My Inquiry
My Account
onsemi SA28A
- Part No.:
- SA28A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA28A.pdf
- Description:
- TVS DIODE 28VWM 45.4VC AXIAL
- Quantity:
- Payment:
- Shipping:
Inventory:5,257
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SA28A from ON Semiconductor is a unidirectional MiniMOSORB Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 28 V working peak reverse voltage (VRWM), 45.4 V maximum clamping voltage at 31 A peak pulse current, 500 W peak pulse power rating (1 ms), <1.0 ns response time, and UL 497B recognition for isolated loop circuit protection - used in industrial power supplies and medical equipment surge protection.
For engineers reviewing the SA28A datasheet, pinout, applications, or equivalent options, key selection criteria include verified clamping performance at 31 A IPP, axial leaded Surmetic package thermal derating behavior, VRWM margin above nominal 24 V systems, and UL 497B certification scope for safety-critical isolation barriers.
Technical Context
The SA28A operates as a unidirectional Zener-based TVS diode, conducting only during reverse overvoltage events above its breakdown threshold (31.1–34.4 V at 1 mA). Its low zener impedance and fast sub-nanosecond response enable effective suppression of ESD and lightning-induced surges without affecting normal circuit operation.
It is rated for 500 W nonrepetitive peak pulse power per 1 ms waveform (Figure 4), with thermal derating to 3.0 W steady-state at 75°C lead temperature. The device meets Class 3 ESD immunity (>16 kV HBM) and exhibits <1 µA leakage above 8.5 V, ensuring minimal standby power loss in protected circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 28 V - Maximum continuous reverse operating voltage; must exceed system's nominal DC rail (e.g., 24 V) to avoid conduction during normal operation. |
| VBR (min/typ/max) | 31.1 / 32.75 / 34.4 V @ 1 mA - Confirmed Zener breakdown range; determines precise clamping onset under transient conditions. |
| VC @ IPP | 45.4 V @ 31 A - Maximum clamped voltage during 1 ms surge; defines worst-case overvoltage seen by downstream ICs. |
| PPK | 500 W @ 1 ms - Peak transient energy handling capacity; validates robustness against IEC 61000-4-5 Level 4 surges. |
| Response time | <1.0 ns - Enables suppression before sensitive logic or analog circuitry sustains damage from fast-rising transients. |
| Leakage current | <1 µA @ VRWM - Ensures negligible power drain in always-on or battery-backed systems. |
| UL 497B | Recognized for isolated loop circuit protection - certifies suitability in telecom/data line isolation barriers requiring safety agency approval. |
Pinout & Package
SA28A is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode indicated by a polarity band. Leads are tin-plated copper, solderable at 260°C for 10 seconds at 1/16″ from case.
| 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 | Zener clamping terminal | Connected to protected line (e.g., +24 V rail); conducts when reverse voltage exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| UL 497B Recognition | Validated for use in certified isolated loop protectors - eliminates need for additional safety qualification in industrial comms designs. |
| ESD Rating | Class 3 (>16 kV HBM) - Provides built-in ESD hardening for front-end interfaces without external add-on protection. |
| Low Clamping Ratio | VC/VBR ≈ 1.39 (45.4 V / 32.75 V) - Minimizes overvoltage stress on downstream components during surge events. |
| Pb-Free Packaging | RoHS-compliant Surmetic axial package (SA28ARLG variant) - supports lead-free assembly without requalification. |
| Thermal Robustness | RJL = 33.3°C/W - Enables reliable heat dissipation through leads into PCB copper, critical for repeated surge duty cycles. |
Applications
| Industrial Power Supply Protection | Medical Equipment Input Stage |
|---|---|
Use Scenario: Protecting 24 V DC input stage of PLC power modules against load dump and inductive switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between +24 V rail and chassis ground to limit surge voltage to ≤45.4 V. Use Value: Prevents latch-up or permanent damage to upstream DC/DC controllers and monitoring ICs during 500 W transient events. |
Use Scenario: Safeguarding isolated sensor interface inputs in patient-connected diagnostic devices compliant with IEC 60601-1. IC Role / Device Role / Timing Role: UL 497B-recognized TVS on secondary-side signal lines to maintain reinforced isolation barrier integrity. Use Value: Meets creepage/clearance and surge withstand requirements for Class BF applied parts without compromising isolation test margins. |
| Process Control I/O Modules | Telecom Line Interface Cards |
Use Scenario: Shielding 4–20 mA current loop receivers from field wiring induced surges in factory automation cabinets. IC Role / Device Role / Timing Role: Low-leakage (<1 µA) TVS across loop terminals to avoid calibration drift while clamping transients. Use Value: Maintains measurement accuracy under continuous operation while surviving repetitive 1 ms surges up to 31 A. |
Use Scenario: Front-end protection on Ethernet PHY power rails in carrier-grade access switches exposed to lightning-induced surges. IC Role / Device Role / Timing Role: Fast-response (<1 ns) TVS on +3.3 V and +12 V bias rails feeding magnetics and PHY ICs. Use Value: Limits voltage overshoot below IC absolute maximum ratings during IEC 61000-4-5 combination wave testing. |
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 SMAJ28A | Same VRWM (28 V), slightly higher VC (48.4 V @ 31.3 A), DO-214AC package (SMD), no UL 497B recognition. | Preferred for automated SMT assembly; unsuitable where UL-certified isolation barrier protection is mandated. | Select when board space is constrained and safety certification is handled at system level. |
| Vishay SMF28A | Identical VRWM (28 V), lower PPK (200 W), same DO-214AC package, no UL 497B listing. | Applicable only for lower-energy transients (e.g., ESD-only); insufficient for IEC 61000-4-5 Level 3+ surge immunity. | Choose only for cost-sensitive consumer applications with limited surge exposure. |
Compared with SMAJ28A and SMF28A, the SA28A delivers higher surge robustness (500 W vs. 200–400 W), axial-leaded mechanical reliability for high-vibration environments, and UL 497B validation essential for industrial isolators - making it the preferred choice where safety certification and repeatable high-energy clamping are required.
Availability
SA28A is available at Aetrix Electronics and suitable for industrial power supplies, medical equipment input stages, and process control I/O modules requiring stable component supply with full regulatory documentation and traceable sourcing.
Supply support for SA28A 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 supplier specializing in power management, analog, sensors, and discrete devices for automotive, industrial, and cloud power applications.
The SA28A belongs to the SA5.0A Series MiniMOSORB TVS family, engineered specifically for high-reliability transient suppression in safety-critical industrial and medical systems requiring UL 497B certification and robust 500 W surge handling.
FAQ
What is the clamping voltage of SA28A at its rated peak pulse current?
The SA28A has a maximum clamping voltage (VC) of 45.4 V at 31 A peak pulse current (IPP), measured per the 1 ms exponential waveform defined in Figure 4 of the datasheet. This value ensures downstream components see no more than 45.4 V during worst-case surge events, making SA28A suitable for protecting 24 V systems where ICs have 48 V absolute maximum ratings.
Is SA28A certified for safety-critical isolation applications?
Yes, SA28A carries UL 497B recognition (File #E116110, QVGV2 category) for isolated loop circuit protection - a requirement for many industrial and medical isolation barriers. This certification covers tests including strike voltage breakdown, endurance conditioning, and dielectric withstand, distinguishing SA28A from generic TVS diodes lacking such validation.
What package type does SA28A use, and how is polarity identified?
SA28A uses ON Semiconductor's proprietary Surmetic axial-leaded plastic package (Case 59AA), with cathode polarity indicated by a visible band near one lead end. The package supports manual or wave soldering at 260°C for 10 seconds at 1/16″ from the case body, and is rated for operation from –55°C to +175°C junction temperature.
How does SA28A compare to SA24A and SA30A in terms of voltage rating and clamping performance?
SA28A offers a 28 V VRWM, positioned between SA24A (24 V) and SA30A (30 V). Its VBR range (31.1–34.4 V) and VC (45.4 V) provide tighter clamping margin than SA30A (VC = 48.4 V) while maintaining higher standoff than SA24A (VC = 38.9 V), making SA28A optimal for 24 V systems needing headroom against tolerance drift and transient overshoot.
Does SA28A meet RoHS and lead-free assembly requirements?
Yes, the SA28ARLG variant of SA28A is explicitly designated as Pb-Free in the ordering information and complies with RoHS Directive 2011/65/EU. Its Surmetic package uses lead-free terminations compatible with standard SAC305 reflow profiles and 260°C wave soldering, with full compliance documentation available from onsemi.
SA28A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- MiniMosorb™
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 11A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- Axial
SA28A FAQ
1.How can I place an order for SA28A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA28A 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 SA28A reliable?
The price and inventory of SA28A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA28A is usually 5 days.
3.What payment methods are accepted for SA28A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA28A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA28A?
SA28A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA28A 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 SA28A?
For technical support, including SA28A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA28A requirements.
6.How does Aetrix verify that SA28A is sourced from the original manufacturer or authorized distributors?
All SA28A 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 SA28A meets industry standards.
7.What is the process for return or replacement of SA28A?
All SA28A units undergo pre-shipment inspection (PSI). If there is an issue with SA28A, 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 SA28A part is unused and in its original packaging.
Return procedure for SA28A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA28A Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
