1SMA4751 Zener Diode Equivalent & Substitute Parts

Part Overview

The 1SMA4751 is a 30 V, 1.25 W surface mount zener diode manufactured by Taiwan Semiconductor Corporation in the DO-214AC (SMA) package. This component is classified as Active and maintains full RoHS3 compliance with unlimited moisture sensitivity rating (MSL 1). The 1SMA4751 serves as a voltage regulation and transient protection element in electronic circuits requiring precise 30 V zener reference characteristics.

Substitute parts become necessary when the primary part number experiences inventory constraints, supply chain discontinuation, or when alternative manufacturers' specifications align with application requirements while maintaining electrical and mechanical compatibility.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	30	V
Tolerance	±5	%
Power - Max	1.25	W
Impedance (Max)	40	Ohms
Current - Reverse Leakage @ Vr	1	µA @ 22.8 V
Operating Temperature Range	-55 to 175	°C (TJ)
Mounting Type	Surface Mount
Package / Case	DO-214AC, SMA
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the 1SMA4751 is determined by the following critical parameters:

Primary Matching Criteria:

Voltage - Zener (Nom): 30 V (exact match required)
Tolerance: ±5% (exact match required)
Package / Case: DO-214AC, SMA (exact match required)
Mounting Type: Surface Mount (exact match required)
RoHS Status: ROHS3 Compliant (exact match required)

Secondary Compatibility Parameters:

Power - Max: 1.25 W or greater
Impedance (Max): 40 Ohms or lower
Current - Reverse Leakage @ Vr: 1 µA @ 22.8 V or lower
Operating Temperature Range: Must encompass or exceed -55°C to 175°C

Substitute parts are grouped into two categories:

Parametric Equivalents: Parts with identical electrical specifications and packaging, differing only in packaging format (tape, reel, or cut tape configuration) or manufacturer designation.

Similar Parts: Parts meeting all primary matching criteria with variations in secondary parameters. These parts maintain functional compatibility while offering different power ratings, impedance characteristics, or temperature ranges.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Impedance (Max)	Reverse Leakage @ Vr	Temp Range	Package	Status
1SMA4751	Taiwan Semiconductor Corporation	30 V	±5%	1.25 W	40 Ohms	1 µA @ 22.8 V	-55 to 175°C	DO-214AC (SMA)	Active
1SMA4751 R3G	Taiwan Semiconductor Corporation	30 V	±5%	1.25 W	40 Ohms	1 µA @ 22.8 V	-55 to 175°C	DO-214AC (SMA)	Discontinued at DiGi Electronics
1SMA5936BT3G	onsemi	30 V	±5%	1.5 W	26 Ohms	500 nA @ 22.8 V	-65 to 150°C	DO-214AC (SMA)	Active
3SMAJ5936B-TP	Micro Commercial Co	30 V	±5%	3 W	28 Ohms	1 µA @ 22.8 V	-55 to 150°C	DO-214AC (SMA)	Active
SMAZ30-TP	Micro Commercial Co	30 V	±5%	1 W	15 Ohms	500 nA @ 22.8 V	-65 to 150°C	DO-214AC (SMA)	Active
SZ1SMA5936BT3G	onsemi	30 V	±5%	1.5 W	26 Ohms	500 nA @ 22.8 V	-65 to 150°C	DO-214AC (SMA)	Active

Engineering Selection Recommendations

Direct Parametric Equivalent:

The 1SMA4751 R3G is a parametric equivalent manufactured by Taiwan Semiconductor Corporation with identical electrical specifications and package configuration. However, this part is discontinued at DiGi Electronics and should not be selected for new designs or long-term supply requirements.

Active Substitutes with Enhanced Performance:

The 1SMA5936BT3G (onsemi) and SZ1SMA5936BT3G (onsemi) both provide 1.5 W power rating compared to the 1.25 W specification of the 1SMA4751, with improved impedance characteristics (26 Ohms versus 40 Ohms) and lower reverse leakage current (500 nA versus 1 µA). Both parts maintain Active product status and full RoHS3 compliance. The SZ1SMA5936BT3G carries AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade reliability.

Higher Power Alternative:

The 3SMAJ5936B-TP (Micro Commercial Co) offers 3 W power dissipation capacity with improved impedance (28 Ohms) and maintains the same reverse leakage specification as the original part. This part is suitable for applications requiring enhanced thermal performance or higher transient energy absorption.

Lower Power Alternative:

The SMAZ30-TP (Micro Commercial Co) provides 1 W power rating with superior impedance characteristics (15 Ohms) and lower reverse leakage (500 nA). This part is appropriate for applications with reduced power dissipation requirements or where lower impedance is beneficial.

All substitute parts maintain RoHS3 compliance, MSL 1 rating, and surface mount DO-214AC (SMA) package compatibility with the original 1SMA4751.

Frequently Asked Questions (FAQ)

Q: Can the 1SMA5936BT3G directly replace the 1SMA4751 in my circuit?

A: Yes. The 1SMA5936BT3G maintains the same 30 V zener voltage, ±5% tolerance, DO-214AC (SMA) package, and surface mount configuration. The increased power rating (1.5 W versus 1.25 W) and improved impedance (26 Ohms versus 40 Ohms) provide enhanced performance margins without affecting circuit functionality.

Q: What is the difference between 1SMA5936BT3G and SZ1SMA5936BT3G?

A: Both parts are manufactured by onsemi with identical electrical specifications: 30 V zener voltage, 1.5 W power rating, 26 Ohms impedance, and DO-214AC (SMA) package. The SZ1SMA5936BT3G carries AEC-Q101 automotive qualification and is designated for automotive applications. Select SZ1SMA5936BT3G for automotive or mission-critical applications requiring automotive-grade reliability.

Q: Why would I select the 3SMAJ5936B-TP over the 1SMA4751?

A: The 3SMAJ5936B-TP provides triple the power dissipation capacity (3 W versus 1.25 W) with improved impedance (28 Ohms versus 40 Ohms). Select this part when circuit design requires higher transient energy absorption, enhanced thermal performance, or when operating conditions approach the power limits of the original specification.

Q: Is the SMAZ30-TP suitable as a substitute?

A: The SMAZ30-TP meets all primary matching criteria with 30 V zener voltage, ±5% tolerance, and DO-214AC (SMA) package. However, the 1 W power rating is lower than the 1.25 W specification of the original part. This substitute is appropriate only when circuit design confirms that power dissipation remains below 1 W under all operating conditions.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain RoHS3 compliance and MSL 1 (unlimited) moisture sensitivity rating, matching the environmental and regulatory status of the original 1SMA4751.

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

A: Impedance (Zzt) affects the dynamic response of the zener diode during transient voltage events. Lower impedance values (such as 15 Ohms in SMAZ30-TP or 26 Ohms in 1SMA5936BT3G) provide faster voltage regulation response compared to the original 40 Ohms specification. Higher impedance does not affect substitution eligibility but may result in slower transient response.

Q: Can I use 1SMA4751 R3G as a substitute?

A: The 1SMA4751 R3G is a parametric equivalent with identical specifications. However, this part is discontinued at DiGi Electronics and should not be selected for new designs or applications requiring long-term supply availability.

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