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onsemi 1SMB85AT3
- Part No.:
- 1SMB85AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB85AT3.pdf
- Description:
- TVS DIODE 85VWM 137VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:3,871
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Product details
Overview
1SMB85AT3 from onsemi is a unidirectional 600 W transient voltage suppressor (TVS) diode designed for parallel overvoltage protection of DC power rails and signal lines. It features a working peak reverse voltage (VRWM) of 85 V, breakdown voltage (VBR) of 94.4–104 V at 1 mA, clamping voltage (VC) of 137 V at 4.4 A peak pulse current, and response time < 1.0 ns - deployed in automotive power supplies, industrial I/O interfaces, and telecom surge protection circuits.
For engineers reviewing the 1SMB85AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin below protected IC absolute maximum rating, UL 497B recognition for isolated loop compliance, and SMB package thermal performance under repetitive surge conditions.
Technical Context
The 1SMB85AT3 operates as a Zener-based avalanche clamp, conducting only when reverse voltage exceeds its specified VBR range (94.4–104 V), with low dynamic impedance ensuring stable clamping during 1 ms 600 W transients. Its unidirectional polarity enables asymmetric protection where forward conduction is acceptable or required.
Thermal design relies on junction-to-lead resistance (RJL = 40 °C/W) and junction-to-ambient resistance (RJA = 226 °C/W) under defined PCB footprint conditions; derating begins above 75°C for lead temperature and above 25°C for ambient temperature per published curves.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 600 W @ 1 ms - withstands IEC 61000-4-5 Level 4 surges without failure |
| Working Peak Reverse Voltage (VRWM) | 85 V - sets minimum system operating voltage threshold before clamping activates |
| Breakdown Voltage (VBR) | 94.4–104 V @ 1 mA - defines precise avalanche onset range for predictable turn-on |
| Clamping Voltage (VC) | 137 V @ 4.4 A - maximum voltage seen by protected circuit during full-rated surge |
| Leakage Current (IR) | 55 µA @ 85 V - negligible standby power loss in high-impedance bias networks |
| Response Time | < 1.0 ns - ensures clamping initiates before most semiconductor damage thresholds are exceeded |
| ESD Rating | Class 3 HBM (>16 kV) - meets IEC 61000-4-2 system-level ESD immunity requirements |
Pinout & Package
SMB (Case 403A) surface-mount plastic package with cathode band marking; anode and cathode terminals only; optimized for automated placement and reflow soldering with modified L-bend leads and 260°C/10s max soldering temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction path / low-side reference | Connects to ground or lower-potential rail in unidirectional clamp configuration |
| Cathode | Reverse-biased clamping node | Connects to protected line; conducts avalanche current when VRWM exceeded |
Key Features
| Feature | Design Value |
|---|---|
| UL 497B Recognition (QVGQ2) | Validated for isolated loop circuit protection - eliminates need for separate certification testing |
| Surmetic® Package | Void-free thermoset molding ensures long-term reliability under thermal cycling and humidity stress |
| Low Clamping Ratio (VC/VBR) | 137 V / 99.2 V ≈ 1.38 - tight ratio minimizes overvoltage margin required for downstream ICs |
| Pb-Free (G suffix) | RoHS-compliant construction with compatible reflow profile and no lead contamination risk |
| High Surge Current Capability | 4.4 A peak pulse current - supports repeated lightning-induced transients in industrial fieldbus nodes |
Applications
| Automotive Power Supply Protection | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: 12 V/24 V battery-fed ECUs exposed to load dump (ISO 7637-2 Pulse 5a) and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed across input filter capacitor to clamp transients before DC-DC converter input stage. Use Value: 137 V clamping voltage ensures protected regulator remains below its 140 V abs max rating during 600 W surges. |
Use Scenario: 24 V digital input modules receiving signals from external sensors in factory automation environments. IC Role / Device Role / Timing Role: Parallel-connected TVS on each input channel to absorb induced surges from relay switching or EMI coupling. Use Value: 85 V VRWM matches standard 24 V nominal + 25% tolerance, preventing false triggering during normal operation. |
| Telecom Line Interface Protection | Medical Equipment Power Entry |
Use Scenario: Low-voltage Ethernet or RS-485 ports in base station equipment subjected to lightning-induced common-mode surges. IC Role / Device Role / Timing Role: Paired with common-mode choke and gas discharge tube for hybrid surge suppression architecture. Use Value: Sub-1 ns response time ensures clamping occurs before coupled energy reaches PHY transceivers. |
Use Scenario: AC/DC front-end of diagnostic imaging devices requiring reinforced isolation and low leakage. IC Role / Device Role / Timing Role: Secondary-side TVS on isolated DC bus to prevent transient propagation into sensitive analog acquisition stages. Use Value: 55 µA IR at 85 V avoids loading precision voltage references or sensor bias networks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ85A | Same VRWM (85 V), higher PPK (600 W), identical SMB package; VBR min 94.4 V, VC 137 V - functionally aligned | No UL 497B recognition; lacks isolated loop certification | Select when UL compliance is not required and cost optimization is prioritized |
| 1.5SMC85A | Higher PPK (1500 W), larger SMC package (7.1 × 6.2 mm vs. SMB 4.6 × 3.6 mm); VRWM 85 V, VC 137 V, same VBR range | Requires PCB layout change; suited for higher-energy threat environments (e.g., outdoor telecom) | Select when surge energy exceeds 600 W and board space permits larger footprint |
Compared with SMBJ85A, the 1SMB85AT3 provides UL 497B certification critical for medical and industrial isolated systems; compared with 1.5SMC85A, it delivers identical electrical protection in 45% smaller area - enabling compact, certified designs without sacrificing surge margin.
Availability
1SMB85AT3 is available at Aetrix Electronics and suitable for automotive power supply protection, industrial PLC digital input protection, and telecom line interface protection requiring stable component supply, RoHS compliance, and UL-certified surge performance.
Supply support for 1SMB85AT3 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud, and consumer markets.
The 1SMB85AT3 belongs to the SMB series of unidirectional TVS diodes engineered specifically for robust, standardized surge protection in safety-critical and regulated applications - emphasizing UL recognition, repeatable clamping, and high-reliability packaging.
FAQ
What is the clamping voltage of the 1SMB85AT3 under full-rated surge conditions?
The 1SMB85AT3 has a maximum clamping voltage (VC) of 137 V at 4.4 A peak pulse current (IPP), measured using the standard 10/1000 µs waveform. This value represents the highest voltage that will appear across the protected circuit during a 600 W transient event, making it essential for verifying margin against downstream IC absolute maximum ratings in the 1SMB85AT3 application layout.
Does the 1SMB85AT3 meet UL 497B requirements for isolated loop protection?
Yes, the 1SMB85AT3 is UL Recognized under file E210057, category QVGQ2, specifically for protector applications per UL 497B. This certification covers performance in isolated loop circuits including strike voltage breakdown, endurance conditioning, and dielectric withstand tests - a key differentiator versus non-certified alternatives like SMBJ85A in the 1SMB85AT3 product family.
What is the thermal resistance and derating behavior of the 1SMB85AT3?
The 1SMB85AT3 has a junction-to-lead thermal resistance (RJL) of 40 °C/W and junction-to-ambient resistance (RJA) of 226 °C/W under specified PCB conditions. Its DC power dissipation derates linearly above 75°C for lead temperature and above 25°C for ambient temperature, with published curves in the 1SMB5.0AT3 Series datasheet guiding thermal design for sustained surge duty cycles.
How does the 1SMB85AT3 differ from bidirectional TVS diodes like the 1SMB85CAT3?
The 1SMB85AT3 is unidirectional and blocks forward current while clamping only in reverse - ideal for DC rail protection where polarity is fixed. In contrast, the 1SMB85CAT3 is bidirectional and clamps symmetrically in both polarities, suited for AC lines or data buses with undefined signal swing. The 1SMB85AT3 offers tighter VBR tolerance and lower leakage than its bidirectional counterpart, optimizing performance in DC-coupled 1SMB85AT3 use cases.
What is the maximum allowable soldering temperature and duration for the 1SMB85AT3?
The 1SMB85AT3 supports a maximum soldering temperature of 260°C for up to 10 seconds, consistent with IPC/JEDEC J-STD-020 moisture sensitivity level (MSL) requirements. Its Surmetic® package uses void-free thermoset plastic with corrosion-resistant, readily solderable leads - verified for compatibility with standard reflow profiles used in high-volume 1SMB85AT3 assembly.
1SMB85AT3 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):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 220pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB85AT3 FAQ
1.How can I place an order for 1SMB85AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB85AT3 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 1SMB85AT3 reliable?
The price and inventory of 1SMB85AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB85AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB85AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB85AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB85AT3?
1SMB85AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB85AT3 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 1SMB85AT3?
For technical support, including 1SMB85AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB85AT3 requirements.
6.How does Aetrix verify that 1SMB85AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB85AT3 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 1SMB85AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB85AT3?
All 1SMB85AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB85AT3, 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 1SMB85AT3 part is unused and in its original packaging.
Return procedure for 1SMB85AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB85AT3 Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
Diodes Incorporated
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onsemi
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Diodes Incorporated
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Diodes Incorporated
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DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
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D12V0L1B2LP-7B
Diodes Incorporated
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PESD2V0Y1BSFYL
Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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