3KASMC18AHE3_A/I Transient Voltage Suppressor Diode - Equivalent & Substitute Parts

Part Overview

The 3KASMC18AHE3_A/I is an 18V Zener transient voltage suppressor diode manufactured by Vishay General Semiconductor - Diodes Division, designed for surface mount applications in the DO-214AB (SMC) package. This unidirectional TVS diode provides 29.2V clamping voltage with 103A peak pulse current capability and 3000W peak pulse power dissipation. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	20	V
Voltage - Clamping (Max) @ Ipp	29.2	V
Current - Peak Pulse (10/1000µs)	103	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-65 to 185	°C (TJ)
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Grade	Automotive	—
Qualification	AEC-Q101	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the 3KASMC18AHE3_A/I is determined by strict electrical and mechanical parameter matching:

Critical Matching Parameters:

Voltage - Reverse Standoff: 18V (±tolerance)
Voltage - Clamping (Max) @ Ipp: 29.2V
Package / Case: DO-214AB, SMC
Mounting Type: Surface Mount
Unidirectional Channels: 1

Acceptable Variation Parameters:

Current - Peak Pulse (10/1000µs): Minimum 103A (higher values acceptable for enhanced performance)
Power - Peak Pulse: Minimum 3000W (higher values acceptable)
Operating Temperature Range: Minimum -65°C to 150°C (wider ranges acceptable)
Product Status: Active preferred over obsolete

Substitute parts are grouped into two categories: direct electrical equivalents with identical or superior electrical specifications, and functional alternatives that meet the core voltage and package requirements while offering enhanced current handling or power dissipation capabilities.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Clamping (Max) @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temperature (°C)	Package	Product Status
3KASMC18AHE3_A/I	Vishay General Semiconductor	18	29.2	103	3000	-65 to 185	DO-214AB, SMC	Obsolete
3KASMC18AHE3_B/I	Vishay General Semiconductor	18	29.2	103	3000	-65 to 185	DO-214AB, SMC	Active
SMC30J18A	STMicroelectronics	18	29.2	103	3000	-55 to 175	DO-214AB, SMC	Active
5.0SMDJ18A	Taiwan Semiconductor Corporation	18	29.2	172	5000	-55 to 175	DO-214AB, SMC	Active
SMCJ18A	MDD	18	29.2	51.4	1500	-50 to 150	DO-214AB, SMC	Active
SMCJ18A-HR	Littelfuse Inc.	18	29.2	51.4	1500	-65 to 150	DO-214AB, SMC	Active
SMCJ18A-HRA	Littelfuse Inc.	18	29.2	51.4	1500	-65 to 150	DO-214AB, SMC	Active
SMCJ16A	EVVO Semi	16	26	57.7	600	-65 to 150	DO-214AC, SMA	Active

Engineering Selection Recommendations

Tier 1 - Direct Replacement (Recommended): The 3KASMC18AHE3_B/I from Vishay General Semiconductor is the primary substitute. It maintains identical electrical specifications (18V standoff, 29.2V clamping, 103A peak pulse, 3000W power) and package configuration (DO-214AB, SMC) while offering active product status. This part preserves the automotive grade and AEC-Q101 qualification of the original design.

Tier 2 - Electrical Equivalents with Enhanced Performance: The SMC30J18A (STMicroelectronics) and 5.0SMDJ18A (Taiwan Semiconductor Corporation) provide identical voltage parameters and package compatibility. The 5.0SMDJ18A offers superior current handling (172A vs. 103A) and power dissipation (5000W vs. 3000W), suitable for applications requiring enhanced transient protection margins. Both parts maintain ROHS3 compliance and are actively produced.

Tier 3 - Functional Alternatives: The SMCJ18A variants (MDD, Littelfuse SMCJ18A-HR, Littelfuse SMCJ18A-HRA) meet voltage and package requirements but provide reduced peak pulse current (51.4A) and power dissipation (1500W). These are suitable only for applications where the original 103A specification is not a design requirement. Littelfuse variants maintain the -65°C lower temperature limit of the original part.

Not Recommended: The SMCJ16A (EVVO Semi) does not meet substitution criteria. It specifies 16V standoff voltage and 26V clamping voltage, deviating from the required 18V/29.2V parameters. Additionally, it uses the DO-214AC (SMA) package, which is mechanically incompatible with the DO-214AB (SMC) footprint.

Frequently Asked Questions (FAQ)

Q: Can the 3KASMC18AHE3_B/I directly replace the obsolete 3KASMC18AHE3_A/I? A: Yes. The 3KASMC18AHE3_B/I is the direct successor from the same manufacturer with identical electrical specifications and package configuration. The only difference is product status (Active vs. Obsolete) and packaging format (Tape & Reel vs. bulk).

Q: What is the difference between the 3KASMC18AHE3_B/I and the 5.0SMDJ18A? A: Both maintain the required 18V standoff and 29.2V clamping voltages in the DO-214AB (SMC) package. The 5.0SMDJ18A provides higher peak pulse current (172A vs. 103A) and power dissipation (5000W vs. 3000W), offering enhanced transient protection capability. Selection depends on whether the application requires the additional performance margin.

Q: Why is the SMCJ16A not suitable as a substitute? A: The SMCJ16A specifies 16V reverse standoff voltage and 26V clamping voltage, which do not match the required 18V/29.2V parameters. Additionally, it uses the DO-214AC (SMA) package, which has a different footprint than the required DO-214AB (SMC) package and is not mechanically compatible.

Q: Are the Littelfuse SMCJ18A-HR and SMCJ18A-HRA interchangeable? A: Both parts meet the voltage and package requirements with identical electrical specifications. They are functionally interchangeable for applications where 51.4A peak pulse current and 1500W power dissipation are sufficient. The -HR and -HRA designations indicate different internal construction or qualification variants from Littelfuse.

Q: What is the impact of using a substitute with lower peak pulse current, such as the SMCJ18A (51.4A vs. 103A)? A: The SMCJ18A provides half the peak pulse current capability. This is acceptable only if the application's transient energy profile does not exceed the reduced specification. For designs originally specified with 103A capability, using a 51.4A part may result in inadequate protection during high-energy transient events.

Q: Can I use the 5.0SMDJ18A in place of the original part if my application has higher transient energy requirements? A: Yes. The 5.0SMDJ18A maintains the required voltage parameters and package compatibility while providing superior current handling (172A) and power dissipation (5000W). This part is suitable for applications with enhanced transient protection requirements or higher energy transient environments.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance, consistent with the original 3KASMC18AHE3_A/I specification.

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