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Taiwan Semiconductor Corporation SA78CH
- Part No.:
- SA78CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA78CH.pdf
- Description:
- 500W, 94.9V, 10%, BIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:6,315
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Product details
Overview
SA78CH from Taiwan Semiconductor is a unidirectional AEC-Q101-qualified 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 139V maximum clamping voltage (VC) at 3.7A peak pulse current - designed for automotive-level ESD and load-dump protection in power supply rails and signal lines.
For engineers reviewing the SA78CH datasheet, SA78CH pinout, SA78CH application, or SA78CH equivalent, this part delivers verified bidirectional-capable clamping performance, low leakage (<1μA @ 78V), fast response (<1.0ps), and robust junction temperature range (–55°C to +175°C) critical for under-hood automotive electronics, industrial power interfaces, and lighting control systems.
Technical Context
The SA78CH operates as a unidirectional avalanche diode with precise breakdown voltage of 86.7–103V at 1mA test current, enabling reliable overvoltage clamping before downstream IC damage occurs. Its low dynamic impedance ensures stable clamping under surge conditions, while the AEC-Q101 qualification confirms suitability for automotive environments including engine control units and body electronics.
Designed for non-repetitive transients per IEC 61000-4-5 and ISO 7637-2, the SA78CH sustains 500W peak pulse power with thermal derating above 25°C and supports 70A single half-sine forward surge current (8.3ms). Its DO-204AC package provides mechanical robustness and solderability compliant with J-STD-002.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping initiates; defines safe system rail margin. |
| VBR min/max | 86.7 / 103 V @ 1 mA - Confirmed avalanche breakdown window; ensures consistent turn-on across production lots. |
| VC @ IPPM | 139 V @ 3.7 A - Clamping voltage during 10/1000μs surge; limits stress on protected ICs to ≤139V. |
| PPK | 500 W - Peak pulse power handling per 10/1000μs waveform; meets ISO 7637-2 Pulse 5a requirements. |
| IR @ VWM | <1 μA - Reverse leakage at 78V; minimizes standby power loss in battery-critical systems. |
| TJ max | +175 °C - Maximum junction temperature; enables placement near high-heat sources like power MOSFETs. |
| Package | DO-204AC (DO-15) - Industry-standard axial-leaded package with UL 94V-0 molding and pure tin plating. |
Pinout & Package
DO-204AC (DO-15) package: axial-leaded, molded epoxy case with cathode band marking for unidirectional polarity. Leads are pure tin-plated, solderable per J-STD-002, and meet JESD 201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-impedance return path; completes clamping loop during transient events. |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., 12V rail); conducts avalanche current when V > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use including temperature cycling, humidity, and mechanical shock per AEC standard. |
| 500W 10/1000μs surge rating | Withstands ISO 7637-2 Pulse 5a load-dump surges without degradation or parametric shift. |
| <1.0ps response time | Clamps within sub-picosecond from 0V to VBR - faster than most microcontroller I/O protection needs. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and EU RoHS Directive; suitable for green manufacturing and export compliance. |
| Low IR & high TJ | Leakage <1μA at 78V and operation up to +175°C enable use in always-on automotive modules. |
Applications
| Automotive Power Rail Protection | Industrial LED Driver Input Protection |
|---|---|
Use Scenario: Protecting 12V/24V power distribution networks in engine control units against ISO 7637-2 load-dump transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and DC-DC converter input. Use Value: Limits clamped voltage to 139V, preventing overvoltage failure of 40V-rated input MOSFETs and regulators. |
Use Scenario: Safeguarding constant-current LED drivers from inductive kickback during PWM switching in streetlight systems. IC Role / Device Role / Timing Role: Parallel-connected TVS across driver input terminals to absorb flyback energy. Use Value: Absorbs 500W surge energy without latch-up, preserving driver IC lifetime under repeated switching stress. |
| Automotive Lighting ESD Protection | Industrial PLC Digital Input Protection |
Use Scenario: Shielding CAN-connected headlamp control ICs from ESD events per IEC 61000-4-2 (±15kV contact). IC Role / Device Role / Timing Role: Local TVS on each LIN/CAN node power line, adjacent to connector entry point. Use Value: Sub-1ps response ensures clamping before ESD pulse couples into sensitive analog front-end circuitry. |
Use Scenario: Protecting 24V digital input channels on programmable logic controllers exposed to field wiring transients. IC Role / Device Role / Timing Role: TVS installed at terminal block entry to shunt induced surges before optocoupler input stage. Use Value: 78V VWM matches standard 24V industrial supply tolerance; 139V VC stays below optocoupler isolation rating. |
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 SMAJ78A | Same DO-204AC package, 78V VWM, but bidirectional; clamping voltage 129V @ 3.9A; no AEC-Q101 certification. | Requires polarity-aware layout if used unidirectionally; lacks automotive qualification documentation. | Select SMAJ78A only for cost-sensitive industrial designs where AEC-Q101 is not mandated. |
| ON Semiconductor 1.5SMC78AH | DO-214AB (SMC) package; 78V VWM; 139V VC @ 3.7A; AEC-Q101 qualified; surface-mount only. | Not pin-compatible - requires PCB redesign; better thermal dissipation but higher mounting height. | Choose 1.5SMC78AH when board space allows SMT and higher thermal performance is needed over axial leads. |
Compared with SMAJ78A and 1.5SMC78AH, the SA78CH uniquely combines axial DO-204AC form factor, AEC-Q101 qualification, and exact 139V clamping at 3.7A - making it optimal for legacy automotive harness interfaces and through-hole production lines requiring zero layout change.
Availability
SA78CH is available at Aetrix Electronics and suitable for automotive power rail protection, industrial LED driver input protection, automotive lighting ESD protection, and industrial PLC digital input protection requiring stable component supply across long-lifecycle programs.
Supply support for SA78CH 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-compliant production lines.
The SA Series was developed specifically for automotive-grade transient suppression - emphasizing reliability under thermal stress, surge robustness, and compatibility with harsh-environment assembly processes.
FAQ
What does the "H" suffix in SA78CH indicate?
The "H" suffix in SA78CH denotes AEC-Q101 qualification - confirming that the device has passed rigorous automotive reliability testing including temperature cycling, humidity bias, and mechanical shock. This makes SA78CH suitable for under-hood applications where standard commercial-grade TVS diodes would fail prematurely.
Is SA78CH unidirectional or bidirectional?
SA78CH is a unidirectional TVS diode, as confirmed by its cathode band marking, specified VBR/VWM values, and absence of symmetric bidirectional parameters in the datasheet. It protects against positive transients on the cathode side relative to anode (ground), and must be oriented accordingly in circuit design.
What is the maximum clamping voltage of SA78CH and at what current?
The maximum clamping voltage of SA78CH is 139 V at 3.7 A peak pulse current (IPPM), measured under the standard 10/1000μs double-exponential surge waveform. This value is guaranteed across the full operating temperature range and defines the upper voltage limit imposed on protected circuitry during surge events.
Can SA78CH replace SA78A in existing designs?
SA78CH and SA78A share identical electrical specs (VWM = 78 V, VBR = 86.7–103 V, VC = 139 V), but SA78CH adds AEC-Q101 qualification and uses the same DO-204AC package. Replacement is electrically valid and mechanically identical - however, SA78CH should be selected when automotive qualification is required.
What is the junction-to-ambient thermal resistance (RθJA) of SA78CH?
RθJA for SA78CH is not published in the provided documentation. Thermal performance is characterized via derating curves (Fig.2) and steady-state power dissipation (PD = 3 W at TL = 75°C with 9.5mm lead length). For thermal modeling, use the absolute maximum junction temperature (TJ = 175°C) and ambient derating guidelines from the datasheet.
SA78CH 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:
- 139V
- Current - Peak Pulse (10/1000µs):
- 3.7A
- 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)
SA78CH FAQ
1.How can I place an order for SA78CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SA78CH 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 SA78CH reliable?
The price and inventory of SA78CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA78CH is usually 5 days.
3.What payment methods are accepted for SA78CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA78CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA78CH?
SA78CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA78CH 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 SA78CH?
For technical support, including SA78CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA78CH requirements.
6.How does Aetrix verify that SA78CH is sourced from the original manufacturer or authorized distributors?
All SA78CH 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 SA78CH meets industry standards.
7.What is the process for return or replacement of SA78CH?
All SA78CH units undergo pre-shipment inspection (PSI). If there is an issue with SA78CH, 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 SA78CH part is unused and in its original packaging.
Return procedure for SA78CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA78CH Tags
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