onsemi UESD3.3ST5G

Overview

UESD3.3ST5G from onsemi is a unidirectional ESD protection diode in SOD-723 package, designed for I/O line protection in portable electronics. It features 3.3 V working peak reverse voltage, <1 ns response time, 10.9 V clamping voltage at 10.4 A peak pulse current, and 80 pF capacitance - enabling robust Class 3 HBM (>16 kV) and IEC61000-4-2 Level 4 (±30 kV air/±30 kV contact) protection in space-constrained interfaces like USB, audio jacks, and camera data lines.

For engineers reviewing the UESD3.3ST5G datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 10.4 A surge, low 2.5 nA leakage at 3.3 V, compatibility with high-speed signal paths (<80 pF), and Pb-free SOD-723 footprint suitability for automated assembly in mobile PCBs.

Technical Context

The UESD3.3ST5G operates as a transient voltage suppression (TVS) diode with unidirectional conduction, leveraging silicon avalanche breakdown to clamp ESD transients before they reach sensitive IC inputs. Its 3.3 V VRWM ensures compatibility with 3.3 V logic rails while maintaining margin above typical IO supply levels.

It delivers 113 W peak power dissipation during an 8/20 µs surge event and meets IEC61000-4-4 Level 4 (40 A EFT), making it suitable for front-end protection of high-impedance analog and digital interfaces where fast response and minimal capacitive loading are critical.

Key Specifications

Pinout & Package

UESD3.3ST5G uses the ultra-small SOD-723 surface-mount package (1.40 mm × 0.60 mm × 0.50 mm), optimized for high-density portable PCB layouts and compatible with standard reflow profiles (MSL 1, 260°C max).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ESD protection applications.

Compared with ESD3.3D5T5G and CM1213A-03SO, the UESD3.3ST5G offers the best balance of low clamping (10.9 V), moderate capacitance (80 pF), and proven 10.4 A surge capability in the smallest SOD-723 form factor - making it optimal for new designs targeting USB 2.0, audio, and MIPI interfaces in smartphones and wearables.

Availability

UESD3.3ST5G is available at Aetrix Electronics and suitable for smartphone USB interfaces, portable audio subsystems, digital camera data links, and wearable sensor buses requiring stable component supply and full IEC61000-4-2 Level 4 compliance.

Supply support for UESD3.3ST5G 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 focused on energy-efficient technologies for automotive, industrial, cloud, and portable electronics.

The ESDxxST5G series was developed specifically for ultra-compact, high-fidelity ESD protection in space-constrained portable devices - emphasizing low capacitance, tight clamping, and seamless integration into automated SMT lines.

FAQ

What is the maximum clamping voltage of UESD3.3ST5G under ESD stress?

The UESD3.3ST5G clamps to a maximum of 10.9 V when subjected to a 10.4 A peak pulse current (8/20 µs waveform), as specified in its electrical characteristics table. This clamping level is measured at room temperature and ensures protected 3.3 V I/O pins remain below destructive voltage thresholds during IEC61000-4-2 Level 4 contact discharge events. The UESD3.3ST5G maintains this performance across its operating junction temperature range of −55 °C to +150 °C.

Does UESD3.3ST5G support bidirectional ESD protection?

No, the UESD3.3ST5G is a unidirectional ESD protection diode, configured with cathode and anode terminals for line-to-ground clamping on positive transients. It is not rated for reverse polarity surge suppression. For bidirectional applications, designers must use two UESD3.3ST5G devices in series opposition or select a dedicated bidirectional variant such as UESD5.0ST5G. The UESD3.3ST5G datasheet explicitly defines its operation as unidirectional.

What is the thermal resistance (RθJA) of UESD3.3ST5G on a standard FR-5 board?

The UESD3.3ST5G does not specify RθJA in its datasheet; instead, it provides a total power dissipation limit of 150 mW on an FR-5 board at TA = 25°C. This value reflects steady-state thermal performance under continuous DC conditions, not transient ESD events. Since ESD pulses are sub-microsecond, thermal mass dominates transient behavior - so RθJA is not a design factor for ESD protection. The UESD3.3ST5G relies on low thermal mass and short pulse duration to avoid junction overheating during clamping.

Can UESD3.3ST5G be used on 5 V logic lines?

No, the UESD3.3ST5G has a 3.3 V working peak reverse voltage (VRWM) and begins conducting significantly above ~5.0 V breakdown voltage - making it unsuitable for reliable 5 V rail protection. Using it on 5 V lines risks premature conduction, increased leakage, and potential signal distortion. For 5 V interfaces, the UESD5.0ST5G (5.0 V VRWM) is the functionally matched variant in the same SOD-723 package and should be selected instead of UESD3.3ST5G.

Is UESD3.3ST5G compliant with RoHS and REACH regulations?

Yes, the UESD3.3ST5G is a Pb-free device with 100% matte tin lead finish and complies with both RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Its packaging material meets UL 94 V-0 flammability rating, and the device is qualified to MSL 1 per J-STD-020, supporting lead-free reflow soldering up to 260°C. These compliance attributes are documented in the official onsemi datasheet for UESD3.3ST5G.