1N751ATR Equivalent & Substitute Parts

Part Overview

The 1N751ATR is a Zener diode manufactured by onsemi, rated at 5.1 V nominal with 500 mW power dissipation and ±5% tolerance. This component operates across a temperature range of -65°C to 200°C in a Through Hole DO-35 package. The part is classified as Obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and procurement needs.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	5.1	V
Tolerance	±5%	-
Power - Max	500	mW
Impedance (Max)	17	Ohms
Current - Reverse Leakage @ Vr	1	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.5	V @ 200 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 1N751ATR is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Critical Parameters for Substitution:

Voltage - Zener (Nom): 5.1 V (exact match required)
Tolerance: ±5% or tighter (±2% acceptable as upgrade)
Power - Max: 500 mW minimum (higher ratings acceptable for higher-power applications)
Impedance (Max): 17 Ohms or lower (lower impedance acceptable)
Operating Temperature: -65°C minimum and 175°C or higher maximum
Mounting Type: Through Hole
Package / Case: DO-35 or equivalent axial package

Substitute parts are categorized as follows:

Parametric Equivalents: Parts with identical electrical specifications and DO-35 packaging, differing only in manufacturer or tolerance grade.

Similar Substitutes: Parts with matching nominal voltage and tolerance but higher power ratings or different package designations (DO-41), suitable for applications requiring increased thermal capability.

Upgrade Parts: Active production alternatives with improved specifications or compliance certifications, directly replacing the obsolete 1N751ATR.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Package	Status	Temp Range
1N751ATR	onsemi	5.1 V	±5%	500 mW	17 Ω	DO-35	Obsolete	-65 to 200°C
1N5231B	Microchip Technology	5.1 V	±5%	500 mW	17 Ω	DO-35	Active	-65 to 175°C
1N5231BTR	onsemi	5.1 V	±5%	500 mW	17 Ω	DO-35	Active	-65 to 200°C
1N5231CTR	Fairchild Semiconductor	5.1 V	±2%	500 mW	17 Ω	DO-35	Active	-65 to 200°C
BZX79C5V1	Taiwan Semiconductor Corporation	5.1 V	±5%	500 mW	60 Ω	DO-35	Active	-65 to 175°C
1N751A	Microchip Technology	5.1 V	±5%	500 mW	17 Ω	DO-35	Active	-65 to 175°C
1N751A-1	Microchip Technology	5.1 V	±5%	500 mW	14 Ω	DO-35	Active	-65 to 175°C
1N751C	Microchip Technology	5.1 V	±2%	500 mW	17 Ω	DO-35	Active	-65 to 175°C
1N751	Microchip Technology	5.1 V	±10%	400 mW	19 Ω	DO-35	Active	-65 to 175°C
1N4733A	Lumimax Optoelectronic Technology	5.1 V	±5%	1 W	7 Ω	DO-41	Active	-65 to 200°C
1N5918BP-TP	Micro Commercial Co	5.1 V	±5%	1.5 W	4 Ω	DO-41	Active	-55 to 150°C

Engineering Selection Recommendations

Direct Replacement (Parametric Equivalents):

The 1N5231BTR (onsemi) is the primary direct replacement for the 1N751ATR. Both components share identical electrical specifications (5.1 V, ±5%, 500 mW, 17 Ω impedance) and DO-35 packaging. The 1N5231BTR maintains the full operating temperature range (-65°C to 200°C) and is in active production status with ROHS3 compliance.

The 1N5231CTR (Fairchild Semiconductor) provides an upgraded alternative with tighter tolerance (±2% versus ±5%), identical power rating, and matching temperature range. This part is suitable for applications requiring improved voltage regulation accuracy.

Equivalent Alternatives (Same Package, Matching Specifications):

The 1N751A and 1N751A-1 (Microchip Technology) are active production equivalents with matching 5.1 V nominal voltage and 500 mW power rating in DO-35 packages. The 1N751A-1 offers improved impedance (14 Ω versus 17 Ω). Both parts operate to -65°C to 175°C, which covers the majority of industrial applications. These parts are suitable for direct substitution in standard voltage regulation circuits.

The 1N751C (Microchip Technology) provides tighter tolerance (±2%) with identical electrical and thermal specifications to the 1N751A series, appropriate for precision voltage reference applications.

Higher Power Alternatives (Different Package):

The 1N4733A (Lumimax Optoelectronic Technology) and 1N5918BP-TP (Micro Commercial Co) are higher-power variants rated at 1 W and 1.5 W respectively, packaged in DO-41 format. These components maintain the 5.1 V nominal voltage and ±5% tolerance but require PCB layout modifications due to different package geometry. Selection of these parts is appropriate only when thermal dissipation requirements exceed 500 mW.

Compliance Considerations:

The 1N5231BTR and 1N5231CTR carry ROHS3 compliance certification, suitable for applications subject to RoHS regulations. The BZX79C5V1 (Taiwan Semiconductor Corporation) is ROHS3 compliant with REACH unaffected status.

Temperature Range Considerations:

Applications requiring operation above 175°C should specify the 1N5231BTR or 1N5231CTR, which maintain the full -65°C to 200°C range of the original 1N751ATR. Applications with maximum operating temperatures below 175°C can utilize the broader range of Microchip Technology alternatives.

Frequently Asked Questions (FAQ)

Q: Can the 1N5231B replace the 1N751ATR directly?

A: The 1N5231B is electrically equivalent with matching 5.1 V nominal voltage, ±5% tolerance, 500 mW power rating, and DO-35 packaging. The primary difference is the maximum operating temperature: 1N5231B operates to 175°C versus 200°C for the 1N751ATR. Direct substitution is appropriate for applications with maximum operating temperatures at or below 175°C.

Q: What is the difference between 1N751A and 1N751A-1?

A: Both parts are 5.1 V, 500 mW Zener diodes in DO-35 packages with ±5% tolerance. The 1N751A-1 offers lower maximum impedance (14 Ω versus 17 Ω), resulting in improved voltage regulation characteristics. Both operate across -65°C to 175°C. Selection between these parts depends on impedance requirements for the specific application.

Q: Why would I select 1N4733A or 1N5918BP-TP over the standard 500 mW alternatives?

A: These higher-power variants (1 W and 1.5 W respectively) are selected when circuit design requires thermal dissipation exceeding 500 mW. The trade-off is different package geometry (DO-41 versus DO-35), requiring PCB layout modifications. Both maintain 5.1 V nominal voltage and ±5% tolerance.

Q: What is the significance of tolerance grades (±5% versus ±2%)?

A: Tolerance grade specifies the allowable deviation of the Zener voltage from the nominal 5.1 V rating. The ±2% grade (1N5231CTR, 1N751C) provides tighter voltage regulation suitable for precision applications. The ±5% grade (1N751ATR, 1N5231B) is appropriate for general-purpose voltage regulation where tighter tolerance is not required.

Q: Is the BZX79C5V1 suitable as a direct replacement?

A: The BZX79C5V1 matches the 5.1 V nominal voltage, ±5% tolerance, 500 mW power rating, and DO-35 packaging. However, the maximum impedance is 60 Ω compared to 17 Ω for the 1N751ATR. This higher impedance affects voltage regulation characteristics and may not be suitable for all applications. Verification of impedance requirements is necessary before selection.

Q: What packaging considerations apply when selecting substitute parts?

A: The 1N751ATR uses DO-35 axial packaging. Direct replacements (1N5231B, 1N5231BTR, 1N751A series, 1N751C) maintain identical DO-35 packaging and require no PCB modifications. Higher-power alternatives (1N4733A, 1N5918BP-TP) use DO-41 packaging with different lead spacing and body dimensions, requiring PCB layout changes.

Q: Are there RoHS compliance differences among substitute parts?

A: The 1N5231BTR, 1N5231CTR, and BZX79C5V1 carry ROHS3 compliance certification. The 1N5231B is RoHS non-compliant. The 1N751A-1 is RoHS non-compliant. Selection of RoHS-compliant alternatives is required for applications subject to RoHS regulations.

Q: How do I determine which substitute part is appropriate for my application?

A: Identify the critical parameters for your circuit: required Zener voltage (5.1 V for all listed parts), maximum power dissipation (500 mW, 1 W, or 1.5 W), required tolerance grade (±5% or ±2%), operating temperature range, and compliance requirements (RoHS, REACH). Match these requirements to the substitute part specifications provided in the Parameter Comparison table.

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