STMicroelectronics SM6T22CA

Overview

SM6T22CA from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode in SMB package, designed for IEC 61000-4-2 ESD protection (30 kV air/contact) and IEC 61000-4-4 surge immunity (4 kV level 4). It features a 22 V nominal breakdown voltage (V_BR = 18.8–23.1 V), 30.6 V clamping voltage (V_CL) at 20 A (10/1000 µs), low leakage (≤1 µA at 85 °C), and operates up to 150 °C junction temperature - deployed in industrial power supplies and automotive body control modules.

For engineers reviewing the SM6T22CA datasheet, SM6T22CA pinout, SM6T22CA application, or SM6T22CA equivalent, this page delivers verified electrical parameters, SMB package layout, real-world clamping behavior under 8/20 µs and 10/1000 µs transients, thermal resistance data, and direct alternatives with documented V_CL, I_PP, and leakage differences.

Technical Context

The SM6T22CA employs planar silicon junction technology optimized for low leakage and high-temperature stability, enabling reliable operation at T_j = 150 °C with ≤1 µA reverse current. Its bidirectional architecture provides symmetrical clamping for AC-coupled signal lines and differential buses without polarity constraints.

Clamping performance is defined by dynamic resistance (R_D = 0.375 Ω at 10/1000 µs), enabling fast voltage limiting during sub-microsecond ESD events and longer surges. The device complies with UL497B (file E136224) as an isolated loop circuit protector and meets IEC 61000-4-2 level 4 (30 kV) and IEC 61000-4-4 level 4 (4 kV).

Key Specifications

Pinout & Package

The SM6T22CA is housed in an SMB (DO-214AA) surface-mount package measuring 3.3–3.95 mm × 5.1–5.6 mm × 1.9–2.45 mm (L × W × H), with matte tin-plated leads compliant with J-STD-002 and JEDEC MO-136. Thermal resistance R_th(j-a) is 140 °C/W on standard FR4 PCB with 1 cm² copper per lead.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional TVS diode applications.

Compared with SMAJ22CA and P6SMB22CA, the SM6T22CA delivers the lowest clamping voltage (30.6 V) and best thermal stability (150 °C rating), making it optimal for space-constrained, high-reliability 24 V industrial and automotive applications where voltage margin is tight.

Availability

SM6T22CA is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, RS-485 communication interfaces, and smart meter current sensing circuits requiring stable component supply and full compliance with IEC 61000-4-2/4-4 and UL497B standards.

Supply support for SM6T22CA 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, MEMS, and microcontroller technologies for industrial, automotive, and consumer markets.

The SM6T series belongs to ST's high-reliability TVS portfolio, engineered specifically for robust ESD and surge protection in harsh environments - emphasizing low leakage, high-temperature operation, and UL497B certification for isolated loop safety.

FAQ

What is the maximum peak pulse power rating for SM6T22CA at 25 °C?

The SM6T22CA is rated for 600 W peak pulse power under the 10/1000 µs waveform at ambient temperature, and 4 kW under the 8/20 µs waveform. Its power capability de-rates linearly with junction temperature, delivering up to 350 W at T_j = 150 °C for the 10/1000 µs condition, as confirmed in Figure 3 of DS0684 Rev 15.

Does SM6T22CA meet IEC 61000-4-2 level 4 ESD requirements?

Yes - the SM6T22CA exceeds IEC 61000-4-2 level 4, with validated performance of 30 kV for both air discharge and contact discharge testing (C = 150 pF, R = 330 Ω). This is explicitly stated in the "Complies with the following standards" section and verified in Table 1 of the datasheet.

How does the bidirectional configuration affect PCB layout versus unidirectional TVS diodes?

The SM6T22CA's bidirectional structure eliminates polarity marking and orientation constraints - either terminal can connect to either side of a differential or AC-coupled line. Unlike unidirectional TVS diodes (e.g., SM6T22A), no cathode-anode alignment is needed, reducing assembly errors and simplifying layout for RS-485, CAN, or audio lines.

What is the thermal resistance from junction to ambient (R_th(j-a)) for SM6T22CA on standard FR4?

On a standard epoxy FR4 PCB with 70 µm copper thickness and recommended IPC7531 footprint (Figure 14), the SM6T22CA exhibits R_th(j-a) = 140 °C/W for a single pulse, as shown in Figure 12 of DS0684 Rev 15. This value assumes 1 cm² copper area under each lead and is critical for calculating steady-state temperature rise during repetitive surge events.