3KASMC12AHM3_A/I Equivalent & Substitute Parts

Part Overview

The 3KASMC12AHM3_A/I is a unidirectional transient voltage suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division, designed for surface mount applications in the DO-214AB (SMC) package. This component operates with a 12V reverse standoff voltage and provides 19.9V maximum clamping voltage at peak pulse current of 151A, delivering 3000W peak pulse power dissipation. The part is qualified to AEC-Q101 automotive standards and operates across -65°C to 185°C junction temperature range. Currently listed as obsolete, equivalent substitute parts with active product status are available to maintain design continuity and ensure supply chain reliability.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	12V
Voltage - Breakdown (Min)	13.3V
Voltage - Clamping (Max) @ Ipp	19.9V
Current - Peak Pulse (10/1000µs)	151A
Power - Peak Pulse	3000W
Package / Case	DO-214AB, SMC
Operating Temperature Range	-65°C ~ 185°C (TJ)
Type	Zener
Unidirectional Channels	1
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the 3KASMC12AHM3_A/I is determined by strict alignment of the following electrical and mechanical parameters:

Critical Matching Parameters:

Voltage - Reverse Standoff: 12V
Voltage - Breakdown (Min): 13.3V
Voltage - Clamping (Max) @ Ipp: 19.9V
Package / Case: DO-214AB, SMC
Unidirectional Channels: 1
Mounting Type: Surface Mount
Type: Zener

Allowable Variation Parameters:

Current - Peak Pulse (10/1000µs): Substitute parts may exceed 151A (higher current capability is acceptable)
Power - Peak Pulse: Substitute parts may exceed 3000W (higher power rating is acceptable)
Operating Temperature Range: Substitute parts may have narrower or equivalent ranges
Product Status: Active status preferred over obsolete

All substitute parts listed maintain identical voltage specifications and package form factor, ensuring direct electrical and mechanical compatibility. Variations in peak pulse current and power dissipation represent enhanced or equivalent performance characteristics.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package	Operating Temperature	Product Status
3KASMC12AHM3_A/I	Vishay	12V	19.9V	151A	3000W	DO-214AB (SMCJ)	-65°C ~ 185°C	Obsolete
3KASMC12AHM3_B/I	Vishay	12V	19.9V	151A	3000W	DO-214AB (SMC)	-65°C ~ 185°C	Active
SMC30J12A	STMicroelectronics	12V	19.9V	151A	3000W	DO-214AB (SMC)	-55°C ~ 175°C	Active
5.0SMDJ12A	HY Electronic (Cayman) Limited	12V	19.9V	252A	5000W	DO-214AB (SMCJ)	-65°C ~ 150°C	Active
SMCJ12A	MDD	12V	19.9V	75.4A	1500W	DO-214AB (SMC)	-50°C ~ 150°C	Active
SMCJ12A-HR	Littelfuse Inc.	12V	19.9V	75.4A	1500W	DO-214AB (SMCJ)	-65°C ~ 150°C	Active
SMCJ12A-HRA	Littelfuse Inc.	12V	19.9V	75.4A	1500W	DO-214AB (SMCJ)	-65°C ~ 150°C	Active
SMCJ12A-HRAT7	Littelfuse Inc.	12V	19.9V	75.4A	1500W	DO-214AB (SMCJ)	-65°C ~ 150°C	Active

Engineering Selection Recommendations

Direct Replacement (Highest Compatibility): The 3KASMC12AHM3_B/I from Vishay is the direct successor to the obsolete 3KASMC12AHM3_A/I, maintaining identical electrical specifications and operating temperature range while offering active product status. Both parts carry AEC-Q101 automotive qualification and ROHS3 compliance.

Equivalent Performance (Matching Voltage & Package): The SMC30J12A from STMicroelectronics provides identical voltage and clamping specifications with equivalent peak pulse current and power ratings. Operating temperature range is narrower (-55°C to 175°C versus -65°C to 185°C), which may be acceptable depending on application requirements. Active product status and ROHS3 compliance are confirmed.

Enhanced Performance (Higher Current/Power Capability): The 5.0SMDJ12A from HY Electronic (Cayman) Limited exceeds the original specifications with 252A peak pulse current and 5000W power dissipation, providing design margin for transient protection. Voltage specifications remain identical. Operating temperature maximum is reduced to 150°C. REACH status is affected; verify regulatory compliance for your application.

Reduced Performance (Lower Current/Power Rating): SMCJ12A variants from MDD and Littelfuse Inc. (SMCJ12A-HR, SMCJ12A-HRA, SMCJ12A-HRAT7) maintain identical voltage specifications but provide 75.4A peak pulse current and 1500W power dissipation. These parts are suitable only for applications where the original 151A/3000W specification exceeds actual protection requirements. Littelfuse variants offer extended temperature range to -65°C.

Frequently Asked Questions (FAQ)

Q: Can I use SMCJ12A parts as direct replacements for 3KASMC12AHM3_A/I?

A: SMCJ12A variants maintain identical voltage specifications (12V standoff, 19.9V clamping) and package form factor (DO-214AB SMC), ensuring mechanical and electrical compatibility. However, peak pulse current is reduced from 151A to 75.4A, and power dissipation from 3000W to 1500W. Use only if your circuit's transient energy requirements do not exceed the lower rating.

Q: What is the difference between 3KASMC12AHM3_A/I and 3KASMC12AHM3_B/I?

A: Both parts are electrically and thermally identical with matching voltage, current, and temperature specifications. The primary difference is product status: 3KASMC12AHM3_A/I is obsolete, while 3KASMC12AHM3_B/I is active. The 3KASMC12AHM3_B/I is the recommended replacement for new designs and ongoing supply.

Q: Is the 5.0SMDJ12A suitable for my application?

A: The 5.0SMDJ12A maintains identical voltage specifications and provides enhanced current (252A) and power (5000W) ratings, offering superior transient protection margin. However, maximum operating temperature is 150°C compared to the original 185°C. Verify that your application's junction temperature requirements do not exceed 150°C. Additionally, confirm REACH compliance requirements for your end market.

Q: Why do some substitutes have lower peak pulse current ratings?

A: Lower current ratings (75.4A versus 151A) indicate reduced transient energy handling capability. These parts are suitable for applications with lower transient stress levels. Selection depends on actual circuit protection requirements, not the original part's specification alone.

Q: Are all substitute parts automotive qualified?

A: The 3KASMC12AHM3_A/I and 3KASMC12AHM3_B/I carry AEC-Q101 automotive qualification. SMC30J12A from STMicroelectronics does not list automotive qualification in provided specifications. Littelfuse SMCJ12A variants and MDD SMCJ12A do not list automotive qualification. Verify AEC-Q101 requirements for your application before selection.

Q: What is the operating temperature difference impact?

A: The original part operates -65°C to 185°C. STMicroelectronics SMC30J12A operates -55°C to 175°C (10°C narrower at both extremes). MDD and Littelfuse variants operate -50°C to 150°C or -65°C to 150°C. Confirm your application's actual junction temperature range to ensure compatibility.

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