3KASMC40HE3_A/I Equivalent & Substitute Parts

Part Overview

The 3KASMC40HE3_A/I is a unidirectional transient voltage suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division, rated for 40V reverse standoff voltage with a 71.4V maximum clamping voltage. This component is designed for surface mount applications in the DO-214AB (SMC) package and operates across an automotive temperature range of -65°C to 185°C. The part is currently listed as obsolete, making equivalent substitutes necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	40V
Voltage - Breakdown (Min)	44.4V
Voltage - Clamping (Max) @ Ipp	71.4V
Current - Peak Pulse (10/1000µs)	42A
Power - Peak Pulse	3000W
Package / Case	DO-214AB, SMC
Operating Temperature	-65°C ~ 185°C (TJ)
Grade	Automotive
Qualification	AEC-Q101
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the 3KASMC40HE3_A/I is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Critical Parameters for Substitution:

Voltage - Reverse Standoff: 40V (exact match required)
Voltage - Breakdown (Min): 44.4V (exact match required)
Package / Case: DO-214AB, SMC (mechanical compatibility)
Unidirectional Channels: 1 (functional equivalence)
Type: Zener (device classification)

Secondary Parameters Allowing Variation:

Voltage - Clamping (Max) @ Ipp: 64.5V to 84V (acceptable range for transient suppression)
Current - Peak Pulse: 23.2A to 119A (dependent on power dissipation requirements)
Power - Peak Pulse: 1500W to 5000W (application-dependent)
Operating Temperature: -55°C to 185°C (application-dependent, with -65°C minimum preferred for automotive)

Substitute parts are grouped by their ability to maintain the 40V standoff and 44.4V minimum breakdown voltage while accommodating variations in clamping voltage and peak pulse current based on specific circuit requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package	Operating Temperature	Product Status
3KASMC40HE3_A/I	Vishay	40V	44.4V	71.4V	42A	3000W	DO-214AB (SMCJ)	-65°C ~ 185°C	Obsolete
3KASMC40AHE3_B/I	Vishay	40V	44.4V	64.5V	46.5A	3000W	DO-214AB (SMC)	-65°C ~ 185°C	Active
SMLJ40E3/TR13	Microchip Technology	40V	44.4V	71.4V	42A	300W	DO-214AB (SMC)	-55°C ~ 150°C	Active
5.0SMDJ40A	Taiwan Semiconductor Corporation	40V	44.4V	64.5V	77.6A	5000W	DO-214AB (SMC)	-55°C ~ 175°C	Active
SMCJ40A	Meritek	40V	44.4V	64.5V	23.26A	1500W	DO-214AB (SMC)	-55°C ~ 150°C	Active
SMCJ40A-13-F	Diodes Incorporated	40V	44.4V	64.5V	23.2A	1500W	DO-214AB (SMC)	-55°C ~ 150°C	Active
SMCJ40A-TR	STMicroelectronics	40V	44.4V	84V	119A (8/20µs)	1500W	DO-214AB (SMC)	-55°C ~ 150°C	Active
SMDJ40A	Alpha & Omega Semiconductor Inc.	40V	44.4V	64.5V	46.6A	3000W	DO-214AB (SMC)	-55°C ~ 150°C	Active
SMDJ40A-T7	Littelfuse Inc.	40V	44.4V	64.5V	46.5A	3000W	DO-214AB (SMCJ)	-65°C ~ 150°C	Active

Engineering Selection Recommendations

Primary Substitute (Closest Match): The 3KASMC40AHE3_B/I from Vishay is the primary substitute. It maintains identical voltage specifications (40V standoff, 44.4V breakdown), operates across the same automotive temperature range (-65°C to 185°C), carries AEC-Q101 qualification, and is currently in active production status. The clamping voltage is reduced to 64.5V with increased peak pulse current to 46.5A, both acceptable variations for transient suppression applications.

Secondary Substitutes (Electrical Equivalence with Temperature Constraints): The SMDJ40A-T7 from Littelfuse maintains the -65°C lower temperature limit and provides 3000W peak pulse power matching the original specification. Operating temperature range is -65°C to 150°C, which is acceptable for most automotive applications. The SMDJ40A from Alpha & Omega Semiconductor provides identical 3000W power rating with 46.6A peak pulse current but operates only to -55°C minimum.

Alternative Substitutes (Reduced Temperature Range): The SMCJ40A-13-F from Diodes Incorporated and SMCJ40A from Meritek provide active production status with reduced power dissipation (1500W) and lower peak pulse current (23.2A to 23.26A). These are suitable for applications with lower transient energy requirements. Operating temperature range is -55°C to 150°C.

High-Power Alternative: The 5.0SMDJ40A from Taiwan Semiconductor Corporation offers the highest power dissipation capability (5000W) with 77.6A peak pulse current, suitable for high-energy transient suppression. Operating temperature range is -55°C to 175°C.

Not Recommended: The SMLJ40E3/TR13 from Microchip Technology exhibits significantly reduced power dissipation (300W) compared to the original 3000W specification, making it unsuitable as a direct substitute for applications requiring the full power rating.

Frequently Asked Questions (FAQ)

Q: Can I use SMCJ40A-TR as a direct replacement for 3KASMC40HE3_A/I? A: SMCJ40A-TR maintains the required 40V standoff and 44.4V breakdown voltage in the DO-214AB package. However, the clamping voltage is elevated to 84V with peak pulse current of 119A (8/20µs), and the operating temperature range is limited to -55°C to 150°C. This part is suitable only if your circuit design accommodates the higher clamping voltage and does not require operation below -55°C.

Q: What is the difference between the clamping voltage variations in the substitute parts? A: Clamping voltage determines the maximum voltage transient suppression level. The original part clamps at 71.4V. Substitutes range from 64.5V to 84V. Lower clamping voltages (64.5V) provide tighter transient suppression; higher clamping voltages (84V) allow larger transient peaks. Selection depends on your circuit's transient voltage tolerance.

Q: Why do some substitutes have lower power ratings? A: Power dissipation capability (1500W vs. 3000W vs. 5000W) reflects the device's ability to absorb transient energy. Lower-rated parts are suitable for circuits with lower transient energy content. If your application requires 3000W dissipation, select substitutes rated for 3000W or higher.

Q: Is the DO-214AB package the same across all substitutes? A: Yes. All listed substitutes use the DO-214AB (SMC) package, ensuring mechanical and footprint compatibility. Some manufacturers designate this package as SMCJ or SMC, but these refer to the same physical package.

Q: Which substitute is best for automotive applications requiring -65°C operation? A: The 3KASMC40AHE3_B/I and SMDJ40A-T7 both support -65°C minimum operating temperature. The 3KASMC40AHE3_B/I is preferred as it maintains the full -65°C to 185°C range and carries AEC-Q101 qualification identical to the original part.

Q: Are all substitutes RoHS3 compliant? A: Yes. All listed substitute parts are RoHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

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