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onsemi 1SMB120AT3
- Part No.:
- 1SMB120AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB120AT3.pdf
- Description:
- TVS DIODE 120VWM 193VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:9,237
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Product details
Overview
1SMB120AT3 from ON Semiconductor is a unidirectional 600 W transient voltage suppressor (TVS) diode designed for overvoltage protection in DC power rails and signal lines. It features a 120 V working peak reverse voltage (VRWM), 193 A maximum peak pulse current (IPP), clamping voltage of 193 V at IPP, <5 µA leakage at VRWM, and sub-1 ns response time. It is used to protect automotive ECUs, industrial power supplies, and telecom interface circuits against ESD and lightning-induced surges.
For engineers reviewing the 1SMB120AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to IC absolute maximum ratings, UL 497B certification for isolated loop protection, and SMB package thermal performance under repetitive surge conditions.
Technical Context
The 1SMB120AT3 operates as a Zener-based avalanche clamp, triggered when reverse voltage exceeds its breakdown threshold (VBR = 133–147 V @ IT = 1.0 A). Its low zener impedance ensures stable clamping during high-current transients, while its thermally robust Surmetic SMB package enables reliable heat dissipation during 600 W, 1 ms pulses.
It complies with UL 497B for isolated loop circuit protection and meets Class 3 ESD immunity (>16 kV HBM). The device exhibits typical junction capacitance of 160 pF at 0 V bias (1 MHz), making it suitable for lower-speed power-line and control-signal protection-not high-frequency data lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 120 V - Maximum continuous reverse operating voltage before clamping begins; must be ≥ circuit's peak DC or AC waveform voltage. |
| VBR (min/typ/max) | 133 / 140 / 147 V @ IT = 1.0 A - Confirmed avalanche onset range; determines minimum overvoltage threshold for protection activation. |
| VC @ IPP | 193 V @ 193 A - Clamped voltage seen by downstream circuitry during full 600 W transient; defines worst-case stress on protected ICs. |
| IPP | 193 A - Peak pulse current capability per 1 ms 10/1000 µs waveform; defines surge energy handling (600 W) without failure. |
| IR @ VRWM | <5.0 µA - Reverse leakage at rated working voltage; ensures negligible standby power loss and no false triggering. |
| Response Time | <1.0 ns - Time from overvoltage onset to conduction; critical for protecting fast logic and analog inputs from nanosecond-scale transients. |
| UL Recognition | UL 497B QVGQ2 - Certified for use in isolated loop protector applications, including telecom and industrial fieldbus interfaces. |
Pinout & Package
1SMB120AT3 is housed in an SMB (DO-214AA) surface-mount package (Case 403A), featuring a cathode band marking and modified L-bend leads for enhanced solder joint reliability. The package is void-free, thermoset plastic with corrosion-resistant finish and Pb-free construction (G suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current sink during forward conduction; grounded reference node in unidirectional TVS configuration | Connected to system ground or low-impedance return path; establishes reference for clamping action. |
| Cathode | High-impedance input during normal operation; clamps to VRWM + margin during overvoltage | Connected to protected line (e.g., 12 V rail, RS-485 bus); conducts surge current to ground when voltage exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| 600 W peak pulse power (1 ms) | Withstands IEC 61000-4-5 Level 4 surges (4 kV, 2 Ω source) without degradation-enables single-device protection for 24 V industrial systems. |
| UL 497B recognition (QVGQ2) | Validated for isolated loop protection in telecom and process control; eliminates need for external certification testing in end equipment. |
| ESD rating >16 kV (HBM) | Meets IEC 61000-4-2 Level 4 requirements out-of-the-box; protects against human-body discharge events without additional shielding. |
| Sub-1 ns response time | Minimizes voltage overshoot during fast transients (e.g., relay bounce, inductive switch-off); preserves integrity of 3.3 V/5 V logic interfaces. |
| SMB package thermal resistance (RJL = 40 °C/W) | Enables sustained operation at 75°C ambient with 3.0 W derated power; supports compact PCB layouts in enclosed enclosures. |
Applications
| Automotive Body Control Module (BCM) | Industrial 24 V DC Power Supply Input |
|---|---|
Use Scenario: Protects microcontroller I/O and CAN transceiver power pins from load dump (ISO 7637-2 Pulse 5a) and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed between 12 V rail and chassis ground; clamps transients above 120 V within 1 ns. Use Value: Prevents latch-up or gate oxide damage in 3.3 V MCU peripherals by limiting rail excursion to ≤193 V during 100 V/100 ms load dump events. |
Use Scenario: Shields AC/DC converter output and PLC I/O drivers from surges induced by nearby motor switching or lightning coupling. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 24 V DC distribution bus; coordinated with upstream fuses and MOVs. Use Value: Maintains system uptime by absorbing 600 W surges without failure-reducing field returns due to power-stage MOSFET destruction. |
| Telecom Remote Terminal Unit (RTU) | Medical Infusion Pump Power Input |
Use Scenario: Safeguards RS-485 communication ports and auxiliary 12 V supply in outdoor base stations exposed to lightning-induced surges. IC Role / Device Role / Timing Role: UL 497B-certified TVS on isolated 12 V loop power feed; placed adjacent to connector per IEC 61000-4-5 layout guidelines. Use Value: Ensures compliance with EN 61000-4-5 (4 kV) and UL 497B without redesign-accelerating certification for Class B telecom equipment. |
Use Scenario: Guards main 24 V DC input of battery-backed infusion pump against hospital-grade power anomalies and ESD from operator contact. IC Role / Device Role / Timing Role: First-line transient suppressor before DC/DC converter; selected for low leakage (<5 µA) to preserve battery life. Use Value: Eliminates risk of unintended pump shutdown during 15 kV HBM ESD events-meeting IEC 60601-1-2 immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ120A | Same VRWM (120 V) and VC (193 V), but 600 W rating tested per 10/1000 µs waveform; identical SMB package and pinout. | No UL 497B recognition; lacks isolated-loop certification required for telecom fieldbus deployments. | Select 1SMB120AT3 where UL 497B compliance or higher HBM ESD rating (>16 kV) is mandatory. |
| 1.5SMC120A | Higher 1.5 kW peak power rating, but larger SMC (DO-214AB) package; VRWM = 120 V, VC = 193 V, IPP = 7.8 A (at 1.5 kW test condition). | Not drop-in compatible-requires PCB footprint change; better suited for high-energy utility meter or solar inverter inputs. | Choose 1.5SMC120A only when surge energy exceeds 600 W and board space allows SMC footprint. |
Compared with SMBJ120A, the 1SMB120AT3 provides certified isolated-loop protection and superior ESD hardness; compared with 1.5SMC120A, it offers identical clamping performance in a smaller, cost-optimized SMB footprint-but with lower total surge energy capacity.
Availability
1SMB120AT3 is available at Aetrix Electronics and suitable for automotive body electronics, industrial 24 V power systems, telecom remote terminal units, and medical device power inputs requiring stable component supply, long-term lifecycle support, and UL-certified surge protection.
Supply support for 1SMB120AT3 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, sensor, and discrete devices for automotive, industrial, and communications markets.
The 1SMB120AT3 belongs to the SMB series of unidirectional TVS diodes, engineered for high-reliability overvoltage protection in harsh environments-emphasizing low clamping voltage, fast response, and regulatory compliance for safety-critical systems.
FAQ
What is the clamping voltage of the 1SMB120AT3 under maximum surge conditions?
The 1SMB120AT3 has a maximum clamping voltage (VC) of 193 V when subjected to its rated peak pulse current (IPP) of 193 A, measured using the standard 10/1000 µs waveform. This value is guaranteed across temperature and represents the highest voltage downstream components will experience during a full 600 W transient event. Designers must ensure that all protected ICs have absolute maximum ratings exceeding 193 V.
Does the 1SMB120AT3 meet UL 497B requirements for isolated loop protection?
Yes, the 1SMB120AT3 carries UL 497B recognition under file QVGQ2, specifically certified for use in isolated loop protector applications such as telecom line cards and industrial fieldbus interfaces. This certification covers performance validation across strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge testing-not just flammability of the package material.
Is the 1SMB120AT3 RoHS-compliant and lead-free?
Yes, the "G" suffix in 1SMB120AT3 indicates a Pb-free (RoHS-compliant) construction. The device uses ON Semiconductor's Surmetic molding compound and conforms to JEDEC J-STD-020 moisture sensitivity level (MSL) 1, with a maximum soldering temperature of 260°C for 10 seconds-fully compatible with standard lead-free reflow profiles.
How does the 1SMB120AT3 compare to bidirectional TVS diodes like 1SMB120AT3-BP?
The 1SMB120AT3 is unidirectional and optimized for DC rail protection where polarity is fixed (e.g., +12 V to ground). Bidirectional variants like 1SMB120AT3-BP are intended for AC or floating signal lines (e.g., RS-485 differential pairs) and exhibit symmetric clamping in both directions. Using the unidirectional 1SMB120AT3 on AC lines risks forward conduction and failure-always match device polarity to circuit topology.
What is the maximum allowable mounting temperature for the 1SMB120AT3 during reflow soldering?
The 1SMB120AT3 supports a maximum case temperature of 260°C for 10 seconds during soldering, per its mechanical specifications. This aligns with IPC/JEDEC J-STD-020 MSL 1 requirements. To avoid thermal stress, maintain uniform heating, limit dwell time above 220°C to <60 seconds, and verify profile compatibility with the PCB's thermal mass and adjacent components.
1SMB120AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AA, SMB
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 120V
- Voltage - Breakdown (Min):
- 133V
- Voltage - Clamping (Max) @ Ipp:
- 193V
- Current - Peak Pulse (10/1000µs):
- 3.1A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 160pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB120AT3 FAQ
1.How can I place an order for 1SMB120AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB120AT3 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 1SMB120AT3 reliable?
The price and inventory of 1SMB120AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB120AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB120AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB120AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB120AT3?
1SMB120AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB120AT3 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 1SMB120AT3?
For technical support, including 1SMB120AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB120AT3 requirements.
6.How does Aetrix verify that 1SMB120AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB120AT3 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 1SMB120AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB120AT3?
All 1SMB120AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB120AT3, 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 1SMB120AT3 part is unused and in its original packaging.
Return procedure for 1SMB120AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB120AT3 Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
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Diodes Incorporated
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Diodes Incorporated
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Diodes Incorporated
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