onsemi SZSMS05T1G

Overview

SZSMS05T1G from onsemi is a quad unidirectional ESD and surge protector in SC-74 package, rated for 5 V working voltage, 350 W peak pulse power (8 × 20 µs), 9.8 V clamping voltage at 23 A, and 25 kV HBM ESD rating. It protects four independent I/O lines in portable electronics such as smartphones and notebooks against transient overvoltage events.

For engineers reviewing the SZSMS05T1G datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin vs. IC V_IO, capacitance (<400 pF @ 0 V), AEC-Q101 qualification, and SC-74 footprint compatibility with space-constrained PCB layouts.

Technical Context

This device integrates four separate unidirectional TVS diodes in a single SC-74 (Case 318F) monolithic silicon structure. Each channel provides low-clamp protection with 5.0 V working peak reverse voltage (V_RWM) and 7.2 V minimum breakdown voltage (V_BR) at 1 mA test current.

It meets IEC 61000-4-2 (15 kV air / 8 kV contact), IEC 61000-4-4 (40 A EFT), and IEC 61000-4-5 (23 A surge, 8/20 µs) immunity standards. The 250–400 pF junction capacitance per channel is specified at 0 V bias and 1 MHz, making it suitable for high-speed data lines up to ~100 Mbps.

Key Specifications

Pinout & Package

SC-74 package (Case 318F, Style 1) with 6-pin leaded surface-mount outline measuring 2.0 mm × 1.25 mm × 0.95 mm. Pin 1 marked by dot or bevel; moisture sensitivity level (MSL) 1 per J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMS05T1G and ESD5Z5.0T1G, SZSMS05T1G uniquely combines AEC-Q101 qualification, quad integration, and 350 W surge capability - enabling single-part compliance for automotive I/O protection without redesigning layout or qualifying multiple components.

Availability

SZSMS05T1G is available at Aetrix Electronics and suitable for USB 2.0 interface protection, automotive infotainment systems, and industrial HMI designs requiring stable component supply and long-term lifecycle support.

Supply support for SZSMS05T1G 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 power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, medical, and IoT applications.

SZSMS05T1G belongs to the SMS05T1 series of quad ESD/surge protectors designed specifically for compact, high-reliability protection of multiple low-voltage I/O lines in automotive and portable electronics.

FAQ

What is the clamping voltage of SZSMS05T1G at its rated surge current?

The SZSMS05T1G has a maximum clamping voltage (V_C) of 9.8 V when subjected to a peak pulse current (I_PP) of 23 A using the 8 × 20 µs waveform. This value is measured per IEC 61000-4-5 test conditions and ensures protected ICs experience minimal overvoltage stress during surge events. The SZSMS05T1G maintains this clamping performance across its full operating temperature range of −55 °C to +150 °C.

Does SZSMS05T1G support bidirectional signal lines like RS-485?

No, SZSMS05T1G is configured exclusively as a quad unidirectional TVS array - each channel conducts only from anode to cathode. It is unsuitable for true bidirectional buses without external circuitry. For RS-485 or other bidirectional interfaces, a dedicated bidirectional TVS such as NUP4105MR6T1G or SMAJ5.0A would be required. The SZSMS05T1G datasheet explicitly specifies unidirectional operation and lists only V_RWM, V_BR, and forward conduction parameters.

How does the AEC-Q101 qualification of SZSMS05T1G differ from standard SMS05T1G?

SZSMS05T1G undergoes additional stress testing per AEC-Q101 including extended temperature cycling (−40 °C to +125 °C, 1000 cycles), unbiased high-temperature operating life (1000 hrs at +150 °C), and mechanical shock validation - all absent in the commercial-grade SMS05T1G. The "SZ" prefix also denotes PPAP-capable manufacturing control and unique site traceability, making SZSMS05T1G appropriate for Tier 1 automotive supply chains where SMS05T1G is not accepted.

What is the thermal resistance of SZSMS05T1G and how does it affect power derating?

SZSMS05T1G has a junction-to-ambient thermal resistance (R_JA) of 556 °C/W on FR-5 board. Its total power dissipation derates linearly above 25 °C at 1.8 mW/°C, limiting continuous power handling to 225 mW at 25 °C. This high R_JA reflects the small SC-74 package size and confirms that the device is intended for transient-only (not steady-state) power dissipation - consistent with its 350 W peak pulse rating over 20 µs durations.

Can SZSMS05T1G be used to protect HDMI or MIPI D-PHY interfaces?

No, SZSMS05T1G is not recommended for HDMI or MIPI D-PHY due to its 250–400 pF capacitance per channel, which exceeds the typical ≤1.5 pF requirement for HDMI 2.0+ and MIPI D-PHY (>800 Mbps). Its 9.8 V clamping voltage also exceeds the 3.3 V or 1.8 V V_IO tolerances of those interfaces. For such high-speed differential lines, purpose-built low-capacitance arrays like ESD7L5.0DPTBG or NUP4201MR6T1G are required instead of SZSMS05T1G.