SMDJ85 Equivalent & Substitute Parts

Part Overview

The SMDJ85 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 21.9A peak pulse current capability in a DO-214AB (SMC) package. The SMDJ85 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, clamping characteristics, and current handling capacity while supporting the same surface-mount package format.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	85	V
Voltage - Breakdown (Min)	89.28	V
Voltage - Clamping (Max) @ Ipp	143.85	V
Current - Peak Pulse (10/1000µs)	21.9	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-65 to 150	°C
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the SMDJ85 are grouped based on strict electrical and mechanical compatibility criteria. All substitute parts must meet the following requirements:

Primary Compatibility Criteria:

Reverse standoff voltage: 85V (nominal)
Breakdown voltage minimum: 89.28V or higher
Unidirectional channel configuration: 1 channel
Package format: DO-214AB (SMC) surface mount
Type: Zener TVS diode
General-purpose application classification
RoHS3 compliance

Secondary Compatibility Parameters:

Clamping voltage (Max) @ Ipp: 137V to 143.85V range
Peak pulse current: 10.4A to 21.9A range
Peak pulse power: 1500W to 3000W range
Operating temperature: minimum -55°C, maximum 150°C or higher

Substitute parts are classified into two groups based on peak pulse current and power dissipation capacity: high-current variants (20.8A–21.9A, 3000W) and standard-current variants (10.4A–11A, 1500W). Selection depends on circuit requirements for transient energy absorption.

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 (°C)	Product Status
SMDJ85	Littelfuse Inc.	85	89.28	143.85	21.9	3000	-65 to 150	Obsolete
SMDJ85A	Alpha & Omega Semiconductor Inc.	85	94.4	137	21.9	3000	-55 to 150	Active
SMCJ85A	MDD	85	94.4	137	11	1500	-50 to 150	Active
SMCJ85A-TP	Micro Commercial Co	85	94.4	137	11	1500	-55 to 175	Active
SMCJ85AE3/TR13	Microchip Technology	85	94.4	137	10.4	1500	-65 to 150	Active
SMLJ85A	Bourns Inc.	85	94.4	137	20.8	3000	-55 to 150	Active
SMLJ85A-TP	Micro Commercial Co	85	94.4	137	20.8	3000	-55 to 175	Active
SMLJ85AE3/TR13	Microchip Technology	85	94.4	137	20.8	300	-55 to 150	Active
TV15C850J-G	Comchip Technology	85	94.4	137	10.95	1500	-55 to 150	Active
TV30C850J-G	Comchip Technology	85	94.4	137	21.9	3000	-55 to 150	Active

Engineering Selection Recommendations

Direct Replacement (Highest Compatibility): SMDJ85A (Alpha & Omega Semiconductor Inc.) and TV30C850J-G (Comchip Technology) provide the closest electrical match to the SMDJ85, maintaining 21.9A peak pulse current and 3000W power dissipation. Both parts are active products with RoHS3 compliance. SMDJ85A supports the original -65°C lower temperature limit, while TV30C850J-G operates to -55°C minimum.

High-Current Alternatives (3000W Class): SMLJ85A (Bourns Inc.) and SMLJ85A-TP (Micro Commercial Co) deliver 20.8A peak pulse current with 3000W power handling, suitable for applications requiring sustained transient energy absorption. SMLJ85A-TP extends the upper operating temperature to 175°C. Both are active products with full RoHS3 compliance.

Standard-Current Alternatives (1500W Class): SMCJ85A (MDD), SMCJ85A-TP (Micro Commercial Co), TV15C850J-G (Comchip Technology), and SMCJ85AE3/TR13 (Microchip Technology) provide 10.4A to 11A peak pulse current with 1500W power dissipation. These parts are suitable for lower-energy transient protection applications. SMCJ85A-TP and SMCJ85AE3/TR13 support extended temperature ranges (-55°C to 175°C and -65°C to 150°C respectively).

Compliance Considerations: All substitute parts maintain RoHS3 compliance. SMLJ85A carries REACH Affected status; all other substitutes are REACH Unaffected. Selection should account for supply chain compliance requirements and inventory availability across manufacturers.

Frequently Asked Questions (FAQ)

Q: Can SMCJ85A (1500W) replace SMDJ85 (3000W) in all applications? A: SMCJ85A is suitable only for applications where peak transient energy does not exceed 1500W. Applications requiring 3000W dissipation capacity must use SMDJ85A, SMLJ85A, SMLJ85A-TP, or TV30C850J-G.

Q: What is the difference between SMLJ85A and SMCJ85A? A: Both maintain 85V standoff voltage and 137V clamping voltage. SMLJ85A delivers 20.8A peak pulse current (3000W), while SMCJ85A delivers 11A peak pulse current (1500W). Selection depends on circuit transient energy requirements.

Q: Are all substitute parts in DO-214AB (SMC) package? A: Yes. All listed substitute parts use DO-214AB (SMC) surface-mount package format, ensuring mechanical and footprint compatibility with the original SMDJ85.

Q: Which substitute offers the widest operating temperature range? A: SMCJ85A-TP and SMLJ85A-TP both support -55°C to 175°C operating range, extending the upper temperature limit by 25°C compared to the original SMDJ85 specification.

Q: Is SMCJ85AE3/TR13 suitable as a direct replacement? A: SMCJ85AE3/TR13 maintains voltage and current specifications but specifies 300W peak pulse power, significantly below the 3000W requirement. This part is not suitable for applications requiring full 3000W transient energy absorption.

Q: What inventory considerations apply to substitute selection? A: SMCJ85A (MDD) offers the highest inventory availability at 17,917 pieces. SMDJ85A (Alpha & Omega) provides 4,552 pieces. Lower-volume alternatives include TV30C850J-G (1,006 pieces) and SMLJ85AE3/TR13 (789 pieces). Inventory levels support both immediate procurement and long-term supply planning.

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