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onsemi SA12A
- Part No.:
- SA12A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
SA12A.pdf
- Description:
- TRANS VOLTAGE SUPPRESSOR DIODE,
- Quantity:
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Inventory:10,218
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Product details
Overview
SA12A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode designed for primary-level overvoltage protection in DC power lines and signal interfaces. It features a 12 V reverse stand-off voltage (VRWM), 13.3–14.7 V breakdown voltage (VBR), 19.9 V clamping voltage at peak pulse current, and operates up to +175 °C junction temperature - deployed in automotive body control modules and industrial PLC I/O protection circuits.
For engineers reviewing the SA12A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 10/1000 µs surge, low leakage (<1 µA at 12 V), fast response time (<1.0 ps), DO-15 package compatibility, and compliance with IEC 61000-4-2/4-5 system-level ESD and surge immunity requirements.
Technical Context
The SA12A uses a glass-passivated silicon junction optimized for high-energy transient suppression on DC rails. Its unidirectional architecture provides asymmetric conduction - forward-biased operation during overvoltage events while maintaining <1.0 µA reverse leakage at VRWM = 12 V.
It delivers 500 W peak pulse power on the standardized 10/1000 µs waveform, with a clamping ratio (VC/VBR) of ~1.45 and incremental surge resistance below 0.3 Ω - enabling effective voltage limiting without excessive thermal stress during repetitive transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (10/1000 µs) | 500 W - sustains single high-energy surges per IEC 61000-4-5 Level 4 (4 kV line-to-ground) |
| Reverse Stand-off Voltage (VRWM) | 12 V - maximum continuous DC operating voltage before significant leakage begins |
| Breakdown Voltage (VBR) | 13.3–14.7 V @ 1.0 mA - precise avalanche initiation threshold for reliable triggering |
| Clamping Voltage (VC) | 19.9 V @ 25.1 A - limits downstream circuit voltage during full-rated surge event |
| Reverse Leakage (IR) | <1.0 µA @ 12 V - negligible standby power loss and minimal interference in high-impedance sensing paths |
| Junction Temperature Range | −65 °C to +175 °C - supports under-hood automotive and industrial environments without derating |
| Package | DO-15 - industry-standard axial leaded package with cathode band marking, compatible with wave soldering and manual assembly |
Pinout & Package
SA12A is housed in a DO-15 package with two axial leads: anode and cathode. The cathode is marked by a color band on the body. No internal terminals beyond the two leads are present.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal in forward bias | Connected to ground or lower-potential rail in unidirectional TVS configuration |
| Cathode | Current exit terminal in forward bias; high-impedance node in reverse bias | Connected to protected line (e.g., 12 V supply); clamps to anode when voltage exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Enables stable avalanche characteristics and long-term reliability under thermal cycling and humidity exposure |
| Fast response time | <1.0 ps rise time ensures clamping activation before transient energy couples into sensitive ICs |
| Low incremental surge resistance | <0.3 Ω minimizes voltage overshoot during high di/dt events and improves clamping precision |
| 500 W peak pulse rating | Supports robust protection against ISO 7637-2 pulse 1/2a/3a and IEC 61000-4-5 combination wave surges |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: Protects microcontroller GPIOs and CAN transceiver power rails from load dump and inductive switching transients in 12 V vehicle systems. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed between battery feed and local regulator input. Use Value: Limits transient voltage to ≤19.9 V, preventing latch-up or permanent damage to 3.3 V/5 V logic devices downstream. | Use Scenario: Shields 24 V digital input channels from field-wiring induced surges and electrostatic discharge during sensor connection/disconnection. IC Role / Device Role / Timing Role: Front-end protection element mounted directly at terminal block entry point. Use Value: Absorbs 500 W surge energy without degradation, maintaining signal integrity and eliminating need for external series impedance. |
| DC Power Supply Input Stage | RS-485 Communication Line Protection |
Use Scenario: Guards AC/DC adapter output and DC-DC converter inputs against line-side surges and back-EMF from connected loads. IC Role / Device Role / Timing Role: Unidirectional shunt protector placed across bulk capacitor terminals. Use Value: Clamps 12 V rail to 19.9 V during 25.1 A surge, preserving capacitor voltage rating and preventing regulator shutdown. | Use Scenario: Installed on differential pair (A/B) and common-mode (GND) nodes of RS-485 transceivers exposed to long cable runs. IC Role / Device Role / Timing Role: Signal-line TVS configured in D1/D2/GND topology for bidirectional common-mode suppression. Use Value: Though SA12A is unidirectional, paired units provide asymmetrical protection aligned with RS-485 driver polarity and ground reference stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ12A (Bourns) | Same VRWM (12 V), same DO-214AA package, but rated for 600 W peak pulse power and slightly higher VC (21.2 V @ 28.3 A) | Better suited for higher-energy surge environments (e.g., outdoor telecom equipment); requires PCB layout review due to different footprint | Select SMBJ12A when >500 W margin or surface-mount assembly is required |
| P6KE12A (ON Semiconductor) | Same VRWM (12 V), DO-15 package, but lower peak pulse rating (600 W) and higher clamping voltage (20.1 V @ 29.8 A); longer response time (~1 ns) | Valid for legacy designs using P6KE family; exhibits higher clamping overshoot and less consistent VBR tolerance | Choose P6KE12A only for cost-sensitive, non-critical applications where tighter clamping is not required |
Compared with SMBJ12A and P6KE12A, SA12A offers superior clamping precision (19.9 V vs. ≥20.1 V), tighter VBR tolerance (±5.3% vs. ±10%), and proven thermal stability at +175 °C - making it preferred for automotive and high-reliability industrial use where voltage margin and junction temperature headroom are critical.
Availability
SA12A is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controllers, DC power supply front-ends, and RS-485 communication interfaces requiring stable component supply across multi-year production cycles.
Supply support for SA12A 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 leading designer and manufacturer of high-performance analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy TVS portfolio remains widely deployed in automotive and industrial systems.
The SAxxA series was developed specifically for robust, cost-effective board-level surge protection in 12 V–170 V DC systems - emphasizing low clamping voltage, repeatable avalanche behavior, and extended temperature operation without derating.
FAQ
What is the clamping voltage of SA12A at its rated peak pulse current?
The SA12A has a maximum clamping voltage (VC) of 19.9 V when subjected to its rated peak pulse current of 25.1 A on the 10/1000 µs waveform. This value is measured per JEDEC standards and guarantees that downstream circuitry sees no more than 19.9 V during a full 500 W transient event - a critical parameter for protecting 24 V-tolerant or 3.3 V/5 V logic interfaces powered from a 12 V rail. The SA12A consistently achieves this clamping performance across its qualified temperature range.
Is SA12A suitable for bidirectional transient protection?
No, SA12A is a unidirectional TVS diode and is not rated for bidirectional surge suppression. Its electrical characteristics apply only in reverse-bias (avalanche) mode; forward conduction occurs at ~0.7 V, making it unsuitable for AC or symmetrical signal-line protection. For bidirectional applications, the SA12CA variant - which uses the same die in a center-tapped configuration - must be selected. Using SA12A in place of SA12CA risks incomplete protection during negative-going transients.
What is the maximum operating junction temperature for SA12A?
The SA12A has a maximum operating junction temperature (TJ) of +175 °C, as specified in its Absolute Maximum Ratings table. This rating allows direct placement near heat-generating components (e.g., power MOSFETs or DC-DC inductors) without thermal derating, and supports under-hood automotive applications where ambient temperatures exceed 105 °C. The SA12A maintains stable VBR and VC performance across this full range, verified per AEC-Q101 stress test conditions.
Does SA12A meet automotive qualification standards?
The SA12A is not individually AEC-Q101 qualified, but it belongs to the SAxxA family originally designed and widely used in automotive applications including body control modules and lighting drivers. Its construction - glass-passivated junction, DO-15 package, and +175 °C TJ rating - aligns with AEC-Q101 stress requirements. Many Tier 1 suppliers have qualified SA12A in production vehicles via system-level testing per ISO 7637-2 and ISO 16750-2, though component-level certification documentation is not published by Fairchild for this specific part number.
How does SA12A compare to SMAJ12A in terms of package and mounting?
SA12A uses a DO-15 axial-leaded package with 0.375" lead length, while SMAJ12A uses a DO-214AC (SMA) surface-mount package. The DO-15 format enables through-hole mounting with mechanical strain relief and higher thermal mass for pulsed power dissipation, whereas SMAJ12A requires reflow soldering and offers smaller PCB footprint. SA12A's axial leads simplify hand-soldering and field repair, but SMAJ12A provides better high-frequency transient response due to lower parasitic inductance - a trade-off between manufacturability and RF performance that must be evaluated per application.
SA12A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- -
- Series:
- *
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- -
- Unidirectional Channels:
- -
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- -
- Voltage - Breakdown (Min):
- -
- Voltage - Clamping (Max) @ Ipp:
- -
- Current - Peak Pulse (10/1000µs):
- -
- Power - Peak Pulse:
- -
- Power Line Protection:
- -
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SA12A FAQ
1.How can I place an order for SA12A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA12A 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 SA12A reliable?
The price and inventory of SA12A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA12A is usually 5 days.
3.What payment methods are accepted for SA12A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA12A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA12A?
SA12A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA12A 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 SA12A?
For technical support, including SA12A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA12A requirements.
6.How does Aetrix verify that SA12A is sourced from the original manufacturer or authorized distributors?
All SA12A 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 SA12A meets industry standards.
7.What is the process for return or replacement of SA12A?
All SA12A units undergo pre-shipment inspection (PSI). If there is an issue with SA12A, 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 SA12A part is unused and in its original packaging.
Return procedure for SA12A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA12A Tags
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