Vishay General Semiconductor - Diodes Division BZM55C43-TR

Overview

BZM55C43-TR from Vishay Semiconductors is a silicon planar Zener diode in MicroMELF (SOD-80) package, designed for precision voltage regulation and reference applications. It delivers a nominal Zener voltage of 43 V at 2.5 mA test current, with ±7% tolerance (40–46 V), dynamic resistance of 33 Ω at 2.5 mA, and temperature coefficient of +0.04%/K at 25 °C - enabling stable operation in power supply feedback loops and analog sensor biasing circuits.

For engineers reviewing the BZM55C43-TR datasheet, BZM55C43-TR pinout, BZM55C43-TR application, or BZM55C43-TR equivalent, key selection criteria include its 43 V nominal Zener voltage, low reverse leakage (<0.1 μA at VR = 33.2 V), 500 mW power rating, MicroMELF hermetic package for high reliability, and suitability for space-constrained voltage stabilization in industrial and automotive subsystems.

Technical Context

The BZM55C43-TR operates as a single-element, two-terminal Zener diode with sharp reverse breakdown characteristic and low noise performance. Its Zener voltage is specified under pulsed test conditions (tp ≤ 10 ms, T/tp > 1000) to minimize self-heating effects, and it exhibits a positive temperature coefficient (+0.04%/K at 25 °C, +0.12%/K at 125 °C), indicating increasing V_Z with junction temperature - critical for thermal drift compensation in precision references.

Designed for surface-mount reflow or wave soldering on epoxy-glass PCBs, it features a junction-to-ambient thermal resistance of 300 K/W when mounted per fig. 8, and supports continuous operation up to 175 °C junction temperature. The MicroMELF glass-body construction ensures hermetic sealing, high stability, and compatibility with automated pick-and-place assembly.

Key Specifications

Pinout & Package

MicroMELF (SOD-80) package: cylindrical glass body with axial leads, cathode identified by a dark band. Hermetic sealing provides long-term stability and low parameter drift. Dimensions: 1.8 mm diameter × 3.6 mm length; weight ≈12 mg; flammability rating UL 94 V-0; MSL Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZM55C43-TR, BZM55B43-TR improves initial voltage accuracy at the expense of tighter process control cost, while 1N4749A-TAP trades MicroMELF reliability and miniaturization for higher power and through-hole compatibility - making BZM55C43-TR optimal for SMT-based, space-constrained, medium-accuracy regulation.

Availability

BZM55C43-TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, and test equipment requiring stable component supply, consistent parametric performance, and RoHS-compliant MicroMELF packaging.

Supply support for BZM55C43-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 high-temperature performance.

The BZM55-Series targets high-stability voltage reference and regulation in demanding environments, leveraging Vishay's expertise in glass-passivated Zener technology and hermetic MicroMELF packaging for automotive, industrial, and aerospace applications.

FAQ

What is the Zener voltage tolerance of BZM55C43-TR?

The BZM55C43-TR has a Zener voltage range of 40 V to 46 V at 2.5 mA test current, corresponding to a nominal 43 V with ±7% tolerance. This specification is verified per Vishay Document 85597 Rev. 2.3 and applies under standard test conditions (T_amb = 25 °C, pulsed measurement). The tolerance reflects manufacturing spread for cost-optimized general-purpose regulation, distinct from the tighter ±2% of the BZM55B43-TR variant.

Can BZM55C43-TR be used in reflow soldering processes?

Yes, BZM55C43-TR is qualified for reflow soldering with a peak temperature of up to 260 °C, per J-STD-020 MSL Level 1 classification. Its MicroMELF (SOD-80) package is designed for compatibility with standard Pb-free reflow profiles. Footprint recommendations specify 0.8 mm pad width and 1.4 mm pad length for reliable thermal and mechanical attachment, as detailed in Vishay's package drawing 6.560-5007.01-4.

What is the maximum reverse leakage current for BZM55C43-TR?

The maximum reverse leakage current for BZM55C43-TR is <0.1 μA at V_R = 33.2 V (95% of minimum V_Z), measured at T_j = 25 °C. This ultra-low leakage enables use in battery-backed circuits and high-impedance bias networks where standby current must remain below 100 nA. The value is confirmed in the Electrical Characteristics table of Vishay's BZM55-Series datasheet (Document 85597, page 2).

How does the temperature coefficient affect BZM55C43-TR in real-world operation?

The BZM55C43-TR exhibits a temperature coefficient of +0.04%/K at 25 °C and +0.12%/K at 125 °C, meaning its Zener voltage increases with junction temperature. At full rated junction temperature (175 °C), V_Z rises by approximately +1.2 V relative to 25 °C. This behavior must be factored into thermal design - for example, in automotive under-hood applications, derating or compensation may be needed to maintain regulation accuracy within ±2%.

Is BZM55C43-TR suitable for overvoltage protection?

Yes, BZM55C43-TR is commonly deployed as a shunt overvoltage protector for 36 V systems, clamping transients to ≤46 V. With 500 mW power rating and fast response (low junction capacitance ~5 pF), it handles short-duration surges like ISO 7637-2 pulse 1 and pulse 2a. However, for sustained overvoltage events, external current limiting (e.g., series resistor or active foldback) is required to prevent thermal runaway - the device itself does not provide current limiting.