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Taiwan Semiconductor Corporation SA18A
- Part No.:
- SA18A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA18A.pdf
- Description:
- TVS DIODE 18VWM 39.4VC DO204AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,361
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Product details
Overview
SA18A 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), 20.0–22.1V breakdown voltage (VBR), and 39.4V clamping voltage (VC) at 17.9A peak pulse current-designed for automotive ESD and inductive load protection.
For engineers reviewing the SA18A datasheet, SA18A pinout, SA18A application, or SA18A equivalent, this page delivers verified electrical parameters, mechanical package details, real-world protection use cases, and validated alternative parts for circuit-level surge immunity design in automotive lighting, powertrain sensors, and industrial control I/O interfaces.
Technical Context
The SA18A operates as a unidirectional avalanche diode, triggering when reverse voltage exceeds its VBR range (20.0–22.1V) to clamp transients within 1.0ps response time. It sustains 500W non-repetitive surge energy per 10/1000μs waveform while maintaining low leakage (<1μA at 18V) and thermal stability up to TJ = 175°C.
Its DO-204AC (DO-15) axial-leaded package supports lead-free soldering (J-STD-002), meets UL 94V-0 flammability, and complies with JESD201 Class 2 whisker resistance-enabling reliable mounting on PCBs with 10×10 mm copper pads per terminal for optimal thermal dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 20.0 / 22.1 V - Breakdown occurs within this range at 1 mA test current, defining turn-on threshold |
| VC @ IPPM | 39.4 V at 17.9 A - Clamped voltage during 500W surge, limiting downstream IC stress |
| PPK | 500 W - Peak pulse power handling capability per 10/1000μs waveform |
| IR @ VWM | <1 μA - Negligible leakage current ensures minimal standby power loss |
| TJ max | +175 °C - Junction temperature limit enabling under-hood automotive deployment |
| Package | DO-204AC (DO-15) - Axial-leaded, RoHS-compliant, halogen-free molding compound |
Pinout & Package
DO-204AC (DO-15) package with axial leads: cathode indicated by band marking; anode and cathode terminals support through-hole mounting. Leads are pure tin-plated and solderable per J-STD-002.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Reverse voltage reference | Connected to system ground or low-side return path in unidirectional TVS configuration |
| Cathode | Clamping output / Surge current sink | Connected to protected line (e.g., CAN_H, LIN, sensor supply); conducts surge current to ground when VREV > VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, humidity, and mechanical shock per AEC standard |
| 1.0ps response time | Enables sub-nanosecond clamping onset-critical for protecting high-speed CAN/LIN transceivers from ESD events |
| 500W surge rating | Withstands ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 Level 3 surges without degradation |
| Low clamping ratio (VC/VBR ≈ 1.77) | Minimizes overvoltage margin between breakdown and clamping-reducing stress on downstream 24V-rated ICs |
| Halogen-free & RoHS | Complies with IEC 61249-2-21 and EU RoHS Directive for environmentally constrained applications |
Applications
| Automotive Lighting Control | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting LED driver ICs and microcontrollers in headlamp modules from load-dump and inductive kickback during relay switching. IC Role / Device Role / Timing Role: Unidirectional TVS placed between 12V supply rail and ground, clamping transients before they reach sensitive analog front-ends. Use Value: Limits voltage excursion to ≤39.4V during 500W surges, preventing latch-up or gate oxide damage in 3.3V/5V logic and PWM controllers. | Use Scenario: Safeguarding 4–20mA current-loop transmitters and RS-485 nodes in factory automation against EFT and cable discharge events. IC Role / Device Role / Timing Role: Mounted across signal lines (e.g., TX/RX pairs) or supply inputs to absorb fast transients without disrupting communication timing. Use Value: Sub-1ns response ensures clamping initiates before EFT burst edges (5ns rise time) propagate into PHY layers, preserving data integrity. |
| Powertrain Position Sensor Protection | Onboard Charger (OBC) DC Link Monitoring |
Use Scenario: Shielding Hall-effect and resolver interface circuits in EV motor control units from high-dV/dt noise coupled from inverter switching. IC Role / Device Role / Timing Role: Placed at sensor supply input (VDD) and output (OUT) pins to suppress common-mode and differential transients. Use Value: 175°C max junction temperature allows placement near high-heat zones (e.g., inverter heatsinks), maintaining protection integrity without derating. | Use Scenario: Protecting voltage dividers and isolated ADC inputs monitoring 400V–800V DC link in bidirectional OBCs during plug/unplug and fault recovery. IC Role / Device Role / Timing Role: Used in series with high-impedance sense networks to limit transient energy entering precision measurement paths. Use Value: Low IR (<1μA) prevents loading of high-Z resistor networks, preserving measurement accuracy while delivering robust 500W surge absorption. |
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 | Same DO-214AC package; VBR = 20.0–22.2V, VC = 29.2V @ 17.1A; lower clamping voltage but 400W rating | Better clamping performance for 24V systems with tighter voltage margins; less robust for repetitive surge exposure | Select SMAJ18A when lower VC is critical and peak surge energy remains ≤400W |
| P6SMB18A | DO-214AA package; VBR = 20.0–22.1V, VC = 29.2V @ 17.1A; identical electrical specs but different mechanical footprint | Requires PCB layout change due to wider body and different lead spacing; not drop-in compatible | Choose P6SMB18A only if DO-214AA is already standardized in BOM and thermal constraints allow |
Compared with SMAJ18A and P6SMB18A, the SA18A offers higher 500W surge capacity in the DO-204AC form factor-making it preferable for automotive environments where ISO 7637-2 Pulse 5a (load dump) demands sustained energy handling without package derating.
Availability
SA18A is available at Aetrix Electronics and suitable for automotive lighting control, industrial sensor interface protection, and powertrain position sensor protection requiring stable component supply across extended temperature ranges and high-reliability production cycles.
Supply support for SA18A 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs with global distribution and AEC-Q101 qualification capabilities.
The SA Series was designed specifically for automotive and industrial transient suppression-emphasizing high surge robustness, low clamping ratios, and extended temperature operation in harsh environments.
FAQ
What is the maximum clamping voltage of SA18A at its rated peak pulse current?
The SA18A has a maximum clamping voltage (VC) of 39.4 V at its rated peak pulse current (IPPM) of 17.9 A under the 10/1000μs waveform. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuitry during a full 500W surge event. The SA18A maintains this clamping performance across its specified operating temperature range.
Is SA18A suitable for bidirectional transient protection?
No, SA18A is a unidirectional TVS diode intended for DC-biased lines such as automotive 12V/24V supplies or sensor VDD rails. For bidirectional protection (e.g., AC lines or data buses like CAN), the SA18CA variant must be used-its datasheet specifies symmetrical breakdown and clamping in both polarities. Using SA18A on AC-coupled signals risks forward conduction and failure.
Does SA18A meet AEC-Q101 qualification requirements?
Yes, SA18A is AEC-Q101 qualified-confirmed in the official Taiwan Semiconductor SA Series documentation (Version L2105). This qualification covers stress tests including high-temperature operating life, temperature cycling, and ESD robustness, making SA18A suitable for automotive powertrain, chassis, and body electronics applications where reliability is mission-critical.
What is the thermal derating behavior of SA18A above 25°C ambient?
SA18A's peak pulse power (PPK) is derated linearly above TA = 25°C per Figure 2 in the datasheet: at 75°C ambient, PPK drops to ~350W; at 125°C, it falls to ~175W. Derating applies to non-repetitive pulses only. For continuous operation, steady-state power dissipation (PD) is limited to 3 W at TL = 75°C with 9.5mm lead lengths mounted on 10×10 mm copper pads.
Can SA18A be used in place of SMAJ18A without PCB changes?
No-SA18A uses the DO-204AC (DO-15) axial package, while SMAJ18A uses DO-214AC (SMA) surface-mount packaging. Their footprints, thermal paths, and mounting methods are incompatible. Substituting SA18A for SMAJ18A requires mechanical redesign, reflow profile adjustment, and validation of creepage/clearance distances due to differing body dimensions and lead geometry.
SA18A 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:
- 39.4V
- Current - Peak Pulse (10/1000µs):
- 17.9A
- 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)
SA18A FAQ
1.How can I place an order for SA18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA18A 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 SA18A reliable?
The price and inventory of SA18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA18A is usually 5 days.
3.What payment methods are accepted for SA18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA18A?
SA18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA18A 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 SA18A?
For technical support, including SA18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA18A requirements.
6.How does Aetrix verify that SA18A is sourced from the original manufacturer or authorized distributors?
All SA18A 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 SA18A meets industry standards.
7.What is the process for return or replacement of SA18A?
All SA18A units undergo pre-shipment inspection (PSI). If there is an issue with SA18A, 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 SA18A part is unused and in its original packaging.
Return procedure for SA18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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