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Taiwan Semiconductor Corporation SA78AH
- Part No.:
- SA78AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA78AH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO204AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,071
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Product details
Overview
SA78AH 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 - deployed for automotive ECU and power-line surge protection.
For engineers reviewing the SA78AH datasheet, SA78AH pinout, SA78AH application, or SA78AH equivalent, this page delivers verified electrical parameters, AEC-Q101 qualification status, clamping performance under 10/1000μs transients, thermal derating behavior up to 175°C junction temperature, and DO-15 mechanical compatibility with standard through-hole PCB layouts.
Technical Context
The SA78AH operates as a unidirectional avalanche diode, triggering conduction when reverse voltage exceeds its 86.7–103V breakdown range (VBR @ IT = 1mA). It clamps transient energy by diverting surge current away from downstream circuitry while maintaining low dynamic impedance during 10/1000μs pulses.
Its 175°C maximum junction temperature, -55°C to +175°C operating range, and AEC-Q101 qualification confirm suitability for under-hood automotive environments. The device exhibits <1μA reverse leakage at 78V and fast response (<1.0ps from 0V to VBR), enabling protection of sensitive CAN/LIN interface ICs and microcontrollers against EFT and load-dump events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse voltage before clamping begins; sets system-level overvoltage threshold for 12V/24V automotive rails. |
| VBR min/max | 86.7 V / 103 V @ 1 mA - Confirmed avalanche onset range; ensures reliable turn-on without premature conduction during normal operation. |
| VC @ IPPM | 139 V @ 3.7 A - Clamped voltage during 10/1000μs surge; defines worst-case stress on protected ICs during ISO 7637-2 Pulse 1/2a/5a events. |
| PPK | 500 W - Peak pulse power rating per 10/1000μs waveform; supports robust protection against repetitive transients in engine control modules. |
| TJ max | +175 °C - Maximum junction temperature; enables placement near high-heat sources like power MOSFETs or ignition drivers without thermal derating loss. |
| IR @ VWM | <1 μA - Reverse leakage at 78V; minimizes standby power loss and avoids false triggering in low-current sensor circuits. |
| Package | DO-204AC (DO-15) - Industry-standard axial-leaded package with tin-plated leads; compatible with wave soldering and manual rework. |
Pinout & Package
DO-204AC (DO-15) package: axial-leaded, molded epoxy case with cathode band marking 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 | Forward current path / Ground reference | Connected to system ground or low-side return; completes conduction path during reverse-transient clamping. |
| Cathode | Transient voltage input / Protection node | Connected to protected line (e.g., battery rail or LIN bus); absorbs surge energy when voltage exceeds VWM. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - required for powertrain and body-control module deployment. |
| 500W 10/1000μs surge rating | Withstands ISO 7637-2 Pulse 5a (load dump) up to 120V/500W without degradation - eliminates need for external series impedance in many 24V systems. |
| Clamping voltage ≤139V @ 3.7A | Ensures protected ICs (e.g., SBCs, CAN transceivers) remain below absolute maximum ratings during worst-case transients. |
| Response time <1.0ps | Activates faster than typical ESD events (IEC 61000-4-2), providing first-line defense before secondary protection stages engage. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and automotive material restrictions - supports end-of-life recycling and regulatory compliance in EU/China markets. |
Applications
| Automotive Power Rail Protection | LIN Bus Transient Suppression |
|---|---|
Use Scenario: Protecting 12V/24V battery-fed ECUs from load-dump and jump-start surges per ISO 7637-2. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp transients before LDOs or DC-DC controllers. Use Value: Limits peak voltage to ≤139V during 500W load-dump events, preventing latch-up or destruction of downstream PMICs and MCUs. |
Use Scenario: Safeguarding LIN transceivers (e.g., TJA1020) against EFT bursts and cable discharge events. IC Role / Device Role / Timing Role: TVS connected between LIN line and ground to shunt fast transients while preserving signal integrity at 19.2 kbps. Use Value: Sub-1.0ps response ensures clamping occurs within first nanosecond of EFT edge, avoiding bit errors or bus lockup. |
| Engine Control Module Input Protection | Body Control Module Sensor Interface |
Use Scenario: Shielding injector driver inputs from inductive kickback generated by solenoid switching. IC Role / Device Role / Timing Role: SA78AH placed across coil driver output to absorb flyback energy and prevent gate oxide damage to high-side switches. Use Value: 175°C TJ max allows direct mounting near injector drivers without thermal isolation, reducing BOM count and board area. |
Use Scenario: Protecting analog sensor inputs (e.g., temperature, pressure) from ESD and conducted noise in door modules. IC Role / Device Role / Timing Role: Low-leakage (<1μA) TVS used on 5V sensor supply lines to avoid loading precision voltage references. Use Value: Minimal reverse current preserves ADC accuracy and prevents drift in ratiometric sensor measurements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A | Same DO-214AC package, 78V VWM, but lower 400W PPK rating and higher 143V VC @ 3.2A. | Not AEC-Q101 qualified; suitable for industrial but not automotive-critical nodes. | Select SMAJ78A only if AEC-Q101 is not required and layout space permits larger footprint. |
| P6SMB78A | DO-214AA package, identical 78V VWM and 500W rating, but 143V VC @ 3.2A and no AEC-Q101 documentation. | Lacks automotive qualification evidence; may require additional reliability validation for OEM programs. | Prefer SA78AH where AEC-Q101 traceability and documented thermal performance up to 175°C are mandatory. |
Compared with SMAJ78A and P6SMB78A, the SA78AH delivers tighter clamping (139V vs. ≥143V), guaranteed AEC-Q101 compliance, and superior thermal margin - making it the preferred choice for safety-critical automotive power domains requiring zero-rework field reliability.
Availability
SA78AH is available at Aetrix Electronics and suitable for automotive ECU design, LIN bus protection, and engine control module development requiring stable component supply and full AEC-Q101 traceability.
Supply support for SA78AH 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 automotive and industrial certifications.
The SA Series was designed specifically for AEC-Q101-compliant transient suppression in 12V/24V automotive systems - emphasizing low clamping voltage, high surge robustness, and extended temperature operation.
FAQ
What is the AEC-Q101 qualification status of SA78AH?
The SA78AH is explicitly AEC-Q101 qualified per the manufacturer's ordering code "H" suffix and datasheet Version L2105. This includes full stress testing across temperature cycling, high-temperature reverse bias, and ESD - confirming suitability for automotive powertrain and chassis applications without additional qualification effort.
Does SA78AH support bidirectional transient suppression?
No, SA78AH is a unidirectional TVS diode, as confirmed by its single cathode band marking, absence of bidirectional VBR specifications in its row of the parameter table, and listing only unidirectional test conditions (e.g., VF = 3.5V at 35A). For bidirectional protection, SA78A (not SA78AH) must be selected.
What is the maximum clamping voltage of SA78AH under standard 10/1000μs surge conditions?
The SA78AH has a maximum clamping voltage (VC) of 139 V at 3.7 A peak pulse current (IPPM), measured per 10/1000μs waveform. This value is specified in the "MAXIMUM RATINGS AND ELECTRICAL CHARACTERISTICS" table for SA78A/SA78AH and defines the upper voltage limit imposed on protected circuitry during standardized surge events.
Can SA78AH be used in surface-mount designs?
No, SA78AH uses the DO-204AC (DO-15) axial-leaded package and is intended for through-hole mounting only. Its lead form, mechanical dimensions, and soldering specifications (e.g., 9.5mm lead length for PD rating) are incompatible with SMT reflow or paste processes - use SMAJ78A or SMCJ78A for surface-mount alternatives.
How does SA78AH's thermal performance compare to standard industrial TVS diodes?
The SA78AH supports a maximum junction temperature of +175°C - exceeding typical industrial TVS limits of +150°C - and maintains full 500W surge capability up to +125°C ambient, as shown in Fig.2 derating curve. This enables direct placement near heat-generating components in engine compartments without thermal throttling.
SA78AH 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):
- 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)
SA78AH FAQ
1.How can I place an order for SA78AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SA78AH 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 SA78AH reliable?
The price and inventory of SA78AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA78AH is usually 5 days.
3.What payment methods are accepted for SA78AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA78AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA78AH?
SA78AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA78AH 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 SA78AH?
For technical support, including SA78AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA78AH requirements.
6.How does Aetrix verify that SA78AH is sourced from the original manufacturer or authorized distributors?
All SA78AH 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 SA78AH meets industry standards.
7.What is the process for return or replacement of SA78AH?
All SA78AH units undergo pre-shipment inspection (PSI). If there is an issue with SA78AH, 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 SA78AH part is unused and in its original packaging.
Return procedure for SA78AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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