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onsemi SA18ARL
- Part No.:
- SA18ARL
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA18ARL.pdf
- Description:
- TVS DIODE 18VWM 29.2VC AXIAL
- Quantity:
- Payment:
- Shipping:
Inventory:6,203
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Product details
Overview
SA18ARL from onsemi is a unidirectional 500 W peak power MiniMOSORB 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 maximum clamping voltage at 20 A peak pulse current (IPP), <1 µA leakage at VRWM, and sub-1 ns response time. It is used in industrial power supplies, medical equipment surge protection, and communication interface circuits.
For engineers reviewing the SA18ARL datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC VDD, thermal derating at elevated lead temperature, UL 497B certification for isolated loop protection, and axial leaded Surmetic package compatibility with through-hole reflow or wave soldering.
Technical Context
The SA18ARL operates as a voltage-clamping device in reverse-biased configuration, conducting only when transient voltage exceeds its breakdown threshold (VBR = 20–22.1 V at 1 mA). Its low zener impedance and fast response (<1 ns) enable effective suppression of ESD and lightning-induced surges without affecting normal circuit operation.
It is rated for 500 W nonrepetitive peak power per 1 ms pulse (per Figure 4), with steady-state power dissipation limited to 3.0 W at TL ≤ 75°C and thermal resistance RJL = 33.3°C/W. The device meets UL 497B for isolated loop circuit protection and Class 3 HBM ESD (>16 kV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; must exceed system DC rail voltage. |
| VBR @ IT = 1 mA | 20–22.1 V - Breakdown voltage range defining turn-on threshold; ensures reliable triggering above nominal rail. |
| VC @ IPP = 20 A | 29.2 V - Maximum clamped voltage during 1 ms transient; determines peak stress on downstream components. |
| IPP | 20 A - Peak pulse current capability at rated clamping voltage; defines surge energy handling (500 W @ 1 ms). |
| IR @ VRWM | <1 µA - Reverse leakage current at 18 V; negligible power loss and no loading effect on sensitive analog/signal paths. |
| Response Time | <1 ns - Time from overvoltage onset to conduction; critical for protecting high-speed interfaces and logic ICs. |
| UL Recognition | UL 497B QVGV2 - Certified for use in isolated loop protectors; validates performance under strike voltage, endurance, and dielectric tests. |
Pinout & Package
SA18ARL is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode identified by a polarity band. Leads are corrosion-resistant, readily solderable, and rated for 260°C for 10 seconds at 1/16 inch from case.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Ground reference terminal | Connected to system ground or low-side return path; completes clamping current loop during transient events. |
| Cathode | Protected line input | Connected to the line being protected (e.g., +12 V rail); reverse-biased during normal operation, conducts during overvoltage. |
Key Features
| Feature | Design Value |
|---|---|
| 500 W peak pulse power | Handles IEC 61000-4-5 Level 4 surges (4 kV/2 Ω) on 12–24 V systems without failure or parameter shift. |
| UL 497B recognition | Validated for safety-critical isolated loop applications including telecom line cards and industrial fieldbus interfaces. |
| ESD rating >16 kV (HBM) | Withstands human-body-model ESD events without degradation-critical for front-panel connectors and test points. |
| Low zener impedance | Ensures tight clamping voltage tolerance across production lots and temperature range (−55°C to +175°C). |
| Pb-free Surmetic package | RoHS-compliant axial lead construction with proven long-term reliability in high-humidity and thermal cycling environments. |
Applications
| Industrial Power Supply Protection | Medical Equipment Surge Suppression |
|---|---|
Use Scenario: Protecting 24 V DC input stage of PLC power modules against load dump and inductive switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between input rail and chassis ground to clamp transients before they reach upstream regulators and controllers. Use Value: Limits peak voltage to 29.2 V during 20 A surges, preventing latch-up or damage to 36 V-rated DC/DC converters and microcontrollers. |
Use Scenario: Safeguarding RS-485 communication ports in patient monitors exposed to defibrillator discharge coupling. IC Role / Device Role / Timing Role: Line-to-ground TVS on differential bus pair, leveraging fast response to suppress sub-microsecond ESD bursts. Use Value: Clamps 15 kV HBM ESD events within 1 ns while maintaining <1 µA leakage-preserving signal integrity and common-mode rejection. |
| Telecom Interface Protection | Process Control Signal Conditioning |
Use Scenario: Shielding Ethernet PHY power pins (3.3 V or 5 V) in industrial gateways from induced surges on PoE or adjacent AC wiring. IC Role / Device Role / Timing Role: Rail-to-rail TVS on VDD supply, selected for VRWM ≥ 1.2× nominal voltage to avoid false triggering. Use Value: Delivers 500 W surge immunity without derating at board-level ambient up to 75°C, meeting IEC 61000-4-4 compliance. |
Use Scenario: Protecting 4–20 mA current loop inputs in programmable logic controllers from accidental 24 V short-to-rail faults. IC Role / Device Role / Timing Role: Reverse-biased TVS across loop terminals to absorb fault energy and prevent op-amp saturation or ADC overrange. Use Value: Maintains <1 µA leakage at 18 V VRWM, ensuring full 4–20 mA accuracy without offset error or calibration drift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Surface-mount SMA package (vs. axial SA18ARL); same VRWM (18 V), but higher VC = 29.7 V @ 20.9 A; lower PPK = 400 W. | Requires PCB redesign for SMT placement; better suited for space-constrained consumer electronics vs. industrial through-hole assemblies. | Select SMAJ18A only if board layout supports SMT and thermal mass limits allow lower peak power handling. |
| P6KE18A | DO-15 axial package; identical VRWM (18 V) and VC = 29.2 V @ 20 A, but rated for 600 W peak power and higher IFSM = 100 A. | Higher surge robustness suits automotive load-dump scenarios; lacks UL 497B recognition and has higher leakage (5 µA). | Choose P6KE18A where higher single-pulse energy tolerance is required and UL certification is not mandated. |
Compared with SA18ARL, SMAJ18A offers smaller footprint but reduced surge margin and no UL 497B listing, while P6KE18A delivers greater peak power and surge current capability at the cost of higher leakage and missing safety certification-making SA18ARL optimal for UL-compliant industrial power and communications systems.
Availability
SA18ARL is available at Aetrix Electronics and suitable for industrial power supply protection, medical equipment surge suppression, and telecom interface protection requiring stable component supply and long-lifecycle support.
Supply support for SA18ARL 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud, medical, and IoT applications.
The SA5.0A Series-including SA18ARL-is part of onsemi's MiniMOSORB TVS portfolio, engineered specifically for robust, certified transient protection in safety-critical and high-reliability industrial systems.
FAQ
What is the maximum clamping voltage of the SA18ARL under a 20 A transient pulse?
The SA18ARL has a maximum clamping voltage (VC) of 29.2 V when subjected to a 20 A peak pulse current (IPP) with a 1 ms waveform. This value is measured per the standard surge test defined in Figure 4 of the SA5.0A datasheet and represents the upper limit of voltage seen by protected circuitry during worst-case transient events. Designers must ensure this clamping level remains below the absolute maximum ratings of downstream components.
Does the SA18ARL meet UL 497B certification, and what does that mean for my design?
Yes, the SA18ARL is UL 497B recognized under file E116110 for isolated loop circuit protection. This certification confirms it has passed rigorous tests including strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge validation-unlike basic flammability-only listings. For your design, this means SA18ARL can be used in safety-certified end equipment (e.g., medical or industrial control systems) without requiring additional external validation of surge protection functionality.
How does the SA18ARL differ from the SA18A (non-RoHS) variant?
The SA18ARL is the Pb-free version of the SA18A, packaged in onsemi's RoHS-compliant Surmetic axial leaded case (59AA) with matte tin-plated leads. Electrically and thermally identical to SA18A, the "RLG" suffix denotes tape-and-reel packaging (5000 units/reel) and Pb-free construction. No performance or reliability differences exist-only environmental compliance and packaging format distinguish SA18ARL from legacy SA18A.
Can the SA18ARL be used in bidirectional protection configurations?
No-the SA18ARL is a unidirectional TVS diode optimized for DC rail or single-polarity signal line protection. It conducts only in reverse bias above VBR. For AC or bidirectional signal paths (e.g., RS-232, USB D+/D−), a dedicated bidirectional device such as the SA18C or SMBJ18CA is required. Using SA18ARL in bidirectional applications risks forward conduction during normal signal swings and potential damage.
What is the thermal derating behavior of the SA18ARL above 75°C lead temperature?
At lead temperatures above 75°C, the SA18ARL's steady-state power dissipation (PD) derates linearly at 30 mW/°C, dropping from 3.0 W at 75°C to zero at approximately 175°C. This derating applies only to continuous power-not transient pulses-and is based on thermal resistance RJL = 33.3°C/W. Designers must calculate actual lead temperature under expected ambient and power conditions using Figure 5 in the datasheet to ensure safe long-term operation.
SA18ARL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- MiniMosorb™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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):
- 17.2A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- Axial
SA18ARL FAQ
1.How can I place an order for SA18ARL through Aetrix?
Please submit a Request for Quotation (RFQ) for SA18ARL 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 SA18ARL reliable?
The price and inventory of SA18ARL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA18ARL is usually 5 days.
3.What payment methods are accepted for SA18ARL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA18ARL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA18ARL?
SA18ARL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA18ARL 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 SA18ARL?
For technical support, including SA18ARL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA18ARL requirements.
6.How does Aetrix verify that SA18ARL is sourced from the original manufacturer or authorized distributors?
All SA18ARL 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 SA18ARL meets industry standards.
7.What is the process for return or replacement of SA18ARL?
All SA18ARL units undergo pre-shipment inspection (PSI). If there is an issue with SA18ARL, 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 SA18ARL part is unused and in its original packaging.
Return procedure for SA18ARL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA18ARL 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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Diodes Incorporated
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D5V0P1B2LP-7B
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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D12V0L1B2LP-7B
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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