SMBJ40C Transient Voltage Suppressor Diode - Equivalent & Substitute Parts

Part Overview

The SMBJ40C is a bidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc. in the DO-214AA (SMB) surface mount package. This component is designed for general-purpose overvoltage protection applications with a 40V reverse standoff voltage rating and 67.73V maximum clamping voltage at peak pulse current.

The SMBJ40C is classified as obsolete. Equivalent and substitute parts are available from multiple manufacturers with active product status, offering comparable electrical performance and identical package compatibility for direct board-level replacement.

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	—
Bidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the SMBJ40C is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff: 40V (exact match required)
Voltage - Breakdown (Min): 42.08V to 44.4V (acceptable range)
Package / Case: DO-214AA, SMB (identical footprint)
Mounting Type: Surface Mount (identical assembly method)
Bidirectional Channels: 1 (functional equivalence)

Secondary Compatibility Parameters:

Current - Peak Pulse (10/1000µs): 9.3A minimum (equal or greater acceptable)
Power - Peak Pulse: 600W minimum (equal or greater acceptable)
Operating Temperature Range: -55°C to 150°C minimum (equal or wider acceptable)
RoHS Status: ROHS3 Compliant (regulatory requirement)

Substitute parts meeting all primary criteria and maintaining or exceeding secondary parameters are electrically and mechanically compatible for direct replacement.

Parameter Comparison

Manufacturer 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
SMBJ40C	Littelfuse Inc.	40	42.08	67.73	9.3	600	-65 to 150	Obsolete
SMBJ40CA	MDD	40	44.4	64.5	9.3	600	-50 to 150	Active
SZ1SMB40CAT3G	Littelfuse Inc.	40	44.4	64.5	9.3	600	-65 to 150	Active
SM6T47CAY	STMicroelectronics	40	44.4	84	48 (8/20µs)	600	-55 to 150	Active
SMB8J40CA-E3/5B	Vishay General Semiconductor - Diodes Division	40	44.4	64.5	12.4	800	-55 to 150	Active
SMBJ40CA-13-F	Diodes Incorporated	40	44.4	64.5	9.3	600	-55 to 150	Active
SMBJ40CA-M3/52	Vishay General Semiconductor - Diodes Division	40	44.4	64.5	9.3	600	-55 to 150	Active
SMBJ40CA-M3/5B	Vishay General Semiconductor - Diodes Division	40	44.4	64.5	9.3	600	-55 to 150	Active

Engineering Selection Recommendations

Direct Replacement (Preferred): SMBJ40CA (MDD), SMBJ40CA-13-F (Diodes Incorporated), SMBJ40CA-M3/52 (Vishay), and SMBJ40CA-M3/5B (Vishay) provide electrical equivalence with identical reverse standoff voltage, breakdown voltage range, clamping voltage, and peak pulse current. All are active products with ROHS3 compliance and DO-214AA package compatibility.

Enhanced Performance Alternative: SZ1SMB40CAT3G (Littelfuse Inc.) maintains electrical equivalence while offering the same manufacturer as the original part, extended operating temperature range (-65°C to 150°C), and active product status. This option provides continuity with the original design source.

Higher Current Capacity Alternative: SMB8J40CA-E3/5B (Vishay) and SM6T47CAY (STMicroelectronics) exceed the original peak pulse current specification (12.4A and 48A respectively) and provide higher power dissipation capability (800W and 600W). These parts are suitable for applications requiring enhanced transient protection margin. SM6T47CAY includes automotive-grade qualification (AEC-Q101).

Product Status Consideration: All substitute parts listed maintain active product status, ensuring long-term availability and supply chain stability compared to the obsolete SMBJ40C.

Frequently Asked Questions (FAQ)

Q: Can SMBJ40CA directly replace SMBJ40C on existing PCBs? A: Yes. SMBJ40CA shares identical reverse standoff voltage (40V), DO-214AA package footprint, and surface mount assembly requirements. Electrical performance is equivalent within specified tolerances.

Q: What is the difference between SMBJ40CA variants from different manufacturers? A: All SMBJ40CA variants (MDD, Vishay, Diodes Incorporated) meet the same electrical specifications for 40V reverse standoff, 64.5V clamping voltage, and 9.3A peak pulse current. Differences exist in packaging options (tape & reel vs. cut tape), operating temperature ranges, and automotive qualification status. Selection depends on supply chain preference and application requirements.

Q: Why does SM6T47CAY show higher peak pulse current (48A vs. 9.3A)? A: SM6T47CAY is rated for 48A peak pulse current at 8/20µs pulse duration, compared to the standard 10/1000µs pulse duration used for other parts. This represents a different transient profile and higher energy absorption capability. It is suitable for applications with more severe transient events.

Q: Is SZ1SMB40CAT3G suitable for extended temperature applications? A: Yes. SZ1SMB40CAT3G operates across -65°C to 150°C, matching the original SMBJ40C temperature range and exceeding most alternative parts (-50°C to -55°C minimum). This makes it appropriate for industrial and automotive environments with wide temperature extremes.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All substitute parts listed are ROHS3 compliant, meeting current environmental and regulatory requirements for electronic component manufacturing and use.

Q: What packaging options are available for substitute parts? A: Substitute parts are available in multiple packaging formats: bulk (loose), cut tape (CT) & Digi-Reel®, and tape & reel (TR). Selection depends on assembly volume and procurement workflow. All maintain identical DO-214AA (SMB) component footprint.

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