1SMB40CAT3G Equivalent & Substitute Parts

Part Overview

The 1SMB40CAT3G is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface mount applications. This component features a 40V reverse standoff voltage with 64.5V maximum clamping voltage and 9.3A peak pulse current capability in a DO-214AA (SMB) package. The part is currently classified as obsolete, necessitating identification of active equivalent alternatives that maintain identical electrical and mechanical specifications for continued circuit protection functionality.

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)	9.3	A
Power - Peak Pulse	600	W
Package / Case	DO-214AA, SMB	—
Mounting Type	Surface Mount	—
Bidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the 1SMB40CAT3G is determined by strict equivalence across the following critical parameters:

Voltage - Reverse Standoff (Typ): 40V
Voltage - Breakdown (Min): 44.4V
Voltage - Clamping (Max) @ Ipp: 64.5V
Current - Peak Pulse (10/1000µs): 9.3A (±tolerance acceptable)
Power - Peak Pulse: 600W
Package / Case: DO-214AA, SMB
Mounting Type: Surface Mount
Bidirectional Channels: 1

Substitute parts are grouped into two categories based on electrical performance alignment:

Category A - Direct Electrical Equivalents (64.5V Clamping): Parts maintaining identical clamping voltage of 64.5V with peak pulse current of 9.3A or 9.7A. These include SMBJ40CA (MDD), SMBJ40CA-HR (Littelfuse), SMBJ40CA-HRA (Littelfuse), SMBJ40CA-13-F (Diodes Incorporated), SMBJ40CA-TP (Micro Commercial Co), and SMBJ40CA-TR (STMicroelectronics).

Category B - Alternative Performance Profile (84V Clamping): SM6T47CAY (STMicroelectronics) maintains the 40V reverse standoff and 44.4V breakdown specifications but features higher clamping voltage (84V) and significantly higher peak pulse current (48A at 8/20µs). This part is suitable only where higher transient energy absorption is required.

Category C - Direct Manufacturer Equivalent: TV06B400JB-G (Comchip Technology) provides direct electrical equivalence with 64.5V clamping and 9.3A peak pulse current.

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	Package / Case	Product Status	Operating Temperature
1SMB40CAT3G	Littelfuse Inc.	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Obsolete	-65°C ~ 150°C
SMBJ40CA	MDD	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	-50°C ~ 150°C
SMBJ40CA-HR	Littelfuse Inc.	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	-65°C ~ 150°C
SMBJ40CA-HRA	Littelfuse Inc.	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	-65°C ~ 150°C
TV06B400JB-G	Comchip Technology	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	Not specified
SM6T47CAY	STMicroelectronics	40V	44.4V	84V	48A (8/20µs)	600W	DO-214AA, SMB	Active	-55°C ~ 150°C
SMBJ40CA-13-F	Diodes Incorporated	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	-55°C ~ 150°C
SMBJ40CA-TP	Micro Commercial Co	40V	44.4V	64.5V	9.3A	600W	DO-214AA, SMB	Active	-55°C ~ 175°C
SMBJ40CA-TR	STMicroelectronics	40V	44.4V	64.5V	9.7A	600W	DO-214AA, SMB	Active	-55°C ~ 150°C

Engineering Selection Recommendations

For direct replacement of the obsolete 1SMB40CAT3G, select from Category A equivalents that maintain identical electrical specifications (64.5V clamping, 9.3A peak pulse current). The following active parts provide full functional equivalence:

Primary Recommendations:

SMBJ40CA-HR and SMBJ40CA-HRA (Littelfuse Inc.) are preferred for applications requiring the original operating temperature range of -65°C to 150°C. Both parts are active products with ROHS3 compliance and MSL 1 rating, ensuring long-term availability and environmental compliance.

SMBJ40CA (MDD) offers identical electrical performance with active product status and ROHS3 compliance. Operating temperature range is -50°C to 150°C, suitable for most general-purpose applications.

SMBJ40CA-13-F (Diodes Incorporated) and SMBJ40CA-TP (Micro Commercial Co) provide direct electrical equivalence with extended upper operating temperature limits (-55°C to 150°C and -55°C to 175°C respectively), beneficial for high-temperature environments.

SMBJ40CA-TR (STMicroelectronics) maintains electrical equivalence with 9.7A peak pulse current (within acceptable tolerance of 9.3A specification) and active product status.

TV06B400JB-G (Comchip Technology) provides direct electrical equivalence in DO-214AA package with identical voltage and current ratings.

Alternative Selection:

SM6T47CAY (STMicroelectronics) is suitable only when circuit design permits higher clamping voltage (84V) and requires enhanced transient energy absorption capability (48A peak pulse current). This part includes AEC-Q101 automotive qualification and is not a direct substitute for standard applications.

All recommended substitutes maintain ROHS3 compliance, MSL 1 rating, and surface mount DO-214AA (SMB) packaging, ensuring compatibility with existing PCB designs and manufacturing processes.

Frequently Asked Questions (FAQ)

Q: Can SMBJ40CA-TR be used as a direct replacement for 1SMB40CAT3G?

A: Yes. SMBJ40CA-TR maintains all critical electrical parameters: 40V reverse standoff, 44.4V breakdown voltage, 64.5V clamping voltage, and 9.7A peak pulse current. The 0.4A difference in peak pulse current is within acceptable tolerance for TVS diode specifications. Both parts use DO-214AA (SMB) surface mount packaging.

Q: What is the difference between SMBJ40CA-HR and SMBJ40CA-HRA?

A: Both parts are manufactured by Littelfuse Inc. and maintain identical electrical specifications (40V standoff, 64.5V clamping, 9.3A peak pulse). The primary difference is series designation (SMBJ-HR versus SMBJ-HRA). Both are active products with -65°C to 150°C operating temperature range and are suitable for direct replacement.

Q: Why is SM6T47CAY listed as a substitute if it has different clamping voltage?

A: SM6T47CAY maintains the same reverse standoff voltage (40V) and breakdown voltage (44.4V) as the original part, but features higher clamping voltage (84V) and significantly higher peak pulse current (48A). This part is included as an alternative for applications where enhanced transient suppression is required, but it is not a direct electrical equivalent and should only be selected when circuit design permits higher clamping voltage.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, ensuring environmental compliance and compatibility with modern manufacturing processes.

Q: What packaging options are available for these substitutes?

A: All substitute parts use DO-214AA (SMB) surface mount packaging, identical to the original 1SMB40CAT3G. Packaging variations (Tape & Reel, Cut Tape, or bulk) are available from different manufacturers but do not affect electrical performance or PCB compatibility.

Q: Can I use SMBJ40CA-TP in applications with operating temperatures above 150°C?

A: SMBJ40CA-TP is rated for -55°C to 175°C operating temperature, making it suitable for high-temperature applications where the original part's -65°C to 150°C range is insufficient. However, verify that your circuit design and PCB materials support this extended temperature range.

Q: Is the original 1SMB40CAT3G still available?

A: The 1SMB40CAT3G is classified as obsolete. While inventory may exist from distributors (15,300 pcs noted as in stock), long-term availability is not guaranteed. Migration to active substitute parts is recommended for new designs and ongoing production.

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