SMAJ300 Equivalent & Substitute Parts

Part Overview

The SMAJ300 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose transient voltage protection in surface-mount applications. The device features a 300V reverse standoff voltage with a 510.3V maximum clamping voltage and 800mA peak pulse current capability in a DO-214AC (SMA) package. The SMAJ300 is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

SMAJ300

Littelfuse Inc.In Stock: 1052SMAJ300 Datasheet

Current PartRFQ

SMAJ300A

MeritekIn Stock: 3720SMAJ300A Datasheet

DirectRFQ

SMAJ300A

MeritekIn Stock: 3720SMAJ300A Datasheet

DirectRFQ

P4SMA350A

Eaton - Electronics DivisionIn Stock: 20167P4SMA350A Datasheet

MFR RecommendedRFQ

SMAJP4KE350A-TP

Micro Commercial CoIn Stock: 1162SMAJP4KE350A-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the SMAJ300 is determined by the following critical parameters:

• Voltage - Reverse Standoff: Must be 300V (±0V tolerance for direct substitution)
• Package / Case: Must be DO-214AC (SMA) for mechanical and electrical compatibility
• Mounting Type: Must be Surface Mount
• Unidirectional Channels: Must be 1
• Type: Must be Zener TVS diode
• Voltage - Clamping (Max) @ Ipp: Acceptable range 482V to 510.3V (within transient suppression design margins)
• Current - Peak Pulse (10/1000µs): Acceptable range 800mA to 900mA (within thermal design margins)
• Power - Peak Pulse: Must be 400W
• RoHS Status: Must be ROHS3 Compliant or equivalent
• Moisture Sensitivity Level (MSL): Must be 1 (Unlimited)

All substitute parts listed maintain these critical parameters within acceptable engineering tolerances for direct board-level replacement.

Parameter Comparison

Engineering Selection Recommendations

SMAJ300A (Meritek) is a direct equivalent with active product status. It maintains identical reverse standoff voltage (300V) and package configuration (DO-214AC, SMA). The clamping voltage is 486V (24.3V lower than the original) and peak pulse current is 820mA (20mA higher). Both values remain within acceptable design margins for general-purpose transient suppression. ROHS3 compliance and MSL 1 rating match the original specification. This part is recommended as the primary substitute for direct replacement.

P4SMA350A (Eaton - Electronics Division) is a manufacturer-recommended substitute with active product status. It maintains the 300V reverse standoff voltage and DO-214AC (SMA) package. The clamping voltage is 482V and peak pulse current is 900mA, both within acceptable operational margins. The part carries RoHS compliance and MSL 1 rating. Higher inventory availability (20,120 pcs) supports procurement reliability. This part is suitable for applications where Eaton component qualification is preferred.

SMAJP4KE350A-TP (Micro Commercial Co) is a manufacturer-recommended substitute with active product status. It maintains the 300V reverse standoff voltage and DO-214AC (SMA) package. The clamping voltage is 482V and peak pulse current is 900mA. This part offers an extended operating temperature range (-55°C ~ 175°C) compared to the original (-65°C ~ 150°C), providing additional thermal margin for high-temperature applications. ROHS3 compliance and MSL 1 rating are maintained.

All substitute parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity ratings, ensuring compliance with current environmental and reliability standards.

Frequently Asked Questions (FAQ)

Q: Can SMAJ300A be used as a direct replacement for SMAJ300?

A: Yes. SMAJ300A maintains the critical 300V reverse standoff voltage and DO-214AC (SMA) package configuration. The clamping voltage (486V vs. 510.3V) and peak pulse current (820mA vs. 800mA) variations are within acceptable design tolerances for general-purpose transient suppression applications.

Q: What is the difference between the clamping voltage specifications across these parts?

A: The original SMAJ300 specifies a maximum clamping voltage of 510.3V. Substitute parts (SMAJ300A, P4SMA350A, SMAJP4KE350A-TP) specify lower clamping voltages (482V to 486V). These lower values provide improved transient suppression performance while remaining compatible with 300V standoff voltage applications. The variation reflects different manufacturing processes and design optimization across manufacturers.

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

A: Yes. All substitute parts use the DO-214AC (SMA) surface-mount package, ensuring mechanical and electrical compatibility with the original SMAJ300 footprint and PCB layout.

Q: Which substitute part has the best temperature performance?

A: SMAJP4KE350A-TP offers the widest operating temperature range (-55°C ~ 175°C), compared to the original SMAJ300 (-65°C ~ 150°C). This extended range provides additional thermal margin for high-temperature circuit environments. However, the original SMAJ300 supports lower minimum temperatures (-65°C vs. -55°C).

Q: Do all substitute parts meet RoHS compliance requirements?

A: Yes. All substitute parts carry RoHS compliance certification (ROHS3 or RoHS Compliant), meeting current environmental and regulatory standards. All parts maintain MSL 1 (Unlimited) moisture sensitivity ratings.

Q: What is the inventory status of these substitute parts?

A: SMAJ300A (Meritek) has 3,614 pcs in stock. P4SMA350A (Eaton) has 20,120 pcs in stock, providing the highest availability. SMAJP4KE350A-TP (Micro Commercial Co) has 1,142 pcs in stock. The original SMAJ300 (Littelfuse) has 1,039 pcs in stock but is classified as obsolete.