BZX55C3V3 Equivalent & Substitute Parts

Part Overview

The BZX55C3V3 is a Zener diode manufactured by onsemi, rated at 3.3 V nominal with 500 mW power dissipation and ±6% tolerance. This component is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. The through-hole DO-35 package and axial mounting configuration remain standard across the Zener diode category, enabling direct mechanical and electrical substitution with compatible alternatives.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	3.3	V
Tolerance	±6%	%
Power - Max	500	mW
Impedance (Max)	85	Ohms
Current - Reverse Leakage @ Vr	2	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.3	V @ 100 mA
Operating Temperature	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AH, DO-35, Axial	—

Substitute Part Grouping Explanation

Substitution of the BZX55C3V3 is determined by the following critical parameters:

Primary Matching Criteria:

Voltage - Zener (Nom): 3.3 V (exact match required)
Power - Max: 500 mW (exact match required)
Package / Case: DO-35 through-hole axial configuration (exact match required)
Mounting Type: Through Hole (exact match required)

Secondary Compatibility Parameters:

Tolerance: ±6% or tighter (±5% acceptable as improvement)
Operating Temperature Range: Minimum -65°C to +175°C or higher
Impedance (Max): Values within acceptable circuit performance margins
Current - Reverse Leakage: Values acceptable for application requirements

All substitute parts listed maintain identical nominal Zener voltage, power rating, and physical package specifications. Variations in tolerance, impedance, and leakage current reflect manufacturing differences between suppliers while remaining functionally compatible for standard voltage regulation applications.

Parameter Comparison

Parameter	BZX55C3V3 (onsemi)	BZX79C3V3-T50A (Fairchild)	1N5226B (Microchip)	BZX79C3V3 (Taiwan Semi)
Voltage - Zener (Nom)	3.3 V	3.3 V	3.3 V	3.3 V
Tolerance	±6%	±5%	±5%	±5%
Power - Max	500 mW	500 mW	500 mW	500 mW
Impedance (Max)	85 Ohms	95 Ohms	28 Ohms	95 Ohms
Current - Reverse Leakage @ Vr	2 µA @ 1 V	25 µA @ 1 V	25 µA @ 1 V	25 µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 100 mA	1.5 V @ 100 mA	1.5 V @ 200 mA	1.5 V @ 100 mA
Operating Temperature	-65 to 200°C	-65 to 200°C	-65 to 175°C	-65 to 175°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	DO-35	DO-35	DO-35	DO-35
Product Status	Obsolete	Active	Active	Active

Engineering Selection Recommendations

BZX79C3V3-T50A (Fairchild Semiconductor) is a direct substitute with active product status. This part maintains identical voltage, power, and package specifications. The tolerance improves to ±5%, and the operating temperature range extends to 200°C, matching the original specification. Impedance increases marginally to 95 Ohms, and reverse leakage current increases to 25 µA, both within acceptable performance parameters for standard voltage regulation circuits. REACH Affected status indicates compliance with current regulatory requirements.

1N5226B (Microchip Technology) is functionally equivalent with active product status. Nominal voltage, power rating, and package remain identical. Tolerance improves to ±5%, and impedance reduces to 28 Ohms, providing superior voltage stability. Operating temperature range is -65 to 175°C, which is 25°C lower than the original maximum. Reverse leakage current is 25 µA. RoHS non-compliant status may require evaluation against application requirements.

BZX79C3V3 (Taiwan Semiconductor Corporation) is a direct substitute with active product status. All critical parameters match: 3.3 V nominal, 500 mW power, DO-35 package. Tolerance improves to ±5%, and operating temperature extends to 175°C. Impedance is 95 Ohms, and reverse leakage is 25 µA. RoHS3 compliance and REACH Unaffected status indicate alignment with modern regulatory standards.

Selection among these three substitutes depends on application-specific requirements regarding operating temperature range, impedance characteristics, and regulatory compliance status.

Frequently Asked Questions (FAQ)

Q: Can BZX79C3V3-T50A replace BZX55C3V3 in existing designs?

A: Yes. Both parts share identical nominal Zener voltage (3.3 V), power rating (500 mW), and DO-35 through-hole package. The BZX79C3V3-T50A features improved tolerance (±5% vs. ±6%) and maintains the same operating temperature range (-65 to 200°C). Impedance and reverse leakage specifications differ slightly but remain compatible for standard voltage regulation applications.

Q: What is the difference between 1N5226B and BZX79C3V3?

A: Both are 3.3 V, 500 mW Zener diodes in DO-35 packages with ±5% tolerance. The 1N5226B has lower impedance (28 Ohms vs. 95 Ohms), providing better voltage stability. The 1N5226B operates to 175°C maximum, while BZX79C3V3 also operates to 175°C. The 1N5226B is RoHS non-compliant, whereas BZX79C3V3 is RoHS3 compliant.

Q: Why does the BZX55C3V3 show as obsolete?

A: The BZX55C3V3 is classified as obsolete by onsemi, indicating it is no longer in active production. Active equivalent parts from other manufacturers (Fairchild, Microchip, Taiwan Semiconductor) provide identical electrical and mechanical functionality for new designs and production continuity.

Q: Are all substitute parts available in the same packaging?

A: Yes. All substitute parts are supplied in DO-35 through-hole axial packages. BZX79C3V3-T50A is supplied in Bulk packaging, 1N5226B in Bulk, and BZX79C3V3 in Tape & Reel (TR). The physical component package remains identical across all options.

Q: What is the impact of tolerance differences (±6% vs. ±5%)?

A: The BZX55C3V3 has ±6% tolerance, while all substitutes have ±5% tolerance. This means substitute parts have tighter voltage regulation, reducing the acceptable voltage variation band. For applications requiring the full ±6% tolerance window, this represents an improvement in performance consistency.

Q: Can I use these parts interchangeably on the same PCB?

A: Yes. All parts are mechanically and electrically compatible for through-hole soldering on standard PCBs. The DO-35 package footprint is identical across all options. No PCB redesign is required for substitution.

Q: Which substitute has the best voltage stability?

A: The 1N5226B has the lowest impedance specification (28 Ohms) compared to BZX79C3V3-T50A and BZX79C3V3 (both 95 Ohms). Lower impedance provides superior voltage regulation stability across varying load conditions.

Q: What is the maximum operating temperature for each substitute?

A: BZX79C3V3-T50A operates to 200°C, matching the original BZX55C3V3. Both 1N5226B and BZX79C3V3 operate to 175°C maximum. Application requirements determine which temperature range is appropriate.

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