3SMAJ5940B-TP Equivalent & Substitute Parts

Part Overview

The 3SMAJ5940B-TP is a surface mount Zener diode manufactured by Micro Commercial Co, rated at 43 V nominal Zener voltage with 3 W maximum power dissipation in a DO-214AC (SMA) package. This component is classified as Active product status and is RoHS3 compliant. Equivalent and substitute parts are identified based on matching electrical specifications including Zener voltage, tolerance, forward voltage characteristics, and thermal operating range, while accounting for variations in maximum power rating and impedance that may affect circuit performance in specific applications.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	43	V
Tolerance	±5%	%
Power - Max	3	W
Impedance (Max)	53	Ohms
Voltage - Forward (Max) @ If	1.5 V @ 200 mA	V
Operating Temperature Range	-55 to 150	°C
Package / Case	DO-214AC, SMA	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the 3SMAJ5940B-TP is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage (Nom): 43 V
Tolerance: ±5%
Package / Case: DO-214AC, SMA
Mounting Type: Surface Mount
RoHS Status: ROHS3 Compliant

Secondary Consideration Parameters:

Power - Max: Substitutes with lower power ratings (1.5 W or 1 W) are acceptable only in applications where the circuit does not require the full 3 W dissipation capability
Impedance (Max): Variations in impedance affect transient response and regulation characteristics
Operating Temperature Range: Substitutes with narrower or different temperature ranges must be evaluated against application requirements
Current - Reverse Leakage: Variations affect standby current and leakage performance

The three identified substitute parts maintain the core electrical specifications (43 V Zener voltage, ±5% tolerance, SMA package) while differing in power rating, impedance, and thermal characteristics. Selection depends on whether the application circuit can operate within the reduced power dissipation limits of the substitute devices.

Parameter Comparison

Parameter	3SMAJ5940B-TP (Main)	1SMA5940BT3G	SML4755A-E3/61	SZ1SMA5940BT3G
Manufacturer	Micro Commercial Co	onsemi	Vishay General Semiconductor - Diodes Division	onsemi
Voltage - Zener (Nom)	43 V	43 V	43 V	43 V
Tolerance	±5%	±5%	±5%	±5%
Power - Max	3 W	1.5 W	1 W	1.5 W
Impedance (Max)	53 Ohms	53 Ohms	70 Ohms	53 Ohms
Current - Reverse Leakage @ Vr	1 µA @ 32.7 V	500 nA @ 32.7 V	5 µA @ 32.7 V	500 nA @ 32.7 V
Voltage - Forward (Max) @ If	1.5 V @ 200 mA	1.5 V @ 200 mA	Not specified	1.5 V @ 200 mA
Operating Temperature Range	-55 to 150 °C	-65 to 150 °C	150 °C (max only)	-65 to 150 °C
Package / Case	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Active	Active	Active	Active
Grade / Qualification	—	—	—	Automotive / AEC-Q101

Engineering Selection Recommendations

1SMA5940BT3G (onsemi)

This substitute is electrically equivalent to the 3SMAJ5940B-TP in Zener voltage, tolerance, impedance, and forward voltage characteristics. The primary difference is reduced maximum power dissipation (1.5 W versus 3 W). This part is suitable for applications where circuit design limits current through the Zener diode to levels compatible with 1.5 W dissipation. The operating temperature range extends to -65°C, providing broader low-temperature coverage. All compliance certifications (RoHS3, REACH Unaffected, MSL 1) are equivalent.

SML4755A-E3/61 (Vishay General Semiconductor - Diodes Division)

This substitute maintains the 43 V Zener voltage and ±5% tolerance but has the lowest maximum power rating (1 W) and highest impedance (70 Ohms) among the identified substitutes. The impedance increase affects transient response and regulation performance. Reverse leakage current is higher at 5 µA. Operating temperature specification is provided as maximum only (150°C), without a minimum temperature rating. This part is suitable only for low-power applications with minimal transient current requirements. All compliance certifications are equivalent.

SZ1SMA5940BT3G (onsemi)

This substitute is electrically equivalent to the 3SMAJ5940B-TP across all primary parameters: Zener voltage, tolerance, impedance, forward voltage, and reverse leakage. Maximum power dissipation is 1.5 W. This part carries automotive grade qualification (AEC-Q101), making it suitable for automotive applications requiring enhanced reliability and traceability. Operating temperature range is -65 to 150°C. All compliance certifications are equivalent.

Frequently Asked Questions (FAQ)

Q: Can I use a 1.5 W substitute in place of the 3 W 3SMAJ5940B-TP?

A: Yes, provided the circuit design ensures that the Zener diode current remains within limits that produce dissipation below 1.5 W. The 1.5 W substitutes (1SMA5940BT3G and SZ1SMA5940BT3G) are electrically equivalent in voltage regulation and impedance characteristics. If the application requires full 3 W dissipation capability, a 1.5 W substitute will overheat and fail.

Q: What is the impact of impedance variation between 53 Ohms and 70 Ohms?

A: Impedance affects the Zener diode's transient response and dynamic regulation. The SML4755A-E3/61 with 70 Ohms impedance exhibits slower response to current transients compared to the 53 Ohms devices. In applications with fast-changing load currents or high-frequency noise filtering, the higher impedance may result in reduced regulation performance.

Q: Are all substitutes pin-compatible with the 3SMAJ5940B-TP?

A: Yes. All identified substitutes use the DO-214AC (SMA) surface mount package with identical pin configuration and footprint. Direct PCB replacement is possible without layout modification.

Q: What is the difference between 1SMA5940BT3G and SZ1SMA5940BT3G?

A: Both parts are manufactured by onsemi with identical electrical specifications (43 V, 1.5 W, 53 Ohms impedance). The SZ1SMA5940BT3G carries automotive grade qualification (AEC-Q101) and is intended for automotive applications. The 1SMA5940BT3G is the standard industrial version. Selection depends on application requirements for automotive certification.

Q: Does the SML4755A-E3/61 have a specified minimum operating temperature?

A: The provided data specifies only the maximum operating temperature (150°C) for the SML4755A-E3/61. The minimum operating temperature is not provided. This incomplete specification requires clarification from the manufacturer before use in applications requiring low-temperature operation below 0°C.

Q: Are all substitutes RoHS3 compliant?

A: Yes. All identified substitutes (1SMA5940BT3G, SML4755A-E3/61, and SZ1SMA5940BT3G) are RoHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level, matching the compliance profile of the 3SMAJ5940B-TP.

Q: Which substitute should I select for automotive applications?

A: The SZ1SMA5940BT3G is qualified to AEC-Q101 automotive standard and is the appropriate choice for automotive applications. This part maintains electrical equivalence with the main part while providing automotive-grade reliability and traceability.

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