SML4757A-E3/5A Zener Diode Equivalent & Substitute Parts

Part Overview

The SML4757A-E3/5A is a 51 V, 1 W surface mount zener diode manufactured by Vishay General Semiconductor - Diodes Division in the DO-214AC (SMA) package. This component is classified as Active and is ROHS3 compliant. Equivalent and substitute parts are identified based on matching electrical specifications, package compatibility, and manufacturing standards. Alternative part numbers may be required due to inventory availability, supply chain considerations, or specific application requirements such as automotive qualification or enhanced power ratings.

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
Operating Temperature	150	°C
Mounting Type	Surface Mount	—
Package / Case	DO-214AC, SMA	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the SML4757A-E3/5A are classified into three categories based on electrical and mechanical compatibility:

Parametric Equivalents (Identical Specifications): Parts that match all critical electrical parameters including 51 V zener voltage, ±5% tolerance, 1 W power rating, 95 Ohms maximum impedance, and 5 µA reverse leakage current at 38.8 V. These parts are interchangeable in applications where the exact original specifications are required. Parametric equivalents include SML4757A-E3/61 and SML4757AHE3_A/H.

Direct Manufacturer Alternatives (Same Base Specifications, Different Manufacturer): Parts manufactured by alternative suppliers that maintain the same 51 V zener voltage, ±5% tolerance, 1 W power rating, and DO-214AC package. The SMAJ4757A-TP from Micro Commercial Co falls into this category, offering identical electrical performance with potential differences in reverse leakage measurement conditions.

Manufacturer Recommended Upgrades (Enhanced Power Rating): Parts with identical 51 V zener voltage and ±5% tolerance but increased power dissipation capability (1.5 W instead of 1 W) and improved impedance characteristics (70 Ohms instead of 95 Ohms). These include 1SMA5942BT3G, SMAJ5942B-TP, and SZ1SMA5942BT3G. These parts provide enhanced thermal performance and lower dynamic impedance while maintaining full backward compatibility in the DO-214AC/SMA package.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Temp Range	Package	Automotive Grade
SML4757A-E3/5A	Vishay	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	150°C	DO-214AC	—
SML4757A-E3/61	Vishay	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	150°C	DO-214AC	—
SML4757AHE3_A/H	Vishay	51 V	±5%	1 W	95 Ω	5 µA @ 38.8 V	150°C	DO-214AC	AEC-Q101
SMAJ4757A-TP	Micro Commercial Co	51 V	±5%	1 W	95 Ω	5 µA @ 51 V	-65°C ~ 150°C	DO-214AC	—
1SMA5942BT3G	onsemi	51 V	±5%	1.5 W	70 Ω	500 nA @ 38.8 V	-65°C ~ 150°C	DO-214AC	—
SMAJ5942B-TP	Micro Commercial Co	51 V	±5%	1.5 W	70 Ω	500 nA @ 38.8 V	150°C	DO-214AC	—
SZ1SMA5942BT3G	onsemi	51 V	±5%	1.5 W	70 Ω	500 nA @ 38.8 V	-65°C ~ 150°C	DO-214AC	AEC-Q101

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): Select SML4757A-E3/61 or SML4757AHE3_A/H when exact parametric equivalence to the SML4757A-E3/5A is required. Both parts maintain 51 V zener voltage, ±5% tolerance, 1 W power rating, and 95 Ohms maximum impedance. The SML4757AHE3_A/H variant includes AEC-Q101 automotive qualification and is suitable for automotive applications requiring enhanced reliability standards.

For Alternative Manufacturer Supply: The SMAJ4757A-TP from Micro Commercial Co provides equivalent electrical performance with identical 51 V zener voltage, ±5% tolerance, 1 W power rating, and DO-214AC package. This part extends the operating temperature range to -65°C ~ 150°C and is suitable for applications requiring broader temperature performance.

For Enhanced Thermal Performance: The 1SMA5942BT3G, SMAJ5942B-TP, and SZ1SMA5942BT3G are manufacturer-recommended upgrades offering 1.5 W power dissipation and 70 Ohms maximum impedance compared to the original 1 W and 95 Ohms specifications. These parts maintain the 51 V zener voltage and ±5% tolerance while providing improved thermal characteristics and lower dynamic impedance. The SZ1SMA5942BT3G includes AEC-Q101 automotive qualification for automotive applications.

All substitute parts are ROHS3 compliant, carry Moisture Sensitivity Level 1 (Unlimited), and are classified as Active products. Selection should be based on specific application requirements including thermal dissipation needs, temperature range requirements, and automotive qualification status.

Frequently Asked Questions (FAQ)

Q: Can SML4757A-E3/61 be used as a direct replacement for SML4757A-E3/5A?

A: Yes. Both parts are manufactured by Vishay and share identical electrical specifications: 51 V zener voltage, ±5% tolerance, 1 W power rating, 95 Ohms maximum impedance, and 5 µA reverse leakage current at 38.8 V. The difference in part number suffix reflects manufacturing lot or packaging reel configuration and does not affect electrical performance or compatibility.

Q: What is the difference between SML4757AHE3_A/H and the standard SML4757A-E3/5A?

A: The SML4757AHE3_A/H is an automotive-grade variant with AEC-Q101 qualification. Electrical specifications are identical (51 V, ±5%, 1 W, 95 Ohms impedance). The automotive qualification indicates enhanced reliability testing and traceability suitable for automotive applications. This part is a direct replacement for non-automotive applications and a required upgrade for automotive designs.

Q: Why would I select a 1.5 W zener diode instead of the original 1 W part?

A: The 1.5 W variants (1SMA5942BT3G, SMAJ5942B-TP, SZ1SMA5942BT3G) provide increased thermal dissipation capability and lower dynamic impedance (70 Ohms versus 95 Ohms). These characteristics improve circuit stability and thermal performance in applications with higher power dissipation requirements. The 51 V zener voltage and ±5% tolerance remain identical, ensuring functional compatibility.

Q: Are all substitute parts available in the same DO-214AC package?

A: Yes. All substitute parts listed are packaged in DO-214AC (SMA) format, ensuring mechanical and electrical compatibility with the original SML4757A-E3/5A. This package designation is consistent across all Vishay, Micro Commercial Co, and onsemi variants.

Q: What is the significance of the reverse leakage current difference between 1 W and 1.5 W variants?

A: The 1.5 W variants exhibit lower reverse leakage current (500 nA at 38.8 V) compared to the 1 W original (5 µA at 38.8 V). This represents improved leakage characteristics and indicates enhanced semiconductor material quality. Lower leakage current reduces standby power consumption and improves circuit performance in precision applications.

Q: Can SMAJ4757A-TP from Micro Commercial Co be used in automotive applications?

A: The SMAJ4757A-TP is not automotive-qualified. For automotive applications requiring AEC-Q101 certification, select SML4757AHE3_A/H or SZ1SMA5942BT3G. Both parts carry AEC-Q101 qualification and are suitable for automotive-grade designs.

Q: What is the operating temperature range difference between parts?

A: The original SML4757A-E3/5A and SMAJ5942B-TP are rated to 150°C maximum. The SMAJ4757A-TP, 1SMA5942BT3G, and SZ1SMA5942BT3G extend the lower temperature limit to -65°C, providing -65°C ~ 150°C operating range. This extended range is beneficial for applications exposed to extreme cold environments or requiring broader thermal performance specifications.

Q: Are all parts ROHS3 compliant?

A: Yes. All substitute parts listed are ROHS3 compliant and carry Moisture Sensitivity Level 1 (Unlimited), indicating no moisture sensitivity restrictions during storage or handling. All parts are REACH unaffected and classified under ECCN EAR99.

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