3KASMC18HE3_A/I Equivalent & Substitute Parts

Part Overview

The 3KASMC18HE3_A/I is an 18V Transient Voltage Suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division, housed in a DO-214AB (SMCJ) surface mount package. This unidirectional Zener diode is designed for transient voltage protection with a peak pulse power rating of 3000W and peak pulse current of 93.2A. The part is classified as Obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	18V
Voltage - Breakdown (Min)	20V
Voltage - Clamping (Max) @ Ipp	32.2V
Current - Peak Pulse (10/1000µs)	93.2A
Power - Peak Pulse	3000W
Operating Temperature Range	-65°C ~ 185°C (TJ)
Package / Case	DO-214AB, SMC
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Grade	Automotive
Qualification	AEC-Q101

Substitute Part Grouping Explanation

Substitution eligibility for the 3KASMC18HE3_A/I is determined by the following critical parameters:

Voltage - Reverse Standoff: 18V (primary voltage rating)
Voltage - Breakdown (Min): 20V (minimum trigger threshold)
Package / Case: DO-214AB, SMC (mechanical and thermal compatibility)
Mounting Type: Surface Mount (assembly compatibility)
Unidirectional Channels: 1 (functional topology)
Type: Zener (diode classification)

Substitute parts must maintain the 18V standoff voltage and 20V minimum breakdown voltage to ensure circuit protection performance. Package compatibility (DO-214AB/SMC) is mandatory for PCB assembly without redesign. Operating temperature range, power rating, and peak pulse current may vary within acceptable limits for the application, but voltage parameters are non-negotiable.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Package	Product Status
3KASMC18HE3_A/I	Vishay	18V	20V	32.2V	93.2A	3000W	-65°C ~ 185°C	DO-214AB (SMCJ)	Obsolete
3KASMC18AHE3_B/I	Vishay	18V	20V	29.2V	103A	3000W	-65°C ~ 185°C	DO-214AB (SMC)	Active
SMLJ18E3/TR13	Microchip Technology	18V	20V	32.2V	93.2A	300W	-55°C ~ 150°C	DO-214AB (SMC)	Active
5.0SMDJ18A	Taiwan Semiconductor Corporation	18V	20V	29.2V	172A	5000W	-55°C ~ 175°C	DO-214AB (SMC)	Active
SMCJ18A	MDD	18V	20V	29.2V	51.4A	1500W	-50°C ~ 150°C	DO-214AB (SMC)	Active
SMCJ18A-HR	Littelfuse Inc.	18V	20V	29.2V	51.4A	1500W	-65°C ~ 150°C	DO-214AB (SMCJ)	Active
SMCJ18A-HRA	Littelfuse Inc.	18V	20V	29.2V	51.4A	1500W	-65°C ~ 150°C	DO-214AB (SMCJ)	Active

Engineering Selection Recommendations

Primary Substitute: 3KASMC18AHE3_B/I (Vishay)

This part is the direct successor from the original manufacturer. It maintains identical voltage specifications (18V standoff, 20V breakdown) and package format (DO-214AB/SMC). Both parts carry Automotive grade and AEC-Q101 qualification. The clamping voltage is slightly lower (29.2V vs 32.2V), and peak pulse current is higher (103A vs 93.2A), providing enhanced transient suppression capability. Operating temperature range remains -65°C ~ 185°C. This is the recommended first choice for direct replacement.

Alternative Substitute: 5.0SMDJ18A (Taiwan Semiconductor Corporation)

This part maintains the critical 18V standoff and 20V breakdown voltages with DO-214AB/SMC package compatibility. It offers superior peak pulse power rating (5000W vs 3000W) and higher peak pulse current (172A vs 93.2A), providing additional margin for transient protection. Operating temperature range is -55°C ~ 175°C. This option is suitable for applications requiring enhanced surge protection capability.

Secondary Substitute: SMCJ18A-HR or SMCJ18A-HRA (Littelfuse Inc.)

Both parts maintain the 18V standoff and 20V breakdown specifications with DO-214AB/SMCJ package compatibility. Operating temperature extends to -65°C, matching the original part. Peak pulse power is 1500W with 51.4A peak pulse current, representing a lower-power alternative suitable for applications with reduced transient stress. These parts are Active status with established supply availability.

Not Recommended: SMCJ16A (EVVO Semi)

This part has a 16V standoff voltage and 17.8V minimum breakdown voltage, which do not meet the 18V/20V specification requirement. Package is DO-214AC/SMA, incompatible with the original DO-214AB/SMC footprint. This part is unsuitable for direct substitution.

Not Recommended: SMLJ18E3/TR13 (Microchip Technology)

While voltage specifications match (18V standoff, 20V breakdown, 32.2V clamping), the peak pulse power rating is only 300W compared to the original 3000W. Operating temperature range is limited to -55°C ~ 150°C, below the original -65°C ~ 185°C specification. This part is unsuitable for applications requiring the full 3000W transient protection capability.

Frequently Asked Questions (FAQ)

Q: Can I use SMCJ18A (MDD) as a direct replacement for 3KASMC18HE3_A/I?

A: SMCJ18A maintains the critical voltage specifications (18V standoff, 20V breakdown) and DO-214AB/SMC package compatibility. However, the peak pulse power rating is 1500W versus the original 3000W, and operating temperature range is -50°C ~ 150°C versus -65°C ~ 185°C. This part is suitable only if your application does not require the full 3000W transient protection capability and operates within the -50°C ~ 150°C temperature range.

Q: What is the difference between 3KASMC18AHE3_B/I and 5.0SMDJ18A?

A: Both parts maintain the required 18V standoff and 20V breakdown voltages with DO-214AB/SMC package compatibility. The 3KASMC18AHE3_B/I is the direct Vishay successor with Automotive grade and AEC-Q101 qualification, matching the original part's certifications. The 5.0SMDJ18A offers higher peak pulse power (5000W vs 3000W) and current (172A vs 103A), providing additional transient suppression margin. Choose 3KASMC18AHE3_B/I for direct replacement; choose 5.0SMDJ18A for enhanced protection.

Q: Why is SMCJ16A not suitable as a substitute?

A: SMCJ16A has a 16V standoff voltage and 17.8V minimum breakdown voltage, which fall below the required 18V/20V specification. Additionally, the package is DO-214AC/SMA, which is mechanically incompatible with the original DO-214AB/SMC footprint. This part cannot provide equivalent circuit protection and requires PCB redesign.

Q: Are Littelfuse SMCJ18A-HR and SMCJ18A-HRA interchangeable?

A: Both parts have identical electrical specifications (18V standoff, 20V breakdown, 29.2V clamping, 51.4A peak pulse current, 1500W power) and package format (DO-214AB/SMCJ). They are functionally interchangeable. The designation difference (-HR vs -HRA) reflects internal manufacturing or qualification variants from Littelfuse but does not affect electrical performance or compatibility.

Q: Does operating temperature range affect substitution eligibility?

A: Operating temperature range is a secondary consideration for substitution. The primary criteria are voltage specifications (18V standoff, 20V breakdown) and package compatibility (DO-214AB/SMC). If your circuit operates within the substitute part's temperature range, it is acceptable. If your application requires the original -65°C ~ 185°C range, select 3KASMC18AHE3_B/I or SMCJ18A-HR/SMCJ18A-HRA, which extend to -65°C.

Q: Can I use a higher power-rated part like 5.0SMDJ18A in place of the original 3000W part?

A: Yes. A higher power-rated part (5.0SMDJ18A at 5000W) provides additional transient suppression margin and is electrically compatible if voltage specifications and package format match. This is a conservative design choice that enhances circuit protection without introducing compatibility issues.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message