onsemi SZMMQA6V8T1

Overview

SZMMQA6V8T1 from onsemi is a quad unidirectional transient voltage suppressor (TVS) diode array in SC-74 package, featuring common-anode configuration with 6.8 V nominal breakdown voltage, 9.8 V max clamping voltage at peak pulse current, and 150 W peak pulse power (20 µs waveform). It provides ESD protection exceeding 16 kV HBM across four independent I/O lines in space-constrained interfaces such as USB, HDMI, or keyboard controllers.

For engineers reviewing the SZMMQA6V8T1 datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin versus system rail, leakage current impact on high-impedance sensor nodes, thermal derating on FR-5 vs. alumina substrates, and compatibility with automated SMT placement for high-density PCBs.

Technical Context

The SZMMQA6V8T1 integrates four monolithic silicon junctions sharing a common anode terminal (Pin 2 and Pin 5), enabling compact bidirectional protection of four signal lines using only one SC-74 package. Its unidirectional operation requires external biasing to ground or V_CC, and it is not rated for reverse-biased AC signals.

Designed per AEC-Q101 for automotive and industrial applications, the device delivers 150 W peak surge power under 8/20 µs waveform (per Figure 6), with thermal resistance of 417 °C/W on alumina substrate and 556 °C/W on FR-5 board - critical for sustained transient handling in thermally constrained environments.

Key Specifications

Pinout & Package

SC-74 package (Case 318F, Style 1) is a 6-pin, void-free thermosetting plastic surface-mount package optimized for automated assembly and high-density PCBs. Dimensions: 3.0 mm × 1.5 mm × 1.0 mm (L × W × H), with 0.95 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SZMMQA6V8T1, SZMMQA6V8T3 offers identical protection performance with logistics optimization, while TPD4E001DPYR trades higher surge robustness for lower parasitic capacitance - making it suitable only where speed outweighs ruggedness.

Availability

SZMMQA6V8T1 is available at Aetrix Electronics and suitable for USB interface protection, HDMI signal conditioning, and industrial keypad ESD hardening requiring stable component supply across automotive, medical, and computing end markets.

Supply support for SZMMQA6V8T1 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 specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer applications.

The SZMMQA series belongs to onsemi's transient voltage suppressor product line, engineered specifically for high-density, multi-line ESD protection in space-constrained PCBs where quad-channel integration reduces bill-of-materials and improves reliability.

FAQ

What is the exact breakdown voltage range for SZMMQA6V8T1?

The SZMMQA6V8T1 has a guaranteed breakdown voltage (V_ZT) range of 6.46 V to 7.14 V at 1.0 mA test current, measured per JEDEC JESD201 standards. This tolerance ensures consistent triggering behavior across production lots and temperature extremes from −55°C to +150°C. The nominal value of 6.8 V reflects the center point of this specification band, and the SZMMQA6V8T1 must meet this range to pass final test screening.

Can SZMMQA6V8T1 be used for bidirectional signal lines like RS-485?

No, SZMMQA6V8T1 is strictly unidirectional and requires external DC bias to operate correctly - it cannot protect AC-coupled or true bidirectional buses. For RS-485, use bidirectional TVS arrays such as SMBJxxCA or SP3022-01UTG. The SZMMQA6V8T1's common-anode architecture only conducts when cathodes are driven positive relative to the anode pins (2 and 5); reverse polarity causes open-circuit behavior.

What is the maximum operating temperature for SZMMQA6V8T1 in continuous service?

The SZMMQA6V8T1 supports continuous operation from −55°C to +150°C for both junction and storage conditions. However, its steady-state power dissipation derates linearly above 25°C ambient: on FR-5 board, it drops from 225 mW at 25°C to zero at ~145°C (per Figure 3). The SZMMQA6V8T1 must be thermally modeled in context of actual board layout and airflow to ensure TJ remains below 150°C under worst-case surge duty cycles.

How does the dual-anode pin configuration (Pins 2 and 5) affect PCB layout?

The dual-anode design (Pins 2 and 5) allows low-inductance grounding via multiple vias or direct copper pour connection - critical for minimizing clamping voltage overshoot during fast transients. Layout best practice for SZMMQA6V8T1 is to tie both pins to the same low-impedance ground plane with short, wide traces and ≥2 thermal vias per pin. Separating Pins 2 and 5 degrades ESD performance and violates the device's internal current-sharing architecture.

Is SZMMQA6V8T1 compliant with automotive qualification standards?

Yes, SZMMQA6V8T1 is AEC-Q101 qualified and PPAP capable, meeting stress test requirements for temperature cycling, humidity bias, mechanical shock, and ESD robustness in automotive environments. The "SZ" prefix explicitly denotes automotive-grade traceability, lot control, and failure analysis protocols. This makes SZMMQA6V8T1 suitable for infotainment, body control, and ADAS subsystems where long-term reliability under thermal and vibration stress is mandatory.