to clamp surges before they reach rectifier, bulk capacitor, and controller IC. Use Value: 29.2 V clamping voltage ensures protected downstream components (e.g., LM5005, TPS5430) remain within 30 V absolute max rating during 1500 W transients. |
Use Scenario: LIN bus line protection in BCM where ESD events and battery disconnect spikes threaten transceiver ICs like MC33661. IC Role / Device Role / Timing Role: Parallel-connected TVS on LIN data line referenced to chassis ground, activated within <1 ns to limit voltage excursion. Use Value: UL 497B certification confirms suitability for safety-critical isolated loop applications; 20 V VRWM aligns with LIN's 12 V nominal but 18 V max operating range. |
| Medical Equipment Input Filtering | Telecom Interface Surge Protection |
Use Scenario: Auxiliary 24 V supply input to patient monitor with strict IEC 60601-1 creepage/clearance and surge immunity requirements. IC Role / Device Role / Timing Role: Primary-level TVS on secondary-side DC input, coordinated with common-mode chokes and X/Y capacitors. Use Value: Pb-free Surmetic package supports medical RoHS compliance; 1500 W rating meets IEC 61000-4-5 Level 4 (4 kV line-earth) test severity. |
Use Scenario: Ethernet PHY interface (10/100BASE-TX) on network switch exposed to induced surges from nearby AC lines or lightning coupling. IC Role / Device Role / Timing Role: Discrete TVS pair (one per differential line) referenced to local ground, placed immediately after RJ45 magnetics. Use Value: Sub-1 ns response prevents overshoot exceeding PHY's 3.3 V tolerance; 29.2 V clamping compatible with 24 V bias rails used in PoE midspan injectors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ20A | 600 W peak power, SMB package (smaller footprint, higher RJA = 195 °C/W) | Limited to lower-energy transients; unsuitable for IEC 61000-4-5 Level 4 | Select when board space is constrained and surge threat level is ≤600 W (e.g., consumer USB ports) |
| 1.5SMC20A | Same 1500 W rating and SMC package, but non-Pb-free (legacy SnPb terminations) | No UL 497B recognition; lacks documented isolated loop certification | Use only in non-safety-critical, legacy industrial designs where RoHS exemption applies |
Compared with SMBJ20A and 1.5SMC20A, the 1SMC20AT3 provides certified UL 497B compliance, Pb-free construction, and identical 1500 W surge handling in the industry-standard SMC outline - making it the preferred choice for new designs requiring regulatory traceability and environmental compliance.
Availability
1SMC20AT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive control units, and medical equipment requiring stable component supply with full regulatory documentation and RoHS/REACH compliance.
Supply support for 1SMC20AT3 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
ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensor, and discrete devices for automotive, industrial, and communications markets.
The 1SMC20AT3 belongs to the SMC-series Zener TVS family, engineered specifically for high-reliability transient suppression in harsh environments - emphasizing low clamping ratio, fast response, and regulatory certifications like UL 497B.
FAQ
What is the clamping voltage of the 1SMC20AT3 under full-rated surge conditions?
The 1SMC20AT3 has a maximum clamping voltage (VC) of 29.2 V when subjected to its rated peak pulse current of 64.7 A (per 8.3 ms half-sine waveform). This value is measured at the device terminals and represents the highest voltage imposed on the protected circuit during worst-case transient events - critical for ensuring downstream ICs remain within their absolute maximum voltage ratings.
Is the 1SMC20AT3 suitable for bidirectional signal line protection?
No, the 1SMC20AT3 is a unidirectional TVS diode and must not be used on AC or bidirectional data lines without external circuitry. Its design assumes cathode connected to the protected line and anode to ground; reverse connection would forward-bias the device during normal operation. For bidirectional protection, use a dedicated bidirectional part such as SMBJ20CA or specify a dual-diode array configuration.
Does the 1SMC20AT3 meet UL 497B requirements for isolated loop protection?
Yes, the entire 1SMC5.0AT3 series - including the 1SMC20AT3 - carries Underwriters Laboratories recognition under UL 497B (File #E210057) for protector classification. This certification covers validated performance in strike voltage breakdown, endurance conditioning, temperature stress, dielectric withstand, and discharge testing - confirming suitability for telecom and industrial isolated loop interfaces.
What is the thermal resistance and derating behavior of the 1SMC20AT3 on a standard PCB?
The 1SMC20AT3 has a junction-to-ambient thermal resistance (RJA) of 165 °C/W when mounted on an FR-4 board using ON Semiconductor's minimum recommended footprint. Power dissipation must be linearly derated above 25 °C ambient: at 75 °C, maximum DC power drops to 0.75 W; at 100 °C, it falls to approximately 0.31 W - requiring careful layout and thermal relief for sustained surge duty cycles.
How does the 1SMC20AT3 compare to the older 1.5SMC20A in terms of compliance and packaging?
The 1SMC20AT3 replaces the 1.5SMC20A with Pb-free (RoHS-compliant) terminations, UL 497B certification, and updated Surmetic package construction. While both share identical electrical specs and SMC outline, only the 1SMC20AT3 carries documented isolated loop protector recognition and lead-free process validation - making it the mandatory choice for new designs targeting modern environmental and safety standards.
1SMC20AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AB, SMC
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 46.3A
- Power - Peak Pulse:
- 1500W (1.5kW)
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMC
1SMC20AT3 FAQ
1.How can I place an order for 1SMC20AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMC20AT3 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 1SMC20AT3 reliable?
The price and inventory of 1SMC20AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMC20AT3 is usually 5 days.
3.What payment methods are accepted for 1SMC20AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMC20AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMC20AT3?
1SMC20AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMC20AT3 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 1SMC20AT3?
For technical support, including 1SMC20AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMC20AT3 requirements.
6.How does Aetrix verify that 1SMC20AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMC20AT3 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 1SMC20AT3 meets industry standards.
7.What is the process for return or replacement of 1SMC20AT3?
All 1SMC20AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMC20AT3, 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 1SMC20AT3 part is unused and in its original packaging.
Return procedure for 1SMC20AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMC20AT3 Tags
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