STMicroelectronics SMAJ30A-TR

Overview

SMAJ30A-TR from STMicroelectronics is a unidirectional 30 V standoff transient voltage suppression (TVS) diode in SMA package, rated for 400 W peak pulse power (10/1000 µs), 64.3 A peak pulse current, and clamping voltage of 48.4 V at 8.3 A, designed to protect I/O lines and power rails against ESD per IEC 61000-4-2 (±30 kV air/contact) and EFT per IEC 61000-4-4 (4 kV).

For engineers reviewing the SMAJ30A-TR datasheet, SMAJ30A-TR pinout, SMAJ30A-TR application, or SMAJ30A-TR equivalent, key selection criteria include clamping voltage margin relative to protected IC V_CC, leakage current at operating temperature, junction temperature derating above 25 °C, and compatibility with IPC-7531 SMA footprint for PCB layout.

Technical Context

This TVS diode operates as a voltage-clamped shunt protector: under normal bias it presents <0.2 µA leakage at 30 V and 25 °C; during transients, it avalanches at 33.3–35.1 V (V_BR) and clamps to ≤48.4 V (V_CL) at 8.3 A (10/1000 µs). Its planar silicon construction enables stable performance up to T_j = 150 °C and low dynamic resistance (0.762 Ω) for fast energy diversion.

The device complies with JEDEC DO-214AC (SMA) mechanical outline, UL94 V0 flammability rating, J-STD-020 MSL Level 1, and IEC 61000-4-2 Level 4 ESD immunity-making it suitable for automotive infotainment interfaces, industrial PLC I/O modules, and telecom power supply inputs where long-term reliability under thermal cycling is critical.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), JEDEC-registered surface-mount outline with 2.25–2.90 mm body width (D), 4.80–5.35 mm length (E), and 0.75–1.50 mm lead length (L); compatible with IPC-7531 standard footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ30AHE3_A/H, SMAJ30A-TR lacks AEC-Q200 certification but offers identical clamping performance at lower cost for non-automotive use; versus P6SMB33A, it provides tighter V_BR tolerance and lower V_CL, enabling safer protection of 5 V logic rails.

Availability

SMAJ30A-TR is available at Aetrix Electronics and suitable for industrial PLC I/O protection, automotive infotainment ESD hardening, and telecom power supply surge suppression requiring stable component supply across multi-year production cycles.

Supply support for SMAJ30A-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 microcontrollers, power management ICs, sensors, and discrete protection devices to industrial, automotive, and consumer markets.

The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for board-level ESD and surge immunity in space-constrained applications where low leakage, high T_j, and JEDEC-standard packaging are mandatory.

FAQ

What is the maximum clamping voltage of SMAJ30A-TR under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 48.4 V at 8.3 A for a 10/1000 µs waveform, measured at T_amb = 25 °C. This value increases with junction temperature at a coefficient of 9.9 × 10⁻⁴ per °C, reaching ~51.2 V at T_j = 125 °C per the α_T parameter in Table 2.

Can SMAJ30A-TR be used in bidirectional signal lines like RS-485?

No - SMAJ30A-TR is unidirectional and must be connected with cathode toward the protected line and anode to ground. For bidirectional data lines, the SMAJ30CA variant (center-tapped, symmetrical breakdown) is required to clamp both positive and negative transients without forward conduction.

How does the leakage current change at elevated ambient temperatures?

At 25 °C, leakage is ≤0.2 µA at V_RWM = 30 V; at 85 °C, it rises to ≤1 µA. Figure 9 in DS1251 shows exponential increase beyond 100 °C, reaching ~100 nA at 125 °C and ~1 µA at 150 °C - still within safe limits for most 3.3 V/5 V logic interfaces.

Is the SMAJ30A-TR RoHS-compliant and halogen-free?

Yes - SMAJ30A-TR is manufactured in ST's ECOPACK2-compliant process, meeting RoHS Directive 2011/65/EU and halogen-free requirements per IEC 61249-2-21. The "-TR" suffix denotes tape-and-reel packaging with 5000 units per reel, fully traceable to ST's certified production lines.