STMicroelectronics BZW50-27

Overview

BZW50-27 from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for high-energy surge protection in power supply and interface lines. It features a 27 V stand-off voltage (VRM), 30 V minimum breakdown voltage (VBR), 48.3 V maximum clamping voltage (VCL) at 103 A (10/1000 µs), 5000 W peak pulse power, and operates up to 175 °C junction temperature - deployed in industrial SMPS input stages and telecom line cards.

For engineers reviewing the BZW50-27 datasheet, BZW50-27 pinout, BZW50-27 application, or BZW50-27 equivalent, key selection criteria include clamping voltage margin vs. protected IC V_MAX, leakage current (<5 µA at VRM), thermal derating above 25 °C, and R6 package soldering compatibility with IPC/JEDEC J-STD-020 reflow profiles.

Technical Context

The BZW50-27 uses planar silicon junction technology optimized for low leakage and stable VBR over temperature (α_T = 9.8 × 10⁻⁴/°C). Its unidirectional configuration provides forward conduction path during negative transients while blocking reverse DC bias up to 27 V.

Clamping behavior follows VCL = VCL_25°C × [1 + α_T(T_j − 25)], with dynamic resistance RD = 0.147 Ω enabling predictable voltage rise under surge current. Peak pulse capability de-rates linearly from 5000 W at T_j = 25 °C to 3700 W at T_j = 175 °C per Figure 3.

Key Specifications

Pinout & Package

Package: R6 axial leaded package (DO-201AD equivalent), 9.1 mm max length × 9.1 mm max diameter, matte tin-plated leads, UL94 V0 rated epoxy body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ27A and P6KE27A, the BZW50-27 uniquely combines 5 kW surge rating in axial R6 form factor, 175 °C operation, and full IEC/UL certification - making it the only choice for high-reliability, high-energy, through-hole mounted protection in harsh-environment power systems.

Availability

BZW50-27 is available at Aetrix Electronics and suitable for industrial SMPS input protection, telecom line card surge suppression, and automotive BCM power rail protection requiring stable component supply and long-lifecycle support.

Supply support for BZW50-27 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 microcontrollers - with over 40 years of TVS diode innovation and automotive-grade qualification expertise.

The BZW50 series belongs to ST's high-power discrete protection portfolio, engineered specifically for robust, high-temperature, high-energy transient suppression in industrial power supplies, renewable energy systems, and transportation electronics.

FAQ

What is the maximum allowable surge current for BZW50-27 at 125 °C junction temperature?

At T_j = 125 °C, the peak pulse power derates to ~4100 W (per Figure 3). Using VCL = 48.3 V, the corresponding maximum IPP is approximately 85 A (4100 W ÷ 48.3 V). This value assumes 10/1000 µs waveform and accounts for temperature coefficient α_T = 9.8 × 10⁻⁴/°C.

Can BZW50-27 be used in bidirectional configurations?

No - BZW50-27 is unidirectional only. The bidirectional variant is BZW50-27B, which has symmetrical clamping in both polarities and no cathode marking. Substituting BZW50-27 for BZW50-27B will result in forward conduction during negative transients and potential failure.

Is the R6 package compatible with automated through-hole insertion and wave soldering?

Yes - the R6 package meets IPC-A-610 Class 2 mechanical tolerances and supports wave soldering per AN5088 guidelines. Lead spacing (B = 25.4 mm) and diameter (D = 1.2–1.3 mm) are optimized for standard axial insertion machines and dual-wave solder profiles with preheat ≤120 °C and peak ≤260 °C.

How does leakage current change at elevated temperature and voltage?

Per Figure 9, IR increases exponentially with T_j: at VRM = 27 V, leakage is ~100 nA at 25 °C, ~1.2 µA at 100 °C, and ~12 µA at 150 °C. This remains well below the 5 µA max spec at 25 °C and does not compromise functionality in typical 24–48 V systems.