BZX85C3V9 Zener Diode Equivalent & Substitute Parts

Part Overview

The BZX85C3V9 is a 3.9 V, 1 W zener diode manufactured by onsemi in DO-204AL (DO-41) through-hole axial package. This component is classified as obsolete, though 820 pieces remain in stock as new original inventory. The part operates across a temperature range of -65°C to 200°C with ±5% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Due to the obsolete product status, equivalent and substitute zener diodes with matching or superior electrical characteristics are available from active manufacturers. Substitutes maintain the 3.9 V nominal zener voltage while offering variations in power dissipation, impedance, and package options to accommodate different circuit requirements and manufacturing processes.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	3.9	V
Tolerance	±5%	—
Power - Max	1	W
Impedance (Max)	15	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.2	V @ 200 mA
Operating Temperature	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AL, DO-41, Axial	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the BZX85C3V9 is determined by the following critical parameters:

Electrical Compatibility Criteria:

Nominal zener voltage must equal 3.9 V
Voltage tolerance must be ±5% or tighter
Power dissipation rating must be equal to or greater than 1 W
Operating temperature range must encompass the application requirements
Forward voltage and reverse leakage characteristics must be compatible with circuit design

Mechanical Compatibility Criteria:

Mounting type (through-hole vs. surface mount) determines PCB assembly compatibility
Package designation (DO-41, DO-35, DO-213AB, T-18) affects physical fit and thermal performance
Axial lead configuration is standard for through-hole zener diodes

Compliance and Status Criteria:

Active product status ensures ongoing availability and supply chain reliability
RoHS and REACH compliance status affects regulatory acceptance in target markets
Automotive qualification (AEC-Q101) applies to specific application domains

Substitutes are grouped into three categories: direct equivalents (identical electrical and package specifications), functional equivalents (same electrical performance with different packages), and enhanced alternatives (superior electrical characteristics within the same voltage class).

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vf (Max) @ If	Temp Range	Package	Status
BZX85C3V9	onsemi	3.9 V	±5%	1 W	15 Ω	1.2 V @ 200 mA	-65 to 200°C	DO-41	Obsolete
1N4730A,113	Nexperia USA Inc.	3.9 V	±5%	1 W	9 Ω	1.2 V @ 200 mA	-65 to 200°C	DO-41	Active
BZX85C3V9-TAP	Vishay General Semiconductor	3.9 V	±5%	1.3 W	15 Ω	—	-55 to 175°C	DO-41	Active
1N4730AG	Microsemi Corporation	3.9 V	±5%	1 W	9 Ω	1.2 V @ 200 mA	-65 to 175°C	DO-41	Active
1N4730 G	Microsemi Corporation	3.9 V	±10%	1 W	9 Ω	1.2 V @ 200 mA	-65 to 175°C	DO-41	Active
1N5915DG	Microsemi Corporation	3.9 V	±1%	1.25 W	7.5 Ω	1.2 V @ 200 mA	-65 to 175°C	DO-41	Active
1N5228B	Microchip Technology	3.9 V	±5%	500 mW	23 Ω	1.5 V @ 200 mA	-65 to 175°C	DO-35	Active
1N4730AUR	Microchip Technology	3.9 V	±5%	1 W	9 Ω	1.2 V @ 200 mA	-65 to 175°C	DO-213AB (SMD)	Active
1N5335BRLG	onsemi	3.9 V	±5%	5 W	2 Ω	1.2 V @ 1 A	-65 to 200°C	T-18 Axial	Active
2EZ3.9D5	Microsemi Corporation	3.9 V	±5%	2 W	5 Ω	1.2 V @ 200 mA	-65 to 150°C	DO-41	Active

Engineering Selection Recommendations

Direct Equivalents (Recommended for Direct Replacement):

The 1N4730A,113 manufactured by Nexperia USA Inc. is the primary direct equivalent. It matches the BZX85C3V9 in nominal zener voltage (3.9 V), tolerance (±5%), power rating (1 W), forward voltage characteristics, and operating temperature range (-65 to 200°C). The part is active and available in DO-41 package. The impedance specification (9 Ω) is superior to the original part (15 Ω), providing better voltage regulation performance. This part carries RoHS3 compliance and AEC-Q101 automotive qualification.

The 1N4730AG from Microsemi Corporation provides equivalent electrical performance with identical voltage, tolerance, power, and impedance specifications. Operating temperature range is -65 to 175°C, which is acceptable for most applications. This part is active and available in bulk packaging.

Enhanced Alternatives (Superior Performance):

The 1N5915DG from Microsemi Corporation offers tighter voltage tolerance (±1% versus ±5%), lower impedance (7.5 Ω), and higher power rating (1.25 W). These characteristics provide superior voltage regulation accuracy and thermal performance. Operating temperature range is -65 to 175°C. This part is active and suitable for precision voltage reference applications.

The 2EZ3.9D5 from Microsemi Corporation provides doubled power dissipation (2 W) with significantly lower impedance (5 Ω), enabling higher current handling and improved regulation. Operating temperature range is -65 to 150°C. This part is RoHS3 compliant and suitable for applications requiring enhanced thermal performance.

Higher Power Alternative:

The 1N5335BRLG from onsemi is a 5 W zener diode in T-18 axial package. This part is selected when circuit requirements demand substantially higher power dissipation. Impedance is 2 Ω, providing excellent voltage regulation. Operating temperature range matches the original part (-65 to 200°C). This part is RoHS3 compliant and active.

Surface Mount Alternative:

The 1N4730AUR from Microchip Technology is a surface-mount equivalent in DO-213AB (MELF) package. Electrical specifications match the original part (3.9 V, ±5%, 1 W). This part is selected when PCB assembly requires surface-mount technology. Operating temperature range is -65 to 175°C.

Lower Power Alternative (Space-Constrained Applications):

The 1N5228B from Microchip Technology is a 500 mW zener diode in DO-35 package. This part is selected only when circuit design permits reduced power dissipation and the smaller package footprint is advantageous. Impedance is higher (23 Ω), affecting voltage regulation performance. Operating temperature range is -65 to 175°C.

Compliance Considerations:

Parts with RoHS3 compliance (1N4730A,113, 1N5335BRLG, 2EZ3.9D5) are required for applications subject to RoHS Directive 2011/65/EU. Parts with AEC-Q101 automotive qualification (BZX85C3V9-TAP) are required for automotive applications. All listed parts maintain REACH compliance and EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can I use a lower power-rated zener diode as a substitute?

A: No. The 1N5228B (500 mW) is not suitable as a direct replacement for the 1 W BZX85C3V9 in applications requiring full 1 W power dissipation. Lower power ratings result in thermal stress and reduced component lifespan. Use equal or higher power ratings only.

Q: What is the difference between DO-41 and DO-35 packages?

A: DO-41 and DO-35 are both through-hole axial packages for zener diodes. DO-35 is physically smaller than DO-41. The 1N5228B in DO-35 package occupies less PCB space but has lower power dissipation (500 mW). Package selection depends on PCB layout constraints and thermal requirements. They are not mechanically interchangeable.

Q: Can I substitute a surface-mount zener diode (1N4730AUR) for a through-hole part?

A: No. Surface-mount and through-hole components require different PCB designs and assembly processes. The 1N4730AUR (DO-213AB) cannot be directly installed in a PCB designed for through-hole DO-41 components. Select surface-mount alternatives only if your PCB assembly process supports surface-mount technology.

Q: Why does the 1N5915DG have ±1% tolerance instead of ±5%?

A: The 1N5915DG is manufactured to tighter voltage tolerance specifications, providing more precise zener voltage regulation. This is beneficial for precision voltage reference circuits but is not necessary for general-purpose voltage regulation. Both ±1% and ±5% parts are functionally compatible; tolerance selection depends on circuit accuracy requirements.

Q: Is the BZX85C3V9-TAP suitable for automotive applications?

A: Yes. The BZX85C3V9-TAP carries AEC-Q101 automotive qualification and is rated for -55 to 175°C operating temperature. This part is suitable for automotive applications. However, the operating temperature range is narrower than the original BZX85C3V9 (-65 to 200°C), which may affect suitability in extreme temperature environments.

Q: What does impedance (Zzt) mean, and why does it vary between parts?

A: Impedance (Zzt) is the dynamic impedance of the zener diode in the breakdown region. Lower impedance values (2 to 9 Ω) provide better voltage regulation and lower output impedance. Higher impedance values (15 to 23 Ω) result in greater voltage variation with load current changes. Select lower impedance parts for precision regulation applications.

Q: Can I use the 1N5335BRLG (5 W) in place of the 1 W BZX85C3V9?

A: Yes. The 1N5335BRLG is electrically compatible and provides superior power handling (5 W versus 1 W) and lower impedance (2 Ω versus 15 Ω). This part is suitable for applications requiring higher current capacity or improved voltage regulation. The T-18 package is physically larger than DO-41, so verify PCB layout compatibility.

Q: What is the difference between RoHS compliant and RoHS non-compliant parts?

A: RoHS3 compliant parts (such as 1N4730A,113 and 2EZ3.9D5) meet the Restriction of Hazardous Substances Directive 2011/65/EU and contain no lead, mercury, cadmium, or other restricted substances. RoHS non-compliant parts may contain lead. RoHS compliance is mandatory for products sold in the European Union and many other markets. Select RoHS3 compliant parts for regulatory compliance.

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

A: No. Packaging varies by manufacturer and part number. The BZX85C3V9 is available in DO-41 through-hole package. Substitutes are available in DO-41, DO-35, DO-213AB (surface mount), and T-18 packages. Verify package compatibility with your PCB design before selecting a substitute part.

Q: What is the significance of the "Active" product status?

A: Active product status indicates that the part is currently manufactured and available from the supplier. Obsolete parts (such as the original BZX85C3V9) are no longer manufactured and may have limited inventory. Active parts ensure long-term supply chain reliability and availability for production and repair applications.

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