1N4757G R0G Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N4757G R0G is a 51 V, 1 W Zener diode manufactured by Taiwan Semiconductor Corporation in DO-204AL (DO-41) axial through-hole packaging. This component is classified as Active product status with full RoHS3 compliance and REACH unaffected designation. Equivalent and substitute parts are identified based on matching or exceeding the electrical specifications and mechanical compatibility within the Zener diode category. Substitution becomes necessary when the primary part experiences supply constraints, obsolescence, or when design requirements permit operation with alternative electrical characteristics within defined tolerance bands.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	51	V
Tolerance	±5%	%
Power - Max	1	W
Impedance (Max)	95	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 38.8 V
Voltage - Forward (Max) @ If	1.2	V @ 200 mA
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AL, DO-41, Axial	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution logic for the 1N4757G R0G is based on the following critical parameters: nominal Zener voltage (51 V), voltage tolerance (±5%), maximum power dissipation capability, impedance characteristics, reverse leakage current, forward voltage drop, and operating temperature range. Parts are grouped into three categories:

Category A: Direct Electrical Equivalents (51 V Zener Voltage) Parts with identical 51 V nominal Zener voltage, ±5% tolerance, and compatible power ratings (1 W to 1.31 W) that maintain functional equivalence in standard circuit applications.

Category B: Enhanced Performance Variants (51 V Zener Voltage, Higher Power) Parts with 51 V nominal Zener voltage but increased power dissipation (3 W), suitable for applications requiring higher thermal headroom while maintaining the same voltage regulation point.

Category C: Voltage Offset Variants (56 V Zener Voltage) Parts with 56 V nominal Zener voltage representing a 9.8% increase from the primary specification. These are not direct substitutes but are listed as alternatives when circuit design permits voltage deviation within system tolerance margins.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power Max	Zzt (Max)	Reverse Leakage @ Vr	Vf (Max) @ If	Temp Range	Package	Status
1N4757G R0G	Taiwan Semiconductor	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 200°C	DO-204AL (DO-41)	Active
1N4757A	Fairchild Semiconductor	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	DO-41	Active
1N4757A-TAP	Vishay General Semiconductor	51 V	±5%	1.31 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-55 to 175°C	DO-204AL (DO-41)	Active
1N4758A	SMC Diode Solutions	56 V	±5%	1 W	110 Ω	5 µA @ 42.6 V	1.2 V @ 200 mA	-65 to 200°C	DO-41	Obsolete
1N4758A-T50A	onsemi	56 V	±5%	1 W	110 Ω	5 µA @ 42.6 V	Not Specified	-65 to 200°C	DO-41	Active
1N5942BRLG	onsemi	51 V	±5%	3 W	70 Ω	1 µA @ 38.8 V	1.5 V @ 200 mA	-65 to 200°C	Axial	Active
BZX85C51-TAP	Vishay General Semiconductor	51 V	±5%	1.3 W	115 Ω	500 nA @ 39 V	Not Specified	-55 to 175°C	DO-204AL (DO-41)	Active
BZX85C51-TR	Vishay General Semiconductor	51 V	±5%	1.3 W	115 Ω	500 nA @ 39 V	Not Specified	-55 to 175°C	DO-204AL (DO-41)	Active
ZPY51-TR	Vishay General Semiconductor	51 V	±5%	1.3 W	45 Ω	500 nA @ 38 V	Not Specified	-55 to 175°C	DO-204AL (DO-41)	Active

Engineering Selection Recommendations

Direct Substitutes (Category A)

The 1N4757A (Fairchild Semiconductor) provides direct electrical equivalence with identical voltage, tolerance, power rating, and impedance specifications. Operating temperature range is reduced to -65 to 175°C compared to the primary part's -65 to 200°C specification. This part is suitable for applications where the upper temperature limit of 175°C is acceptable.

The 1N4757A-TAP (Vishay General Semiconductor) offers enhanced power dissipation at 1.31 W while maintaining all other electrical parameters. This part carries AEC-Q101 automotive qualification and is available in higher inventory quantities. Operating temperature is limited to -55 to 175°C.

Enhanced Performance Variant (Category B)

The 1N5942BRLG (onsemi) maintains the 51 V Zener voltage with significantly increased power dissipation (3 W) and improved impedance characteristics (70 Ω). Reverse leakage current is reduced to 1 µA. This part is suitable for applications requiring higher thermal capacity while maintaining voltage regulation at 51 V. Operating temperature range matches the primary part (-65 to 200°C). Package configuration is axial, which may require circuit board layout modification.

Voltage Offset Alternatives (Category C)

The 1N4758A-T50A (onsemi) and 1N4758A (SMC Diode Solutions) feature 56 V nominal Zener voltage with identical 1 W power rating. These parts are not direct substitutes due to voltage deviation but are listed for applications where 56 V regulation is acceptable. The 1N4758A is marked Obsolete; the 1N4758A-T50A is Active with full RoHS3 compliance.

Automotive-Grade Alternatives

The BZX85C51-TAP, BZX85C51-TR, and ZPY51-TR (all Vishay General Semiconductor) are automotive-qualified parts (AEC-Q101) with 51 V Zener voltage and 1.3 W power rating. These parts feature significantly lower reverse leakage current (500 nA) compared to the primary part (5 µA). Operating temperature is limited to -55 to 175°C. The ZPY51-TR exhibits lower impedance (45 Ω) compared to the primary part (95 Ω).

Compliance and Certification

All recommended substitutes maintain RoHS3 compliance and REACH unaffected status. Parts carrying AEC-Q101 qualification (1N4757A-TAP, BZX85C51-TAP, BZX85C51-TR, ZPY51-TR) are suitable for automotive applications requiring formal qualification documentation.

Frequently Asked Questions (FAQ)

Q: Can the 1N4757A directly replace the 1N4757G R0G?

A: The 1N4757A provides electrical equivalence with identical Zener voltage (51 V), tolerance (±5%), power rating (1 W), and impedance (95 Ω). The primary difference is the reduced operating temperature range (-65 to 175°C versus -65 to 200°C). Direct substitution is valid for applications operating within the -65 to 175°C range.

Q: What is the difference between the 1N4757A-TAP and the primary part?

A: The 1N4757A-TAP maintains identical electrical specifications but offers increased power dissipation (1.31 W versus 1 W). This provides additional thermal margin in the same package. Operating temperature is limited to -55 to 175°C. The part carries AEC-Q101 automotive qualification.

Q: Can I use the 1N5942BRLG as a substitute?

A: The 1N5942BRLG maintains the 51 V Zener voltage but increases power dissipation to 3 W. This part is suitable for applications requiring higher thermal capacity. The package configuration is axial rather than DO-41, which may require circuit board layout modification. Impedance is improved (70 Ω), and reverse leakage is reduced (1 µA).

Q: Why are the 1N4758A and 1N4758A-T50A listed if they have different voltage?

A: These parts feature 56 V nominal Zener voltage, representing a 9.8% increase from the 51 V specification. They are listed as alternatives for applications where circuit design permits voltage deviation within system tolerance margins. These are not direct substitutes but are available alternatives when voltage offset is acceptable.

Q: What are the advantages of automotive-qualified parts like BZX85C51-TAP?

A: Automotive-qualified parts (AEC-Q101) undergo formal qualification testing and documentation. The BZX85C51 series features significantly lower reverse leakage current (500 nA versus 5 µA), which may be beneficial in high-impedance circuit applications. These parts are suitable for automotive and industrial applications requiring formal qualification.

Q: Does package type affect substitution?

A: Yes. The primary part uses DO-204AL (DO-41) axial packaging. Most substitutes maintain this package configuration. The 1N5942BRLG uses axial packaging, which is mechanically compatible but may require circuit board layout modification. Packaging compatibility must be verified before substitution.

Q: Are all substitute parts RoHS3 compliant?

A: All listed substitute parts maintain RoHS3 compliance and REACH unaffected status, matching the primary part's regulatory compliance profile.

Q: What is the significance of impedance differences between parts?

A: Impedance (Zzt) affects voltage regulation stability and transient response. The primary part specifies 95 Ω maximum impedance. The 1N5942BRLG offers improved impedance at 70 Ω, while the ZPY51-TR provides 45 Ω. Lower impedance generally provides better voltage regulation under transient conditions. Higher impedance (BZX85C51 series at 115 Ω) may affect regulation performance in sensitive applications.

Q: Can I substitute based on power rating alone?

A: No. Power rating is one of several critical parameters. Zener voltage, tolerance, impedance, and operating temperature range must all be verified for compatibility. A part with higher power rating does not automatically qualify as a substitute if other electrical parameters differ.

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