onsemi 1SMB64AT3

Overview

1SMB64AT3 from ON Semiconductor is a unidirectional 600 W peak power Zener transient voltage suppressor (TVS) in SMB package, designed for parallel clamping protection of DC power rails and signal lines. It features a 64 V working peak reverse voltage (VRWM), 71.1 V minimum breakdown voltage (VBR) at 1 mA, 103 V maximum clamping voltage (VC) at 5.8 A peak pulse current (IPP), and sub-1 ns response time - deployed in industrial power supplies and automotive ECUs to suppress ESD and lightning-induced surges.

For engineers reviewing the 1SMB64AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC < protected IC's absolute maximum rating, IPP capability under IEC 61000-4-5 waveform, and UL 497B recognition for isolated loop protection compliance.

Technical Context

The 1SMB64AT3 operates as a voltage-clamping Zener diode, entering avalanche conduction when transient voltage exceeds its VBR, limiting downstream voltage to ≤103 V at 5.8 A. Its low zener impedance and fast <1 ns response enable effective suppression of ESD (IEC 61000-4-2, >16 kV HBM) and surge events (IEC 61000-4-5, 10/1000 µs).

Thermal design relies on junction-to-lead resistance (RJL = 40 °C/W) and junction-to-ambient resistance (RJA = 226 °C/W), with derating required above 75°C for lead temperature and above 25°C for ambient. The device uses a Surmetic™ molded plastic case (Case 403A) with modified L-bend leads for robust solder joint reliability.

Key Specifications

Pinout & Package

SMB package (Case 403A), surface-mount, unidirectional configuration with cathode indicated by polarity band. Dimensions: 4.32 mm × 2.13 mm × 2.26 mm (L × W × H); Pb-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMBJ64A and P6SMB64A, the 1SMB64AT3 offers identical clamping performance and package compatibility but distinguishes itself via ON Semiconductor's Surmetic™ molding process and broader legacy qualification in industrial motor drives - making it preferred where long-term supply continuity and proven field reliability in high-temperature environments are prioritized.

Availability

1SMB64AT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, medical sensor interfaces, and telecom line cards requiring stable component supply and UL-certified transient protection.

Supply support for 1SMB64AT3 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 part of onsemi) is a global semiconductor supplier specializing in power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud power applications.

The 1SMB64AT3 belongs to the SMB series of unidirectional TVS diodes engineered for high-energy transient suppression in cost-sensitive, high-reliability applications - emphasizing robust surge handling, fast response, and regulatory compliance in harsh environments.

FAQ

What is the maximum clamping voltage of the 1SMB64AT3 under standard test conditions?

The 1SMB64AT3 has a maximum clamping voltage (VC) of 103 V when subjected to its rated peak pulse current (IPP) of 5.8 A using the 10/1000 µs waveform. This value is guaranteed across temperature and manufacturing lot, ensuring predictable overvoltage limiting for protected circuits. The 1SMB64AT3 achieves this clamping performance while maintaining low leakage (<5 µA at 64 V) and fast response (<1 ns), making it suitable for protecting sensitive 75 V-tolerant ICs.

Is the 1SMB64AT3 RoHS-compliant and lead-free?

Yes, the "G" suffix in 1SMB64AT3 indicates a Pb-free, RoHS-compliant package per ON Semiconductor's specifications. The device uses matte tin-plated leads and meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 requirements. The 1SMB64AT3 is qualified for reflow soldering at 260°C for 10 seconds, aligning with standard lead-free assembly processes without compromising surge robustness or long-term reliability.

Does the 1SMB64AT3 meet UL 497B requirements for isolated loop protection?

Yes, the entire 1SMB5.0AT3 series, including the 1SMB64AT3, carries UL 497B recognition under file #E210057 in the Protector category (QVGQ2). This certification covers dielectric withstand, strike voltage breakdown, endurance conditioning, and discharge testing - validating its use in telecom line interfaces, isolated sensor bridges, and other safety-critical isolated loops where transient immunity must be formally certified.

How does the thermal derating of the 1SMB64AT3 work above 75°C lead temperature?

The 1SMB64AT3's DC power dissipation is rated at 3.0 W at TL = 75°C, with linear derating of 25 mW/°C above that temperature. For example, at TL = 100°C, allowable PD drops to 2.375 W. This derating reflects junction-to-lead thermal resistance (RJL = 40 °C/W) and ensures safe operation under sustained high-temperature conditions such as under-hood automotive or enclosed industrial enclosures. The 1SMB64AT3 maintains full 600 W surge capability regardless of ambient temperature, as surge events are non-repetitive.

Can the 1SMB64AT3 be used for bidirectional transient suppression?

No, the 1SMB64AT3 is strictly unidirectional and must be installed with correct polarity: cathode toward the protected line, anode to ground. For bidirectional protection (e.g., AC lines or differential buses), ON Semiconductor offers the 1SMB64CAT3 variant. Using the 1SMB64AT3 in reverse-biased configuration provides no clamping - only forward conduction (~3.5 V drop) - and risks failure if reverse voltage exceeds its 64 V VRWM. Always verify polarity during PCB layout and assembly for the 1SMB64AT3.