STMicroelectronics SMAJ5.0A-TR

Overview

SMAJ5.0A-TR from STMicroelectronics is a unidirectional 5.0 V standoff transient voltage suppression (TVS) diode in SMA package, rated for 400 W peak pulse power (10/1000 µs), 9.2 V clamping voltage at 43.5 A surge current, and 0.2 µA leakage at 25 °C - designed to protect USB ports, industrial I/O lines, and automotive sensor interfaces against IEC 61000-4-2 ESD and IEC 61000-4-4 electrical fast transients.

For engineers reviewing the SMAJ5.0A-TR datasheet, SMAJ5.0A-TR pinout, SMAJ5.0A-TR application, or SMAJ5.0A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC V_DD, junction temperature derating above 85 °C, bidirectional vs. unidirectional polarity requirements, and PCB footprint compatibility with IPC 7531 SMA land pattern.

Technical Context

This TVS diode operates as a voltage-clamped shunt protector: under normal bias (V_RWM = 5.0 V), it exhibits <0.2 µA reverse leakage; during transient events, it avalanches at V_BR ≥ 6.40 V (IBR = 10 mA) and clamps to ≤9.2 V at 43.5 A (10/1000 µs), limiting energy dissipation via low dynamic resistance (0.049 Ω).

Its planar silicon junction enables stable operation up to T_j = 150 °C, with thermal impedance of ~100 °C/W on standard FR4 (70 µm Cu), and complies with JEDEC DO-214AC (SMA) mechanical outline, J-STD-020 MSL level 1, and IEC 61000-4-2 level 4 (±30 kV contact/air discharge).

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), JEDEC registered, IPC 7531 compliant footprint with 5.43 mm × 2.63 mm pad pitch and 1.40 mm pad width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ5.0A-TR, SM5A5.0A offers slightly lower breakdown but higher clamping, while P6SMB5.0A matches clamping performance but introduces moisture sensitivity - making the ST device optimal for high-reliability, reflow-ready industrial designs.

Availability

SMAJ5.0A-TR is available at Aetrix Electronics and suitable for USB interface protection, automotive sensor conditioning, and industrial PLC I/O requiring stable component supply with full traceability and no obsolescence risk through 2030.

Supply support for SMAJ5.0A-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, specializing in power management, analog, MEMS, and automotive-grade ICs with strong focus on industrial and automotive reliability.

The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for high-junction-temperature, low-leakage ESD/EFT defense in space-constrained, mission-critical systems.

FAQ

What is the maximum surge current SMAJ5.0A-TR can handle at 10/1000 µs?

The device sustains 43.5 A peak pulse current at 10/1000 µs waveform while clamping to ≤9.2 V. This value is measured per IEC 61000-4-4 test conditions and confirmed in Table 2 of DS1251 Rev 15. Derating applies above 85 °C ambient due to thermal impedance limitations on standard PCBs.

Is SMAJ5.0A-TR bidirectional or unidirectional?

SMAJ5.0A-TR is unidirectional: it protects only against reverse-polarity transients on a positive-rail line, with cathode connected to ground. The "A" suffix denotes unidirectional configuration; "CA" indicates bidirectional variants like SMAJ5.0CA, which protect both polarities symmetrically.

Does this TVS diode require a heatsink for 400 W pulse handling?

No heatsink is required for single-event 400 W pulses (10/1000 µs), as energy dissipation occurs in microseconds. Thermal design focuses on PCB copper area: Figure 12 shows R_th(j-a) drops from ~140 °C/W (no copper) to ~4.5 °C/W with 5 cm² total copper under both leads - sufficient for repetitive surges.

How does leakage current change with temperature?

Leakage rises exponentially with junction temperature: Figure 9 shows 0.2 µA at 25 °C, ~1 µA at 85 °C, and ~10 µA at 125 °C under V_RWM. For battery-powered applications, this must be factored into worst-case quiescent current budgets, especially above 85 °C ambient.