BZX55C20 Equivalent & Substitute Parts

Part Overview

The BZX55C20 is a through-hole zener diode manufactured by onsemi, rated at 20 V nominal zener voltage with 500 mW power dissipation capability in a DO-35 axial package. This component is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and procurement continuity. The BZX55C20 operates across a temperature range of -65°C to 200°C with ±6% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Substiute Parts

BZX55C20

onsemiIn Stock: 829BZX55C20 Datasheet

Current PartRFQ

NZX20B,133

Nexperia USA Inc.In Stock: 1023NZX20B,133 Datasheet

SimilarRFQ

BZX79C20

Taiwan Semiconductor CorporationIn Stock: 825BZX79C20 Datasheet

Parametric EquivalentRFQ

BZX79C20-T50A

Fairchild SemiconductorIn Stock: 30767BZX79C20-T50A Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BZX55C20 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

• Zener voltage (Vz): 20 V nominal or within acceptable tolerance band
• Power dissipation rating: 500 mW minimum
• Package type: DO-35 axial through-hole configuration
• Impedance (Zzt): 55 Ohms maximum
• Operating temperature range: Must encompass or exceed -65°C to 200°C

Substitute Classification:

Similar Manufacturer Part (Functional Equivalent): NZX20B,133 meets the 20 V zener voltage and 500 mW power requirements with improved tolerance (±2%) and lower reverse leakage characteristics. Operating temperature range is -55°C to 175°C, which is narrower than the main part.

Parametric Equivalents (Direct Replacements): BZX79C20 and BZX79C20-T50A both provide identical 20 V zener voltage, 500 mW power rating, and 55 Ohms impedance in DO-35 packages. These parts maintain electrical compatibility with ±5% tolerance specifications.

Parameter Comparison

Engineering Selection Recommendations

BZX79C20-T50A (Fairchild Semiconductor) is the primary substitute for the obsolete BZX55C20. This part maintains identical electrical specifications (20 V, 500 mW, 55 Ohms impedance) and extends the upper operating temperature limit to 200°C, matching the original component's thermal range. The part is currently in active production status with 30,749 units in stock, ensuring long-term availability. Operating temperature coverage of -65°C to 200°C provides full compatibility with the original design envelope.

BZX79C20 (Taiwan Semiconductor Corporation) serves as a secondary parametric equivalent with identical zener voltage, power rating, and impedance specifications. This part is ROHS3 compliant and actively produced. The operating temperature range extends to -65°C but is limited to 175°C maximum, which may restrict use in applications requiring the full 200°C upper thermal limit of the original BZX55C20.

NZX20B,133 (Nexperia USA Inc.) is a functional equivalent offering superior voltage tolerance (±2% versus ±6%) and lower reverse leakage current (50 nA versus 100 nA). However, the operating temperature range of -55°C to 175°C is narrower than the original specification. This part is ROHS3 compliant and actively produced. The impedance specification of 60 Ohms exceeds the 55 Ohms maximum of the original part by 5 Ohms.

Frequently Asked Questions (FAQ)

Q: Can BZX79C20-T50A directly replace BZX55C20 in all applications?

A: Yes. BZX79C20-T50A maintains identical zener voltage (20 V), power dissipation (500 mW), impedance (55 Ohms), and operating temperature range (-65°C to 200°C). The DO-35 axial package is mechanically and electrically compatible with the original BZX55C20 footprint.

Q: What is the difference between the NZX20B,133 and BZX79C20 substitutes?

A: NZX20B,133 offers tighter voltage tolerance (±2% versus ±5%) and lower reverse leakage (50 nA versus 100 nA), but has a narrower operating temperature range (-55°C to 175°C) and slightly higher impedance (60 Ohms versus 55 Ohms). BZX79C20 maintains the original impedance specification and extends the lower temperature limit to -65°C but is also limited to 175°C maximum.

Q: Are there package compatibility concerns with these substitutes?

A: BZX79C20 and BZX79C20-T50A use standard DO-35 axial packages identical to the original BZX55C20. NZX20B,133 uses an ALF2 package designation but maintains the same DO-35 axial form factor and through-hole mounting configuration, ensuring PCB compatibility.

Q: Which substitute is recommended for high-temperature applications?

A: BZX79C20-T50A is the only substitute that maintains the full operating temperature range of the original BZX55C20 (-65°C to 200°C). Applications requiring operation at temperatures above 175°C must use this part.

Q: What compliance certifications apply to these substitutes?

A: BZX79C20 and NZX20B,133 are ROHS3 compliant. BZX79C20-T50A does not have RoHS status listed. All three parts are REACH unaffected and carry EAR99 ECCN classification, matching the original BZX55C20 regulatory status.

Q: How do the electrical characteristics compare for voltage regulation accuracy?

A: NZX20B,133 provides the tightest voltage tolerance at ±2%, followed by BZX79C20 and BZX79C20-T50A at ±5%, and the original BZX55C20 at ±6%. For applications requiring precise voltage regulation, NZX20B,133 offers superior performance, provided the narrower temperature range is acceptable.