1N4757A-T Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N4757A-T is a 51 V, 1 W zener diode manufactured by Diodes Incorporated in DO-41 through-hole package configuration. This component is classified as obsolete, though 1,022 units remain in stock as new original inventory. The 1N4757A-T serves voltage regulation and transient suppression applications requiring a nominal zener voltage of 51 V with ±5% tolerance and 1 W maximum power dissipation.

Equivalent and substitute parts are necessary due to the obsolete product status of the 1N4757A-T. Active production alternatives with identical or superior electrical characteristics are available from multiple manufacturers, ensuring long-term design reliability and supply chain continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	51	V
Tolerance	±5%	—
Power - Maximum	1	W
Impedance (Maximum)	95	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 38.8 V
Voltage - Forward (Maximum) @ If	1.2	V @ 200 mA
Operating Temperature Range	-65 to 175	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AL, DO-41, Axial	—

Substitute Part Grouping Explanation

Substitution of the 1N4757A-T is determined by the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 51 V nominal
Tolerance: ±5% (acceptable) or ±10% (acceptable with design margin verification)
Power rating: 1 W minimum (higher ratings acceptable for thermal margin)
Impedance: 95 Ohms maximum (lower impedance acceptable)
Reverse leakage current: 5 µA maximum @ 38.8 V (lower values acceptable)
Forward voltage: 1.2 V maximum @ 200 mA
Operating temperature: -65°C to 175°C minimum (extended ranges acceptable)
Package: DO-204AL / DO-41 through-hole axial configuration

Substitute Categories:

Direct Equivalents (Identical Electrical Specifications): Parts with 51 V nominal zener voltage, ±5% tolerance, 1 W power rating, and -65°C to 175°C operating range. These include 1N4757A (Fairchild Semiconductor), 1N4757AG (Microsemi Corporation), and 1N4757AP/TR8 (Microchip Technology).

Enhanced Performance Substitutes (Superior Power Rating): Parts with 51 V nominal zener voltage, ±5% tolerance, and power ratings exceeding 1 W (1.3 W, 1.31 W, 1.5 W, 2 W, or 3 W). These include 1N4757A-TR (Vishay, 1.3 W), 1N4757A-TAP (Vishay, 1.31 W), 1N5942BP-TP (Micro Commercial Co, 1.5 W), 1N5942B3P-TP (Micro Commercial Co, 3 W), 2EZ51D5-TP (Micro Commercial Co, 2 W), and 2EZ51D5/TR8 (Microsemi Corporation, 2 W).

Tolerance Variant Substitute (±10%): Part 1N4757G (Microsemi Corporation) with 51 V nominal zener voltage, ±10% tolerance, and 1 W power rating. This part is suitable for applications where ±10% voltage tolerance is acceptable.

All substitute parts maintain DO-41 through-hole axial package compatibility and are available in active production status.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Vf (Max) @ If	Temp Range	Product Status	RoHS
1N4757A-T	Diodes Inc.	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Obsolete	ROHS3
1N4757A	Fairchild Semi.	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Active	—
1N4757AG	Microsemi Corp.	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Active	Non-compliant
1N4757AP/TR8	Microchip Tech.	51 V	±5%	1 W	90 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 150°C	Active	Non-compliant
1N4757G	Microsemi Corp.	51 V	±10%	1 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Active	Non-compliant
1N4757A-TR	Vishay Semi.	51 V	±5%	1.3 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Active	ROHS3
1N4757A-TAP	Vishay Semi.	51 V	±5%	1.31 W	95 Ω	5 µA @ 38.8 V	1.2 V @ 200 mA	-65 to 175°C	Active	ROHS3
1N5942BP-TP	Micro Comm. Co	51 V	±5%	1.5 W	70 Ω	1 µA @ 38.8 V	1.5 V @ 200 mA	-55 to 175°C	Active	ROHS3
1N5942B3P-TP	Micro Comm. Co	51 V	±5%	3 W	70 Ω	1 µA @ 38.8 V	1.5 V @ 200 mA	-55 to 175°C	Active	—
2EZ51D5-TP	Micro Comm. Co	51 V	±5%	2 W	48 Ω	500 nA @ 38.8 V	1.2 V @ 200 mA	-55 to 150°C	Active	—
2EZ51D5/TR8	Microsemi Corp.	51 V	±5%	2 W	48 Ω	500 nA @ 38.8 V	1.2 V @ 200 mA	-65 to 150°C	Active	Non-compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

The 1N4757A (Fairchild Semiconductor) is the primary direct equivalent, offering identical electrical specifications to the 1N4757A-T with active product status and 5,300 units in stock. This part maintains the same zener voltage (51 V), tolerance (±5%), power rating (1 W), impedance (95 Ohms), and operating temperature range (-65°C to 175°C).

The 1N4757AG (Microsemi Corporation) provides an alternative direct equivalent with identical electrical specifications and 1,040 units available. This part is suitable for applications where Microsemi sourcing is preferred.

For RoHS3 Compliance:

The 1N4757A-TAP and 1N4757A-TR (both Vishay General Semiconductor) are RoHS3 compliant direct substitutes with enhanced power ratings (1.31 W and 1.3 W respectively) and AEC-Q101 automotive qualification. These parts are suitable for designs requiring RoHS3 compliance and automotive-grade reliability.

For Enhanced Thermal Performance:

The 1N5942BP-TP (Micro Commercial Co, 1.5 W) and 2EZ51D5-TP (Micro Commercial Co, 2 W) provide increased power dissipation capability while maintaining 51 V zener voltage and ±5% tolerance. These parts are suitable for applications requiring additional thermal margin or higher current handling.

For Tolerance Flexibility:

The 1N4757G (Microsemi Corporation) with ±10% tolerance is suitable for applications where voltage tolerance of ±10% is acceptable, offering cost optimization without compromising core functionality.

For Temperature Range Considerations:

Parts with -65°C to 175°C operating range (1N4757A, 1N4757AG, 1N4757A-TR, 1N4757A-TAP) are preferred for applications requiring the full temperature specification of the original 1N4757A-T. Parts with -55°C to 175°C or -65°C to 150°C ranges require design verification for temperature-critical applications.

Frequently Asked Questions (FAQ)

Q: Can I use 1N4757A as a direct replacement for 1N4757A-T?

A: Yes. The 1N4757A (Fairchild Semiconductor) is a direct equivalent with identical zener voltage (51 V), tolerance (±5%), power rating (1 W), impedance (95 Ohms), and operating temperature range (-65°C to 175°C). The primary difference is product status: 1N4757A-T is obsolete while 1N4757A is active production.

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

A: Both are Vishay General Semiconductor parts with identical zener specifications (51 V, ±5%, -65°C to 175°C). The primary differences are power rating (1N4757A-TR: 1.3 W; 1N4757A-TAP: 1.31 W) and packaging format (both Cut Tape). Both are RoHS3 compliant and AEC-Q101 qualified.

Q: Can I substitute a 2 W zener diode for the 1 W 1N4757A-T?

A: Yes, for applications where thermal margin is beneficial. Parts such as 2EZ51D5-TP (2 W) and 2EZ51D5/TR8 (2 W) maintain the same 51 V zener voltage and ±5% tolerance. Higher power ratings do not degrade performance in 1 W applications; they provide additional thermal headroom. Verify impedance specifications (2EZ51 series: 48 Ohms vs. 1N4757: 95 Ohms) for circuit-specific requirements.

Q: What does ±10% tolerance mean for the 1N4757G?

A: The 1N4757G zener voltage will fall within the range of 45.9 V to 56.1 V (51 V ±10%), compared to the 1N4757A-T specification of 48.45 V to 53.55 V (51 V ±5%). The ±10% tolerance part is suitable for applications where voltage regulation does not require the tighter ±5% specification.

Q: Are all substitute parts available in DO-41 package?

A: Yes. All substitute parts listed are available in DO-204AL / DO-41 through-hole axial package configuration, ensuring mechanical and electrical compatibility with the original 1N4757A-T footprint.

Q: What is the difference between Tape & Reel (TR) and Cut Tape (CT) packaging?

A: Tape & Reel (TR) and Cut Tape (CT) are supply formats for automated assembly. Both formats contain identical components in DO-41 package. TR format is supplied on continuous reel for high-volume pick-and-place assembly. CT format is supplied in cut tape strips for lower-volume or manual assembly. Electrical specifications are identical between formats.

Q: Why do some substitute parts have lower reverse leakage current?

A: Lower reverse leakage current (e.g., 1 µA vs. 5 µA, or 500 nA vs. 5 µA) indicates improved device quality and lower standby power consumption. Lower leakage is acceptable and beneficial in all applications; it does not create compatibility issues.

Q: Is RoHS3 compliance required for my application?

A: RoHS3 compliance is required for products sold in the European Union and certain other markets. If your application requires RoHS3 compliance, select 1N4757A-TAP or 1N4757A-TR (both Vishay, RoHS3 compliant). If RoHS compliance is not required, all listed parts are functionally suitable.

Q: Can I use 1N4757AP/TR8 (Microchip) if my design requires -65°C to 175°C operation?

A: The 1N4757AP/TR8 operates from -65°C to 150°C, which is 25°C below the 1N4757A-T specification of 175°C maximum. For applications requiring operation at temperatures above 150°C, use 1N4757A, 1N4757AG, 1N4757A-TR, or 1N4757A-TAP instead.

Q: What is AEC-Q101 qualification?

A: AEC-Q101 is an automotive industry qualification standard for discrete semiconductors. Parts bearing AEC-Q101 qualification (1N4757A-TR and 1N4757A-TAP from Vishay) have undergone rigorous testing for automotive applications and are suitable for automotive-grade designs requiring enhanced reliability.

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