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Taiwan Semiconductor Corporation SA78CA
- Part No.:
- SA78CA
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA78CA.pdf
- Description:
- TVS DIODE 78VWM 126VC DO204AC
- Quantity:
- Payment:
- Shipping:
Inventory:5,751
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Product details
Overview
SA78CA 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, 78V working stand-off voltage (VWM), and clamps to ≤139V at 3.7A peak pulse current. It delivers fast response (<1.0ps), low leakage (<1μA @ 78V), and AEC-Q101 qualification for automotive-grade surge protection.
For engineers reviewing the SA78CA datasheet, SA78CA pinout, SA78CA application, or SA78CA equivalent, this device is selected for high-reliability DC bus protection in automotive lighting modules, industrial sensor interfaces, and power supply input stages where precise clamping, thermal robustness (TJ max = 175°C), and RoHS/halogen-free compliance are required.
Technical Context
The SA78CA operates as a unidirectional avalanche diode with a specified breakdown voltage range of 86.7–103V at 1mA test current, enabling reliable overvoltage clamping above its 78V stand-off threshold. Its low dynamic impedance ensures effective suppression of fast transients including EFT and inductive switching spikes.
Designed for non-repetitive surge events per IEC 61000-4-5 and ANSI/IEEE C62.35, it sustains 70A peak forward surge current (8.3ms half-sine) and exhibits a temperature coefficient of 105 mV/°C for VBR, supporting stable performance across –55°C to +175°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 86.7 / 103 V @ 1 mA - Ensures predictable turn-on margin above VWM for noise immunity |
| VC @ IPPM | 139 V @ 3.7 A - Clamping voltage during 10/1000μs surge defines protected circuit's maximum stress level |
| PPK | 500 W - Peak pulse power rating determines survivability against standardized lightning/surge waveforms |
| IR @ VWM | <1 μA - Negligible leakage preserves system efficiency and battery life in always-on circuits |
| TJ max | +175 °C - Enables deployment in under-hood automotive environments and high-power industrial enclosures |
| Package | DO-204AC (DO-15) - Industry-standard axial leaded package with UL 94V-0 molding and J-STD-002 solderability |
Pinout & Package
DO-204AC (DO-15) package with axial leads: cathode indicated by band marking; anode and cathode terminals support through-hole mounting on PCBs with 10×10 mm copper pads per lead for thermal derating compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point in forward bias; connected to protected circuit ground or low-side return path | Completes clamping loop during transient events; must be routed with low-inductance path to reference plane |
| Cathode | Current exit point in forward bias; connected to protected line (e.g., 78V rail) | Acts as high-impedance node until VBR exceeded; polarity marking prevents reverse installation |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units and body electronics requiring zero defect reliability |
| 500W 10/1000μs surge rating | Meets IEC 61000-4-5 Level 4 (4kV) surge immunity requirements without external series impedance |
| Clamping voltage ≤139V @ 3.7A | Provides ≥10% safety margin below typical 150V-rated downstream IC absolute maximum ratings |
| Response time <1.0ps | Engages before most microsecond-scale transients fully develop, minimizing voltage overshoot |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and automotive ELV directives for sustainable manufacturing and end-of-life processing |
Applications
| Automotive LED Headlamp Driver Protection | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: Protects LED driver ICs and MOSFETs from load dump and alternator ripple transients in 12V/24V vehicle electrical systems. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and ground to clamp positive-going surges exceeding 78V. Use Value: Prevents catastrophic failure of buck controller ICs by limiting transient voltage to ≤139V, preserving functional safety integrity. | Use Scenario: Shields 24V digital input channels of programmable logic controllers from EFT bursts and inductive kickback from solenoid coils. IC Role / Device Role / Timing Role: Standoff protector on field-side input traces, absorbing repetitive 5kHz EFT pulses per IEC 61000-4-4. Use Value: Maintains signal integrity and prevents false triggering by suppressing sub-10ns edge transients with <1.0ps response. |
| DC Power Supply Input Stage | Smart Sensor Node ESD Protection |
Use Scenario: Guards primary-side rectifier and controller ICs in AC/DC adapters and DC/DC converters against lightning-induced surges. IC Role / Device Role / Timing Role: First-line defense on DC input bus, triggered only during overvoltage events >78V while remaining invisible during normal operation. Use Value: Eliminates need for additional RC snubbers or varistors due to precise VWM/VBR ratio and low leakage. | Use Scenario: Integrated into battery-powered IoT sensor nodes to survive contact ESD events per IEC 61000-4-2 ±8kV air/±4kV contact discharge. IC Role / Device Role / Timing Role: Low-capacitance (typ. <100pF) unidirectional clamp on analog sensor lines referenced to local ground. Use Value: Preserves signal fidelity in millivolt-level sensor outputs while dissipating 500W transient energy without latch-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78A | Bidirectional configuration; same VWM (78V) but symmetric clamping (VC = 121V @ 4.1A); SMC package | Required where bidirectional transients (e.g., AC-coupled signals) dominate; not suitable for DC rail polarity-sensitive designs | Select SMBJ78A only if bipolar surge immunity is mandatory and board space allows SMC footprint |
| P6KE78A | Same unidirectional function and DO-204AC package; lower PPK (600W vs 500W); higher VC (125V @ 4.8A) | Acceptable for less stringent surge levels; higher clamping voltage reduces margin for 150V-rated components | Choose P6KE78A when cost sensitivity outweighs clamping performance and thermal derating is not critical |
Compared with SMBJ78A and P6KE78A, the SA78CA offers tighter VBR tolerance (86.7–103V vs ±5%), AEC-Q101 qualification for automotive use, and optimized clamping (139V) for 78V DC systems-making it preferred for mission-critical automotive and industrial deployments where reliability and precision matter.
Availability
SA78CA is available at Aetrix Electronics and suitable for automotive lighting systems, industrial PLC inputs, DC power supply input stages, and smart sensor node designs requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SA78CA 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, and rectifiers with global distribution and AEC-Q101 validation capability.
The SA Series is engineered specifically for high-energy transient suppression in automotive and industrial environments, emphasizing robust surge handling, tight parametric control, and compliance with stringent environmental standards.
FAQ
What is the breakdown voltage range of the SA78CA?
The SA78CA has a minimum breakdown voltage (VBR) of 86.7 V and a maximum of 103 V, measured at 1 mA test current. This range ensures reliable turn-on behavior above its 78 V working stand-off voltage while maintaining sufficient margin against false triggering from ripple or noise. The SA78CA's specified VBR window supports consistent clamping performance across production lots and temperature extremes.
Is the SA78CA suitable for automotive applications?
Yes, the SA78CA is AEC-Q101 qualified, making it suitable for automotive applications including engine control units, body electronics, and lighting systems. Its operating junction temperature range of –55°C to +175°C, robust surge capability (500W at 10/1000μs), and halogen-free, RoHS-compliant construction meet key automotive reliability and regulatory requirements. The SA78CA is explicitly designed for under-hood and chassis-mounted deployments where thermal and electrical stress are severe.
What is the clamping voltage of the SA78CA under surge conditions?
The SA78CA clamps to a maximum of 139 V at its rated peak pulse current of 3.7 A (10/1000μs waveform). This clamping voltage defines the upper voltage limit imposed on protected circuitry during transient events. With a 78 V working stand-off voltage, the SA78CA provides a controlled 61 V overvoltage margin, ensuring downstream components rated for 150 V or higher remain within safe operating limits during surge exposure.
Does the SA78CA have polarity marking, and how is it configured?
Yes, the SA78CA is a unidirectional TVS diode with a cathode band marking on the DO-204AC (DO-15) package body. The banded end is the cathode and must be connected to the protected line (e.g., 78 V rail), while the unbanded end (anode) connects to ground or return path. Correct orientation is essential: reverse installation renders the device ineffective for positive transients and may cause failure under surge conditions. The SA78CA's polarity marking follows JEDEC standard DO-15 conventions.
How does the SA78CA compare to the SA78A variant?
The SA78CA differs from the SA78A in that it includes AEC-Q101 qualification and uses "CA" suffix per TSC ordering nomenclature (where "H" denotes AEC-Q101, and "CA" indicates AEC-Q101 + green compound). Both share identical electrical specs: VWM = 78 V, VBR = 86.7–103 V, VC = 139 V @ 3.7 A. The SA78CA is intended for automotive-grade production, whereas SA78A serves general industrial applications. For designs targeting ISO/TS 16949 compliance, the SA78CA is the validated choice.
SA78CA 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:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 4.1A
- 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)
SA78CA FAQ
1.How can I place an order for SA78CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SA78CA 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 SA78CA reliable?
The price and inventory of SA78CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA78CA is usually 5 days.
3.What payment methods are accepted for SA78CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA78CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA78CA?
SA78CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA78CA 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 SA78CA?
For technical support, including SA78CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA78CA requirements.
6.How does Aetrix verify that SA78CA is sourced from the original manufacturer or authorized distributors?
All SA78CA 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 SA78CA meets industry standards.
7.What is the process for return or replacement of SA78CA?
All SA78CA units undergo pre-shipment inspection (PSI). If there is an issue with SA78CA, 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 SA78CA part is unused and in its original packaging.
Return procedure for SA78CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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