BZX55C4V3 Zener Diode Equivalent & Substitute Parts

Part Overview

The BZX55C4V3 is a through-hole zener diode rated at 4.3 V nominal with 500 mW power dissipation and ±7% tolerance, manufactured by onsemi in DO-35 axial package configuration. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement continuity. Equivalent parts maintain identical or superior electrical performance within the specified parameter ranges while offering active product status and improved availability.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	4.3	V
Tolerance	±7%	-
Power - Max	500	mW
Impedance (Max)	75	Ohms
Current - Reverse Leakage @ Vr	1	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.3	V @ 100 mA
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	-
Package / Case	DO-35, Axial	-

Substitute Part Grouping Explanation

Substitution eligibility for the BZX55C4V3 is determined by the following critical parameters: nominal zener voltage of 4.3 V, maximum power rating of 500 mW, through-hole mounting configuration, and DO-35 axial package format. Substitute parts must maintain the 4.3 V zener voltage specification and 500 mW power rating. Tolerance variations (±7% to ±5%) are acceptable within standard circuit design margins. Impedance, reverse leakage current, and forward voltage characteristics may vary within acceptable ranges for general-purpose zener diode applications. Operating temperature range and product status (active versus obsolete) are secondary considerations for functional equivalency but critical for procurement and long-term supply assurance.

Parameter Comparison

Parameter	BZX55C4V3	BZX55C4V3RL	BZX79C4V3	BZX79C4V3-T50A	1N5229B
Manufacturer	onsemi	onsemi	Taiwan Semiconductor	onsemi	Taiwan Semiconductor
Product Status	Obsolete	Active	Active	Active	Active
Voltage - Zener (Nom)	4.3 V	4.3 V	4.3 V	4.3 V	4.3 V
Tolerance	±7%	±7%	±5%	±5%	±5%
Power - Max	500 mW	500 mW	500 mW	500 mW	500 mW
Impedance (Max)	75 Ohms	75 Ohms	90 Ohms	90 Ohms	22 Ohms
Current - Reverse Leakage @ Vr	1 µA @ 1 V	1 µA @ 1 V	5 µA @ 1 V	5 µA @ 1 V	5 µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 100 mA	1.3 V @ 100 mA	1.5 V @ 100 mA	1.5 V @ 100 mA	1.1 V @ 200 mA
Operating Temperature Range	-65 to 200°C	-65 to 200°C	-65 to 175°C	-65 to 200°C	200°C (TJ)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	DO-35, Axial	DO-35, Axial	DO-35, Axial	DO-35, Axial	DO-35, Axial
RoHS Status	-	-	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

BZX55C4V3RL (onsemi) is the primary parametric equivalent, offering identical electrical specifications to the BZX55C4V3 with active product status. This part maintains ±7% tolerance, 75 Ohm impedance, and -65 to 200°C operating range. Bulk packaging provides cost efficiency for high-volume applications. This selection is appropriate for direct replacement in existing designs without circuit modification.

BZX79C4V3-T50A (onsemi) provides an active alternative with improved tolerance (±5%) and extended temperature capability to 200°C. Impedance increases to 90 Ohms and reverse leakage rises to 5 µA, acceptable for general-purpose applications. ROHS3 compliance and Tape & Box packaging support modern supply chain requirements. This part is suitable for new designs prioritizing active product status and regulatory compliance.

BZX79C4V3 (Taiwan Semiconductor Corporation) offers equivalent electrical performance with ±5% tolerance and 90 Ohm impedance. Operating temperature range extends to 175°C. ROHS3 compliance and Tape & Reel packaging support automated assembly processes. This selection is appropriate for applications requiring tighter tolerance specifications and active product availability.

1N5229B (Taiwan Semiconductor Corporation) provides superior impedance characteristics at 22 Ohms with ±5% tolerance and ROHS3 compliance. Forward voltage is reduced to 1.1 V at 200 mA, offering improved efficiency in certain circuit topologies. This part is suitable for applications where lower impedance and forward voltage characteristics provide circuit performance advantages.

Frequently Asked Questions (FAQ)

Q: Can BZX55C4V3RL directly replace the obsolete BZX55C4V3?

A: Yes. BZX55C4V3RL maintains identical nominal zener voltage (4.3 V), tolerance (±7%), power rating (500 mW), impedance (75 Ohms), and operating temperature range (-65 to 200°C). Both use DO-35 axial through-hole packaging. No circuit modifications are required.

Q: What is the difference between BZX79C4V3 and BZX79C4V3-T50A?

A: Both parts share identical electrical specifications: 4.3 V nominal, ±5% tolerance, 500 mW power, 90 Ohm impedance, and 5 µA reverse leakage. The primary difference is packaging: BZX79C4V3 uses Tape & Reel (TR) format, while BZX79C4V3-T50A uses Tape & Box (TB) format. BZX79C4V3-T50A extends operating temperature to 200°C versus 175°C for BZX79C4V3.

Q: Is 1N5229B suitable as a substitute despite lower impedance?

A: 1N5229B maintains the critical 4.3 V nominal zener voltage and 500 mW power rating with ±5% tolerance. The 22 Ohm impedance is significantly lower than the original 75 Ohms, resulting in improved voltage regulation and reduced dynamic impedance. This part is suitable for applications where lower impedance provides circuit performance benefits. Circuit validation is necessary to confirm compatibility with specific application requirements.

Q: What are the packaging differences among substitute parts?

A: BZX55C4V3RL is supplied in Bulk packaging. BZX79C4V3 uses Tape & Reel (TR) format for automated assembly. BZX79C4V3-T50A uses Tape & Box (TB) format. All parts maintain identical DO-35 axial through-hole package configuration and are mechanically interchangeable on printed circuit boards.

Q: Are all substitute parts RoHS compliant?

A: BZX55C4V3RL compliance status is not specified in available documentation. BZX79C4V3, BZX79C4V3-T50A, and 1N5229B are all ROHS3 compliant. For applications requiring RoHS certification, BZX79C4V3-T50A or 1N5229B are recommended selections.

Q: What is the operating temperature consideration for BZX79C4V3?

A: BZX79C4V3 operates from -65 to 175°C (TJ), which is 25°C lower than the original BZX55C4V3 specification of -65 to 200°C. For applications requiring full -65 to 200°C operation, BZX55C4V3RL or BZX79C4V3-T50A are appropriate selections.

Q: Can these parts be used interchangeably in high-precision voltage reference circuits?

A: Tolerance and impedance variations affect voltage regulation precision. BZX55C4V3RL and BZX55C4V3 both offer ±7% tolerance and 75 Ohm impedance. BZX79C4V3 and BZX79C4V3-T50A provide tighter ±5% tolerance but with 90 Ohm impedance. 1N5229B offers the lowest impedance at 22 Ohms with ±5% tolerance. Selection depends on specific circuit precision requirements and voltage regulation characteristics.

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