3KASMC40AHM3_A/I Equivalent & Substitute Parts

Part Overview

The 3KASMC40AHM3_A/I is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division. This component is rated for 40V reverse standoff voltage with a 64.5V maximum clamping voltage and 46.5A peak pulse current in a DO-214AB (SMC) surface mount package. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for new designs or production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	40	V
Voltage - Breakdown (Min)	44.4	V
Voltage - Clamping (Max) @ Ipp	64.5	V
Current - Peak Pulse (10/1000µs)	46.5	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-65°C to 185°C	TJ
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the 3KASMC40AHM3_A/I is determined by strict equivalence in the following electrical and mechanical parameters:

Voltage - Reverse Standoff: 40V (nominal)
Voltage - Breakdown (Min): 44.4V
Voltage - Clamping (Max) @ Ipp: 64.5V
Current - Peak Pulse (10/1000µs): 46.5A (±tolerance acceptable)
Power - Peak Pulse: 3000W minimum
Package / Case: DO-214AB, SMC
Mounting Type: Surface Mount
Unidirectional Channels: 1

Substitute parts are grouped into two categories:

Category A - Full Electrical & Thermal Equivalents (3000W, 46.5A nominal): Parts maintaining identical peak pulse current (46.5A) and power dissipation (3000W) with operating temperature ranges of -65°C or lower minimum.

Category B - Electrical Equivalents with Reduced Peak Pulse Current (1500W, ~23A): Parts with identical voltage parameters but reduced peak pulse current (23.2A to 23.26A) and power dissipation (1500W). These are suitable only for applications with lower transient current requirements.

Category C - Enhanced Performance (5000W, 77.6A): Parts with identical voltage parameters but higher peak pulse current (77.6A) and power dissipation (5000W). These provide additional margin and are backward compatible.

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 Range (°C)	Product Status	AEC-Q101
3KASMC40AHM3_A/I	Vishay	40	44.4	64.5	46.5	3000	-65 to 185	Obsolete	Yes
3KASMC40AHM3_B/I	Vishay	40	44.4	64.5	46.5	3000	-65 to 185	Active	Yes
SMDJ40A	Alpha & Omega Semiconductor	40	44.4	64.5	46.6	3000	-55 to 150	Active	No
SMDJ40A-HR	Littelfuse	40	44.4	64.5	46.5	3000	-65 to 150	Active	No
SMDJ40A-HRA	Littelfuse	40	44.4	64.5	46.5	3000	-65 to 150	Active	No
TPSMD40A	Littelfuse	40	44.4	64.5	46.5	3000	-65 to 150	Active	Yes
5.0SMDJ40A	Taiwan Semiconductor Corporation	40	44.4	64.5	77.6	5000	-55 to 175	Active	No
SMCJ40A	Meritek	40	44.4	64.5	23.26	1500	-55 to 150	Active	No
SMCJ40A-13-F	Diodes Incorporated	40	44.4	64.5	23.2	1500	-55 to 150	Active	No

Engineering Selection Recommendations

Primary Recommendation - Direct Replacement: 3KASMC40AHM3_B/I is the direct active equivalent. Identical electrical specifications, same manufacturer (Vishay), same operating temperature range (-65°C to 185°C), and AEC-Q101 automotive qualification. Packaging is Tape & Reel (TR) versus the original part's unspecified packaging.

Secondary Recommendations - Full Electrical Equivalents (3000W, 46.5A): SMDJ40A-HR, SMDJ40A-HRA, and TPSMD40A maintain the 3000W power rating and 46.5A peak pulse current. TPSMD40A carries AEC-Q101 qualification matching the original part's automotive grade. Operating temperature minimums range from -65°C to -55°C; applications requiring the full -65°C minimum should verify thermal performance.

Alternative - Enhanced Performance (5000W, 77.6A): 5.0SMDJ40A provides higher peak pulse current (77.6A) and power dissipation (5000W), offering additional transient protection margin. Suitable for applications where higher surge capacity is beneficial. Operating temperature range is -55°C to 175°C.

Lower Power Alternative (1500W, 23.26A): SMCJ40A and SMCJ40A-13-F are suitable only for applications with reduced transient current requirements (approximately 50% of the original specification). These parts maintain voltage parameters but are not direct replacements for designs requiring 3000W dissipation.

Compliance Considerations: The original part is AEC-Q101 qualified for automotive applications. Direct replacement should prioritize 3KASMC40AHM3_B/I or TPSMD40A to maintain automotive qualification. Other substitutes lack explicit AEC-Q101 certification and require design review for non-automotive or less stringent applications.

Frequently Asked Questions (FAQ)

Q: Can SMCJ40A replace 3KASMC40AHM3_A/I directly? A: No. While SMCJ40A matches voltage parameters (40V standoff, 64.5V clamping), it provides only 1500W peak pulse power versus the original 3000W specification. Use only if your application requires less than 1500W transient energy dissipation.

Q: What is the difference between 3KASMC40AHM3_A/I and 3KASMC40AHM3_B/I? A: Both are identical in electrical and thermal specifications. The primary difference is product status (obsolete versus active) and packaging format (unspecified versus Tape & Reel). 3KASMC40AHM3_B/I is the active production equivalent.

Q: Is 5.0SMDJ40A a suitable replacement? A: Yes, with design consideration. 5.0SMDJ40A provides higher peak pulse current (77.6A) and power dissipation (5000W), making it backward compatible. However, its operating temperature minimum is -55°C versus the original -65°C. Verify thermal requirements for your application.

Q: Do all substitute parts use the same DO-214AB (SMC) package? A: Yes. All listed substitutes use DO-214AB (SMC) surface mount packaging, ensuring mechanical and PCB layout compatibility.

Q: Which substitute maintains automotive qualification? A: 3KASMC40AHM3_B/I and TPSMD40A both carry AEC-Q101 qualification. For automotive applications, these are the preferred choices.

Q: Can I use SMDJ40A-HR in place of the original part? A: Yes, for most applications. SMDJ40A-HR matches the 3000W power and 46.5A peak pulse current. Operating temperature range is -65°C to 150°C (versus original -65°C to 185°C). Verify if your application requires operation above 150°C.

Q: What is the difference between SMDJ40A-HR and SMDJ40A-HRA? A: Both are Littelfuse parts with identical electrical specifications (40V standoff, 64.5V clamping, 46.5A peak pulse, 3000W power). The -HRA designation indicates a different product series variant. Electrical performance is equivalent.

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