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onsemi 1SMB12AT3
- Part No.:
- 1SMB12AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
1SMB12AT3.pdf
- Description:
- TVS DIODE 12V 19.9V SMB
- Quantity:
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- Shipping:
Inventory:5,631
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Product details
Overview
1SMB12AT3 from ON Semiconductor is a unidirectional 600 W peak power Zener transient voltage suppressor (TVS) designed for parallel clamping protection of sensitive electronics against ESD, lightning-induced surges, and inductive switching transients. It features a 12 V working peak reverse voltage (VRWM), 19.9 V maximum clamping voltage (VC) at 30.2 A peak pulse current (IPP), and sub-1 ns response time - deployed in power supply input stages, automotive body control modules, and industrial I/O interfaces.
For engineers reviewing the 1SMB12AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 8.3 ms surge waveforms, UL 497B recognition for isolated loop protection, low zener impedance, and Pb-free SMB package compatibility with automated SMT assembly.
Technical Context
The 1SMB12AT3 operates as a unidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp transient overvoltages above its 13.3–14.7 V breakdown voltage range (VBR @ IT = 1.0 mA). Its clamping action begins within <1.0 ns, limiting voltage across protected circuitry to ≤19.9 V at 30.2 A IPP (10/1000 µs waveform).
Thermal design relies on junction-to-lead resistance of 40 °C/W and 3.0 W DC power dissipation at TL = 75°C, with derating above that temperature. It sustains 100 A non-repetitive forward surge current (IFSM) and exhibits <5.0 µA leakage above 10 V - critical for low-power standby circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 12 V - Maximum continuous reverse operating voltage before clamping initiates; must exceed system DC bus or signal swing. |
| VBR (min/typ/max) | 13.3 / 14.0 / 14.7 V @ 1.0 mA - Ensures reliable, repeatable avalanche turn-on without premature conduction. |
| VC @ IPP | 19.9 V @ 30.2 A - Clamped voltage during 10/1000 µs surge; defines worst-case stress on downstream ICs. |
| PPK | 600 W @ 1.0 ms - Peak transient energy absorption capability; validates robustness against IEC 61000-4-5 Level 4 surges. |
| IR @ VRWM | 5.0 µA max - Low leakage preserves efficiency in high-impedance bias networks and battery-powered circuits. |
| Response Time | <1.0 ns - Enables suppression before fast-edge transients (e.g., ESD, relay bounce) propagate into IC inputs. |
| ESD Rating | Class 3 (>16 kV HBM) - Meets IEC 61000-4-2 requirements for user-accessible ports and connectors. |
Pinout & Package
1SMB12AT3 is housed in an SMB (DO-214AA) surface-mount plastic package (Case 403A), featuring a modified L-bend leadform optimized for solder joint reliability and thermal transfer. Cathode is marked by a polarity band on the case body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current sink during clamping | Connected to ground or low-impedance return path; carries full surge current during transient events. |
| Cathode | Protected line connection | Connected to the line being protected (e.g., +12 V rail); voltage referenced to Anode during clamping. |
Key Features
| Feature | Design Value |
|---|---|
| UL 497B Recognition | Validated for isolated loop circuit protection - enables use in telecom, PoE, and industrial fieldbus interfaces without additional certification effort. |
| Surmetic® Package | Void-free, thermosetting plastic construction with corrosion-resistant leads - ensures long-term reliability in humid or chemically aggressive environments. |
| Low Clamping Ratio (VC/VBR) | ~1.42 (19.9 V / 14.0 V) - Minimizes overvoltage margin between clamping and breakdown, improving protection headroom. |
| Pb-Free Compliant (G suffix) | RoHS-compliant termination and mold compound - supports global environmental compliance without sacrificing surge performance. |
| High Surge Current Handling | 30.2 A IPP (10/1000 µs) - Withstands repeated lightning-induced surges per IEC 61000-4-5, reducing need for redundant protection stages. |
Applications
| Industrial Power Supply Input Protection | Automotive Body Control Module (BCM) Inputs |
|---|---|
|
Use Scenario: 12 V DC input stage of programmable logic controller (PLC) power supply exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Unidirectional TVS placed directly across input terminals to clamp transients before they reach upstream rectifier and regulator ICs. Use Value: Limits voltage to ≤19.9 V during 30.2 A surge, preventing damage to 24 V-rated input capacitors and enabling single-stage protection architecture. |
Use Scenario: LIN bus or sensor input lines in BCM subjected to ESD and battery reversal transients. IC Role / Device Role / Timing Role: Line-side TVS connected between signal line and chassis ground to shunt fast transients away from LIN transceiver ICs. Use Value: Sub-1 ns response and >16 kV HBM rating protect LIN PHY against contact ESD per ISO 10605, maintaining communication integrity. |
| Medical Equipment Signal Interface Protection | Point-of-Sale (POS) Terminal Power Rails |
|
Use Scenario: 5–12 V analog sensor interface in patient monitor exposed to defibrillator discharge coupling. IC Role / Device Role / Timing Role: Low-leakage (5 µA) TVS placed at front-end connector to prevent false triggering and offset drift in precision amplifiers. Use Value: Maintains signal fidelity during standby while clamping transients to safe levels - critical for Class II medical device safety compliance. |
Use Scenario: 12 V auxiliary power rail in POS terminal powering display, printer, and card reader peripherals. IC Role / Device Role / Timing Role: Primary surge suppressor on main DC input, coordinated with fuse and MOV for staged overvoltage defense. Use Value: 600 W peak power rating absorbs multiple 10/1000 µs surges without degradation - extends field service life in retail environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ12A | Same VRWM (12 V) and VC (21.2 V @ 28.3 A), but lower PPK (600 W same), higher IR (10 µA max), and no UL 497B listing. | Lacks UL recognition for isolated loop systems; suitable for general-purpose board-level protection where certification is not required. | Select when cost sensitivity outweighs regulatory compliance needs and leakage tolerance allows ≥10 µA. |
| 1.5SMC12A | Higher PPK (1500 W), larger SMC package (DO-214AB), VRWM = 12 V, VC = 19.9 V @ 75.5 A - identical clamping but different surge capacity and footprint. | Requires PCB layout change due to larger 7.11 × 6.22 mm body; used where higher single-pulse energy (e.g., 10/1000 µs 75 A) is mandated. | Choose only if system-level surge testing exceeds 30 A IPP and board space permits SMC footprint. |
Compared with SMBJ12A and 1.5SMC12A, the 1SMB12AT3 uniquely combines UL 497B recognition, 5 µA low leakage, and SMB footprint - making it optimal for certified industrial and medical designs where space, leakage, and regulatory alignment are jointly constrained.
Availability
1SMB12AT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive control units, and medical instrumentation requiring stable component supply with full traceability and lifecycle continuity.
Supply support for 1SMB12AT3 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 energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and medical markets.
The 1SMB12AT3 belongs to the SMB series of unidirectional TVS diodes engineered specifically for high-reliability transient suppression in harsh electrical environments - emphasizing clamping accuracy, surge endurance, and regulatory compliance.
FAQ
What is the clamping voltage of the 1SMB12AT3 under standard surge conditions?
The 1SMB12AT3 clamps to a maximum of 19.9 V at 30.2 A peak pulse current (IPP), tested with the industry-standard 10/1000 µs double-exponential waveform. This value is guaranteed across temperature and represents the upper limit of voltage seen by protected circuitry during a surge event - critical for ensuring downstream ICs remain within absolute maximum ratings.
Does the 1SMB12AT3 meet UL 497B requirements for isolated loop protection?
Yes, the 1SMB12AT3 is UL Recognized under file E210057 for protector classification QVGQ2 per UL 497B. It has passed all required tests including strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge validation - confirming suitability for telecom, PoE, and industrial fieldbus isolation barriers where certification is mandatory.
What is the maximum reverse leakage current specified for the 1SMB12AT3 at its working voltage?
The 1SMB12AT3 specifies a maximum reverse leakage current (IR) of 5.0 µA at its working peak reverse voltage (VRWM) of 12 V and ambient temperature of 25°C. This low leakage ensures minimal power loss in always-on circuits and avoids false triggering in high-impedance monitoring paths - a key advantage over alternatives with 10 µA or higher IR.
Can the 1SMB12AT3 be used in bidirectional transient protection applications?
No, the 1SMB12AT3 is strictly unidirectional and must be oriented with cathode toward the protected line. For bidirectional protection, ON Semiconductor offers the 1SMB12CAT3 variant (not the 1SMB12AT3). Using the 1SMB12AT3 in reverse-biased AC or symmetrical surge scenarios will result in catastrophic failure due to lack of reverse avalanche capability.
What is the thermal resistance from junction to lead (RJL) for the 1SMB12AT3, and why does it matter?
The 1SMB12AT3 has a junction-to-lead thermal resistance (RJL) of 40 °C/W, measured with zero lead length on FR-4 board. This parameter governs how effectively heat generated during surge events transfers from the silicon junction to the PCB copper - directly impacting safe repetitive surge capability and long-term reliability under frequent transient exposure.
1SMB12AT3 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:
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- Supplier Device Package:
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1SMB12AT3 FAQ
1.How can I place an order for 1SMB12AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB12AT3 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 1SMB12AT3 reliable?
The price and inventory of 1SMB12AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB12AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB12AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB12AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB12AT3?
1SMB12AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB12AT3 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 1SMB12AT3?
For technical support, including 1SMB12AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB12AT3 requirements.
6.How does Aetrix verify that 1SMB12AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB12AT3 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 1SMB12AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB12AT3?
All 1SMB12AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB12AT3, 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 1SMB12AT3 part is unused and in its original packaging.
Return procedure for 1SMB12AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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