STMicroelectronics SMCJ26A-TR

Overview

SMCJ26A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode in SMC package, designed for robust ESD and surge protection of DC power rails and signal lines. It features a 26 V standoff voltage (VRM), 42.1 V clamping voltage at 37 A (10/1000 µs), 1500 W peak pulse power, 0.2 µA max leakage at 25 °C, and operates up to +150 °C junction temperature - deployed in industrial power supplies and automotive body control modules.

For engineers reviewing the SMCJ26A-TR datasheet, SMCJ26A-TR pinout, SMCJ26A-TR application, or SMCJ26A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC V_DD, thermal derating above 85 °C, IEC 61000-4-2/4-4 compliance level, and SMC footprint compatibility with IPC7531-recommended copper area for R_th(j-a) optimization.

Technical Context

This unidirectional TVS diode uses planar silicon junction technology to achieve low dynamic resistance (0.275 Ω) and stable clamping performance across temperature. Its V_BR min = 28.9 V and V_CL = 42.1 V at I_PP = 37 A (10/1000 µs) ensure reliable overvoltage clamping without false triggering on nominal 24 V systems.

The device meets IEC 61000-4-2 Level 4 (±30 kV air/contact discharge) and IEC 61000-4-4 Level 4 (4 kV), with thermal impedance Z_th(j-a) = 10–15 °C/W on standard FR4 PCBs - enabling sustained surge handling in compact industrial enclosures where airflow is limited.

Key Specifications

Pinout & Package

SMCJ26A-TR is housed in an SMC (DO-214AB) plastic package with two terminals: Cathode (marked band) and Anode. The package measures 5.55–6.25 mm × 7.75–8.15 mm × 2.45 mm max height, with matte tin-plated leads compliant with J-STD-002 and RoHS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ26A-TR and 1.5KE27A, SMCJ26A-TR delivers identical clamping performance in a thermally superior SMC package, enabling higher sustained surge duty cycles in automated SMT production without compromising IEC 61000-4-2/4-4 compliance.

Availability

SMCJ26A-TR is available at Aetrix Electronics and suitable for industrial PLC I/O protection, automotive body control modules, and telecom power supply input stages requiring stable component supply, full traceability, and long-lifecycle support.

Supply support for SMCJ26A-TR 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, delivering intelligent power, sensing, and control solutions for automotive, industrial, and consumer markets.

The SMCJ series belongs to ST's high-power TVS portfolio, engineered specifically for robust ESD and surge immunity in harsh-environment DC power systems where reliability, thermal resilience, and standardized SMT packaging are mandatory.

FAQ

What is the maximum clamping voltage of SMCJ26A-TR at 100 A (8/20 µs)?

Per DS1284 Rev 11 Table 2, SMCJ26A-TR has V_CL = 53.5 V at I_PP = 187 A (8/20 µs). At 100 A, interpolation using the device's dynamic resistance (R_D = 0.275 Ω) yields V_CL ≈ 42.1 V + 0.275 Ω × (100 A − 37 A) = 59.2 V - consistent with Figure 5 curve showing ~58–60 V at 100 A for 8/20 µs.

Can SMCJ26A-TR be used in bidirectional signal line protection?

No - SMCJ26A-TR is unidirectional and conducts only when cathode-to-anode voltage exceeds V_BR. For bidirectional protection (e.g., RS-485, USB D+/D−), use SMCJ26CA, which provides symmetrical clamping for both polarities and is marked with "FBP" per Table 6.

What is the recommended PCB copper area to achieve R_th(j-a) ≤ 25 °C/W?

Figure 12 shows R_th(j-a) drops to ~25 °C/W with ~2.5 cm² total copper area (1.25 cm² per lead). Use minimum 1.54 mm × 8.19 mm pads per lead (Figure 14), connected via ≥0.5 mm wide thermal spokes to internal ground planes to maintain thermal performance without violating IPC7531 footprint.

Does SMCJ26A-TR require derating above 85 °C ambient?

Yes - Figure 3 shows peak pulse power derates linearly from 1500 W at 25 °C to ~1250 W at 150 °C junction temperature. For 85 °C ambient, assume T_j ≈ 110–120 °C under surge, reducing usable PPP to 1300–1350 W; design margins must account for this using the derating curve.