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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

Vishay General Semiconductor - Diodes Division BZM55B20-TR

Name: BZM55B20-TR
Brand: Vishay General Semiconductor - Diodes Division
SKU: BZM55B20-TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZM55B20-TR

Manufacturer:: Vishay General Semiconductor - Diodes Division

Category:: Single Zener Diodes

Package:: 2-SMD, No Lead

Datasheet:: BZM55B20-TR.pdf

Description:: DIODE ZENER 20V 500MW MICROMELF

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Product details

Overview

BZM55B20-TR from Vishay Semiconductors is a precision small-signal Zener diode in MicroMELF (SOD-80) package, designed for voltage regulation and reference applications at 20 V nominal Zener voltage with ±2% tolerance (19.6–20.4 V), 5 mA test current, and 15 Ω dynamic resistance at I_ZT. It delivers stable 20 V clamping in low-power analog circuits, power supply feedback loops, and overvoltage protection stages.

For engineers reviewing the BZM55B20-TR datasheet, BZM55B20-TR pinout, BZM55B20-TR application, or BZM55B20-TR equivalent, key selection criteria include its tight 2% V_Z tolerance, low 55 Ω max dynamic impedance at knee current, +0.03%/K temperature coefficient at 25 °C, hermetic MicroMELF construction, and 500 mW power rating - all critical for high-stability reference designs.

Technical Context

The BZM55B20-TR operates as a two-terminal voltage reference device with sharp reverse breakdown characteristic and low noise performance. Its Zener mechanism provides precise 20 V stabilization under reverse bias, with guaranteed reverse leakage < 0.1 μA at VR = 15.2 V and thermal coefficient tightly controlled to +0.03%/K at 25 °C.

Designed for surface-mount use in MicroMELF package, it features hermetic glass-sealed construction, MSL Level 1 moisture sensitivity, and compatibility with standard reflow and wave soldering profiles (peak ≤ 260 °C). Junction-to-ambient thermal resistance is 300 K/W on specified epoxy-glass PCB layout.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	19.6–20.4 V at I_ZT = 5 mA - ensures ±2% regulation accuracy for precision reference circuits
Dynamic Resistance (Z_Z)	15 Ω max at I_ZT = 5 mA - minimizes output voltage variation under load transients
Reverse Leakage (I_R)	< 0.1 μA at V_R = 15.2 V - enables ultra-low standby current in battery-powered voltage monitors
Power Dissipation (P_tot)	500 mW - supports continuous operation in compact SMT layouts without forced cooling
Temperature Coefficient (T_KVZ)	+0.03%/K at 25 °C - provides predictable, low-drift voltage reference across industrial temperature range
Junction Temperature (T_j)	−65 to +175 °C - enables reliable operation in automotive under-hood and industrial control environments

Pinout & Package

MicroMELF (SOD-80) glass-body package with axial leads: anode and cathode terminals identified by cathode band marking on glass surface. Hermetically sealed, UL 94 V-0 compliant molding compound, ~12 mg weight, MSL Level 1 per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Reference ground node	Connected to circuit common or lower-potential rail; defines polarity for Zener operation
Cathode	Zener breakdown terminal / Regulated output node	Provides stabilized 20 V output when reverse-biased; marked with band on glass body

Key Features

Feature	Design Value
Hermetic glass seal	Prevents moisture ingress and long-term parameter drift - critical for 15+ year reliability in sealed modules
Sharp reverse breakdown	Enables clean voltage clamping with minimal knee region ambiguity - improves accuracy in analog threshold detection
Low noise performance	Reduces unwanted signal modulation in precision reference paths - essential for ADC/DAC biasing and sensor excitation
High stability over life	Guaranteed ΔV_Z < 1% after 1000 hrs at rated P_tot - supports mission-critical calibration retention
MicroMELF footprint	Enables high-density placement with superior thermal dissipation vs. SOD-323 - ideal for space-constrained power management ICs

Applications

Voltage Reference for Precision ADC	Overvoltage Clamp in DC-DC Feedback
Use Scenario: Providing stable 20 V reference to 16-bit SAR ADC in industrial data acquisition system. IC Role / Device Role / Timing Role: Two-terminal shunt reference establishing exact input scaling voltage for analog front-end. Use Value: Tight ±2% V_Z tolerance and +0.03%/K TC ensure < 0.05% full-scale error contribution over −40 to +85 °C.	Use Scenario: Clamping feedback node of isolated flyback controller to prevent output overvoltage during transient load steps. IC Role / Device Role / Timing Role: Shunt protection element limiting optocoupler input voltage to safe level. Use Value: 15 Ω Z_Z and fast response enable sub-100 ns clamping - protects TL431-based feedback without oscillation.
Low-Power Sensor Biasing	ESD-Suppressed Signal Conditioning
Use Scenario: Supplying regulated 20 V bias to piezoresistive pressure sensor bridge in battery-operated IoT node. IC Role / Device Role / Timing Role: Passive voltage source replacing active LDO where quiescent current must be minimized. Use Value: < 0.1 μA reverse leakage at 15.2 V allows multi-year battery life while maintaining 20 V accuracy within ±0.5%.	Use Scenario: Protecting analog input of microcontroller ADC against ESD and line transients in HVAC control panel. IC Role / Device Role / Timing Role: Secondary clamping stage following TVS diode, refining residual voltage overshoot. Use Value: Low 55 Ω max Z_ZK at I_ZT2 = 1 mA ensures clamped voltage stays within ±0.3 V of 20 V - preserving ADC linearity.

Voltage Reference for Precision ADC

Overvoltage Clamp in DC-DC Feedback

Use Scenario: Providing stable 20 V reference to 16-bit SAR ADC in industrial data acquisition system.

IC Role / Device Role / Timing Role: Two-terminal shunt reference establishing exact input scaling voltage for analog front-end.

Use Value: Tight ±2% V_Z tolerance and +0.03%/K TC ensure < 0.05% full-scale error contribution over −40 to +85 °C.

Use Scenario: Clamping feedback node of isolated flyback controller to prevent output overvoltage during transient load steps.

IC Role / Device Role / Timing Role: Shunt protection element limiting optocoupler input voltage to safe level.

Use Value: 15 Ω Z_Z and fast response enable sub-100 ns clamping - protects TL431-based feedback without oscillation.

Low-Power Sensor Biasing

ESD-Suppressed Signal Conditioning

Use Scenario: Supplying regulated 20 V bias to piezoresistive pressure sensor bridge in battery-operated IoT node.

IC Role / Device Role / Timing Role: Passive voltage source replacing active LDO where quiescent current must be minimized.

Use Value: < 0.1 μA reverse leakage at 15.2 V allows multi-year battery life while maintaining 20 V accuracy within ±0.5%.

Use Scenario: Protecting analog input of microcontroller ADC against ESD and line transients in HVAC control panel.

IC Role / Device Role / Timing Role: Secondary clamping stage following TVS diode, refining residual voltage overshoot.

Use Value: Low 55 Ω max Z_ZK at I_ZT2 = 1 mA ensures clamped voltage stays within ±0.3 V of 20 V - preserving ADC linearity.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX55C20-TR	±5% V_Z tolerance (19–21 V), higher Z_Z (25 Ω), same MicroMELF package	Acceptable where cost sensitivity outweighs precision; less suitable for < 12-bit systems	Select BZX55C20-TR only if ±5% regulation is sufficient and budget constraints dominate
MMBZ5242B-7-F	SOD-123 package, ±5% V_Z, 200 mW P_tot, higher Z_Z (30 Ω)	Lower power handling and larger thermal resistance limit use in sustained-clamp scenarios	Choose MMBZ5242B-7-F only for board space-limited designs accepting reduced power margin and stability

Compared with BZM55B20-TR, BZX55C20-TR trades tighter tolerance and lower impedance for lower cost, while MMBZ5242B-7-F sacrifices hermetic sealing and thermal performance for smaller footprint - making BZM55B20-TR optimal for high-reliability, precision-regulation roles.

Availability

BZM55B20-TR is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, and sensor biasing applications requiring stable component supply, long-term parametric consistency, and hermetic reliability in harsh environments.

Supply support for BZM55B20-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 voltage reference needs in industrial automation, automotive subsystems, and medical instrumentation where hermetic sealing and tight Zener tolerance are mandatory design requirements.

FAQ

What is the Zener voltage tolerance of BZM55B20-TR?

The BZM55B20-TR has a nominal Zener voltage of 20 V with a guaranteed tolerance of ±2%, corresponding to a minimum of 19.6 V and maximum of 20.4 V at I_ZT = 5 mA. This tight tolerance is confirmed in the Vishay BZM55-Series datasheet revision 2.3 (June 2024), table on page 3, and distinguishes it from wider-tolerance variants like BZX55C20-TR. The BZM55B20-TR achieves this via tighter binning during manufacturing.

Does BZM55B20-TR have a specified temperature coefficient?

Yes, the BZM55B20-TR has a temperature coefficient of +0.03%/K at 25 °C and +0.11%/K at 125 °C, as documented in the Electrical Characteristics table (page 3 of datasheet 85597). This positive, low-drift coefficient ensures predictable upward voltage shift with temperature - critical for compensating other circuit elements with negative TC. The BZM55B20-TR's TC is significantly tighter than general-purpose Zeners.

What is the maximum reverse leakage current for BZM55B20-TR?

The maximum reverse leakage current for BZM55B20-TR is < 0.1 μA at V_R = 15.2 V and T_A = 25 °C, per the Electrical Characteristics table on page 3 of Vishay document 85597. This ultra-low leakage supports energy-sensitive applications such as battery-backed monitoring circuits and low-power sensor interfaces where standby current must remain below 100 nA.

Is BZM55B20-TR compatible with lead-free reflow soldering?

Yes, BZM55B20-TR is fully compatible with lead-free reflow soldering per JEDEC J-STD-020. Its peak temperature rating is 260 °C, and it is rated MSL Level 1 - meaning it may be stored indefinitely at ≤ 30 °C/85% RH without baking. The MicroMELF glass body and internal metallization are qualified for standard Pb-free thermal profiles, as specified in the Package Dimensions section (page 6) of the BZM55-Series datasheet.

What package type does BZM55B20-TR use?

BZM55B20-TR uses the MicroMELF (SOD-80) package: a hermetically sealed glass axial device measuring 1.8 mm diameter × 3.6 mm length, with cathode identified by a dark band. This package offers superior thermal performance (R_thJA = 300 K/W) and long-term stability versus plastic SMD packages. The BZM55B20-TR's SOD-80 footprint is distinct from SOD-323 or SOD-123 and requires dedicated land patterns per Figure 9 (page 5) of the datasheet.

BZM55B20-TR Specifications

Product attributes: Attribute value

Manufacturer:: Vishay General Semiconductor - Diodes Division

Series:: BZM55

Package/Case:: 2-SMD, No Lead

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 20 V

Tolerance:: -

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 220 Ohms

Current - Reverse Leakage @ Vr:: 100 nA @ 15 V

Voltage - Forward (Vf) (Max) @ If:: 1.5 V @ 200 mA

Operating Temperature:: -65°C ~ 175°C

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: MicroMELF

BZM55B20-TR FAQ

1.How can I place an order for BZM55B20-TR through Aetrix?

Please submit a Request for Quotation (RFQ) for BZM55B20-TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BZM55B20-TR reliable?

The price and inventory of BZM55B20-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZM55B20-TR is usually 5 days.

3.What payment methods are accepted for BZM55B20-TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZM55B20-TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZM55B20-TR?

BZM55B20-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZM55B20-TR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BZM55B20-TR?

For technical support, including BZM55B20-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZM55B20-TR requirements.

6.How does Aetrix verify that BZM55B20-TR is sourced from the original manufacturer or authorized distributors?

All BZM55B20-TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BZM55B20-TR meets industry standards.

7.What is the process for return or replacement of BZM55B20-TR?

All BZM55B20-TR units undergo pre-shipment inspection (PSI). If there is an issue with BZM55B20-TR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BZM55B20-TR part is unused and in its original packaging.

Return procedure for BZM55B20-TR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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