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Taiwan Semiconductor Corporation SA18
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- Part No.:
- SA18
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA18.pdf
- Description:
- 500W, 22.2V, UNIDIRECTIONAL, TVS
- Quantity:
- Payment:
- Shipping:
Inventory:9,315
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Product details
Overview
SA18 from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in DO-204AC (DO-15) package, rated for 500W peak pulse power at 10/1000μs, with 18V working stand-off voltage (VWM), 20.0–24.4V breakdown voltage (VBR @ 1mA), and 32.2V clamping voltage (VC) at 16.3A peak pulse current - used to protect automotive power rails and industrial I/O interfaces against ESD and lightning-induced surges.
For engineers reviewing the SA18 datasheet, SA18 pinout, SA18 application, or SA18 equivalent, this page delivers verified electrical parameters, DO-15 terminal polarity mapping, AEC-Q101 qualification status, clamping performance under 10/1000μs transients, and direct alternatives for circuit-level surge protection design.
Technical Context
The SA18 operates as a unidirectional avalanche diode, triggering when reverse voltage exceeds its VBR range (20.0–24.4V) and clamping transient energy within 1.0ps response time. Its low dynamic impedance ensures stable clamping up to 16.3A IPPM while maintaining <1μA reverse leakage at 18V.
Designed for non-repetitive surge suppression per IEC 61000-4-2 (ESD) and IEC 61000-4-5 (surge), it supports junction temperatures from –55°C to +175°C and meets UL 94V-0 flammability and JESD201 Class 2 whisker resistance requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - maximum continuous reverse operating voltage before conduction begins; defines safe system rail margin. |
| VBR @ 1mA | 20.0–24.4 V - measured breakdown range at 1mA test current; determines precise turn-on threshold tolerance. |
| VC @ IPPM | 32.2 V at 16.3 A - clamped voltage during 10/1000μs surge; sets worst-case overvoltage seen by protected IC. |
| PPK | 500 W - peak pulse power rating per 10/1000μs waveform; defines single-event surge energy handling capacity. |
| IR @ VWM | <1 μA - reverse leakage at 18V; ensures minimal standby power loss and signal integrity in high-impedance circuits. |
| TJ max | +175 °C - maximum junction temperature; enables use in under-hood automotive and high-ambient industrial environments. |
| Package | DO-204AC (DO-15) - industry-standard axial-leaded package with cathode band marking; compatible with through-hole reflow and wave soldering. |
Pinout & Package
DO-204AC (DO-15) package with axial leads: Cathode marked by band; Anode and Cathode terminals defined per polarity marking. Leads are pure tin plated, solderable per J-STD-002, and meet JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Surge return path | Connected to ground or low-impedance return node; completes clamping loop during transient events. |
| Cathode | Reverse-biased input / Protected line connection | Connected to the line being protected (e.g., 12V rail); conducts avalanche current when Vline > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified option available (SA18H) | Validated for automotive powertrain and body electronics per stress test requirements including HTOL, TCT, and ESD. |
| 1.0ps response time (unidirectional) | Enables sub-nanosecond clamping onset - critical for protecting high-speed CAN/LIN transceivers from fast-rising ESD. |
| 500W peak pulse power (10/1000μs) | Handles IEC 61000-4-5 Level 4 surge (4kV line-earth) without degradation in single-event applications. |
| RoHS & halogen-free (IEC 61249-2-21) | Complies with environmental regulations for automotive and industrial end-equipment manufacturing and recycling. |
| UL 94V-0 molding compound | Prevents flame propagation during fault conditions - required for safety-critical control modules and lighting systems. |
Applications
| Automotive Power Rail Protection | Industrial I/O Interface Protection |
|---|---|
Use Scenario: 12V battery-supplied ECUs exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp transients before they reach PMIC or MCU power pins. Use Value: Limits peak overvoltage to ≤32.2V during 16.3A surge, preventing latch-up or gate oxide damage in downstream 3.3V/5V logic. |
Use Scenario: RS-485/RS-232 ports on PLCs subjected to field wiring ESD and induced surges. IC Role / Device Role / Timing Role: Line-side TVS connected between differential pair and ground to shunt common-mode transients. Use Value: Sub-1ns response ensures clamping occurs before receiver input stages experience destructive overvoltage. |
| LED Driver Overvoltage Clamp | Automotive Sensor Signal Line Protection |
Use Scenario: Constant-current LED drivers in headlamps facing alternator ripple and jump-start spikes. IC Role / Device Role / Timing Role: TVS placed across driver output to absorb inductive kickback and supply overshoot. Use Value: 500W rating sustains multiple 10/1000μs events without parameter shift, extending driver lifetime. |
Use Scenario: Analog sensor outputs (e.g., pressure, temperature) routed through engine bay harnesses. IC Role / Device Role / Timing Role: Low-leakage (≤1μA) TVS on signal line to ground, preserving millivolt-level accuracy. Use Value: Maintains signal integrity under bias while clamping ESD to <32.2V - below ADC input damage threshold. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ18A | Same DO-214AC package; 18V VWM, 20.0–22.1V VBR, 29.2V VC @ 17.1A; RoHS/halogen-free; no AEC-Q101 variant listed. | Lower clamping voltage (29.2V vs. 32.2V) improves margin for 24V systems but lower IPPM (17.1A vs. 16.3A) offers similar energy handling. | Preferred where tighter clamping is prioritized over automotive qualification; requires validation of lead-free solder compatibility. |
| ON Semiconductor 1.5SMC18A | DO-214AB package; 18V VWM, 20.0–22.1V VBR, 29.2V VC @ 17.1A; AEC-Q101 qualified (1.5SMC18AH); higher thermal mass than DO-15. | Surface-mount format enables automated assembly; larger package improves power derating above 75°C ambient. | Select when SMT layout and AEC-Q101 compliance are mandatory; not drop-in replacement due to different footprint and lead geometry. |
Compared with SA18, SMAJ18A offers lower clamping but lacks automotive qualification, while 1.5SMC18A provides AEC-Q101 support and SMT compatibility at the cost of board space and through-hole redesign.
Availability
SA18 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial I/O interface hardening, and LED driver overvoltage clamping requiring stable component supply across production lifecycles.
Supply support for SA18 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and power MOSFETs since 1979.
The SA Series was developed specifically for robust transient suppression in automotive and industrial environments, emphasizing high surge robustness, low leakage, and AEC-Q101 qualification readiness across voltage grades.
FAQ
What is the exact breakdown voltage range for SA18?
The SA18 has a minimum breakdown voltage (VBR) of 20.0 V and a maximum of 24.4 V, measured at 1 mA test current per ANSI/IEEE C62.35. This range reflects process variation and ensures reliable turn-on across temperature and unit-to-unit tolerances. The SA18 must be selected with system margin in mind - e.g., a 24V rail should use SA24 or higher to avoid false triggering.
Is SA18 suitable for bidirectional transient protection?
No, SA18 is a unidirectional TVS diode and is not rated for bidirectional operation. For symmetrical surge protection (e.g., data lines), the SA18A variant or dedicated bidirectional parts like SA18CA must be used. Using SA18 in reverse-biased AC applications risks forward conduction and permanent damage due to its asymmetrical IV curve.
Does SA18 meet AEC-Q101 qualification?
The base SA18 part is not AEC-Q101 qualified; however, the SA18H variant - identical electrically and mechanically but subjected to full AEC-Q101 stress testing - is available. Designers targeting automotive applications must specify SA18H to ensure compliance with HTOL, temperature cycling, and ESD requirements per the standard.
What is the maximum clamping voltage of SA18 under surge conditions?
The SA18 clamps to a maximum of 32.2 V when subjected to its rated peak pulse current of 16.3 A under the standard 10/1000 μs waveform. This value is guaranteed across temperature and lot variations and defines the upper voltage limit imposed on protected circuitry during worst-case transients.
How does SA18 compare to SA18A in terms of electrical performance?
SA18A has a tighter VBR range (20.0–22.1 V vs. 20.0–24.4 V), lower clamping voltage (39.4 V vs. 32.2 V), and higher peak pulse current (17.9 A vs. 16.3 A), but its higher VC reduces protection margin. SA18 offers superior clamping performance for 12–24V systems, while SA18A trades clamping voltage for improved surge current handling in less sensitive applications.
SA18 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- SA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 32.2V
- Current - Peak Pulse (10/1000µs):
- 16.3A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-204AC (DO-15)
SA18 FAQ
1.How can I place an order for SA18 through Aetrix?
Please submit a Request for Quotation (RFQ) for SA18 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 SA18 reliable?
The price and inventory of SA18 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA18 is usually 5 days.
3.What payment methods are accepted for SA18?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA18 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA18?
SA18 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA18 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 SA18?
For technical support, including SA18 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA18 requirements.
6.How does Aetrix verify that SA18 is sourced from the original manufacturer or authorized distributors?
All SA18 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 SA18 meets industry standards.
7.What is the process for return or replacement of SA18?
All SA18 units undergo pre-shipment inspection (PSI). If there is an issue with SA18, 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 SA18 part is unused and in its original packaging.
Return procedure for SA18:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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