SMBJ40 Equivalent & Substitute Parts

Part Overview

The SMBJ40 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. The device features a 40V reverse standoff voltage with a 67.73V maximum clamping voltage and 9.3A peak pulse current capability in a DO-214AA (SMB) package. The SMBJ40 is classified as obsolete; equivalent and substitute parts from active manufacturers are available to maintain design continuity and ensure supply chain reliability.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	40	V
Voltage - Breakdown (Min)	42.08	V
Voltage - Clamping (Max) @ Ipp	67.73	V
Current - Peak Pulse (10/1000µs)	9.3	A
Power - Peak Pulse	600	W
Operating Temperature Range	-65 to 150	°C (TJ)
Package / Case	DO-214AA, SMB	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the SMBJ40 is determined by the following critical parameters:

Reverse Standoff Voltage (Typ): 40V — all substitutes must maintain this specification
Package / Case: DO-214AA (SMB) — mechanical and electrical compatibility requirement
Peak Pulse Current: 9.3A nominal — substitutes with equivalent or higher ratings are acceptable
Clamping Voltage (Max) @ Ipp: Range 64.5V to 84V — acceptable variation based on application tolerance
Power - Peak Pulse: 600W — all substitutes maintain this rating
Mounting Type: Surface Mount — all substitutes are surface-mount compatible
RoHS Status: ROHS3 Compliant — all substitutes meet this compliance requirement

Substitute parts are grouped into two categories: direct electrical equivalents (matching clamping voltage within 64.5V to 71.4V range) and higher-performance alternatives (84V clamping voltage for enhanced transient suppression).

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	Package / Case	Product Status
SMBJ40	Littelfuse Inc.	40V	42.08V	67.73V	9.3A	600W	-65 to 150°C	DO-214AA, SMB	Obsolete
SMBJ40A	MDD	40V	44.4V	64.5V	9.3A	600W	-50 to 150°C	DO-214AA, SMB	Active
SM6T47AY	STMicroelectronics	40V	44.4V	84V	48A (8/20µs)	600W	-55 to 150°C	DO-214AA, SMB	Active
SMBJ40A-13-F	Diodes Incorporated	40V	44.4V	64.5V	9.3A	600W	-55 to 150°C	DO-214AA, SMB	Active
SMBJ40A-M3/52	Vishay General Semiconductor - Diodes Division	40V	44.4V	64.5V	9.3A	600W	-55 to 150°C	DO-214AA, SMB	Active
SMBJ40A-M3/5B	Vishay General Semiconductor - Diodes Division	40V	44.4V	64.5V	9.3A	600W	-55 to 150°C	DO-214AA, SMB	Active
SMBJ40A-TR	STMicroelectronics	40V	44.4V	64.5V	9.7A	600W	-55 to 150°C	DO-214AA, SMB	Active
SMBJ40E3/TR13	Microchip Technology	40V	44.4V	71.4V	8.4A	600W	-65 to 150°C	DO-214AA, SMB	Active
TV06B400J-HF	Comchip Technology	40V	44.4V	64.5V	9.3A	600W	Not specified	DO-214AA, SMB	Active

Engineering Selection Recommendations

Direct Electrical Equivalents (Preferred for Drop-In Replacement)

SMBJ40A (MDD), SMBJ40A-13-F (Diodes Incorporated), SMBJ40A-M3/52 (Vishay), SMBJ40A-M3/5B (Vishay), SMBJ40A-TR (STMicroelectronics), and TV06B400J-HF (Comchip Technology) provide direct electrical equivalence with clamping voltages between 64.5V and matching the core 40V reverse standoff specification. All are ROHS3 compliant and active products. These parts are suitable for direct substitution in existing designs without circuit modification.

Enhanced Performance Alternative

SM6T47AY (STMicroelectronics) offers higher clamping voltage (84V) and significantly higher peak pulse current (48A at 8/20µs) compared to the original SMBJ40. This part is AEC-Q101 qualified for automotive applications and provides superior transient suppression capability. Selection of this part requires verification that the application circuit can tolerate the higher clamping voltage without affecting downstream component ratings.

Temperature Range Consideration

SMBJ40E3/TR13 (Microchip Technology) and SMBJ40 (original) support the extended operating temperature range of -65°C to 150°C. Most active substitutes operate within -50°C to -55°C minimum temperature. For applications requiring -65°C operation, SMBJ40E3/TR13 is the appropriate selection.

Packaging and Supply Chain

All substitute parts are available in active production status with established supply chains. Packaging variants (Tape & Reel, Cut Tape, Digi-Reel) are specified per manufacturer; verify packaging compatibility with assembly processes.

Frequently Asked Questions (FAQ)

Q: Can SMBJ40A directly replace SMBJ40 without circuit modification?

A: Yes. SMBJ40A maintains the same 40V reverse standoff voltage, 9.3A peak pulse current, 600W power rating, and DO-214AA package. The clamping voltage is 64.5V compared to the original 67.73V; this 3.23V difference is within acceptable tolerance for general-purpose overvoltage protection applications.

Q: What is the difference between SMBJ40A-M3/52 and SMBJ40A-M3/5B?

A: Both parts are manufactured by Vishay and share identical electrical specifications (40V standoff, 64.5V clamping, 9.3A peak pulse). The suffix designates different packaging configurations and tape specifications. Selection depends on assembly equipment compatibility and supply chain availability.

Q: When should SM6T47AY be selected instead of standard SMBJ40A equivalents?

A: SM6T47AY is selected when higher transient suppression performance is required. The 84V clamping voltage and 48A peak pulse current provide enhanced protection for sensitive circuits. This part is qualified to AEC-Q101 automotive standards. Circuit design must confirm that downstream components tolerate the higher clamping voltage.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant and suitable for applications requiring RoHS compliance.

Q: What is the operating temperature range for substitute parts?

A: Most active substitutes operate from -50°C to -55°C minimum temperature. SMBJ40E3/TR13 (Microchip) extends the minimum to -65°C, matching the original SMBJ40 specification. Verify application temperature requirements before part selection.

Q: Does package type (DO-214AA vs. SMB designation) affect substitution?

A: No. DO-214AA and SMB refer to the same physical package. All listed parts use this package and are mechanically and electrically interchangeable on standard PCB layouts.

Q: Is TV06B400J-HF suitable for all applications?

A: TV06B400J-HF (Comchip Technology) provides electrical equivalence but does not specify operating temperature range in the available data. Confirm temperature specification with the manufacturer before selection for temperature-critical applications.

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