Vishay General Semiconductor - Diodes Division BZG04-27TR

Overview

BZG04-27TR from Vishay Semiconductors is a glass-passivated, surface-mount Zener diode designed for transient voltage suppression in power rails and signal lines. It features a nominal Zener voltage of 27 V at 25 mA, 3 W steady-state power dissipation (at T_amb = 100 °C with R_thJA < 25 K/W), 300 W non-repetitive peak surge power (10/1000 µs pulse), and clamps transients to 46.2 V at 6.5 A. It is used in DC power supply overvoltage protection circuits.

For engineers reviewing the BZG04-27TR datasheet, BZG04-27TR pinout, BZG04-27TR application, or BZG04-27TR equivalent, key selection criteria include its 27 V standoff voltage, 46.2 V clamping voltage at 6.5 A, DO-214AC package thermal resistance (100–150 K/W depending on PCB mounting), surge current rating (50 A half-sine), and RoHS-compliant lead-free construction.

Technical Context

The BZG04-27TR operates as a unidirectional voltage-clamping device, leveraging avalanche breakdown in a glass-passivated junction to divert transient energy away from sensitive downstream circuitry. Its fast response time (≤1 ps) ensures effective suppression of nanosecond-scale ESD and lightning-induced surges.

Thermal performance is highly dependent on PCB layout: R_thJA ranges from 100 K/W (on Al₂O₃ ceramic) to 150 K/W (on standard epoxy-glass), while R_thJL is fixed at 25 K/W - critical for estimating junction temperature rise during surge events.

Key Specifications

Pinout & Package

DO-214AC (SMA) package: molded plastic body with axial leads trimmed and formed for surface-mount soldering; cathode indicated by band; case material meets UL 94 V-0 flammability rating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener-based transient suppression applications.

Compared with SMBJ27A and P6SMB27A, the BZG04-27TR offers lower cost, wider V_Z tolerance (±10 %), and optimized thermal resistance for compact PCB layouts - making it ideal for cost-sensitive industrial controls where 300 W surge capacity suffices.

Availability

BZG04-27TR is available at Aetrix Electronics and suitable for DC power supply protection, automotive body control modules, and industrial PLC input modules requiring stable component supply, RoHS compliance, and proven surge resilience.

Supply support for BZG04-27TR 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

Vishay Semiconductors is a global leader in discrete semiconductors, specializing in high-reliability diodes, MOSFETs, and optoelectronics for industrial, automotive, and computing markets.

The BZG04-Series was engineered specifically for high-surge, surface-mount transient voltage suppression in space-constrained power systems - emphasizing glass passivation, tight thermal resistance control, and consistent clamping performance across temperature.

FAQ

What is the Zener voltage tolerance of the BZG04-27TR?

The BZG04-27TR has a Zener voltage tolerance of ±10 % at I_ZT = 25 mA, meaning its breakdown voltage falls between 24.3 V and 29.7 V under specified test conditions. This tolerance is confirmed in the Electrical Characteristics table of Vishay Document Number 85594 Rev. 2.2. The BZG04-27TR's V_Z stability is enhanced by its glass-passivated junction, which reduces parameter drift over time and temperature cycling.

Can the BZG04-27TR be used in bidirectional transient suppression?

No, the BZG04-27TR is a unidirectional Zener diode and not rated for bidirectional operation. It conducts only in reverse breakdown (cathode positive relative to anode) and forward conduction (anode positive). For bidirectional protection, two BZG04-27TR devices must be connected in series opposition, or a dedicated bidirectional TVS like SMAJ27CA should be selected. The BZG04-27TR datasheet specifies parameters exclusively for unidirectional use.

What is the maximum allowable junction temperature for the BZG04-27TR?

The maximum junction temperature (T_j) for the BZG04-27TR is 150 °C, as stated in the Absolute Maximum Ratings table. Exceeding this temperature risks permanent degradation of the glass-passivated junction. Derating curves in the datasheet show that sustained power dissipation must be reduced above 100 °C ambient, and thermal design must ensure R_thJA remains ≤100 K/W for high-reliability operation - especially during repetitive surge events.

How does PCB layout affect the thermal performance of the BZG04-27TR?

PCB layout directly determines R_thJA: Vishay specifies 150 K/W on standard epoxy-glass (Fig. 1a), 125 K/W on enhanced epoxy-glass (Fig. 1b), and 100 K/W on Al₂O₃ ceramic. Increasing copper area around pads, using thermal vias, and minimizing trace length reduce thermal resistance. Poor layout can raise junction temperature beyond 150 °C during surge, causing premature failure - a critical consideration for the BZG04-27TR in high-power industrial designs.

Is the BZG04-27TR suitable for ESD protection on data lines?

The BZG04-27TR is not optimized for high-speed data line ESD protection due to its 475 pF junction capacitance at 0 V, which would distort signals above ~1 MHz. It is intended for power rail and low-bandwidth signal protection (e.g., digital inputs, sensor power). For USB, CAN, or Ethernet lines, lower-capacitance TVS arrays or specialized ESD suppressors (e.g., 10–15 pF devices) are recommended instead of the BZG04-27TR.