BZX85C33 Zener Diode 33V 1W Equivalent & Substitute Parts

Part Overview

The BZX85C33 is a through-hole zener diode rated for 33 V nominal voltage and 1 W maximum power dissipation in a DO-41 (DO-204AL) axial package. Manufactured by onsemi, this component is classified as obsolete product status. Due to its obsolete designation, identifying equivalent and substitute parts from active manufacturers is necessary to maintain design continuity and ensure ongoing component availability for production and repair applications.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	33	V
Tolerance	±6%	—
Power - Max	1	W
Impedance (Max)	35	Ohms
Current - Reverse Leakage @ Vr	500 nA @ 23 V	—
Voltage - Forward (Vf) (Max) @ If	1.2 V @ 200 mA	—
Operating Temperature Range	-65°C to 200°C	—
Mounting Type	Through Hole	—
Package / Case	DO-204AL, DO-41, Axial	—

Substitute Part Grouping Explanation

Substitution of the BZX85C33 is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 33 V nominal
Maximum power rating: 1 W or greater
Package type: DO-41 (DO-204AL) through-hole axial configuration
Operating temperature range: Must encompass or exceed -65°C to 200°C

Secondary Compatibility Factors:

Voltage tolerance: ±6% or tighter (±5%, ±2%)
Impedance (Zzt): Maximum 35 to 45 Ohms
Reverse leakage current: 500 nA to 10 µA @ specified voltage
Forward voltage: 1.2 V to 1.5 V @ 200 mA

Substitute parts are grouped into three categories:

Direct Equivalents (1 W Power Rating): Parts with identical 1 W power rating, 33 V zener voltage, and DO-41 package. These include 1N4752A, 1N3032B-1, 1EZ33D5-TP, and 1N4752 variants from Microchip Technology.
Higher Power Alternatives (3 W Power Rating): The 1N5937BRLG offers increased power dissipation capability (3 W) while maintaining 33 V zener voltage and through-hole axial mounting, suitable for applications requiring thermal margin.
Automotive-Qualified Variant: The BZX85C33-TAP from Vishay provides direct series compatibility with AEC-Q101 qualification and enhanced power rating (1.3 W), maintaining the BZX85 series designation.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vf @ 200 mA	Temp Range	Package	Status
BZX85C33	onsemi	33 V	±6%	1 W	35 Ω	1.2 V	-65 to 200°C	DO-41	Obsolete
1N4752A	Lumimax Optoelectronic Technology	33 V	±5%	1 W	45 Ω	1.2 V	-65 to 200°C	DO-41	Active
1N5937BRLG	onsemi	33 V	±5%	3 W	33 Ω	1.5 V	-65 to 200°C	Axial	Active
BZX85C33-TAP	Vishay General Semiconductor	33 V	±5%	1.3 W	35 Ω	—	-55 to 175°C	DO-41	Active
1EZ33D5-TP	Micro Commercial Co	33 V	±5%	1 W	45 Ω	1.2 V	-55 to 150°C	DO-41	Active
1N3032B-1	Microchip Technology	33 V	±5%	1 W	45 Ω	1.2 V	-55 to 175°C	DO-41	Active
1N4752AP/TR12	Microchip Technology	33 V	±5%	1 W	45 Ω	1.2 V	-65 to 150°C	DO-41	Active
1N4752CE3/TR13	Microchip Technology	33 V	±2%	1 W	45 Ω	1.2 V	-65 to 150°C	DO-41	Active
1N4752CP/TR12	Microchip Technology	33 V	±2%	1 W	45 Ω	1.2 V	-65 to 150°C	DO-41	Active
1N4752CP/TR8	Microchip Technology	33 V	±2%	1 W	45 Ω	1.2 V	-65 to 150°C	DO-41	Active
1N4752CPE3/TR12	Microchip Technology	33 V	±2%	1 W	45 Ω	1.2 V	-65 to 150°C	DO-41	Active

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

The BZX85C33-TAP from Vishay General Semiconductor provides the closest functional equivalent. This part maintains the BZX85 series designation, offers AEC-Q101 automotive qualification, and delivers 1.3 W power rating with identical 35 Ohm impedance. The operating temperature range (-55°C to 175°C) is narrower than the original but covers standard industrial and automotive applications. This part is ROHS3 compliant and carries active product status.

For Standard Industrial Applications:

The 1N4752A from Lumimax Optoelectronic Technology serves as a direct 1 W equivalent with ±5% tolerance, matching the original operating temperature range (-65°C to 200°C). This part is RoHS compliant and maintains active status with substantial inventory availability.

For Applications Requiring Extended Temperature Operation:

The 1N4752AP/TR12 from Microchip Technology supports the full -65°C to 150°C range and offers ±5% tolerance. Multiple variants (1N4752CE3/TR13, 1N4752CP/TR12, 1N4752CP/TR8, 1N4752CPE3/TR12) provide tighter ±2% tolerance specifications for precision voltage regulation applications.

For Increased Thermal Margin:

The 1N5937BRLG from onsemi provides 3 W power dissipation while maintaining 33 V zener voltage and through-hole axial mounting. This part is ROHS3 compliant and suitable for applications where thermal headroom is critical.

Compliance Considerations:

BZX85C33-TAP: ROHS3 compliant, AEC-Q101 qualified
1N4752A: RoHS compliant
1N5937BRLG: ROHS3 compliant
1N3032B-1: RoHS non-compliant
1N4752 variants: Mixed compliance (ROHS3 and non-compliant versions available)

All listed parts carry REACH Unaffected status and EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can the BZX85C33 be replaced with any 33 V zener diode?

A: No. Substitution requires matching the 33 V nominal zener voltage, 1 W (or greater) power rating, DO-41 through-hole axial package, and compatible operating temperature range. Impedance and tolerance specifications must also fall within acceptable limits for the application.

Q: What is the difference between the 1 W and 3 W variants?

A: The 1N5937BRLG provides 3 W maximum power dissipation compared to 1 W in the original BZX85C33. This higher power rating allows greater current handling and thermal margin. The 3 W variant maintains identical 33 V zener voltage and through-hole mounting but exhibits lower impedance (33 Ω vs. 35 Ω) and slightly higher forward voltage (1.5 V vs. 1.2 V @ 200 mA).

Q: Are there RoHS-compliant alternatives?

A: Yes. The 1N4752A (RoHS compliant), 1N5937BRLG (ROHS3 compliant), BZX85C33-TAP (ROHS3 compliant), and specific 1N4752 variants (1N4752CE3/TR13, 1N4752CPE3/TR12 with ROHS3 compliance) meet RoHS requirements. The 1N3032B-1 and certain 1N4752 variants are RoHS non-compliant.

Q: Does operating temperature range affect substitution?

A: Yes. The original BZX85C33 operates from -65°C to 200°C. Substitutes with narrower ranges (such as -55°C to 175°C for BZX85C33-TAP or -55°C to 150°C for 1EZ33D5-TP) are acceptable only if the application does not require the full original temperature span. For applications requiring -65°C operation, select parts explicitly rated to -65°C.

Q: What is the significance of voltage tolerance (±6%, ±5%, ±2%)?

A: Tolerance specifies the allowable deviation from the nominal 33 V zener voltage. The original BZX85C33 has ±6% tolerance. Tighter tolerances (±5% or ±2%) provide more precise voltage regulation and are suitable for precision applications. Looser tolerances are acceptable for general-purpose voltage clamping.

Q: Can I use the BZX85C33-TAP as a direct replacement?

A: The BZX85C33-TAP is a direct series equivalent with enhanced specifications (1.3 W vs. 1 W, AEC-Q101 qualified). However, its operating temperature range (-55°C to 175°C) is narrower than the original (-65°C to 200°C). Verify that your application does not require operation below -55°C or above 175°C before substitution.

Q: What packaging options are available?

A: All listed substitutes use through-hole axial mounting in DO-41 (DO-204AL) package format, matching the original BZX85C33. Packaging variants differ only in tape reel specifications (TR12, TR8, TR13) for automated assembly, not in physical component dimensions.

Q: Are there automotive-qualified alternatives?

A: Yes. The BZX85C33-TAP carries AEC-Q101 qualification, making it suitable for automotive applications. This part is the recommended choice for automotive designs requiring a direct BZX85C33 replacement.

Q: How do impedance specifications affect circuit performance?

A: Impedance (Zzt) affects the zener diode's dynamic resistance and voltage regulation quality. The original BZX85C33 specifies 35 Ω maximum impedance. Substitutes with 45 Ω impedance (1N4752A, 1EZ33D5-TP, 1N3032B-1, 1N4752 variants) exhibit slightly higher dynamic resistance but remain functionally equivalent for most applications. The 1N5937BRLG offers superior impedance (33 Ω) for precision regulation.

Q: What is the reverse leakage current specification?

A: Reverse leakage current indicates the diode's leakage in the reverse-biased state. The original BZX85C33 specifies 500 nA @ 23 V. Substitutes range from 500 nA to 10 µA @ 25.1 V. Higher leakage values are acceptable for general-purpose applications but may affect precision circuits requiring minimal standby current.

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