SMAJ85 Equivalent & Substitute Parts

Part Overview

The SMAJ85 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 an 85V reverse standoff voltage with a 143.85V maximum clamping voltage and 2.9A peak pulse current capability in a DO-214AC (SMA) package. The SMAJ85 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility across voltage ratings, current handling, and thermal operating ranges while supporting the same surface-mount package format.

Key Parameters

Parameter	SMAJ85 (Littelfuse)
Voltage - Reverse Standoff (Typ)	85V
Voltage - Breakdown (Min)	89.28V
Voltage - Clamping (Max) @ Ipp	143.85V
Current - Peak Pulse (10/1000µs)	2.9A
Power - Peak Pulse	400W
Operating Temperature Range	-65°C ~ 150°C (TJ)
Package / Case	DO-214AC, SMA
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the SMAJ85 is determined by the following critical parameters:

Voltage - Reverse Standoff (Typ): Must be 85V to maintain circuit protection thresholds
Package / Case: Must be DO-214AC (SMA) for mechanical and electrical compatibility
Mounting Type: Must be Surface Mount
Voltage - Clamping (Max) @ Ipp: Must not exceed 151V to prevent overstress in protected circuits
Current - Peak Pulse (10/1000µs): Must be minimum 2.9A; higher ratings are acceptable
Power - Peak Pulse: Must be minimum 400W; higher ratings are acceptable
Operating Temperature Range: Must support at least -55°C to 150°C
RoHS Status: Must be ROHS3 Compliant
Moisture Sensitivity Level (MSL): Must be MSL 1

Substitute parts are grouped by electrical performance tier based on clamping voltage and peak pulse current characteristics. All qualified substitutes maintain the 85V standoff voltage and DO-214AC package format while offering equivalent or enhanced performance specifications.

Parameter Comparison

Parameter	SMAJ85 (Littelfuse)	SMAJ85A (MDD)	SMA6J85A-TR (STMicroelectronics)	SMAJ85A-13-F (Diodes Inc.)	SMAJ85A-TP (Micro Commercial)	SMAJ85AE3/TR13 (Microchip)	SMAJ85E3/TR13 (Microchip)	TV04A850J-G (Comchip)
Voltage - Reverse Standoff (Typ)	85V	85V	85V	85V	85V	85V	85V	85V
Voltage - Breakdown (Min)	89.28V	94.4V	94V	94.4V	94.4V	94.4V	94.4V	94.4V
Voltage - Clamping (Max) @ Ipp	143.85V	137V	146V	137V	137V	137V	151V	137V
Current - Peak Pulse (10/1000µs)	2.9A	2.9A	22.5A (8/20µs)	2.9A	2.9A	3.6A	3.3A	2.92A
Power - Peak Pulse	400W	400W	600W	400W	400W	500W	500W	400W
Operating Temperature Range	-65°C ~ 150°C (TJ)	-50°C ~ 150°C (TJ)	-55°C ~ 175°C (TJ)	-55°C ~ 150°C (TJ)	-55°C ~ 175°C (TA)	-65°C ~ 150°C (TJ)	-65°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)
Package / Case	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

All substitute parts listed are active production components with ROHS3 compliance and MSL 1 rating, providing long-term availability and environmental regulatory compliance advantages over the obsolete SMAJ85.

Standard Substitutes (Equivalent Performance Tier): SMAJ85A (MDD), SMAJ85A-13-F (Diodes Incorporated), SMAJ85A-TP (Micro Commercial Co), and TV04A850J-G (Comchip Technology) maintain clamping voltages between 137V and 137V with peak pulse currents of 2.9A to 2.92A. These parts provide direct functional equivalence to the original SMAJ85 and are suitable for applications requiring matched electrical characteristics.

Enhanced Performance Substitutes: SMAJ85AE3/TR13 (Microchip Technology) offers increased peak pulse current of 3.6A and 500W power dissipation while maintaining 137V clamping voltage. SMAJ85E3/TR13 (Microchip Technology) provides 151V clamping voltage with 3.3A peak pulse current and 500W power dissipation. SMA6J85A-TR (STMicroelectronics) delivers significantly higher performance with 22.5A peak pulse current (8/20µs) and 600W power dissipation at 146V clamping voltage, suitable for applications requiring enhanced transient protection margins.

Temperature Considerations: SMAJ85A-TP (Micro Commercial Co) and SMA6J85A-TR (STMicroelectronics) support extended upper operating temperatures to 175°C, providing thermal margin advantages in high-temperature environments. SMAJ85A (MDD) operates to -50°C minimum, which may be limiting in extreme cold applications; all other substitutes support -55°C or lower minimum temperatures.

Frequently Asked Questions (FAQ)

Q: Can SMAJ85A (MDD) directly replace SMAJ85 (Littelfuse)?

A: Yes. SMAJ85A maintains the 85V reverse standoff voltage, 137V clamping voltage, 2.9A peak pulse current, and DO-214AC package format. The primary difference is the lower minimum operating temperature of -50°C versus -65°C on the original part. For applications operating above -50°C, this substitute is electrically and mechanically compatible.

Q: What is the difference between SMAJ85AE3/TR13 and SMAJ85E3/TR13?

A: Both are Microchip Technology products in DO-214AC packages with identical operating temperature ranges (-65°C to 150°C). SMAJ85AE3/TR13 provides 137V clamping voltage with 3.6A peak pulse current and 500W power dissipation. SMAJ85E3/TR13 provides 151V clamping voltage with 3.3A peak pulse current and 500W power dissipation. Selection depends on whether lower clamping voltage with higher current handling or higher clamping voltage is required for the application.

Q: Is SMA6J85A-TR (STMicroelectronics) compatible with SMAJ85?

A: SMA6J85A-TR is mechanically compatible (DO-214AC package, surface mount) and electrically compatible (85V standoff voltage). However, it delivers significantly higher performance: 22.5A peak pulse current (8/20µs) versus 2.9A, and 600W power dissipation versus 400W. This part is suitable for applications requiring enhanced transient protection but may introduce different circuit behavior due to substantially lower dynamic impedance. Verify that the application circuit can tolerate the enhanced clamping characteristics.

Q: Are all substitute parts available in Tape & Reel packaging?

A: Yes. All substitute parts listed are supplied in Tape & Reel (TR) packaging, suitable for automated assembly processes.

Q: Do all substitutes meet RoHS and MSL requirements?

A: Yes. All substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, matching the environmental and handling specifications of the original SMAJ85.

Q: Which substitute offers the best thermal performance?

A: SMAJ85A-TP (Micro Commercial Co) and SMA6J85A-TR (STMicroelectronics) both support operating temperatures to 175°C, providing 25°C additional thermal margin compared to the original SMAJ85 specification of 150°C maximum.

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