Equivalent & Substitute Parts for 3KASMC28AHM3_A/I

Part Overview

The 3KASMC28AHM3_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 is rated for 28V reverse standoff voltage with a 45.4V maximum clamping voltage and 66.1A peak pulse current capability, delivering 3000W peak pulse power dissipation. The part is qualified to AEC-Q101 automotive standards and complies with RoHS3 and REACH requirements.

The 3KASMC28AHM3_A/I is currently listed as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications requiring 28V TVS protection.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	28	V
Voltage - Breakdown (Min)	31.1	V
Voltage - Clamping (Max) @ Ipp	45.4	V
Current - Peak Pulse (10/1000µs)	66.1	A
Power - Peak Pulse	3000	W
Type	Zener	—
Unidirectional Channels	1	—
Mounting Type	Surface Mount	—
Package / Case	DO-214AB, SMC	—
Operating Temperature Range	-65°C ~ 185°C (TJ)	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—
Grade	Automotive	—
Qualification	AEC-Q101	—

Substitute Part Grouping Explanation

Substitution of the 3KASMC28AHM3_A/I is determined by strict equivalence across the following critical parameters:

Voltage Rating: Reverse standoff voltage of 28V, breakdown minimum of 31.1V, and maximum clamping voltage of 45.4V
Current Handling: Peak pulse current of 66.1A at 10/1000µs pulse width
Power Dissipation: 3000W peak pulse power rating
Package: DO-214AB (SMC) surface mount configuration
Electrical Type: Unidirectional Zener TVS diode with single channel

Substitute parts are grouped into two categories:

Category A - Full Electrical and Thermal Equivalents (Preferred) Parts that match all critical electrical parameters (28V standoff, 45.4V clamp, 66.1A peak pulse, 3000W power) and maintain equivalent or superior operating temperature ranges. These parts are direct functional replacements with identical performance characteristics.

Category B - Electrical Equivalents with Reduced Peak Pulse Current Parts that maintain voltage ratings and clamping characteristics but specify lower peak pulse current (33A instead of 66.1A) or different clamping voltage profiles. These parts are suitable only for applications where the reduced current rating is acceptable.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Product Status	Grade	Qualification	RoHS Status
3KASMC28AHM3_A/I	Vishay General Semiconductor - Diodes Division	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 185°C	Obsolete	Automotive	AEC-Q101	ROHS3 Compliant
3KASMC28AHM3_B/I	Vishay General Semiconductor - Diodes Division	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 185°C	Active	Automotive	AEC-Q101	ROHS3 Compliant
3.0SMCJ28A-13	Diodes Incorporated	28V	31.1V	45.4V	66.1A	3000W	-55°C ~ 175°C	Active	—	—	ROHS3 Compliant
SM30T33AY	STMicroelectronics	28V	31.1V	45.4V	66.1A	3000W	-55°C ~ 175°C	Active	Automotive	AEC-Q101	ROHS3 Compliant
SMDJ28A	Alpha & Omega Semiconductor Inc.	28V	31.1V	45.4V	66.1A	3000W	-55°C ~ 150°C	Active	—	—	ROHS3 Compliant
SMDJ28A-HR	Littelfuse Inc.	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 150°C	Active	—	—	ROHS3 Compliant
SMDJ28A-HRA	Littelfuse Inc.	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 150°C	Active	—	—	ROHS3 Compliant
SMDJ28A-HRAT7	Littelfuse Inc.	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 150°C	Active	—	—	ROHS3 Compliant
TPSMD28A	Littelfuse Inc.	28V	31.1V	45.4V	66.1A	3000W	-65°C ~ 150°C	Active	Automotive	AEC-Q101	ROHS3 Compliant
1SMC28A TR13 TIN/LEAD	Central Semiconductor Corp	28V	31.1V	45.4V	33A	1500W	-65°C ~ 150°C	Active	—	—	RoHS non-compliant
3.0SMC28A	Littelfuse Inc.	28V	31.1V	59V	470A (8/20µs)	—	-65°C ~ 150°C	Active	—	—	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (Full Electrical Equivalents)

The 3KASMC28AHM3_B/I is the direct successor from Vishay General Semiconductor - Diodes Division. It maintains identical electrical specifications (28V standoff, 45.4V clamp, 66.1A peak pulse, 3000W power), automotive grade qualification, AEC-Q101 certification, and RoHS3 compliance. The only difference is packaging format (Tape & Reel vs. bulk), making this the preferred replacement for the obsolete 3KASMC28AHM3_A/I.

The TPSMD28A from Littelfuse Inc. provides full electrical equivalence with automotive grade and AEC-Q101 qualification. Operating temperature range is -65°C ~ 150°C, which is acceptable for most automotive applications, though 35°C lower than the original part's maximum junction temperature.

The SM30T33AY from STMicroelectronics (TRANSIL™ series) matches all critical electrical parameters and carries automotive grade with AEC-Q101 qualification. Operating temperature is -55°C ~ 175°C, providing adequate thermal performance for automotive environments.

Secondary Substitutes (Full Electrical Equivalents, Non-Automotive)

The 3.0SMCJ28A-13 from Diodes Incorporated and SMDJ28A from Alpha & Omega Semiconductor Inc. provide complete electrical equivalence but lack automotive grade designation and AEC-Q101 qualification. These are suitable for non-automotive applications or where automotive qualification is not required.

The SMDJ28A-HR, SMDJ28A-HRA, and SMDJ28A-HRAT7 from Littelfuse Inc. all deliver full electrical equivalence with identical 28V/45.4V/66.1A/3000W specifications. These parts lack automotive grade and AEC-Q101 certification but are suitable for general-purpose industrial applications.

Not Recommended

The 1SMC28A TR13 TIN/LEAD from Central Semiconductor Corp specifies only 33A peak pulse current and 1500W power dissipation—half the original part's rating. Additionally, this part is RoHS non-compliant. Use only if application requirements permit reduced current handling.

The 3.0SMC28A from Littelfuse Inc. specifies a higher clamping voltage (59V vs. 45.4V) and significantly higher peak pulse current (470A at 8/20µs pulse width). This part is not electrically equivalent and should not be used as a direct substitute.

Frequently Asked Questions (FAQ)

Q: Can I use 3KASMC28AHM3_B/I as a direct replacement for 3KASMC28AHM3_A/I?

A: Yes. The 3KASMC28AHM3_B/I is the active production equivalent. Both parts share identical electrical specifications (28V standoff, 45.4V clamp, 66.1A peak pulse, 3000W power), automotive grade, AEC-Q101 qualification, and RoHS3 compliance. The difference is packaging format: _A/I is bulk packaging while _B/I is Tape & Reel. Electrical performance and reliability are equivalent.

Q: What is the difference between the Littelfuse SMDJ28A-HR, SMDJ28A-HRA, and SMDJ28A-HRAT7 variants?

A: All three Littelfuse variants (SMDJ28A-HR, SMDJ28A-HRA, SMDJ28A-HRAT7) provide identical electrical specifications: 28V standoff, 45.4V clamp, 66.1A peak pulse, and 3000W power dissipation. The suffix designations indicate packaging and tape format variations. Electrical performance is equivalent across all three variants. Selection depends on packaging and supply chain requirements.

Q: Why is the 1SMC28A TR13 TIN/LEAD not recommended as a substitute?

A: The 1SMC28A TR13 TIN/LEAD specifies only 33A peak pulse current and 1500W power dissipation—exactly half the original part's 66.1A and 3000W ratings. This reduced current handling capability makes it unsuitable for applications requiring the full 66.1A transient protection. Additionally, this part is RoHS non-compliant. Use only if your application can tolerate reduced transient current protection.

Q: Can I use the 3.0SMC28A as a substitute?

A: No. The 3.0SMC28A is not electrically equivalent. It specifies a higher clamping voltage (59V vs. 45.4V) and significantly higher peak pulse current (470A at 8/20µs pulse width vs. 66.1A at 10/1000µs). Different pulse width specifications and clamping voltage make this part unsuitable for direct substitution.

Q: What is the impact of operating temperature differences between substitute parts?

A: The original 3KASMC28AHM3_A/I operates from -65°C to 185°C junction temperature. Some substitutes (3.0SMCJ28A-13, SM30T33AY, SMDJ28A) specify maximum junction temperatures of 150°C or 175°C. For applications operating near the upper temperature limit, verify that the substitute part's thermal rating is acceptable. The 3KASMC28AHM3_B/I and TPSMD28A maintain the -65°C lower limit and are preferred for high-temperature environments.

Q: Are all substitute parts RoHS3 compliant?

A: Most substitutes are RoHS3 compliant. The exception is 1SMC28A TR13 TIN/LEAD, which is RoHS non-compliant. For applications requiring RoHS compliance, avoid this part. All other listed substitutes meet RoHS3 requirements.

Q: Which substitute parts carry automotive qualification?

A: Three parts carry automotive grade and AEC-Q101 qualification: 3KASMC28AHM3_B/I (Vishay), SM30T33AY (STMicroelectronics), and TPSMD28A (Littelfuse). For automotive applications, these are the preferred choices. Other substitutes lack automotive qualification and are suitable only for non-automotive or general-purpose applications.

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