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onsemi 1SMB18AT3G
- Part No.:
- 1SMB18AT3G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB18AT3G.pdf
- Description:
- 600 W TRANSIENT VOLTAGE SUPPRESS
- Quantity:
- Payment:
- Shipping:
Inventory:35,740
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Product details
Overview
1SMB18AT3G from ON Semiconductor is a unidirectional 600 W peak power Zener transient voltage suppressor (TVS) in SMB package, designed for parallel overvoltage protection of sensitive electronics. It features a 18 V working peak reverse voltage (VRWM), 22.1 V nominal breakdown voltage (VBR) at 1.0 mA test current, and clamps to ≤29.2 V at 20.5 A peak pulse current (IPP), making it suitable for automotive power line surge suppression and industrial DC supply rail protection.
For engineers reviewing the 1SMB18AT3G datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to system operating voltage, peak pulse current handling under IEC 61000-4-5 waveforms, UL 497B recognition for isolated loop circuits, and Pb-free SMB package compatibility with automated SMT assembly.
Technical Context
The 1SMB18AT3G operates as a silicon avalanche diode optimized for fast transient suppression - its <1.0 ns response time enables effective clamping before downstream ICs experience overstress. It uses a planar junction structure with low zener impedance to maintain stable clamping across temperature and pulse repetition.
Its thermal design relies on junction-to-lead resistance (RJL = 40 °C/W) and junction-to-ambient resistance (RJA = 226 °C/W) to manage 600 W non-repetitive 1 ms pulses, with derating required above 75°C lead temperature or 25°C ambient. The device is rated for −65°C to +150°C operation and supports 100 A forward surge current (IFSM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Power Dissipation | 600 W @ 1 ms pulse - handles IEC 61000-4-5 Level 4 surges without failure |
| Working Peak Reverse Voltage (VRWM) | 18 V - selected to exceed nominal 12 V automotive or 15 V industrial supply rails |
| Breakdown Voltage (VBR) | 22.1 V (nominal) @ IT = 1.0 mA - defines minimum voltage at which avalanche conduction begins |
| Clamping Voltage (VC) | ≤29.2 V @ IPP = 20.5 A - ensures protected circuit remains below 30 V during worst-case transient |
| Reverse Leakage Current (IR) | ≤5.0 µA @ VRWM = 18 V - negligible standby power loss in high-impedance bias networks |
| ESD Rating | Class 3 (>16 kV HBM) - meets IEC 61000-4-2 for system-level ESD immunity |
| UL Recognition | UL 497B QVGQ2 - certified for use in isolated loop circuit protection per safety standard |
Pinout & Package
Package: SMB (Case 403A), surface-mount, Pb-free, void-free thermosetting plastic with modified L-bend leads and cathode polarity band. Dimensions: 4.32 mm × 2.13 mm × 2.26 mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or lowest potential node in clamp configuration; forms return path for surge current |
| Cathode | High-side transient input terminal | Connected to protected line (e.g., 12 V rail); polarity band identifies this terminal for correct PCB placement |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ns - limits voltage overshoot during nanosecond-scale transients like EFT bursts |
| Low clamping ratio | VC/VBR ≈ 1.32 - tight voltage margin between breakdown and clamp improves system robustness |
| High surge capability | 20.5 A IPP at 18 V VRWM - sustains repeated 1 ms surges without parameter shift or degradation |
| Pb-free compliance | RoHS-compliant SMB package - compatible with lead-free reflow profiles (260°C/10 s max) |
| UL 497B certification | Recognized for isolated loop protection - eliminates need for separate safety qualification in telecom/power interface designs |
Applications
| Automotive Power Line Protection | Industrial DC Power Supply Rail |
|---|---|
|
Use Scenario: Suppressing load dump and jump-start transients on 12 V battery-fed ECUs. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and ground, clamping spikes up to ±100 V within nanoseconds. Use Value: Prevents damage to CAN transceivers and microcontrollers by limiting rail voltage to ≤29.2 V during 600 W surges. |
Use Scenario: Protecting programmable logic controllers (PLCs) against switching surges in 24 V DC control systems. IC Role / Device Role / Timing Role: Parallel-connected transient suppressor across input terminals, activated only during overvoltage events. Use Value: Maintains system uptime by absorbing 1 ms, 20.5 A pulses without latch-up or parametric drift. |
| Medical Equipment Input Stage | Telecom Isolated Interface |
|
Use Scenario: Safeguarding patient-connected monitoring devices from ESD and conducted surges on auxiliary power inputs. IC Role / Device Role / Timing Role: First-line overvoltage protector upstream of DC-DC converters and signal conditioning ICs. Use Value: UL 497B recognition validates safe use in isolated loop circuits where patient safety is critical. |
Use Scenario: Protecting RS-485 transceivers and isolation barriers in building automation gateways. IC Role / Device Role / Timing Role: Clamp device on isolated side of transformer-coupled data lines to prevent common-mode surge propagation. Use Value: Low leakage (<5 µA) avoids loading high-impedance bias networks while providing >16 kV HBM ESD immunity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A | Same VRWM (18 V) and VC (29.2 V), but rated for 600 W with tighter VBR tolerance (20.0–22.1 V vs. 20.0–22.1 V); identical SMB package | No functional difference in clamping performance; differs only in manufacturer-specific test conditions and marking | Select SMBJ18A if sourcing from STMicroelectronics or requiring alternate supply chain; electrical behavior is functionally interchangeable |
| P6SMB18A | Identical VRWM (18 V), VBR (20.0–22.1 V), and VC (29.2 V); same 600 W rating and SMB package; minor variation in IR spec (≤10 µA vs. ≤5 µA) | Validated for same automotive and industrial surge standards; slightly higher leakage acceptable in non-battery-critical designs | Choose P6SMB18A when cost optimization is prioritized and ≤10 µA leakage is acceptable in the target application |
Compared with 1SMB18AT3G, SMBJ18A offers identical clamping and surge ratings with equivalent layout compatibility, while P6SMB18A trades minimal leakage increase for broader distributor availability - both serve as drop-in alternatives where UL 497B is not mandated.
Availability
1SMB18AT3G is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, medical monitoring equipment, and telecom interface modules requiring stable component supply and long-term lifecycle support.
Supply support for 1SMB18AT3G 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 energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The 1SMB18AT3G belongs to the SMB series of unidirectional TVS diodes, engineered specifically for high-energy transient suppression in harsh environments - emphasizing reliability, UL safety certification, and robust surge handling in compact surface-mount form.
FAQ
What is the maximum clamping voltage of the 1SMB18AT3G under peak pulse conditions?
The 1SMB18AT3G has a maximum clamping voltage (VC) of 29.2 V when subjected to its rated peak pulse current (IPP) of 20.5 A, measured using the 10/1000 µs waveform per IEC 61000-4-5. This value is guaranteed across temperature and ensures protected circuits remain within safe operating limits during surge events.
Is the 1SMB18AT3G RoHS-compliant and lead-free?
Yes, the "G" suffix in 1SMB18AT3G explicitly denotes a Pb-free, RoHS-compliant version packaged in ON Semiconductor's Surmetic SMB case. It meets JEDEC J-STD-020 reflow requirements with a maximum soldering temperature of 260°C for 10 seconds and is qualified for lead-free assembly processes.
Does the 1SMB18AT3G have UL recognition, and for what standard?
The 1SMB18AT3G carries UL 497B recognition (File #E210057, Category QVGQ2) for use in isolated loop circuit protection. This certification covers performance validation across strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge testing - confirming suitability for safety-critical telecom and industrial interfaces.
How does the 1SMB18AT3G differ from bidirectional TVS diodes like 1SMB18CAT3G?
The 1SMB18AT3G is unidirectional and optimized for DC line protection where polarity is fixed (e.g., 12 V automotive rails), offering lower leakage (<5 µA) and tighter VBR consistency. In contrast, 1SMB18CAT3G is bidirectional and suited for AC or floating signal lines, with symmetrical clamping but higher leakage and no UL 497B listing for isolated loop use.
What is the thermal derating behavior of the 1SMB18AT3G above 25°C ambient?
The 1SMB18AT3G derates linearly above 25°C ambient: its DC power dissipation drops by 4.4 mW/°C, reaching 0.55 W at 25°C and zero at approximately 150°C. For pulsed operation, Figure 3 in the datasheet shows peak power must be reduced to ~50% at 100°C ambient - critical for under-hood or enclosed industrial deployments.
1SMB18AT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AA, SMB
- Series:
- SMB
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 20.5A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 870pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB18AT3G FAQ
1.How can I place an order for 1SMB18AT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB18AT3G 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 1SMB18AT3G reliable?
The price and inventory of 1SMB18AT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB18AT3G is usually 5 days.
3.What payment methods are accepted for 1SMB18AT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB18AT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB18AT3G?
1SMB18AT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB18AT3G 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 1SMB18AT3G?
For technical support, including 1SMB18AT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB18AT3G requirements.
6.How does Aetrix verify that 1SMB18AT3G is sourced from the original manufacturer or authorized distributors?
All 1SMB18AT3G 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 1SMB18AT3G meets industry standards.
7.What is the process for return or replacement of 1SMB18AT3G?
All 1SMB18AT3G units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB18AT3G, 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 1SMB18AT3G part is unused and in its original packaging.
Return procedure for 1SMB18AT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB18AT3G Tags
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