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onsemi 1SMB20AT3
- Part No.:
- 1SMB20AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB20AT3.pdf
- Description:
- TVS DIODE 20VWM 32.4VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:6,351
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Product details
Overview
1SMB20AT3 from ON Semiconductor is a unidirectional 600 W peak power Zener transient voltage suppressor (TVS) in SMB package, rated for 20 V working peak reverse voltage (VRWM), 22.1 V nominal breakdown voltage (VBR) at 1.0 mA test current, and clamps to 32.4 V at 18.5 A peak pulse current (IPP). It delivers sub-1 ns response time and <5 µA leakage above 10 V, designed for overvoltage protection in DC power rails and signal lines.
For engineers reviewing the 1SMB20AT3 datasheet, pinout, applications, or equivalent options, this device serves as a robust, UL 497B–recognized TVS for industrial power supplies, automotive ECUs, and communication interface protection where fast clamping and high surge immunity are required.
Technical Context
The 1SMB20AT3 operates as a unidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp transients above its VRWM of 20 V. Its 32.4 V clamping voltage at 18.5 A IPP ensures safe voltage limiting during 10/1000 µs surges while maintaining low dynamic impedance.
It features a thermally optimized Surmetic SMB package (Case 403A) with modified L-bend leads for enhanced solder joint reliability and thermal dissipation. The device meets Class 3 ESD rating (>16 kV HBM) and is Pb-free compliant per J-STD-609.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Power Dissipation | 600 W @ 1.0 ms 10/1000 µs waveform - enables handling of high-energy lightning-induced surges in industrial environments |
| Working Peak Reverse Voltage (VRWM) | 20 V - sets maximum continuous operating voltage before clamping activation; matches 18–24 V DC systems |
| Breakdown Voltage (VBR) | 22.1 V (nominal) @ IT = 1.0 mA - defines precise avalanche onset point for predictable protection threshold |
| Clamping Voltage (VC) | 32.4 V @ IPP = 18.5 A - limits downstream voltage stress to safe levels during surge events |
| Leakage Current (IR) | <5.0 µA @ VRWM = 20 V - minimizes standby power loss and avoids false triggering in low-power circuits |
| Response Time | <1.0 ns - ensures suppression occurs before sensitive ICs experience damaging overvoltage |
| Junction Capacitance | 790 pF @ 0 V, 1 MHz - low enough for use on RS-485, CAN, and 24 V sensor lines without signal integrity impact |
Pinout & Package
Package: SMB (Surface Mount, Case 403A), void-free thermosetting plastic with cathode band marking and modified L-bend leads for reliable PCB bonding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal during forward conduction | Connected to system ground or low-side reference; enables unidirectional clamping from cathode to anode |
| Cathode | Current exit terminal during reverse-biased clamping | Connected to protected line (e.g., 24 V rail); conducts surge current to ground when voltage exceeds VRWM |
Key Features
| Feature | Design Value |
|---|---|
| UL 497B Recognition (QVGQ2) | Validated for isolated loop circuit protection - enables use in certified industrial safety systems without additional qualification |
| ESD Rating Class 3 (>16 kV HBM) | Withstands human-body model discharges up to 16 kV - protects against common handling and operational ESD events |
| Thermal Resistance (RJL) | 40 °C/W junction-to-lead - supports sustained surge duty cycles with minimal thermal derating on standard FR-4 PCBs |
| Pb-Free Compliant (1SMB20AT3G) | RoHS-compliant Surmetic SMB package - meets global environmental regulations without performance trade-offs |
| Low Clamping Ratio (VC/VBR) | 1.47 (32.4 V / 22.1 V) - indicates efficient energy diversion with minimal overvoltage margin |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
|
Use Scenario: Protecting 24 V DC input rails in programmable logic controllers (PLCs) against load dump and ISO 7637-2 Pulse 5a transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input rail and chassis ground to clamp surges before they reach DC-DC converters and microcontrollers. Use Value: Limits voltage to ≤32.4 V during 18.5 A transients, preventing latch-up or permanent damage to 3.3 V/5 V logic and power management ICs. |
Use Scenario: Safeguarding LIN bus and sensor supply lines in BCMs exposed to battery reversal and jump-start conditions. IC Role / Device Role / Timing Role: Standoff protection device on 12 V sensor VCC lines, absorbing repetitive 100 V/50 ms pulses per ISO 16750-2. Use Value: Maintains leakage <5 µA at 12 V operation while clamping 100 V transients to 32.4 V, preserving signal integrity and MCU uptime. |
| RS-485 Communication Interface | Medical Equipment Power Input |
|
Use Scenario: Protecting differential RS-485 transceivers (e.g., MAX1487) connected to long cable runs subject to induced lightning surges. IC Role / Device Role / Timing Role: Paired unidirectional TVS on A/B lines referenced to local ground, providing common-mode surge suppression. Use Value: 790 pF capacitance and 32.4 V clamping ensure data rates up to 10 Mbps remain unaffected while meeting IEC 61000-4-5 Level 3 (1 kV) |
Use Scenario: Securing AC/DC adapter outputs in diagnostic imaging devices where power interruption must be avoided during ESD events. IC Role / Device Role / Timing Role: Final-stage TVS on regulated 24 V output rail, acting as last-line defense against conducted transients entering via mains input. Use Value: UL 497B recognition confirms suitability for patient-connected equipment; 600 W rating handles worst-case surge coupling from adjacent subsystems. |
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 | Same VRWM (20 V), identical SMB package, but lower 32.4 V VC at 17.6 A IPP (vs. 18.5 A for 1SMB20AT3); slightly higher IR (10 µA vs. 5 µA) | Marginally lower surge current handling; suitable where 17.6 A IPP suffices and cost sensitivity outweighs 1.0 A IPP gain | Select SMBJ20A only if design validation confirms 17.6 A IPP meets IEC 61000-4-5 requirements; verify leakage impact on ultra-low-power sleep modes |
| 1.5SMC20A | Higher 1500 W peak power rating, DO-214AB package (larger footprint), same 20 V VRWM and 32.4 V VC, but slower thermal response due to larger junction mass | Used where higher single-pulse energy tolerance is needed (e.g., telecom central office power feeds), but requires PCB area increase and layout revision | Choose 1.5SMC20A only when 600 W is insufficient; avoid for space-constrained designs due to 7.11 mm × 6.22 mm footprint vs. SMB's 4.60 mm × 3.95 mm |
Compared with SMBJ20A and 1.5SMC20A, the 1SMB20AT3 offers optimal balance of surge current (18.5 A), compact SMB footprint, and low leakage (≤5 µA), making it preferred for high-density industrial and automotive control modules requiring repeatable 600 W transient handling without layout changes.
Availability
1SMB20AT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive electronic control units, and medical equipment requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for 1SMB20AT3 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 (now onsemi) is a global semiconductor supplier specializing in power management, analog, sensors, and discrete devices for automotive, industrial, and cloud power applications.
The 1SMB20AT3 belongs to the SMB series of unidirectional TVS diodes engineered for high-reliability overvoltage protection in harsh environments-designed specifically for robustness in automotive, industrial automation, and medical power systems.
FAQ
What is the clamping voltage of the 1SMB20AT3 at its rated peak pulse current?
The 1SMB20AT3 clamps to 32.4 V at its specified peak pulse current of 18.5 A under the standard 10/1000 µs waveform. This value is measured per the test conditions defined in the ON Semiconductor datasheet and reflects the maximum voltage seen across the device during a surge event, ensuring downstream components remain within safe operating limits. The 1SMB20AT3 maintains this clamping performance consistently across its qualified temperature range of −65°C to +150°C.
Is the 1SMB20AT3 RoHS-compliant and lead-free?
Yes, the 1SMB20AT3 is available in a Pb-free version designated as 1SMB20AT3G, fully compliant with RoHS Directive 2011/65/EU and J-STD-609. The Surmetic SMB package uses lead-free terminations and conforms to reflow soldering profiles up to 260°C for 10 seconds. The 1SMB20AT3G marking includes the "G" suffix, and both variants share identical electrical specifications and thermal performance.
How does the 1SMB20AT3 differ from bidirectional TVS diodes like the 1SMB20CAT3?
The 1SMB20AT3 is unidirectional and functions only during reverse-biased transients, making it ideal for DC power rail protection where polarity is fixed. In contrast, the 1SMB20CAT3 is bidirectional and clamps both positive and negative surges, suited for AC lines or data buses like RS-232. The 1SMB20AT3 has lower leakage (<5 µA @ 20 V) than its bidirectional counterpart and avoids unnecessary conduction during normal negative excursions in DC systems.
Can the 1SMB20AT3 be used in parallel to increase surge current handling?
No, the 1SMB20AT3 should not be paralleled for increased IPP because minor VBR mismatches between units cause current imbalance, leading to thermal runaway and premature failure. ON Semiconductor explicitly advises against paralleling discrete TVS diodes. For higher surge capability, select a single device with appropriate rating (e.g., 1.5SMC20A) or implement staged protection with upstream current-limiting impedance.
What is the maximum operating temperature range for the 1SMB20AT3?
The 1SMB20AT3 is rated for an operating and storage temperature range of −65°C to +150°C. Its thermal resistance from junction-to-lead is 40°C/W, enabling reliable operation at elevated ambient temperatures when mounted on adequate copper area. Derating begins above +75°C for DC power dissipation and above +25°C for ambient-limited ratings, per the datasheet's thermal curves.
1SMB20AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AA, SMB
- 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):
- 18.5A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 790pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB20AT3 FAQ
1.How can I place an order for 1SMB20AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB20AT3 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 1SMB20AT3 reliable?
The price and inventory of 1SMB20AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB20AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB20AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB20AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB20AT3?
1SMB20AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB20AT3 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 1SMB20AT3?
For technical support, including 1SMB20AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB20AT3 requirements.
6.How does Aetrix verify that 1SMB20AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB20AT3 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 1SMB20AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB20AT3?
All 1SMB20AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB20AT3, 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 1SMB20AT3 part is unused and in its original packaging.
Return procedure for 1SMB20AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB20AT3 Tags
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