BZX85C4V3 Zener Diode Equivalent & Substitute Parts

Part Overview

The BZX85C4V3 is a 4.3 V, 1 W Zener diode manufactured by onsemi in DO-204AL (DO-41) through-hole axial package. This part is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design requirements and procurement needs. Substitute parts must maintain the 4.3 V nominal Zener voltage while accommodating variations in power dissipation, tolerance, impedance, and package configuration based on application requirements.

Key Parameters

Parameter	BZX85C4V3 Specification
Voltage - Zener (Nom) (Vz)	4.3 V
Tolerance	±7%
Power - Max	1 W
Impedance (Max) (Zzt)	13 Ohms
Current - Reverse Leakage @ Vr	3 µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.2 V @ 200 mA
Operating Temperature Range	-65°C ~ 200°C
Mounting Type	Through Hole
Package / Case	DO-204AL, DO-41, Axial
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the BZX85C4V3 is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage - Zener (Nom) (Vz): Must equal 4.3 V
Mounting Type: Through Hole required for direct mechanical compatibility
Package / Case: DO-204AL (DO-41) axial preferred for form-factor equivalence

Secondary Substitution Criteria:

Power - Max: Minimum 1 W; higher ratings acceptable for increased thermal margin
Tolerance: ±7% or better acceptable; tighter tolerances provide improved voltage regulation
Impedance (Max) (Zzt): Lower impedance values improve dynamic response
Operating Temperature Range: Must encompass application requirements
Current - Reverse Leakage @ Vr: Lower values preferred for reduced standby current

Substitute parts are grouped into three categories:

Direct Equivalents: Identical 4.3 V rating, 1 W power class, DO-41 package, active product status
Higher Power Variants: 4.3 V rating with increased power dissipation (1.25 W, 1.3 W, 5 W) for applications requiring greater thermal capacity
Lower Power Variants: 4.3 V rating with reduced power dissipation (500 mW) for space-constrained applications
Package Variants: Surface mount (DO-213AB) for alternative assembly methods

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (W)	Zzt (Ohms)	Leakage @ 1V (µA)	Vf @ 200mA (V)	Temp Range (°C)	Package	Status
BZX85C4V3	onsemi	4.3	±7%	1	13	3	1.2	-65 ~ 200	DO-41	Obsolete
BZX85C4V3-TAP	Vishay	4.3	±5%	1.3	13	3	1.2	-55 ~ 175	DO-41	Active
1N4731 G	Microsemi	4.3	±10%	1	9	10	1.2	-65 ~ 175	DO-41	Active
1N4731A G	Microsemi	4.3	±5%	1	9	10	1.2	-65 ~ 175	DO-41	Active
1N4731AUR	Microchip	4.3	±5%	1	9	10	1.2	-65 ~ 175	DO-213AB	Active
1N5229B	Taiwan Semiconductor	4.3	±5%	0.5	22	5	1.1	-65 ~ 200	DO-35	Active
1N5336BRLG	onsemi	4.3	±5%	5	2	10	1.2 @ 1A	-65 ~ 200	Axial	Active
1N5916AG	Microsemi	4.3	±10%	1.25	6	5	1.2	-65 ~ 175	DO-41	Active
1N5916BG	Microsemi	4.3	±5%	1.25	6	5	1.2	-65 ~ 175	DO-41	Active
1N5916CG	Microsemi	4.3	±2%	1.25	6	5	1.2	-65 ~ 175	DO-41	Active
1N5916DG	Microsemi	4.3	±1%	1.25	6	5	1.2	-65 ~ 175	DO-41	Active

Engineering Selection Recommendations

Primary Recommendation for Direct Replacement:

BZX85C4V3-TAP (Vishay) is the preferred direct substitute. This part maintains identical 4.3 V Zener voltage, DO-41 package configuration, and equivalent electrical performance with improved tolerance (±5% versus ±7%). The part is active with AEC-Q101 automotive qualification and ROHS3 compliance. Operating temperature range (-55°C ~ 175°C) is suitable for most applications within the original specification envelope.

Alternative Selections Based on Application Requirements:

For applications requiring tighter voltage tolerance and improved dynamic response:

1N5916CG (±2% tolerance, 6 Ohms impedance) or 1N5916DG (±1% tolerance, 6 Ohms impedance) provide superior voltage regulation with 1.25 W power rating.

For applications with extended high-temperature operation:

1N5336BRLG (5 W, -65°C ~ 200°C) accommodates elevated ambient conditions with significant thermal margin.

For space-constrained through-hole designs:

1N5229B (500 mW, DO-35 package) provides compact form factor with acceptable power rating for low-current applications.

For surface-mount assembly:

1N4731AUR (DO-213AB MELF package) enables automated assembly processes while maintaining 1 W power rating and ±5% tolerance.

Compliance Considerations:

The original BZX85C4V3 carries REACH Unaffected status. Most active substitutes maintain REACH Unaffected designation. The BZX85C4V3-TAP and 1N5336BRLG are ROHS3 compliant. Microsemi 1N4731 and 1N5916 series parts are RoHS non-compliant; these selections require verification against procurement specifications.

Frequently Asked Questions (FAQ)

Q: Can I use a higher power-rated Zener diode as a substitute?

A: Yes. A Zener diode with higher power rating (1.25 W, 1.3 W, or 5 W) is electrically compatible with the BZX85C4V3 provided the 4.3 V nominal voltage is maintained. Higher power ratings provide increased thermal margin and are suitable for applications with higher current demands or elevated ambient temperatures. The physical package size may increase with higher power ratings.

Q: What is the impact of tolerance differences on circuit performance?

A: Tolerance specifies the allowable deviation from the nominal 4.3 V Zener voltage. The original BZX85C4V3 specifies ±7% tolerance, resulting in a voltage range of 4.0 V to 4.6 V. Tighter tolerances (±5%, ±2%, ±1%) reduce this range, improving voltage regulation accuracy. Applications requiring precise voltage reference benefit from lower tolerance values. Looser tolerances (±10%) are acceptable for general-purpose voltage clamping applications.

Q: Can I substitute a DO-35 package (1N5229B) for the DO-41 package?

A: DO-35 and DO-41 packages are both through-hole axial configurations with identical lead spacing and mounting compatibility. The DO-35 package is physically smaller. Substitution is mechanically feasible; however, the 1N5229B has reduced power rating (500 mW versus 1 W). This substitution is suitable only for applications with current demands below 500 mW.

Q: What is the difference between DO-41 and DO-213AB packages?

A: DO-41 is a through-hole axial package requiring manual insertion or wave soldering. DO-213AB (MELF) is a surface-mount package compatible with automated pick-and-place assembly and reflow soldering. Electrical performance is equivalent; package selection depends on assembly process requirements.

Q: Is the BZX85C4V3-TAP suitable for automotive applications?

A: Yes. The BZX85C4V3-TAP carries AEC-Q101 automotive qualification, indicating compliance with automotive reliability and environmental stress testing standards. This part is suitable for automotive and industrial applications requiring enhanced reliability.

Q: How does impedance (Zzt) affect Zener diode performance?

A: Impedance represents the dynamic resistance of the Zener diode at the specified test current. Lower impedance values (2 Ohms for 1N5336BRLG versus 13 Ohms for BZX85C4V3) result in improved voltage regulation and reduced voltage ripple under varying load conditions. Applications requiring stable voltage reference benefit from lower impedance values.

Q: Can I use a surface-mount Zener diode (1N4731AUR) in a through-hole design?

A: Direct substitution is not feasible without circuit board redesign. Surface-mount packages require PCB pads and reflow soldering processes different from through-hole designs. However, 1N4731AUR is electrically equivalent and suitable for new designs utilizing surface-mount assembly.

Q: What is the significance of reverse leakage current?

A: Reverse leakage current represents the small current flowing through the Zener diode when reverse-biased below the Zener voltage. Lower leakage current (3 µA for BZX85C4V3 versus 10 µA for 1N4731 series) reduces standby power consumption. Applications with strict power budget requirements benefit from lower leakage specifications.

Q: Are all substitute parts RoHS compliant?

A: No. The Microsemi 1N4731 and 1N5916 series parts are RoHS non-compliant. The BZX85C4V3-TAP and 1N5336BRLG are ROHS3 compliant. Procurement specifications must verify RoHS compliance requirements for the target application and market region.

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