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onsemi 1SMB18CAT3
- Part No.:
- 1SMB18CAT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB18CAT3.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:4,990
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Product details
Overview
1SMB18CAT3 from ON Semiconductor is a bidirectional 600 W transient voltage suppressor (TVS) diode designed for parallel overvoltage protection of sensitive electronics. It features a 18 V working peak reverse voltage (VRWM), 22.1 V clamping voltage at 20.5 A peak pulse current, and sub-1 ns response time. Used in power supplies, automotive ECUs, and industrial controls to absorb ESD and lightning-induced surges.
For engineers reviewing the 1SMB18CAT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ circuit operating voltage, VC margin below device breakdown threshold, UL 497B certification for isolated loop protection, and SMB package thermal performance under repetitive surge conditions.
Technical Context
The 1SMB18CAT3 operates as a bidirectional Zener-based TVS, leveraging avalanche breakdown to clamp transients symmetrically across both polarities. Its low zener impedance and fast turn-on (<1 ns) enable effective suppression of ESD (Class 3, >16 kV HBM) and 10/1000 µs surge waveforms up to 600 W.
Thermal design relies on junction-to-lead resistance of 40 °C/W and derating above 75°C; maximum case temperature is 260°C for 10 s during soldering. The device uses ON Semiconductor's Surmetic SMB (DO-214AA, Case 403A) package with modified L-bend leads for enhanced pad adhesion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - must be ≥ continuous DC or peak AC operating voltage of protected circuit |
| VBR @ IT=1 mA | 20.0–22.1 V - ensures reliable avalanche initiation before downstream component damage |
| VC @ IPP=20.5 A | 29.2 V - maximum clamped voltage seen by load during 1 ms 600 W transient |
| IPP | 20.5 A - peak surge current capability under standardized 10/1000 µs waveform |
| IR @ VRWM | <5 µA - negligible leakage at operating bias, critical for low-power sensor interfaces |
| Response Time | <1 ns - enables suppression before transient energy couples into IC inputs |
| UL Recognition | UL 497B QVGV2 - certified for isolated loop circuit protection per safety standard |
Pinout & Package
1SMB18CAT3 is housed in the SMB (DO-214AA, Case 403A) surface-mount package: 4.06–4.57 mm length, 3.30–3.81 mm width, 1.90–2.41 mm height, with modified L-bend leads for robust PCB bonding. Polarity band is not marked due to bidirectional symmetry.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode | Bidirectional terminal pair | Identical electrical behavior in either polarity; no marking required; connects in parallel across protected node and ground/rail |
Key Features
| Feature | Design Value |
|---|---|
| 600 W peak pulse power | Withstands IEC 61000-4-5 Level 4 (4 kV) surges without degradation when properly mounted |
| UL 497B recognition | Validated for use in telecom and industrial isolated loop protection circuits per safety compliance |
| ESD Class 3 (>16 kV HBM) | Meets IEC 61000-4-2 requirements for system-level ESD immunity in end equipment |
| Low clamping ratio (VC/VBR ≈ 1.46) | Minimizes overvoltage stress on downstream ICs compared to higher-ratio TVS devices |
| Solderable corrosion-resistant finish | Enables reliable reflow assembly on FR-4 boards using ON Semiconductor's recommended footprint |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module |
|---|---|
Use Scenario: Protects 24 V DC input stage of programmable logic controller (PLC) power supply against load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Bidirectional TVS placed directly across input terminals to clamp positive/negative transients before bulk capacitor and regulator IC. Use Value: Clamps 10/1000 µs surges to ≤29.2 V, preventing overvoltage failure of 36 V-rated input capacitors and enabling compliance with IEC 61000-4-5. | Use Scenario: Shields LIN bus transceiver and microcontroller I/O pins in door module against battery reverse connection and jump-start spikes. IC Role / Device Role / Timing Role: Parallel-connected TVS on LIN line and VCC rail to limit transient excursions during fault events. Use Value: Sub-1 ns response and 29.2 V clamping prevent latch-up or gate oxide damage in 5 V tolerant MCU peripherals under 100 V/100 ms reverse battery stress. |
| Medical Equipment Input Stage | Telecom Line Interface |
Use Scenario: Safeguards isolated 12 V auxiliary supply in patient monitor front-end against ESD and conducted surges from connected peripherals. IC Role / Device Role / Timing Role: TVS installed at primary side of isolated DC-DC converter to protect transformer and controller IC. Use Value: UL 497B certification validates safe operation in medically isolated circuits; <5 µA leakage avoids loading low-current sensor bias networks. | Use Scenario: Protects RJ45 Ethernet PHY interface in VoIP phone against lightning-induced surges coupled via unshielded twisted pair. IC Role / Device Role / Timing Role: Bidirectional TVS placed across differential pair and common-mode lines to suppress common- and differential-mode transients. Use Value: 600 W rating handles 10/700 µs telecom surges; symmetrical clamping preserves signal integrity on full-duplex links without polarity concerns. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18CA | Same VRWM (18 V), identical SMB package, but 600 W rating per JEDEC standards; slightly higher VC (29.7 V @ 20.2 A) | JEDEC-qualified variant with broader automotive qualification history; same PCB layout | Select SMBJ18CA for AEC-Q200-compliant designs requiring extended temperature validation |
| P6SMB18CA | Same electrical specs and package; manufactured by Vishay; UL 497B recognized; VC = 29.2 V @ 20.5 A | Second-source alternative with identical footprint and performance; supported by multiple global distributors | Choose P6SMB18CA for supply chain diversification without redesign or qualification retesting |
Compared with 1SMB18CAT3, SMBJ18CA offers stronger automotive pedigree but marginally higher clamping voltage, while P6SMB18CA delivers identical protection performance with dual-sourcing flexibility-both require no PCB changes and maintain full functional equivalence in non-automotive industrial applications.
Availability
1SMB18CAT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, medical auxiliary power stages, and telecom line interfaces requiring stable component supply and UL-certified transient protection.
Supply support for 1SMB18CAT3 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 consumer markets.
The 1SMB18CAT3 belongs to ON Semiconductor's SMB-series transient voltage suppressors, engineered specifically for high-reliability, surface-mount overvoltage protection in harsh environments where UL 497B compliance and 600 W surge handling are mandatory.
FAQ
What is the clamping voltage of the 1SMB18CAT3 and how is it measured?
The 1SMB18CAT3 has a maximum clamping voltage (VC) of 29.2 V, measured at a peak pulse current (IPP) of 20.5 A under the standardized 10/1000 µs waveform. This value represents the highest voltage the device allows across its terminals during a transient event and is critical for ensuring protected components remain below their absolute maximum ratings. The 1SMB18CAT3 achieves this clamping performance consistently across its operating temperature range.
Is the 1SMB18CAT3 suitable for automotive applications?
Yes, the 1SMB18CAT3 meets key automotive surge immunity requirements including ISO 7637-2 Pulse 1, 2a, and 5a when correctly implemented in the circuit. Its 600 W peak power rating, UL 497B certification, and -65°C to +150°C operating temperature range support use in body control modules and infotainment power rails. While not AEC-Q200 qualified itself, the 1SMB18CAT3 is widely deployed in automotive subsystems where system-level testing validates performance.
Does the 1SMB18CAT3 have polarity markings, and how should it be oriented on the PCB?
No, the 1SMB18CAT3 does not have polarity markings because it is a bidirectional TVS diode. Its anode and cathode terminals are functionally identical, allowing installation in either orientation across the protected node and reference plane. This eliminates orientation errors during automated assembly and simplifies layout for differential or AC-coupled protection schemes.
What is the maximum allowable soldering temperature for the 1SMB18CAT3?
The 1SMB18CAT3 supports a maximum case temperature of 260°C for 10 seconds during reflow soldering, per ON Semiconductor's mechanical specifications. This aligns with standard lead-free reflow profiles. Exceeding this limit risks internal bond wire damage or delamination. Proper thermal profiling using the recommended SMB footprint (Case 403A) ensures reliable joint formation without compromising device integrity.
How does the 1SMB18CAT3 compare to unidirectional TVS diodes like the 1SMB18AT3?
The 1SMB18CAT3 is bidirectional and suppresses transients of either polarity, making it ideal for AC lines, differential buses, or circuits where voltage reversal may occur. In contrast, the unidirectional 1SMB18AT3 only clamps negative-going transients and conducts freely on positive half-cycles. For DC-powered systems with known polarity, 1SMB18AT3 offers slightly lower leakage, but the 1SMB18CAT3 provides universal protection without polarity constraints-critical for robustness in field-deployed equipment.
1SMB18CAT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AA, SMB
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- 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:
- 465pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB18CAT3 FAQ
1.How can I place an order for 1SMB18CAT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB18CAT3 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 1SMB18CAT3 reliable?
The price and inventory of 1SMB18CAT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB18CAT3 is usually 5 days.
3.What payment methods are accepted for 1SMB18CAT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB18CAT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB18CAT3?
1SMB18CAT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB18CAT3 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 1SMB18CAT3?
For technical support, including 1SMB18CAT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB18CAT3 requirements.
6.How does Aetrix verify that 1SMB18CAT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB18CAT3 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 1SMB18CAT3 meets industry standards.
7.What is the process for return or replacement of 1SMB18CAT3?
All 1SMB18CAT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB18CAT3, 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 1SMB18CAT3 part is unused and in its original packaging.
Return procedure for 1SMB18CAT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB18CAT3 Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
Diodes Incorporated
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onsemi
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D5V0H1B2LP-7B
Diodes Incorporated
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Diodes Incorporated
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DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
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Diodes Incorporated
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PESD2V0Y1BSFYL
Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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