STMicroelectronics BAR28

Overview

BAR28 from STMicroelectronics is a small-signal Schottky diode in DO-35 glass package, featuring 70 V repetitive peak reverse voltage, 0.41 V forward voltage at 1 mA, 2 pF junction capacitance at 0 V, 100 ps switching time, and -65 to +200 °C junction temperature range - optimized for UHF/VHF detection and fast pulse applications in RF front-ends.

For engineers reviewing the BAR28 datasheet, BAR28 pinout, BAR28 application, or BAR28 equivalent, key selection criteria include low VF for signal detection sensitivity, ultrafast τ for pulse fidelity, low C for wideband impedance matching, thermal robustness for high-reliability RF modules, and DO-35 lead-form compatibility with legacy through-hole layouts.

Technical Context

The BAR28 employs a metal-to-silicon Schottky junction enabling low forward voltage drop and minimal minority-carrier storage, critical for zero-bias detection in RF receivers. Its 100 ps switching time and 2 pF capacitance support operation up to 1 GHz with minimal phase distortion.

Designed for unclamped, low-current signal routing, it operates without thermal derating below 15 mA continuous forward current and sustains 50 mA non-repetitive surge pulses - making it suitable for envelope detection, sampling gates, and clamp circuits in analog RF subsystems.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode identified by a clear ring at one end; leads are tinned copper, 0.458–0.558 mm diameter, with 15 mm minimum straight axial length before bending.

Key Features

Applications

Availability

BAR28 is available at Aetrix Electronics and suitable for UHF/VHF detection, pulse sampling, RF clamping, and logic-level translation requiring stable component supply across industrial, test & measurement, and legacy RF design programs.

Supply support for BAR28 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, designing and manufacturing analog, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The BAR28 belongs to ST's legacy discrete diode product line, engineered specifically for high-frequency signal conditioning in RF and microwave systems where speed, low capacitance, and thermal resilience are essential.

FAQ

Is BAR28 suitable for zero-bias RF detection?

Yes. With a typical forward voltage of 0.41 V at 1 mA and ultra-low junction capacitance of 2 pF, the BAR28 operates effectively as a zero-bias detector in UHF/VHF receivers, delivering high sensitivity without external bias circuitry or added noise sources.

What is the maximum operating frequency for BAR28 in RF applications?

The BAR28 supports RF operation up to approximately 1 GHz, based on its 2 pF junction capacitance and 100 ps switching time. Performance beyond 1 GHz depends on PCB layout, biasing, and load matching but remains viable in well-designed 50 Ω detector and sampling circuits.

Can BAR28 replace BAT41 or BAT54 in existing designs?

BAR28 is not a direct replacement for BAT41 (V_RRM = 100 V) or BAT54 (dual Schottky, SOT-23). While all are Schottky diodes, BAR28's DO-35 package, 70 V rating, and 15 mA I_F differ significantly in form factor and ratings - redesign verification is required for substitution.

Does BAR28 require heatsinking in continuous operation?

No. With a junction-to-ambient thermal resistance of 400 °C/W and only 15 mA maximum continuous forward current, BAR28 dissipates <10 mW under typical conditions and operates safely without heatsinking in standard DO-35 mounting configurations.