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onsemi 1SMC28AT3
- Part No.:
- 1SMC28AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
1SMC28AT3.pdf
- Description:
- TVS DIODE 28V 45.4V SMC
- Quantity:
- Payment:
- Shipping:
Inventory:7,660
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Product details
Overview
1SMC28AT3 from ON Semiconductor is a unidirectional 1500 W transient voltage suppressor (TVS) diode designed for parallel clamping protection of sensitive electronics against ESD, lightning surges, and inductive switching transients. It features a 28 V working peak reverse voltage (VRWM), 31.9 V minimum breakdown voltage (VBR) at 1 mA, 45.4 V maximum clamping voltage (VC) at 33 A peak pulse current, and sub-1 ns response time - deployed in power supplies, automotive ECUs, and industrial I/O interfaces.
For engineers reviewing the 1SMC28AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC VDD rails, peak pulse current handling under IEC 61000-4-5 surge waveforms, UL 497B certification for isolated loop protection, and SMC package thermal performance in high-density PCB layouts.
Technical Context
The 1SMC28AT3 operates as a silicon avalanche diode with sharp Zener-like breakdown characteristics, optimized for fast transient suppression in DC power lines and signal paths. Its low dynamic impedance (< 1 Ω typical) ensures stable clamping across varying surge currents, while its thermally robust SMC (Case 403) package supports 1500 W peak power dissipation at 25 °C with 54.6 mW/°C derating above 75 °C junction temperature.
Designed for unidirectional operation only, it exhibits < 5 µA leakage at VRWM and meets Class 3 HBM ESD rating (>16 kV). The device is not bidirectional and lacks integrated steering or dual-rail capability - requiring external polarity-aware placement in circuits where reverse voltage stress may occur during normal operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 28 V - Maximum continuous reverse operating voltage before clamping begins; sets minimum system rail voltage compatibility. |
| VBR (min @ IT=1 mA) | 31.9 V - Guaranteed avalanche onset threshold; defines lower bound of protection window above VRWM. |
| VC (max @ IPP=33 A) | 45.4 V - Worst-case clamped voltage during 10/1000 µs surge; must stay below protected IC absolute maximum rating. |
| IPP | 33 A - Peak pulse current corresponding to VC; used to size series impedance (Zin) per IEC 61000-4-5 Level 4 (4 kV). |
| Response Time | < 1 ns - Time from transient rise to clamping onset; enables protection of high-speed logic and analog front-ends. |
| Leakage Current | < 5 µA @ 28 V - Negligible standby power loss; avoids loading low-power sensor or battery-backed circuits. |
| UL Recognition | UL 497B QVGQ2 - Certified for isolated loop circuit protection; validates reliability in telecom and industrial safety-critical interfaces. |
Pinout & Package
1SMC28AT3 is housed in an SMC (DO-214AB) surface-mount package (Case 403), featuring a molded cathode notch for polarity identification, modified L-bend leads for enhanced solder joint reliability, and void-free thermosetting plastic encapsulation rated for 260 °C / 10 s reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current sink during clamping | Connected to ground or low-impedance return path; forms clamp loop with cathode on protected line. |
| Cathode | Protected line connection | Connected to the voltage rail or signal line requiring transient suppression; marked by molded notch. |
Key Features
| Feature | Design Value |
|---|---|
| 1500 W peak pulse power | Supports IEC 61000-4-5 surge testing up to 4 kV (line-to-ground) without degradation when properly mounted. |
| UL 497B recognition | Validates suitability for certified isolated loop protection in telecom and process control systems per safety standard. |
| ESD rating >16 kV HBM | Eliminates need for secondary ESD protection on board-level interfaces exposed to human handling. |
| Low zener impedance | Ensures consistent clamping across production lots and temperature range (−65 °C to +150 °C). |
| Pb-free SURMETIC® package | Complies with RoHS and J-STD-020 moisture sensitivity level (MSL) 1; compatible with lead-free reflow profiles. |
Applications
| Automotive Power Distribution | Industrial PLC Digital I/O |
|---|---|
Use Scenario: Protecting 24 V CAN bus power rails and microcontroller supply inputs from load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between VBAT+ and chassis ground to limit transients to ≤45.4 V during ISO 7637-2 Pulse 5a events. Use Value: Prevents latch-up or permanent damage to 3.3 V/5 V logic supplies downstream of DC-DC converters in engine control units. |
Use Scenario: Safeguarding 24 V digital input channels in programmable logic controllers against field-wiring induced surges. IC Role / Device Role / Timing Role: Parallel-connected transient suppressor on each optocoupler input side to clamp induced voltages before signal conditioning circuitry. Use Value: Maintains functional safety integrity per IEC 61000-4-4/5 by limiting overvoltage to < 50 V during 2 kV burst and 4 kV surge tests. |
| Medical Equipment Power Entry | Telecom Isolated Data Lines |
Use Scenario: Shielding AC/DC adapter outputs and internal 24 V distribution buses in diagnostic imaging devices from mains-borne transients. IC Role / Device Role / Timing Role: Primary-stage TVS on secondary-side DC output, coordinated with fuse and common-mode choke for EN 61000-4-5 compliance. Use Value: Enables Class I medical device certification by suppressing 1.2/50 µs surges to safe levels without compromising low-leakage requirements. |
Use Scenario: Protecting RS-485 transceiver VCC pins and isolated DC-DC converter inputs in base station backhaul modules. IC Role / Device Role / Timing Role: UL 497B-certified clamp on isolated 24 V bias rail feeding isolated data interface ICs. Use Value: Meets telecom safety isolation barrier requirements while providing 1500 W surge immunity without adding discrete isolation components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SZ1SMC28AT3G | Automotive-grade variant qualified to AEC-Q101; identical electrical specs but tighter process controls and PPAP documentation support. | Required for automotive OEM designs; unnecessary for industrial or consumer use where qualification overhead adds cost. | Select 1SMC28AT3 for cost-sensitive non-automotive applications; choose SZ1SMC28AT3G only when AEC-Q101 compliance is contractually mandated. |
| SMCJ28A | Same SMC package and 28 V VRWM, but higher 3000 W peak power rating and 48.4 V clamping at 62.2 A - larger junction area and different thermal design. | Better suited for higher-energy surge environments (e.g., outdoor power equipment); over-spec'd for typical 24 V I/O protection. | Use SMCJ28A only if system-level surge testing exceeds IEC 61000-4-5 Level 4; otherwise 1SMC28AT3 offers optimal cost-performance balance. |
Compared with SZ1SMC28AT3G, the 1SMC28AT3 omits automotive qualification but delivers identical clamping behavior and footprint; versus SMCJ28A, it trades peak power headroom for lower unit cost and tighter board space utilization in standard industrial designs.
Availability
1SMC28AT3 is available at Aetrix Electronics and suitable for automotive power distribution, industrial PLC digital I/O, and medical equipment power entry requiring stable component supply and full traceability through production lifecycles.
Supply support for 1SMC28AT3 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 is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and medical markets.
The 1SMC28AT3 belongs to ON Semiconductor's SMC-series transient voltage suppressors - engineered for high-reliability clamping in harsh electromagnetic environments where UL 497B certification and sub-1 ns response are critical.
FAQ
What is the clamping voltage of the 1SMC28AT3 under a 33 A transient?
The 1SMC28AT3 has a maximum clamping voltage (VC) of 45.4 V when subjected to a 33 A peak pulse current (IPP), measured using the standard 10/1000 µs double-exponential waveform. This value is guaranteed across temperature and production lots, ensuring predictable overvoltage protection for downstream 3.3 V or 5 V logic rails powered from a 24 V source.
Is the 1SMC28AT3 bidirectional or unidirectional?
The 1SMC28AT3 is strictly unidirectional - it conducts only when the cathode is positive relative to the anode. Bidirectional variants are not offered in the SMC series. This means the 1SMC28AT3 must be oriented with cathode toward the protected line and anode to ground; reverse polarity connection will not provide protection and may cause failure under forward bias.
Does the 1SMC28AT3 meet UL 497B requirements?
Yes, the 1SMC28AT3 is UL recognized under file E210057 for classification QVGQ2 per UL 497B, specifically for isolated loop circuit protection. This certification covers dielectric withstand, endurance conditioning, and strike voltage breakdown testing - confirming suitability for telecom and industrial safety-isolated interfaces where regulatory compliance is mandatory.
What is the thermal resistance from junction-to-lead for the 1SMC28AT3?
The 1SMC28AT3 has a thermal resistance from junction-to-lead (RJL) of 54.6 mW/°C, meaning it can dissipate 4.0 W continuously at 75 °C lead temperature before requiring derating. This parameter is critical for PCB layout - the device must be mounted on a minimum 1 in² copper pad on FR-4 to achieve rated power handling, per ON Semiconductor's recommended footprint.
Can the 1SMC28AT3 replace the 1N6267A in existing designs?
No - the 1N6267A is a DO-201 package (axial lead) 28 V TVS with 1500 W rating but different thermal and mechanical characteristics. While electrical parameters overlap, the 1SMC28AT3 uses SMC (DO-214AB) surface-mount packaging with modified L-bend leads and requires revised PCB land pattern, stencil design, and reflow profile. Direct replacement would necessitate layout revision and validation.
1SMC28AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- -
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- -
1SMC28AT3 FAQ
1.How can I place an order for 1SMC28AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMC28AT3 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 1SMC28AT3 reliable?
The price and inventory of 1SMC28AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMC28AT3 is usually 5 days.
3.What payment methods are accepted for 1SMC28AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMC28AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMC28AT3?
1SMC28AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMC28AT3 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 1SMC28AT3?
For technical support, including 1SMC28AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMC28AT3 requirements.
6.How does Aetrix verify that 1SMC28AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMC28AT3 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 1SMC28AT3 meets industry standards.
7.What is the process for return or replacement of 1SMC28AT3?
All 1SMC28AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMC28AT3, 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 1SMC28AT3 part is unused and in its original packaging.
Return procedure for 1SMC28AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMC28AT3 Tags
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