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Taiwan Semiconductor Corporation SA78CAH
- Part No.:
- SA78CAH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA78CAH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO204AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,223
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Product details
Overview
SA78CAH from Taiwan Semiconductor is a bidirectional transient voltage suppressor diode (TVS) in DO-204AC (DO-15) package, rated for 500W peak pulse power at 10/1000μs, with 78V working stand-off voltage (VWM), 86.7–103V breakdown voltage (VBR), and 139V maximum clamping voltage (VC) at 3.7A peak pulse current - deployed for ESD and EFT protection in automotive lighting and power supply input stages.
For engineers reviewing the SA78CAH datasheet, SA78CAH pinout, SA78CAH application, or SA78CAH equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification, low leakage (<1μA @ VWM), fast response time (<5.0ns), and DO-15 mechanical compatibility with high-reliability board-level surge immunity requirements.
Technical Context
The SA78CAH operates as a bidirectional avalanche diode, symmetrically clamping transients above ±86.7V in either polarity while maintaining <1μA reverse leakage at 78V. Its junction structure enables sub-5ns response to fast-rising EFT pulses and supports repetitive surge handling up to 70A IFSM (8.3ms half-sine).
Designed per ANSI/IEEE C62.35, it delivers stable clamping performance across -55°C to +175°C operating junction temperature, with VBR temperature coefficient of 105 mV/°C - enabling predictable overvoltage protection in under-hood automotive environments where thermal drift must be accounted.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous DC or RMS voltage the device blocks without clamping; defines system operating margin before protection engages. |
| VBR min/max | 86.7 V / 103 V @ 1 mA - Breakdown threshold range; ensures reliable turn-on within spec across process variation and temperature. |
| VC @ IPPM | 139 V @ 3.7 A - Clamped voltage during 10/1000μs surge; determines maximum stress imposed on downstream ICs. |
| PPK | 500 W - Peak pulse power rating; validates robustness against ISO 7637-2 Pulse 1/2/5a and IEC 61000-4-4 EFT events. |
| TJ max | +175 °C - Maximum junction temperature; supports placement near heat sources in automotive ECUs and LED drivers. |
| IR @ VWM | <1 μA - Reverse leakage at stand-off voltage; minimizes standby power loss and avoids false triggering in high-impedance circuits. |
| Package | DO-204AC (DO-15) - Industry-standard axial leaded package with UL 94V-0 molding; compatible with legacy through-hole assembly and manual rework. |
Pinout & Package
DO-204AC (DO-15) package: axial-leaded, molded epoxy case with cathode band marking for unidirectional variants; SA78CAH is bidirectional and omits polarity marking - both terminals are electrically symmetrical.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Bidirectional avalanche junction | Either terminal serves as anode or cathode depending on transient polarity; no orientation required during PCB placement. |
| Lead 1 / Lead 2 | Surge current path | Provides low-inductance conduction path for 10/1000μs transients; leads meet J-STD-002 solderability and JESD201 Class 2 whisker resistance. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - suitable for front-end protection in ADAS sensors and body control modules. |
| 500W 10/1000μs surge rating | Withstands repeated ISO 7637-2 Pulse 5a surges up to 500W without degradation - eliminates need for external series impedance in many 12V/24V systems. |
| <5.0 ns response time (bidirectional) | Clamps EFT bursts before sensitive logic thresholds are exceeded - critical for protecting CAN transceivers and microcontroller I/O pins. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and EU RoHS directives - meets Tier 1 automotive supplier material declaration requirements. |
| DO-204AC mechanical standardization | Enables drop-in replacement of legacy TVS diodes (e.g., P6KE78CA) without footprint redesign or requalification. |
Applications
| Automotive LED Headlamp Driver Protection | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: Protecting buck-boost LED driver ICs from load dump and inductive kickback in 24V headlamp systems. IC Role / Device Role: Bidirectional clamping element placed across input rails to shunt ISO 7637-2 Pulse 5a energy. Use Value: Limits rail voltage to ≤139V during 100V/500W transients, preventing damage to 60V-rated MOSFETs and gate drivers. | Use Scenario: Safeguarding 24V digital input channels of programmable logic controllers against field-wiring ESD and EFT. IC Role / Device Role: Front-end TVS on isolated input circuitry, upstream of optocoupler or signal conditioner. Use Value: Sub-5ns response ensures clamping occurs before 1kV/5kHz EFT bursts corrupt logic state sampling. |
| Automotive Body Control Module (BCM) Power Input | Smart Building Sensor Node ESD Protection |
Use Scenario: Input-stage surge suppression for 12V supply rails feeding microcontrollers and LIN transceivers in BCMs. IC Role / Device Role: Primary overvoltage clamp on main VBAT line, coordinated with fuse and LC filter. Use Value: AEC-Q101 qualification guarantees operation at +125°C ambient and survival through 1,000 thermal cycles. | Use Scenario: Protecting RS-485 transceivers and environmental sensor interfaces in battery-powered IoT nodes. IC Role / Device Role: Low-leakage (≤1μA) bidirectional TVS on differential bus lines to preserve signal integrity. Use Value: 78V VWM allows full 24V system operation while clamping ±1kV contact ESD per IEC 61000-4-2. |
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 SMAJ78CA | Same DO-214AC package; 500W rating; VBR = 86.7–103V; VC = 139V @ 3.7A - identical electrical envelope but non-AEC-Q101. | Not qualified for automotive use; suitable for industrial/commercial designs where AEC compliance is not mandated. | Select SMAJ78CA only when AEC-Q101 is unnecessary and DO-214AC SMT footprint is preferred over DO-15 through-hole. |
| ON Semiconductor 1.5KE78CA | Higher PPK (1500W); larger DO-201AD package; VBR = 86.7–103V; VC = 139V @ 10.3A - same clamping but higher surge capacity and thermal mass. | Requires larger PCB area and higher mounting torque; better suited for infrequent high-energy surges (e.g., lightning-induced). | Choose 1.5KE78CA when system-level testing reveals insufficient margin with 500W rating, and board space permits larger package. |
Compared with SMAJ78CA and 1.5KE78CA, the SA78CAH uniquely combines AEC-Q101 qualification, DO-15 through-hole compatibility, and precise 500W/139V clamping - making it optimal for cost-sensitive, high-volume automotive electronics requiring proven reliability without SMT reflow complexity.
Availability
SA78CAH is available at Aetrix Electronics and suitable for automotive lighting systems, industrial PLC inputs, body control module power rails, and smart building sensor node protection requiring stable component supply across multi-year production cycles.
Supply support for SA78CAH 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 devices since 1979.
The SA Series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 compliance, tight VBR tolerance, and robust DO-15 packaging for high-reliability through-hole applications.
FAQ
What does the "H" suffix in SA78CAH signify?
The "H" suffix in SA78CAH indicates AEC-Q101 qualification - confirming that the SA78CAH has passed rigorous automotive-grade stress tests including temperature cycling, highly accelerated life testing (HALT), and ESD robustness per JESD22 standards. This makes SA78CAH suitable for under-hood and safety-critical vehicle subsystems where component reliability is mandated.
Is SA78CAH unidirectional or bidirectional, and how is polarity identified?
SA78CAH is a bidirectional TVS diode, meaning it provides symmetrical clamping for positive and negative transients - no cathode band marking is present. Unlike unidirectional SA78A variants, SA78CAH has identical VBR and VC characteristics in both directions, confirmed by its "CA" designation (C = bidirectional, A = tightened VBR tolerance). This eliminates orientation concerns during assembly.
What is the maximum clamping voltage of SA78CAH under standard test conditions?
The maximum clamping voltage (VC) of SA78CAH is 139 V, measured at 3.7 A peak pulse current using the 10/1000 μs waveform per IEC 61000-4-5. This value defines the upper voltage limit imposed on protected circuitry during surge events and is guaranteed across the full operating temperature range (-55°C to +175°C).
Can SA78CAH replace older P6KE78CA diodes in existing designs?
Yes, SA78CAH is a direct form-fit-function replacement for P6KE78CA: both use DO-204AC (DO-15) package, share identical VWM (78 V), VBR (86.7–103 V), VC (139 V), and 500W rating. SA78CAH further adds AEC-Q101 qualification and halogen-free construction - enabling upgrade paths in automotive redesigns without layout changes.
What is the reverse leakage current specification for SA78CAH at its working voltage?
The reverse leakage current (IR) of SA78CAH is guaranteed to be less than 1 μA when biased at its 78 V working stand-off voltage (VWM) and tested at 25°C. This ultra-low leakage preserves signal integrity in high-impedance sensing circuits and minimizes quiescent power loss in always-on automotive modules.
SA78CAH 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-204AC (DO-15)
SA78CAH FAQ
1.How can I place an order for SA78CAH through Aetrix?
Please submit a Request for Quotation (RFQ) for SA78CAH 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 SA78CAH reliable?
The price and inventory of SA78CAH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA78CAH is usually 5 days.
3.What payment methods are accepted for SA78CAH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA78CAH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA78CAH?
SA78CAH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA78CAH 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 SA78CAH?
For technical support, including SA78CAH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA78CAH requirements.
6.How does Aetrix verify that SA78CAH is sourced from the original manufacturer or authorized distributors?
All SA78CAH 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 SA78CAH meets industry standards.
7.What is the process for return or replacement of SA78CAH?
All SA78CAH units undergo pre-shipment inspection (PSI). If there is an issue with SA78CAH, 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 SA78CAH part is unused and in its original packaging.
Return procedure for SA78CAH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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