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onsemi SA75A
- Part No.:
- SA75A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA75A.pdf
- Description:
- TVS DIODE 75VWM 121VC DO15
- Quantity:
- Payment:
- Shipping:
Inventory:7,539
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Product details
Overview
SA75A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power lines and signal interfaces. It features a 75 V reverse stand-off voltage (VRWM), 83.3–92.1 V breakdown voltage (VBR) at 1.0 mA, clamps to ≤121 V at 4.1 A peak pulse current (IPPM), and operates with <1.0 μA leakage above 10 V.
For engineers reviewing the SA75A datasheet, pinout, applications, or equivalent options, key selection criteria include its DO-15 package compatibility, fast sub-1 ps response time from 0 V to BV, low incremental surge resistance, bidirectional-capable CA variant (SA75CA), and suitability for industrial power supply input stages, automotive body electronics, and telecom line interface protection.
Technical Context
The SA75A employs a glass-passivated junction for stable clamping performance under repetitive surge stress. Its 10/1000 μs waveform rating of 500 W enables robust handling of IEC 61000-4-5 Level 4 surges without degradation.
Designed for unidirectional operation, it exhibits asymmetric conduction: forward surge capability up to 70 A (IFSM), reverse clamping only, and thermal derating to 1.0 W at 75°C ambient with 0.375" lead length.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (10/1000 μs) | 500 W - sustains IEC 61000-4-5 surge events without failure |
| Reverse Stand-off Voltage (VRWM) | 75 V - maximum continuous DC or RMS voltage before significant leakage |
| Breakdown Voltage (VBR) | 83.3–92.1 V at 1.0 mA - precise triggering threshold for overvoltage clamp initiation |
| Clamping Voltage (VC @ IPPM) | ≤121 V at 4.1 A - limits downstream circuit voltage during surge |
| Reverse Leakage (IR) | <1.0 μA at VRWM - negligible standby power loss in protected circuits |
| Response Time | <1.0 ps (0 V to BV) - faster than most microcontroller GPIO protection requirements |
| Junction Temperature Range | –65 °C to +175 °C - supports under-hood automotive and industrial environments |
Pinout & Package
SA75A is housed in a DO-15 axial-leaded package with cathode indicated by a color band. The device has two terminals: anode and cathode, with no internal connections beyond the PN junction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional TVS configuration |
| Cathode | Clamping terminal / high-side connection | Connected to protected line; conducts during reverse overvoltage to shunt energy to ground |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures long-term stability of VBR and leakage under humidity and thermal cycling |
| 500 W peak pulse power | Meets IEC 61000-4-5 4th edition surge immunity requirements for AC/DC inputs |
| Low incremental surge resistance | Minimizes voltage overshoot during fast-rising transients (e.g., ESD, lightning-induced) |
| Sub-1 ps response time (0 V → BV) | Activates before sensitive ICs (e.g., RS-485 transceivers, MCU I/O) can be damaged |
| DO-15 mechanical compatibility | Enables drop-in replacement in legacy board designs using standard axial footprint |
Applications
| Industrial Power Input Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: 24 V DC power rail in programmable logic controllers (PLCs) exposed to load dump and inductive switching noise. IC Role / Device Role: Primary overvoltage clamp placed upstream of DC-DC converters and microcontrollers. Use Value: Limits transient excursions to ≤121 V, preventing damage to 3.3 V/5 V logic supplies and enabling compliance with IEC 61000-4-4/5. |
Use Scenario: LIN bus and sensor supply lines in door modules subject to battery reversal and jump-start surges. IC Role / Device Role: Unidirectional TVS on 12 V feed to local regulators and CAN/LIN transceivers. Use Value: Withstands 70 A non-repetitive forward surge and clamps reverse transients to protect 3.3 V MCU I/O pins. |
| Telecom Line Interface | Renewable Energy Charge Controller |
Use Scenario: RS-485 data lines in outdoor base stations subjected to induced lightning surges. IC Role / Device Role: Secondary protection stage after gas discharge tube (GDT), placed directly at connector. Use Value: Sub-1 ps response ensures clamping before GDT fires, reducing let-through energy to <10 mJ. |
Use Scenario: PV array input stage of solar charge controller exposed to rapid polarity reversal and grid-switching transients. IC Role / Device Role: Reverse-polarity and surge protection on MPPT input before MOSFET switch and sensing circuitry. Use Value: 175 °C max junction temperature allows operation in sealed enclosures with minimal heatsinking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ75A (ON Semiconductor) | DO-214AA package; 75 V VRWM, 121 V VC @ 4.1 A; same 500 W rating but surface-mount | Requires PCB rework for SMT layout; better thermal performance in high-density designs | Select when upgrading from through-hole to SMT or when board space is constrained |
| P6SMB75A (Littelfuse) | DO-214AA package; identical electrical specs (75 V VRWM, 121 V VC); ±5% VBR tolerance vs. Fairchild's ±5.5% | Same clamping behavior but tighter VBR binning; preferred for high-precision clamp thresholds | Select when tighter breakdown voltage consistency across production lots is required |
Compared with SA75A, SMBJ75A offers superior thermal dissipation in compact layouts but requires SMT assembly, while P6SMB75A delivers tighter VBR control for critical clamp accuracy-neither is pin-compatible due to DO-15 vs. DO-214AA packaging.
Availability
SA75A is available at Aetrix Electronics and suitable for industrial power input protection, automotive body electronics, and telecom line interface applications requiring stable component supply and long-lifecycle support.
Supply support for SA75A 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
Fairchild Semiconductor was a U.S.-based designer of high-performance analog and power semiconductors, acquired by ON Semiconductor in 2016; its legacy TVS portfolio remains widely deployed and supported.
The SAxxA series was engineered specifically for cost-sensitive, high-reliability DC line protection in industrial and transportation systems, emphasizing ruggedness, repeatable clamping, and wide temperature operation.
FAQ
What is the maximum clamping voltage of SA75A under surge conditions?
The SA75A clamps to a maximum of 121 V when subjected to its rated peak pulse current of 4.1 A on the 10/1000 μs waveform. This value is guaranteed per the manufacturer's Electrical Characteristics table and defines the upper voltage limit imposed on protected circuitry during transient events. Designers must ensure downstream components have sufficient voltage margin above this 121 V clamping level to avoid damage. The SA75A achieves this clamping with low incremental resistance, minimizing overshoot beyond the specified VC.
Is SA75A suitable for bidirectional surge protection?
No - SA75A is a unidirectional TVS diode intended for DC line protection where polarity is fixed. For bidirectional applications such as AC lines or data buses with voltage swings above and below ground, the SA75CA variant must be used instead. The "C" suffix denotes bidirectional construction, with symmetrical clamping in both directions and no cathode band marking. Using SA75A in a bidirectional configuration would result in forward conduction during negative transients, potentially causing failure.
What is the thermal derating behavior of SA75A at elevated ambient temperatures?
SA75A's steady-state power dissipation derates linearly from 1.0 W at 75°C ambient (with 0.375" lead length) down to zero at 175°C junction temperature. Its pulse power rating also decreases with increasing ambient, as shown in Figure 2 of the datasheet: at 100°C ambient, the 500 W peak pulse capability drops to approximately 350 W. Designers must apply these derating curves when sizing heatsinking or estimating lifetime reliability in high-temperature enclosures.
How does the response time of SA75A compare to typical MOVs or polymer-based protectors?
SA75A responds in less than 1.0 picosecond from 0 V to breakdown voltage - significantly faster than metal-oxide varistors (MOVs), which typically respond in 20–50 ns, and vastly faster than polymer-based TVS devices (>100 ns). This ultrafast activation ensures the SA75A begins clamping before most semiconductor failures occur, making it suitable for protecting high-speed interfaces and microcontroller I/O. MOVs and polymers rely on thermal mechanisms and exhibit higher clamping voltages under fast transients.
Can SA75A be used in parallel to increase surge current handling?
No - SA75A should not be paralleled without external balancing resistors or active current-sharing circuitry. Due to manufacturing variations in breakdown voltage (±5.5%), one device will trigger first and absorb most of the surge energy, risking thermal runaway and failure. If higher IPPM is required, select a single higher-rated device (e.g., SA100A) or use a TVS array with matched characteristics. Parallel use without matching invalidates the 500 W rating and compromises reliability.
SA75A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 75V
- Voltage - Breakdown (Min):
- 83.3V
- Voltage - Clamping (Max) @ Ipp:
- 121V
- Current - Peak Pulse (10/1000µs):
- 4.1A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-15
SA75A FAQ
1.How can I place an order for SA75A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA75A 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 SA75A reliable?
The price and inventory of SA75A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA75A is usually 5 days.
3.What payment methods are accepted for SA75A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA75A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA75A?
SA75A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA75A 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 SA75A?
For technical support, including SA75A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA75A requirements.
6.How does Aetrix verify that SA75A is sourced from the original manufacturer or authorized distributors?
All SA75A 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 SA75A meets industry standards.
7.What is the process for return or replacement of SA75A?
All SA75A units undergo pre-shipment inspection (PSI). If there is an issue with SA75A, 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 SA75A part is unused and in its original packaging.
Return procedure for SA75A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA75A Tags
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