STMicroelectronics SMBJ28CA-TR

Overview

SMBJ28CA-TR 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 28 V standoff voltage (VRM), 45.4 V clamping voltage at 13.8 A (10/1000 µs), 600 W peak pulse power, and operates up to 150 °C junction temperature - deployed on industrial power supply input rails and telecom interface lines.

For engineers reviewing the SMBJ28CA-TR datasheet, SMBJ28CA-TR pinout, SMBJ28CA-TR application, or SMBJ28CA-TR equivalent, key selection criteria include bidirectional clamping behavior, low leakage (0.2 µA @ 25 °C), UL497B recognition (E136224), and SMB footprint compatibility with IPC7531 layout standards.

Technical Context

This bidirectional TVS diode uses planar silicon junction technology to achieve symmetrical reverse/forward clamping, enabling robust protection against both polarity transients without external polarity management. Its dynamic resistance of 0.802 Ω (at 25 °C, 10/1000 µs) ensures minimal voltage overshoot during fast-rising surges.

The device complies with IEC 61000-4-2 (±30 kV ESD), IEC 61000-4-4 (4 kV ring wave), and UL497B as an isolated loop circuit protector. Thermal performance is validated to 150 °C junction operation with derated pulse power down to 350 W at Tj = 150 °C per Figure 3.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), JEDEC registered outline, IPC7531 compliant footprint, matte tin-plated leads (J-STD-002 E3, MIL-STD-750 method 2026).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ28CA-TR, the Vishay alternative offers identical clamping but lacks UL497B assurance for safety-critical loops, while the ON Semiconductor part trades clamping performance for broader commercial availability - making the ST part optimal where regulatory compliance and precise voltage limiting are mandatory.

Availability

SMBJ28CA-TR is available at Aetrix Electronics and suitable for industrial power input protection, telecom interface surge suppression, AC/DC adapter secondary-side clamping, and automotive BCM sensor line protection requiring stable component supply and full regulatory documentation traceability.

Supply support for SMBJ28CA-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, designing and manufacturing microcontrollers, power devices, sensors, and protection components for industrial, automotive, and consumer markets.

The SMBJ series belongs to ST's transient protection product line, engineered specifically for high-reliability IEC/UL-compliant surge and ESD suppression in harsh electromagnetic environments - emphasizing low leakage, high-temperature stability, and standardized packaging.

FAQ

What is the difference between SMBJ28CA-TR and SMBJ28A-TR?

SMBJ28CA-TR is bidirectional, providing symmetrical clamping for both positive and negative transients across its terminals, while SMBJ28A-TR is unidirectional and requires correct polarity orientation relative to ground. The CA version is used on floating or AC-coupled lines; the A version suits DC rails referenced to ground. Their VRM, VCL, and PPP ratings are otherwise matched per datasheet Table 2.

Does SMBJ28CA-TR require heatsinking for 600 W pulse handling?

No dedicated heatsink is required for single 10/1000 µs pulses at 25 °C ambient, as thermal mass and PCB copper suffice. However, Figure 11 shows junction-to-ambient thermal impedance drops from ~100 °C/W (short pulse) to ~40 °C/W (1 s pulse); repeated surges or elevated ambient (>85 °C) demand ≥2 cm² copper per lead (per Figure 12) to maintain Tj ≤ 150 °C.

Can SMBJ28CA-TR be used in place of P6SMB28CA on an existing PCB?

Yes - both use identical SMB (DO-214AA) package dimensions and IPC7531 footprint. Pin-to-pin replacement is mechanically feasible, but verify system-level performance: SMBJ28CA-TR clamps 2.9 V lower (45.4 V vs. 48.3 V), offers ±30 kV ESD rating (vs. unspecified), and carries UL497B recognition - potentially improving protection margin without layout change.

What does the "-TR" suffix indicate in SMBJ28CA-TR?

The "-TR" suffix denotes tape-and-reel packaging per EIA-481 standard: 2500 units per 13-inch reel, with pocket dimensions per Table 4 (P0 = 4.0 mm, W = 12.0 mm). This format enables automated SMT placement and is the standard shipping configuration for volume production orders - distinct from bulk or ammo-pack variants.