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onsemi 1SMA12AT3
- Part No.:
- 1SMA12AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA12AT3.pdf
- Description:
- TVS DIODE 12VWM 19.9VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:7,844
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Product details
Overview
1SMA12AT3 from ON Semiconductor is a unidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 12 V working peak reverse voltage (VRWM), 14.0 V nominal breakdown voltage (VBR) at 1 mA test current, 19.9 V clamping voltage (VC) at 20.1 A peak pulse current (IPP), and sub-1 ns response time. It is used in automotive power supply protection and industrial control I/O interfaces.
For engineers reviewing the 1SMA12AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to protected IC absolute maximum ratings, IPP capability under defined 10/1000 µs surge, thermal derating above 75°C, and SMA package footprint compatibility with IPC-7351B land patterns.
Technical Context
The 1SMA12AT3 operates as a unidirectional avalanche diode, conducting only during reverse overvoltage events while presenting high impedance under normal bias. Its low zener impedance and fast <1 ns response enable effective suppression of ESD (Class 3 >16 kV HBM) and lightning-induced surges per IEC 61000-4-2/5.
It is rated for 400 W peak pulse power (10/1000 µs waveform), with thermal resistance from junction to lead (RJL) of 20 °C/W and junction-to-ambient (RJA) of 250 °C/W on FR-4 board. Maximum operating temperature is +150°C, and soldering tolerance is 260°C for 10 seconds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 12 V - Minimum reverse standoff voltage before significant leakage; must exceed circuit's max continuous DC voltage. |
| VBR @ IT=1 mA | 13.3–14.7 V - Breakdown range defining turn-on threshold; nominal 14.0 V ensures predictable clamping onset. |
| VC @ IPP=20.1 A | 19.9 V - Maximum clamped voltage during 400 W surge; determines worst-case stress on downstream components. |
| IPP | 20.1 A - Peak pulse current supported at 19.9 V clamp; validates compliance with IEC 61000-4-5 Level 3 (1 A–40 A). |
| Response Time | <1 ns - Enables suppression of fast-rising ESD transients before protected ICs experience damage. |
| ESD Rating | Class 3 (>16 kV HBM) - Meets stringent electrostatic discharge immunity requirements for automotive and industrial end equipment. |
| Package | SMA (Case 403D-02) - Surface-mount plastic package with cathode band marking; 4.06 × 2.29 × 1.91 mm footprint. |
Pinout & Package
SMA package (Case 403D-02) is a surface-mount, unidirectional TVS diode with two terminals: anode and cathode. Cathode is marked by a molded polarity band. Mounting position is unrestricted; flat handling surface enables accurate placement for top-side or bottom-side PCB mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path); conducts during forward-biased operation (VF ≤ 3.5 V @ 30 A). |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 12 V rail); avalanche breakdown initiates here during overvoltage events to clamp voltage to VC. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power | Supports robust surge immunity per IEC 61000-4-5 up to 40 A (10/1000 µs) on 12 V systems without thermal runaway. |
| Low zener impedance | Ensures stable clamping voltage across varying surge currents, minimizing voltage overshoot during transient events. |
| Pb-free (1SMA12AT3G) option | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-020 reflow profiles without lead contamination risk. |
| Flat handling surface | Enables consistent pick-and-place accuracy and coplanarity on automated SMT lines using standard vision alignment. |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump (ISO 7637-2 Pulse 5a) and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp transients above 13.5 V. Use Value: Limits clamped voltage to 19.9 V, staying below 20 V absolute max rating of common CAN transceivers and microcontrollers. | Use Scenario: Shielding 24 V digital input modules from inductive kickback when switching solenoids or relays. IC Role / Device Role / Timing Role: Standoff device mounted at connector entry point to shunt surge energy before reaching optocoupler inputs. Use Value: Sub-1 ns response prevents latch-up in upstream logic; 20.1 A IPP handles typical 1 A–10 A inductive spikes. |
| Medical Equipment Power Supply Input | Point-of-Sale Terminal USB Port ESD Protection |
Use Scenario: Safeguarding isolated DC-DC converter inputs in Class II medical devices subjected to ESD and conducted noise. IC Role / Device Role / Timing Role: Primary-level TVS on secondary-side 12 V output to absorb coupling from primary-side transients. Use Value: 16 kV HBM ESD rating exceeds IEC 61000-4-2 Level 4 requirement; low leakage (<2.5 µA @ 12 V) avoids standby current penalty. | Use Scenario: Adding secondary-level ESD protection on VBUS line of USB 2.0 ports in retail kiosks exposed to frequent human contact. IC Role / Device Role / Timing Role: Low-capacitance TVS (typ. ~100 pF) placed between VBUS and GND to divert ESD without degrading signal integrity. Use Value: Clamps 8 kV contact discharge to <20 V within 1 ns, preserving USB enumeration timing and preventing PHY latch-up. |
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 (20.1 V), but 600 W peak power (SMB package); larger footprint (4.57 × 3.94 mm). | Better suited for higher-energy surges (e.g., ISO 16750-2); requires PCB layout change due to SMB pad dimensions. | Select when surge energy exceeds 400 W and board space allows SMB footprint. |
| 1.5SMC12A | Same electrical specs (VRWM=12 V, VC=20.1 V), but 1500 W peak power and DO-214AB (SMC) package (7.11 × 6.22 mm). | Targeted at heavy-duty industrial mains input stages; incompatible with SMA land pattern without redesign. | Choose for front-end AC/DC or DC-DC converter input protection where space permits larger package. |
Compared with SMBJ12A and 1.5SMC12A, the 1SMA12AT3 offers optimal balance of surge robustness (400 W), compact SMA footprint, and cost efficiency for mid-tier automotive and industrial control applications where PCB real estate is constrained but 600+ W rating is unnecessary.
Availability
1SMA12AT3 is available at Aetrix Electronics and suitable for automotive electronics, industrial programmable logic controllers, and medical power supply designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for 1SMA12AT3 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The 1SMAxxAT3 series belongs to onsemi's transient voltage suppressor product line, engineered specifically for reliable, low-profile overvoltage protection in space-constrained DC power and signal interfaces across harsh environments.
FAQ
What is the maximum clamping voltage of the 1SMA12AT3 under surge conditions?
The 1SMA12AT3 has a maximum clamping voltage (VC) of 19.9 V when subjected to its rated peak pulse current of 20.1 A (10/1000 µs waveform). This value is measured at the device terminals and represents the highest voltage that will appear across the protected circuit during a full-power transient event. The 1SMA12AT3 maintains this clamping performance consistently across its operating temperature range of −65°C to +150°C, making it suitable for under-hood automotive and industrial environments.
Is the 1SMA12AT3 compatible with lead-free reflow soldering processes?
Yes, the 1SMA12AT3 is compatible with lead-free reflow soldering. Its maximum soldering temperature is rated at 260°C for 10 seconds, fully meeting JEDEC J-STD-020 requirements for Pb-free assembly. The device uses corrosion-resistant external surfaces and readily solderable leads. For optimal reliability, follow onsemi's recommended thermal profile and use the standard SMA footprint per Case 403D-02 outline. The Pb-free variant is designated 1SMA12AT3G.
How does the 1SMA12AT3 differ from bidirectional TVS diodes like the 1SMA12CAT3?
The 1SMA12AT3 is unidirectional and functions only during reverse-biased overvoltage events, behaving as a low-leakage Zener diode under normal operation. In contrast, the 1SMA12CAT3 is bidirectional and clamps both positive and negative transients symmetrically. The 1SMA12AT3 exhibits lower reverse leakage (<2.5 µA @ 12 V) and is preferred for DC power rail protection, whereas the 1SMA12CAT3 suits AC signal lines or differential buses where polarity reversal occurs. They share identical package and thermal specs but differ fundamentally in conduction directionality.
What is the minimum breakdown voltage specification for the 1SMA12AT3?
The minimum specified breakdown voltage (VBR) for the 1SMA12AT3 is 13.3 V, measured at a test current (IT) of 1 mA and ambient temperature of 25°C. This parameter defines the lowest voltage at which the device enters avalanche conduction during reverse bias. The nominal VBR is 14.0 V, with a maximum of 14.7 V, ensuring design margin for selecting appropriate VRWM in circuits where the maximum steady-state voltage is 12 V.
Can the 1SMA12AT3 be used in parallel to increase surge current handling?
No, the 1SMA12AT3 should not be used in parallel to increase surge current capacity. Due to manufacturing tolerances in VBR (13.3–14.7 V), paralleled units will not share current evenly-lower-VBR devices conduct first and may overheat or fail prematurely. Surge rating is strictly per-device; increasing IPP requires a single higher-rated TVS (e.g., SMBJ12A or 1.5SMC12A) or verified multi-die packaged alternatives. System-level surge testing must validate any configuration.
1SMA12AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 12V
- Voltage - Breakdown (Min):
- 13.3V
- Voltage - Clamping (Max) @ Ipp:
- 19.9V
- Current - Peak Pulse (10/1000µs):
- 20.1A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 925pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA12AT3 FAQ
1.How can I place an order for 1SMA12AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA12AT3 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 1SMA12AT3 reliable?
The price and inventory of 1SMA12AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA12AT3 is usually 5 days.
3.What payment methods are accepted for 1SMA12AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA12AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA12AT3?
1SMA12AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA12AT3 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 1SMA12AT3?
For technical support, including 1SMA12AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA12AT3 requirements.
6.How does Aetrix verify that 1SMA12AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMA12AT3 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 1SMA12AT3 meets industry standards.
7.What is the process for return or replacement of 1SMA12AT3?
All 1SMA12AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA12AT3, 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 1SMA12AT3 part is unused and in its original packaging.
Return procedure for 1SMA12AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA12AT3 Tags
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