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onsemi 1SMB40AT3
- Part No.:
- 1SMB40AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
1SMB40AT3.pdf
- Description:
- TVS DIODE 40V 64.5V SMB
- Quantity:
- Payment:
- Shipping:
Inventory:5,814
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Product details
Overview
1SMB40AT3 from ON Semiconductor is a unidirectional 600 W peak power Zener transient voltage suppressor (TVS) designed for parallel clamping protection of sensitive electronics. It features a 40 V working peak reverse voltage (VRWM), 44.2 V minimum breakdown voltage (VBR) at 1.0 mA test current, and clamps to ≤64.5 V at 9.3 A peak pulse current (IPP), making it suitable for DC power rail surge suppression in industrial power supplies.
For engineers reviewing the 1SMB40AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin vs. system operating voltage, 600 W single-pulse surge capability per 1 ms waveform, UL 497B recognition for isolated loop protection, and SMB package compatibility with automated SMT assembly.
Technical Context
The 1SMB40AT3 operates as a unidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp transients above its VRWM. Its response time is typically <1.0 ns, and it exhibits low zener impedance to maintain tight clamping under fast-rising surges such as ESD or lightning-induced spikes.
It is rated for 600 W peak pulse power (10/1000 µs waveform), supports forward surge current up to 100 A (8.3 ms half-sine), and maintains <5.0 µA leakage at 40 V. Thermal design relies on junction-to-lead resistance of 40 °C/W and junction-to-ambient resistance of 226 °C/W on FR-4 with minimum footprint.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 40 V - Maximum continuous reverse operating voltage before clamping begins; must exceed system DC rail voltage. |
| VBR (min) | 44.2 V @ 1.0 mA - Guaranteed avalanche initiation threshold; ensures reliable turn-on above VRWM. |
| VC @ IPP | 64.5 V @ 9.3 A - Clamped voltage during 600 W transient; defines maximum stress on protected downstream circuitry. |
| IPP | 9.3 A - Peak pulse current supported at 64.5 V; derived from 600 W / 64.5 V calculation. |
| Leakage (IR) | <5.0 µA @ 40 V - Negligible standby power loss and minimal loading on voltage rails. |
| Response Time | <1.0 ns - Enables suppression of nanosecond-scale ESD events without overshoot degradation. |
| ESD Rating | Class 3 (>16 kV HBM) - Meets IEC 61000-4-2 Level 4 for system-level ESD immunity. |
Pinout & Package
1SMB40AT3 is housed in an SMB (DO-214AA) surface-mount plastic package (Case 403A), featuring a cathode band marking and modified L-bend leads for enhanced solder joint reliability. The device has two terminals: anode and cathode.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal during forward conduction | Connected to lower-potential side (e.g., ground or return path) in unidirectional TVS configuration. |
| Cathode | Current exit terminal during reverse clamping | Connected to protected line (e.g., +48 V rail); polarity band identifies this terminal for correct PCB orientation. |
Key Features
| Feature | Design Value |
|---|---|
| 600 W peak pulse power | Supports robust protection against IEC 61000-4-5 surge events (e.g., 4 kV line-to-ground) without thermal runaway. |
| UL 497B recognition | Validated for use in isolated loop circuits including telecom interfaces and analog sensor inputs requiring safety certification. |
| Pb-free (RoHS-compliant) package | SMB package marked "G" suffix meets global environmental compliance requirements without performance trade-offs. |
| Low clamping ratio (VC/VBR ≈ 1.46) | Minimizes overvoltage stress on protected ICs by tightly bounding clamp voltage relative to breakdown threshold. |
| 260°C soldering tolerance | Withstands standard lead-free reflow profiles (JEDEC J-STD-020) without parametric shift or delamination. |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module Inputs |
|---|---|
|
Use Scenario: 48 V DC input stage of programmable logic controller (PLC) power supply exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Unidirectional TVS clamping element placed directly across input terminals to limit transient voltage to safe levels. Use Value: Limits voltage excursion to ≤64.5 V during 9.3 A surge, protecting upstream rectifier and downstream DC-DC controller from overvoltage failure. |
Use Scenario: LIN bus signal line in body control module subjected to ESD and battery reversal transients. IC Role / Device Role / Timing Role: Parallel-connected transient suppressor referenced to ground, absorbing fast spikes before they reach LIN transceiver. Use Value: Sub-1 ns response prevents >64.5 V overshoot from damaging 5 V-tolerant LIN PHY, while <5 µA leakage avoids signal integrity degradation. |
| Medical Equipment AC/DC Adapter Input | Telecom Remote Terminal Unit (RTU) Interface |
|
Use Scenario: Secondary-side DC output of medical-grade AC/DC adapter feeding critical monitoring circuitry. IC Role / Device Role / Timing Role: Output rail protector ensuring no transient exceeds 64.5 V under EN 61000-4-4 EFT bursts. Use Value: Maintains patient safety isolation barrier integrity by preventing voltage breakdown across reinforced insulation due to clamped surges. |
Use Scenario: RS-485 data lines in outdoor RTU exposed to induced lightning surges on long cable runs. IC Role / Device Role / Timing Role: Line-to-ground TVS on each differential pair, referenced to chassis ground via low-inductance layout. Use Value: 600 W rating handles multi-kA induced currents; UL 497B recognition validates suitability for telecom infrastructure surge protection standards. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ40A | Same VRWM (40 V), identical SMB package, but rated for 600 W with slightly higher VC (64.8 V @ 9.2 A). | Functionally interchangeable in most 40 V rail protection designs; minor VC difference requires verification against downstream IC absolute max ratings. | Select SMBJ40A if sourcing from alternate distributors; verify latest revision for UL 497B status, as not all variants carry full recognition. |
| 1.5SMC40A | Higher power rating (1500 W), larger SMC (DO-214AB) package, same 40 V VRWM and comparable VBR (44.4 V min). | Used where higher surge repetition or longer pulse durations (e.g., IEC 61000-4-5 1.2/50 µs) demand greater energy absorption. | Choose 1.5SMC40A only when board space allows SMC footprint and system-level testing confirms need for >600 W capability. |
Compared with SMBJ40A and 1.5SMC40A, the 1SMB40AT3 offers optimal balance of compact SMB footprint, UL 497B certification, and verified 600 W surge handling-making it preferred for space-constrained, safety-certified industrial and medical power interfaces where consistent manufacturability and traceable compliance are required.
Availability
1SMB40AT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive control units, medical equipment adapters, and telecom interface modules requiring stable component supply with full RoHS and UL compliance documentation.
Supply support for 1SMB40AT3 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 part of onsemi) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and medical markets.
The 1SMB40AT3 belongs to the SMB series of unidirectional TVS diodes engineered specifically for high-reliability, high-surge industrial and automotive power rail protection-with emphasis on UL 497B compliance, low clamping ratio, and robust SMT manufacturability.
FAQ
What is the maximum clamping voltage of the 1SMB40AT3 under surge conditions?
The 1SMB40AT3 clamps to a maximum of 64.5 V when subjected to its rated peak pulse current of 9.3 A (corresponding to 600 W at 1 ms pulse width). This value is guaranteed per the datasheet's Electrical Characteristics table and defines the upper voltage limit imposed on protected circuitry during transient events. Designers must ensure downstream components tolerate at least 64.5 V to avoid damage. The 1SMB40AT3 achieves this clamping performance through controlled Zener avalanche characteristics and low dynamic impedance.
Is the 1SMB40AT3 suitable for bidirectional signal line protection?
No, the 1SMB40AT3 is a unidirectional TVS diode and is not suitable for bidirectional signal line protection such as RS-485 or USB data lines without additional circuitry. Its design clamps only in reverse bias above VRWM and conducts forward current like a standard diode below ~0.7 V. For bidirectional protection, ON Semiconductor offers the 1SMB40CAT3 ('C' suffix) variant. Using the 1SMB40AT3 on AC-coupled or differential lines risks forward conduction during negative excursions and inadequate suppression of negative transients.
Does the 1SMB40AT3 meet UL 497B certification, and what does that cover?
Yes, the 1SMB40AT3 carries UL 497B recognition (File #E210057) for use in protectors applied to isolated loop circuits. This certification validates performance in tests including strike voltage breakdown, endurance conditioning, temperature cycling, dielectric withstand, and discharge behavior-going beyond basic flammability ratings. UL 497B approval confirms suitability for telecom, industrial process control, and medical isolation barrier applications where certified surge protection is mandated, distinguishing it from non-recognized alternatives.
What is the thermal resistance and power derating behavior of the 1SMB40AT3?
The 1SMB40AT3 has a junction-to-lead thermal resistance (RJL) of 40 °C/W and junction-to-ambient resistance (RJA) of 226 °C/W on FR-4 with ON Semiconductor's recommended footprint. Its DC power dissipation is rated at 0.55 W at 25°C ambient, derating linearly by 4.4 mW/°C above that temperature. For pulsed operation, peak power remains 600 W at TL = 25°C, but must be reduced per Figure 3 in the datasheet when lead temperature exceeds 25°C. Proper copper pour and thermal vias are essential to maintain safe junction temperatures during repeated surges.
How does the 1SMB40AT3 compare to the 1SMB40AT3G variant?
The 1SMB40AT3 and 1SMB40AT3G are functionally identical in electrical and thermal specifications; the 'G' suffix denotes a Pb-free (RoHS-compliant) version with the same SMB package, marking, and performance. Both share identical VRWM (40 V), VBR (44.2 V min), VC (64.5 V), and surge ratings. The primary distinction is material composition: the 1SMB40AT3G uses lead-free terminations and molding compound, enabling compliance with EU RoHS Directive 2011/65/EU and China RoHS. No design or layout changes are needed when substituting one for the other.
1SMB40AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- -
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- -
- Unidirectional Channels:
- -
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- -
- Voltage - Breakdown (Min):
- -
- Voltage - Clamping (Max) @ Ipp:
- -
- Current - Peak Pulse (10/1000µs):
- -
- Power - Peak Pulse:
- -
- Power Line Protection:
- -
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
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- Grade:
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- Qualification:
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- Mounting Type:
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- Supplier Device Package:
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1SMB40AT3 FAQ
1.How can I place an order for 1SMB40AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB40AT3 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 1SMB40AT3 reliable?
The price and inventory of 1SMB40AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB40AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB40AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB40AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB40AT3?
1SMB40AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB40AT3 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 1SMB40AT3?
For technical support, including 1SMB40AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB40AT3 requirements.
6.How does Aetrix verify that 1SMB40AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB40AT3 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 1SMB40AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB40AT3?
All 1SMB40AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB40AT3, 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 1SMB40AT3 part is unused and in its original packaging.
Return procedure for 1SMB40AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB40AT3 Tags
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