SMDJ18A Equivalent & Substitute Parts

Part Overview

The SMDJ18A is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This surface-mount component operates with an 18V reverse standoff voltage and provides 29.2V maximum clamping voltage at peak pulse current. The part is active in production status and widely available in inventory. Equivalent and substitute parts are identified to support design flexibility, supply chain continuity, and application-specific performance requirements across multiple manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	20	V
Voltage - Clamping (Max) @ Ipp	29.2	V
Current - Peak Pulse (10/1000µs)	102.7	A
Power - Peak Pulse	3000	W
Package / Case	DO-214AB, SMC	—
Operating Temperature Range	-65 to 150	°C
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the SMDJ18A are qualified based on the following electrical and mechanical parameters:

Voltage - Reverse Standoff (Typ): 18V
Voltage - Breakdown (Min): 20V
Voltage - Clamping (Max) @ Ipp: 29.2V
Package / Case: DO-214AB or SMC
Mounting Type: Surface Mount
RoHS Status: ROHS3 Compliant

Substitutes are grouped into two categories based on peak pulse current rating:

Category A (High Current - 102.7A to 103A): Parts with peak pulse current matching or exceeding the SMDJ18A specification, maintaining full 3000W peak pulse power rating. These include SM30T21AY (STMicroelectronics), SMC30J18A (STMicroelectronics), SMLJ18A (Bourns Inc.), and SMLJ18A-TP (Micro Commercial Co).

Category B (Reduced Current - 51.4A): Parts with reduced peak pulse current rating, providing 1500W peak pulse power. These include SMCJ18A (MDD), SMCJ18A-E3/57T (Vishay General Semiconductor), and SMCJ18A-TP (Micro Commercial Co).

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Breakdown (V)	Voltage - Clamping (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temp (°C)	Package
SMDJ18A	Littelfuse Inc.	18	20	29.2	102.7	3000	-65 to 150	DO-214AB, SMC
SM30T21AY	STMicroelectronics	18	20	29.2	102.7	3000	-55 to 175	DO-214AB, SMC
SMC30J18A	STMicroelectronics	18	20	29.2	103	3000	-55 to 175	DO-214AB, SMC
SMCJ18A	MDD	18	20	29.2	51.4	1500	-50 to 150	DO-214AB, SMC
SMCJ18A-E3/57T	Vishay General Semiconductor - Diodes Division	18	20	29.2	51.4	1500	-55 to 150	DO-214AB, SMC
SMCJ18A-TP	Micro Commercial Co	18	20	29.2	51.4	1500	-55 to 175	DO-214AB, SMC
SMLJ18A	Bourns Inc.	18	20	29.2	102.8	3000	-55 to 150	DO-214AB, SMC
SMLJ18A-TP	Micro Commercial Co	18	20	29.2	102.8	3000	-55 to 175	DO-214AB, SMC

Engineering Selection Recommendations

For applications requiring full 3000W peak pulse power and 102.7A+ peak pulse current:

SM30T21AY, SMC30J18A, SMLJ18A, and SMLJ18A-TP maintain electrical performance equivalent to the SMDJ18A. SM30T21AY carries AEC-Q101 automotive qualification and extended operating temperature range (-55°C to 175°C), suitable for automotive and industrial environments. SMC30J18A and SMLJ18A provide equivalent current ratings with standard industrial temperature ranges. SMLJ18A-TP extends the upper operating temperature to 175°C.

For applications tolerating reduced peak pulse power (1500W) and 51.4A peak pulse current:

SMCJ18A, SMCJ18A-E3/57T, and SMCJ18A-TP are suitable alternatives. SMCJ18A-E3/57T is manufactured by Vishay General Semiconductor under the TransZorb® product line. SMCJ18A-TP and SMCJ18A-E3/57T both support extended operating temperature ranges to 175°C.

All substitute parts maintain ROHS3 compliance and DO-214AB/SMC package compatibility with the SMDJ18A.

Frequently Asked Questions (FAQ)

Q: Can SMCJ18A be used as a direct replacement for SMDJ18A?

A: SMCJ18A is electrically compatible in terms of voltage parameters (18V standoff, 20V breakdown, 29.2V clamping). However, it provides reduced peak pulse current (51.4A versus 102.7A) and peak pulse power (1500W versus 3000W). Use SMCJ18A only if your application does not require the full current and power handling capability of the SMDJ18A.

Q: What is the difference between Category A and Category B substitutes?

A: Category A substitutes (SM30T21AY, SMC30J18A, SMLJ18A, SMLJ18A-TP) maintain the full 102.7A to 103A peak pulse current and 3000W power rating, providing direct performance equivalence. Category B substitutes (SMCJ18A, SMCJ18A-E3/57T, SMCJ18A-TP) operate at 51.4A peak pulse current and 1500W power, suitable for lower-energy transient suppression applications.

Q: Are all substitute parts available in the same package?

A: Yes. All substitute parts use the DO-214AB surface-mount package, also designated as SMC. This ensures mechanical and footprint compatibility with the SMDJ18A on printed circuit boards.

Q: Which substitute offers the widest operating temperature range?

A: SM30T21AY, SMC30J18A, SMCJ18A-TP, and SMLJ18A-TP all support -55°C to 175°C operating temperature range, extending the upper limit by 25°C compared to the SMDJ18A (-65°C to 150°C).

Q: Is automotive qualification available in substitute parts?

A: SM30T21AY carries AEC-Q101 automotive qualification and is graded for automotive applications, making it suitable for automotive transient voltage suppression circuits.

Q: Do all parts maintain RoHS3 compliance?

A: Yes. All listed substitute parts are ROHS3 compliant, meeting environmental and regulatory requirements equivalent to the SMDJ18A.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message