3KASMC20HE3_A/I Equivalent & Substitute Parts

Part Overview

The 3KASMC20HE3_A/I is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division. This surface mount component in DO-214AB (SMC) package is designed for transient voltage protection applications with a 20V reverse standoff voltage and 35.8V maximum clamping voltage. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and field replacement requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	20	V
Voltage - Breakdown (Min)	22.2	V
Voltage - Clamping (Max) @ Ipp	35.8	V
Current - Peak Pulse (10/1000µs)	83.8	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-65 to 185	°C (TJ)
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Grade	Automotive	—
Qualification	AEC-Q101	—

Substitute Part Grouping Explanation

Substitution eligibility for the 3KASMC20HE3_A/I is determined by the following critical parameters:

Mandatory Matching Parameters:

Voltage - Reverse Standoff (Typ): 20V
Voltage - Breakdown (Min): 22.2V
Unidirectional Channels: 1
Package / Case: DO-214AB, SMC
Mounting Type: Surface Mount
Type: Zener

Allowable Variation Parameters:

Voltage - Clamping (Max) @ Ipp: 32.4V to 35.8V (within acceptable clamp voltage range)
Current - Peak Pulse (10/1000µs): 46.3A to 155A (higher current ratings acceptable for protection margin)
Power - Peak Pulse: 1500W to 5000W (higher power ratings acceptable)
Operating Temperature Range: Minimum -55°C acceptable; maximum 150°C to 185°C acceptable
RoHS Status: ROHS3 Compliant required
Product Status: Active preferred for ongoing availability

Substitute parts must maintain the same voltage protection threshold while accommodating variations in current handling capacity and power dissipation, provided the package and mounting specifications remain identical.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Breakdown Min (V)	Voltage - Clamping Max @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temp (°C)	Product Status	RoHS
3KASMC20HE3_A/I	Vishay	20	22.2	35.8	83.8	3000	-65 to 185	Obsolete	ROHS3
3KASMC20AHE3_B/I	Vishay	20	22.2	32.4	92.6	3000	-65 to 185	Active	ROHS3
SMLJ20E3/TR13	Microchip Technology	20	22.2	35.8	83.8	300	-55 to 150	Active	ROHS3
3.0SMCJ20A-13	Diodes Incorporated	20	22.2	32.4	62.6	3000	-55 to 175	Active	ROHS3
5.0SMDJ20A	Taiwan Semiconductor Corporation	20	22.2	32.4	155	5000	-55 to 175	Active	ROHS3
5.0SMDJ20A-T7	Littelfuse Inc.	20	22.2	32.4	155	5000	-65 to 150	Active	ROHS3
SMCJ20A	Fairchild Semiconductor	20	22.2	32.4	46.3	1500	-55 to 150	Active	—
SMCJ20A-13-F	Diodes Incorporated	20	22.2	32.4	46.3	1500	-55 to 150	Active	ROHS3
SMCJ20A-HR	Littelfuse Inc.	20	22.2	32.4	46.3	1500	-65 to 150	Active	ROHS3

Engineering Selection Recommendations

Primary Substitute (Highest Compatibility): The 3KASMC20AHE3_B/I from Vishay is the direct active equivalent. It maintains identical voltage specifications (20V standoff, 22.2V breakdown), matching package (DO-214AB, SMC), and operating temperature range (-65 to 185°C). The clamping voltage is 32.4V versus 35.8V on the original, and peak pulse current is 92.6A versus 83.8A, both within acceptable substitution parameters. Product status is active with full AEC-Q101 automotive qualification and ROHS3 compliance.

Secondary Substitutes (Voltage and Power Margin): The 5.0SMDJ20A and 5.0SMDJ20A-T7 provide enhanced protection margins with 155A peak pulse current and 5000W power dissipation. Both maintain the required 20V standoff and 22.2V breakdown voltages. The 5.0SMDJ20A-T7 from Littelfuse extends the lower temperature limit to -65°C, matching the original specification. These parts are suitable for applications requiring higher transient energy absorption.

Tertiary Substitutes (Standard Protection): The SMCJ20A-13-F (Diodes Incorporated) and SMCJ20A-HR (Littelfuse) provide standard 1500W protection with 46.3A peak pulse current. Both are active, ROHS3 compliant, and maintain the required voltage thresholds. The SMCJ20A-HR extends the lower temperature limit to -65°C. These are appropriate for applications where the original 3000W specification exceeds actual transient energy requirements.

Microchip Alternative: The SMLJ20E3/TR13 matches the original clamping voltage (35.8V) and peak pulse current (83.8A) but operates at reduced power dissipation (300W) and narrower temperature range (-55 to 150°C). This part is suitable only for applications with lower thermal stress and non-automotive temperature requirements.

Compliance Consideration: All recommended substitutes maintain ROHS3 compliance and unidirectional Zener topology. Automotive applications should prioritize parts with AEC-Q101 qualification (3KASMC20AHE3_B/I, 3.0SMCJ20A-13, 5.0SMDJ20A-T7, SMCJ20A-13-F, SMCJ20A-HR).

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with lower peak pulse current than the original 3KASMC20HE3_A/I?

A: Yes, provided the substitute meets or exceeds the minimum voltage specifications (20V standoff, 22.2V breakdown). Lower current ratings (46.3A in SMCJ20A variants) are acceptable if the application's actual transient energy is within the substitute's power dissipation limit. Verify the transient pulse characteristics in your circuit to confirm adequacy.

Q: What is the difference between 32.4V and 35.8V clamping voltage?

A: Both values represent the maximum voltage at peak pulse current (Ipp). The 35.8V specification on the original part provides tighter voltage clamping. Substitutes with 32.4V clamping still protect the circuit but allow slightly higher transient voltage. Select based on your protected circuit's voltage tolerance.

Q: Are all substitute parts automotive-grade?

A: Not all. The 3KASMC20AHE3_B/I, 3.0SMCJ20A-13, 5.0SMDJ20A-T7, SMCJ20A-13-F, and SMCJ20A-HR carry AEC-Q101 qualification suitable for automotive applications. The SMLJ20E3/TR13 and standard SMCJ20A lack automotive certification and are general-purpose alternatives.

Q: Can I substitute a part with higher power rating (5000W vs. 3000W)?

A: Yes. Higher power ratings provide additional thermal margin and are directly substitutable. The 5.0SMDJ20A and 5.0SMDJ20A-T7 with 5000W ratings offer enhanced protection without compatibility issues, provided voltage and package specifications match.

Q: Does operating temperature range affect substitution?

A: Yes, for temperature-critical applications. The original part operates -65 to 185°C. Substitutes with narrower ranges (-55 to 150°C) are acceptable only if your application operates within those limits. The 5.0SMDJ20A-T7 and SMCJ20A-HR maintain the -65°C lower limit.

Q: Is the DO-214AB package identical across all substitutes?

A: Yes. All listed substitutes use DO-214AB (SMC) surface mount package with identical footprint and soldering requirements. No PCB layout changes are necessary.

Q: What does ROHS3 compliance mean for substitution?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances regulations. All recommended substitutes are ROHS3 compliant, ensuring environmental and regulatory compatibility with the original part's specification.

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