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onsemi SA28CA
- Part No.:
- SA28CA
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
SA28CA.pdf
- Description:
- TRANS VOLTAGE SUPPRESSOR DIODE,
- Quantity:
- Payment:
- Shipping:
Inventory:5,000
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Product details
Overview
SA28CA from ON Semiconductor is a bidirectional MiniMOSORB™ Zener transient voltage suppressor (TVS) designed for high-energy surge protection in DC power rails and signal lines. It features a 28 V working peak reverse voltage (VRWM), 45 A peak pulse current (IPP), 454 V clamping voltage (VC) at IPP, 31.1–34.4 V breakdown voltage (VBR), and <1 µA leakage at VRWM. It is used in industrial power supplies and communication interfaces requiring UL 497B-certified loop protection.
For engineers reviewing the SA28CA datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 1 ms 500 W transients, bidirectional surge handling capability, axial-leaded Surmetic package compatibility with through-hole PCB assembly, and UL 497B recognition for isolated loop circuits.
Technical Context
The SA28CA operates as a bidirectional avalanche diode, symmetrically clamping positive and negative transients above its breakdown voltage without polarity dependence. Its low zener impedance and sub-1 ns response time enable effective suppression of ESD and lightning-induced surges in unprotected analog/digital I/O and DC bus lines.
It is rated for 500 W nonrepetitive peak power per 1 ms waveform (Figure 3), with thermal derating to 3.0 W steady-state at TL ≤ 75°C and junction-to-lead thermal resistance of 33.3°C/W. The device meets Class 3 ESD immunity (>16 kV HBM) and is UL 497B recognized for isolated loop circuit protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 28 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR (min/typ/max) | 31.1 / 32.75 / 34.4 V - Breakdown occurs within this range at 1 mA test current |
| VC @ IPP | 454 V - Clamped voltage seen by protected circuit during 45 A 1 ms surge |
| IPP | 45 A - Peak surge current the device safely handles per 1 ms pulse |
| Leakage @ VRWM | <1 µA - Negligible standby power loss and minimal loading on source |
| Response Time | <1 ns - Fast enough to protect against ESD and fast-rising transients |
| ESD Rating | Class 3 (>16 kV HBM) - Validated for robust electrostatic discharge immunity |
Pinout & Package
SA28CA uses an axial-leaded Surmetic plastic package (Case 59-09), with cathode band marking for mechanical orientation only - no functional polarity due to bidirectional operation. Leads are solderable up to 230°C for 10 seconds at 1/16″ from case.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Lead 1) | Transient conduction path (bidirectional) | Conducts during negative surges; identical electrical role to cathode lead |
| Cathode (Lead 2, banded) | Transient conduction path (bidirectional) | Conducts during positive surges; marking denotes physical orientation only |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating signal lines without polarity concerns |
| UL 497B recognition | Validates suitability for safety-critical isolated loop protection in telecom and industrial control systems |
| 500 W peak pulse rating | Supports robust protection against IEC 61000-4-5 Level 4 surges (4 kV line-earth) |
| Low zener impedance | Minimizes clamping voltage overshoot during high di/dt events, improving system-level immunity |
| Void-free thermoset molding | Ensures long-term reliability under thermal cycling and humid environments in industrial deployments |
Applications
| Industrial Power Supply Protection | Telecom Line Interface Protection |
|---|---|
Use Scenario: Protecting 24 V DC input rails in PLC modules from load dump and inductive switching transients. IC Role / Device Role / Timing Role: Standoff TVS diode placed across input terminals to clamp surges before they reach downstream regulators and controllers. Use Value: Limits transient voltage to 454 V at 45 A, preventing damage to 36 V-rated input stages while maintaining UL 497B compliance. | Use Scenario: Safeguarding RS-485 transceivers connected to outdoor field wiring exposed to lightning-induced surges. IC Role / Device Role / Timing Role: Bidirectional shunt protector on differential bus lines (A/B) referenced to ground. Use Value: Symmetrical clamping ensures equal protection for both polarities of common-mode surges, critical for balanced data lines. |
| Medical Equipment Signal Isolation | Process Control Sensor Interface |
Use Scenario: Shielding analog sensor inputs (e.g., thermocouple amplifiers) in patient-connected devices from ESD and coupling noise. IC Role / Device Role / Timing Role: Low-leakage (<1 µA) TVS placed at connector entry point before isolation barrier. Use Value: Prevents signal corruption and maintains measurement accuracy while meeting stringent IEC 60601-1 creepage/clearance and safety requirements. | Use Scenario: Protecting 4–20 mA current loop transmitters in hazardous area instrumentation from ground potential differences and surge coupling. IC Role / Device Role / Timing Role: UL 497B-recognized protector installed on loop terminals to meet intrinsic safety interface standards. Use Value: Enables certified use in isolated loop circuits where failure modes must be rigorously controlled per safety agency requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ28CA | Surface-mount SMB package; same VRWM (28 V), lower IPP (35.7 A), lower VC (48.4 V) | Requires SMT layout; better suited for space-constrained designs with lower surge exposure | Select when board real estate is limited and peak surge energy is below 500 W |
| P6SMB28CA | Same SMB package; identical VRWM and VBR range, but higher VC (48.4 V) and lower IPP (35.7 A) | Legacy alternative with broader distributor availability but reduced surge margin | Choose for legacy design refresh where footprint compatibility is mandatory |
Compared with SA28CA, SMBJ28CA offers lower clamping voltage but reduced surge handling, making it suitable for lighter-duty applications; P6SMB28CA provides similar specs but lacks the UL 497B certification required for isolated loop protection in telecom and medical systems.
Availability
SA28CA is available at Aetrix Electronics and suitable for industrial power supplies, telecom line interfaces, medical equipment signal isolation, and process control sensor interfaces requiring stable component supply and UL-recognized surge protection.
Supply support for SA28CA 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
ON Semiconductor (now onsemi) is a global semiconductor manufacturer specializing in power management, analog, sensors, and logic solutions for automotive, industrial, cloud, and medical markets.
The SA5.0CA Series is part of ON Semiconductor's MiniMOSORB™ TVS portfolio, engineered specifically for high-reliability, high-surge industrial and communications infrastructure applications with emphasis on safety certification and thermal robustness.
FAQ
What is the maximum clamping voltage of the SA28CA under a 45 A transient?
The SA28CA exhibits a maximum clamping voltage (VC) of 454 V when subjected to its rated 45 A peak pulse current (IPP) under the standard 1 ms exponential waveform. This value is measured per Figure 3 in the datasheet and defines the upper voltage limit imposed on protected circuitry during worst-case surge events. Designers must ensure downstream components tolerate this clamped voltage level. The SA28CA achieves this performance while maintaining bidirectional symmetry and UL 497B recognition for safety-critical applications.
Is the SA28CA polarity-sensitive during circuit installation?
No, the SA28CA is a bidirectional TVS diode, meaning it functions identically regardless of orientation in the circuit. Although it features a cathode band marking, this serves only as a mechanical reference - not a polarity indicator. Both leads conduct equally during positive and negative transients, enabling straightforward placement across AC-coupled lines or floating nodes without concern for directionality. This behavior is confirmed in the datasheet's "POLARITY: Cathode band does not imply polarity" note and distinguishes the SA28CA from unidirectional variants like SA28A.
Does the SA28CA meet UL 497B certification, and what does that mean for my design?
Yes, the SA28CA carries UL 497B recognition (File #E116110, QVGV2 category) for protector classification in isolated loop circuits. This certification validates successful completion of rigorous tests including strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge performance - far exceeding basic flammability ratings. For your design, UL 497B means the SA28CA is approved for use in safety-critical telecom, medical, and industrial loop interfaces where regulatory compliance and failure-mode predictability are mandatory, unlike non-certified alternatives.
What is the thermal derating behavior of the SA28CA in continuous operation?
The SA28CA is rated for 3.0 W steady-state power dissipation at lead temperature (TL) ≤ 75°C with 3/8″ lead length; it derates linearly at 30 mW/°C above that temperature. Its junction-to-lead thermal resistance is 33.3°C/W, meaning a 3.0 W dissipation yields ~100°C junction-to-lead delta. In practice, the SA28CA is intended for transient-only duty - not continuous conduction - so thermal design focuses on ensuring adequate lead heatsinking during rare surge events rather than sustained power handling. Continuous operation above 3.0 W risks permanent degradation.
How does the SA28CA compare to the SA28A variant?
The SA28CA is bidirectional, while the SA28A is unidirectional - a fundamental functional difference affecting circuit topology and protection scope. The SA28CA clamps both polarities symmetrically and has no functional polarity, whereas the SA28A conducts only in reverse bias and requires correct orientation. Their electrical parameters (VRWM, VBR, VC) differ slightly due to structural asymmetry in the unidirectional version. Datasheet Section 1 explicitly states "*Please see SA5.0A to SA170A for Unidirectional devices," confirming SA28CA and SA28A belong to separate, non-interchangeable product families.
SA28CA 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:
- -
SA28CA FAQ
1.How can I place an order for SA28CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SA28CA 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 SA28CA reliable?
The price and inventory of SA28CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA28CA is usually 5 days.
3.What payment methods are accepted for SA28CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA28CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA28CA?
SA28CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA28CA 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 SA28CA?
For technical support, including SA28CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA28CA requirements.
6.How does Aetrix verify that SA28CA is sourced from the original manufacturer or authorized distributors?
All SA28CA 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 SA28CA meets industry standards.
7.What is the process for return or replacement of SA28CA?
All SA28CA units undergo pre-shipment inspection (PSI). If there is an issue with SA28CA, 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 SA28CA part is unused and in its original packaging.
Return procedure for SA28CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA28CA Tags
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Diodes Incorporated
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Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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