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onsemi 1SMA18CAT3
- Part No.:
- 1SMA18CAT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA18CAT3.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:5,477
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Product details
Overview
1SMA18CAT3 from ON Semiconductor is a bidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 18 V working peak reverse voltage (VRWM), 29.2 V clamping voltage at 13.7 A peak pulse current, and sub-1 ns response time. It is used in automotive power supplies and industrial control I/O protection.
For engineers reviewing the 1SMA18CAT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM margin over operating voltage, clamping voltage vs. protected device's absolute maximum rating, surge current capability under 10/1000 µs waveform, and junction capacitance (335 pF at 0 V) for high-speed signal line compatibility.
Technical Context
The 1SMA18CAT3 operates as a bidirectional avalanche diode, symmetrically clamping both positive and negative transients above its breakdown voltage range (20.0–22.11 V at 1 mA test current). Its low zener impedance and fast <1 ns response enable effective suppression of ESD (Class 3 HBM >16 kV) and lightning-induced surges.
It is rated for 400 W non-repetitive peak power at 1 ms pulse width (10/1000 µs waveform), with thermal derating starting at 75°C junction temperature. The SURMETIC® SMA package (Case 403D) provides robust mechanical mounting and meets Pb-free and AEC-Q101 requirements for automotive use.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's normal peak voltage. |
| VBR (min/typ/max) | 20.0 / 21.06 / 22.11 V @ 1 mA - Ensures predictable turn-on threshold across process variation. |
| VC @ IPP | 29.2 V @ 13.7 A - Clamping voltage during 10/1000 µs surge; determines maximum stress on downstream ICs. |
| IPP | 13.7 A - Peak pulse current supported at rated clamping voltage; defines surge energy handling (400 W). |
| CJ (0 V) | 335 pF - Junction capacitance at zero bias; critical for USB, CAN, or RS-485 line protection without signal distortion. |
| Response Time | <1 ns - Enables suppression of fast-rising ESD events before protected circuitry is damaged. |
| ESD Rating | Class 3 (>16 kV HBM) - Meets IEC 61000-4-2 Level 4 for system-level ESD immunity. |
Pinout & Package
SMA package (Case 403D): surface-mount, low-profile plastic case with flat handling surface; cathode polarity indicated by band marking; compatible with top-slide or bottom-board mounting; RoHS-compliant, Pb-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient return path (bidirectional) | Connects to ground or common reference; completes clamping loop for both polarities. |
| Cathode | Transient input node (bidirectional) | Connects to protected line; functions as "hot" terminal for both positive and negative surges. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Protects AC-coupled or floating signal lines (e.g., RS-485, CAN) without polarity constraints. |
| 400 W peak power rating | Handles IEC 61000-4-5 Level 3 (1 kV/2 Ω) surge waveforms in industrial power inputs. |
| 335 pF junction capacitance | Minimizes signal attenuation on 10 Mbps CAN FD or 480 Mbps USB 2.0 data lines. |
| AEC-Q101 qualified | Validated for automotive under-hood applications including engine control module (ECM) power rail protection. |
| Flat handling surface | Enables precise pick-and-place placement during automated SMT assembly with ≤±0.1 mm placement tolerance. |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: Suppressing load dump and jump-start transients on 12 V battery-fed ECUs. IC Role / Device Role / Timing Role: Bidirectional TVS placed between power rail and chassis ground to clamp ±100 V surges. Use Value: Limits voltage seen by MCU power supply to ≤29.2 V, preventing brownout or latch-up during ISO 7637-2 Pulse 5a. | Use Scenario: Protecting 24 V digital input modules from field-wiring induced surges. IC Role / Device Role / Timing Role: Parallel-connected TVS on each optocoupler input channel to shunt induced transients. Use Value: Withstands repeated 400 W surges per IEC 61000-4-4, extending module service life in factory automation environments. |
| Medical Equipment ESD Shielding | Telecom Line Interface Protection |
Use Scenario: Safeguarding patient-monitor front-panel buttons and sensor connectors against operator ESD. IC Role / Device Role / Timing Role: Localized TVS on each button trace and analog sensor input to ground. Use Value: Class 3 HBM (>16 kV) rating ensures immunity to clinical staff ESD events without false triggers or resets. | Use Scenario: Protecting Ethernet PHY interface pins (MDI) from lightning-induced surges on outdoor cabling. IC Role / Device Role / Timing Role: Bidirectional TVS on differential pairs (TX+/TX−, RX+/RX−) referenced to chassis ground. Use Value: 335 pF capacitance avoids skew or jitter degradation on 100BASE-TX signals while clamping to safe levels. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SZ1SMA18CAT3G | Automotive-grade variant with AEC-Q101 qualification and PPAP documentation support. | Required for OEM automotive designs requiring full PPAP compliance and traceable lot control. | Select when automotive production requires certified change control and site-specific manufacturing validation. |
| 1SMA18AT3G | Unidirectional version; same VRWM and VC but only clamps positive transients. | Suitable for DC-biased signal lines where negative transients are blocked by series capacitor or circuit topology. | Choose only if circuit polarity is fixed and negative surges are inherently suppressed elsewhere. |
Compared with 1SMA18CAT3, SZ1SMA18CAT3G adds automotive qualification overhead but enables Tier 1 sourcing, while 1SMA18AT3G reduces cost and capacitance (310 pF) but sacrifices bidirectional protection-making it unsuitable for AC-coupled or floating interfaces.
Availability
1SMA18CAT3 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC digital I/O protection, medical equipment ESD shielding, and telecom line interface protection requiring stable component supply and long-term lifecycle assurance.
Supply support for 1SMA18CAT3 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, sensors, and discrete devices for automotive, industrial, and cloud power applications.
The 1SMA18CAT3 belongs to the SMA-series TVS family, engineered for high-surge, low-clamping protection in space-constrained surface-mount applications where reliability under repetitive transients is critical.
FAQ
What is the clamping voltage of the 1SMA18CAT3 under a standard 10/1000 µs surge?
The 1SMA18CAT3 has a maximum clamping voltage (VC) of 29.2 V at 13.7 A peak pulse current under the 10/1000 µs waveform. This value is measured per R.E.A. standard and ensures downstream components see no more than 29.2 V during surge events. The 1SMA18CAT3 maintains this clamping performance across its specified operating temperature range.
Is the 1SMA18CAT3 suitable for protecting high-speed data lines like USB or CAN?
Yes, the 1SMA18CAT3 is suitable for USB 2.0 and CAN FD lines due to its 335 pF junction capacitance at 0 V bias and sub-1 ns response time. These parameters minimize signal integrity impact while providing robust ESD and surge protection. However, designers should verify eye diagram margins and jitter budgets in final layout, as the 1SMA18CAT3's capacitance may require careful trace length matching.
How does the 1SMA18CAT3 differ from unidirectional TVS diodes like 1SMA18AT3G?
The 1SMA18CAT3 is bidirectional and clamps transients of either polarity, making it ideal for AC-coupled or floating interfaces such as RS-485 or CAN bus. In contrast, 1SMA18AT3G only clamps positive transients and requires a DC bias path for negative surge handling. The 1SMA18CAT3's symmetrical structure eliminates polarity dependency, simplifying design for differential or dual-rail systems.
Does the 1SMA18CAT3 meet automotive qualification standards?
The 1SMA18CAT3 itself is not AEC-Q101 qualified; however, its automotive-grade counterpart SZ1SMA18CAT3G is fully AEC-Q101 qualified and PPAP capable. For production automotive applications requiring formal qualification, designers should specify SZ1SMA18CAT3G. The 1SMA18CAT3 remains appropriate for non-automotive industrial and medical uses where AEC-Q101 is not mandated.
What is the thermal derating behavior of the 1SMA18CAT3 above 75°C ambient?
The 1SMA18CAT3's DC power dissipation derates linearly at 20 mW/°C above 75°C ambient, based on zero-lead-length measurement conditions. At 100°C ambient, its usable DC power drops to 1.0 W (from 1.5 W at 75°C). For pulsed operation, peak power remains 400 W up to TJ = 150°C, but designers must ensure junction temperature stays within −65°C to +150°C limits using board-level thermal modeling for the SMA package.
1SMA18CAT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- 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):
- 13.7A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 335pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA18CAT3 FAQ
1.How can I place an order for 1SMA18CAT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA18CAT3 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 1SMA18CAT3 reliable?
The price and inventory of 1SMA18CAT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA18CAT3 is usually 5 days.
3.What payment methods are accepted for 1SMA18CAT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA18CAT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA18CAT3?
1SMA18CAT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA18CAT3 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 1SMA18CAT3?
For technical support, including 1SMA18CAT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA18CAT3 requirements.
6.How does Aetrix verify that 1SMA18CAT3 is sourced from the original manufacturer or authorized distributors?
All 1SMA18CAT3 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 1SMA18CAT3 meets industry standards.
7.What is the process for return or replacement of 1SMA18CAT3?
All 1SMA18CAT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA18CAT3, 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 1SMA18CAT3 part is unused and in its original packaging.
Return procedure for 1SMA18CAT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA18CAT3 Tags
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