Vishay General Semiconductor - Diodes Division BZM55B27-TR

Overview

BZM55B27-TR from Vishay Semiconductors is a precision 27 V Zener diode in MicroMELF (SOD-80) package, designed for voltage regulation and reference applications with ±2.2% nominal Zener voltage tolerance (26.4 V to 27.6 V at 5 mA), 20 Ω dynamic resistance, and low 0.1 μA reverse leakage at rated voltage. It delivers stable clamping in power supply feedback loops and analog reference circuits.

For engineers reviewing the BZM55B27-TR datasheet, BZM55B27-TR pinout, BZM55B27-TR application, or BZM55B27-TR equivalent, key selection criteria include its tight 27 V Zener tolerance, low temperature coefficient (+0.04 %/K at 25 °C), hermetic MicroMELF construction, and compatibility with reflow/wave soldering per J-STD-020 MSL level 1.

Technical Context

The BZM55B27-TR operates as a single-junction, silicon-based Zener diode optimized for stable reverse-bias breakdown at precisely 27 V. Its design targets low-noise voltage reference generation with sharp knee characteristics and high long-term stability under continuous DC bias.

It exhibits a positive temperature coefficient of +0.04 %/K at 25 °C and +0.12 %/K at 125 °C, enabling predictable drift compensation in temperature-sensitive circuits. Thermal resistance is specified at R_thJA = 300 K/W on epoxy-glass PCB and R_thJL = 300 K/W to lead, supporting reliable 500 mW power dissipation up to 175 °C junction temperature.

Key Specifications

Pinout & Package

MicroMELF (SOD-80) package: cylindrical glass body with axial leads; cathode identified by band marking on glass surface. Dimensions: Ø1.8 mm × L3.6 mm; weight ≈12 mg; UL 94 V-0 molding compound; MSL level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX55C27 and MMBZ5256B, the BZM55B27-TR offers tighter voltage tolerance, lower dynamic resistance, superior thermal capability, and hermetic reliability-making it the preferred choice for industrial and automotive voltage reference and clamping applications demanding long-term stability.

Availability

BZM55B27-TR is available at Aetrix Electronics and suitable for industrial sensor reference circuits, automotive ECU voltage clamping, and programmable logic controller input protection requiring stable component supply across extended temperature ranges and high-reliability deployments.

Supply support for BZM55B27-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

Vishay Intertechnology is a global semiconductor manufacturer specializing in discrete components, sensors, and passive elements with emphasis on reliability, precision, and ruggedized packaging.

The BZM55-Series targets high-stability Zener reference and clamping applications in automotive, industrial, and medical systems where hermetic sealing, tight tolerances, and wide temperature operation are essential.

FAQ

What is the Zener voltage tolerance of the BZM55B27-TR?

The BZM55B27-TR has a nominal Zener voltage of 27 V with a guaranteed range of 26.4 V to 27.6 V at 5 mA test current, corresponding to ±2.2% tolerance. This tight specification is achieved through binning and process control, making it suitable for precision reference applications where standard ±5% Zeners like the BZX55C27 are insufficient. The BZM55B27-TR maintains this tolerance across its full operating temperature range.

Does the BZM55B27-TR require derating at elevated ambient temperatures?

Yes-the BZM55B27-TR must be derated linearly above 25 °C ambient per its thermal data: maximum power dissipation drops from 500 mW at 25 °C to zero at 175 °C junction temperature, yielding a derating slope of 3.33 mW/°C. For example, at 100 °C ambient, allowable power is reduced to approximately 250 mW. This derating is defined in Fig. 1 of the Vishay datasheet (Doc. #85597) and applies regardless of PCB layout or heatsinking.

Can the BZM55B27-TR be used in place of a TL431 shunt regulator?

The BZM55B27-TR can serve as a basic 27 V reference in simple circuits but lacks the active feedback, adjustable output, and current-sinking capability of the TL431. It is appropriate for fixed-voltage clamping or passive biasing where no regulation loop is needed. For closed-loop feedback applications requiring dynamic response or programmability, the TL431 remains necessary. The BZM55B27-TR complements rather than replaces the TL431 in most designs.

What is the reverse leakage current specification for the BZM55B27-TR at 20.3 V?

At V_R = 20.3 V (75% of nominal V_Z), the BZM55B27-TR guarantees reverse leakage current ≤ 0.1 μA at 25 °C ambient. This ultra-low leakage supports high-impedance bias networks and extends battery life in always-on monitoring circuits. Measured values typically fall below 50 nA under these conditions, consistent with the "< 0.1 μA" limit stated in the electrical characteristics table for all BZM55B-series devices including the BZM55B27-TR.

Is the BZM55B27-TR RoHS-compliant and halogen-free?

Yes-the BZM55B27-TR complies with RoHS Directive 2011/65/EU and is halogen-free per Vishay's material declaration (Doc. #99912). Its MicroMELF package uses UL 94 V-0 compliant molding compound and contains no brominated flame retardants, chlorine, or fluorine above threshold limits. Full compliance documentation, including substance declarations and test reports, is available via Vishay's website or upon request from Aetrix Electronics.