SMAJ250 Equivalent & Substitute Parts

Part Overview

The SMAJ250 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features a 250V reverse standoff voltage with a 425.25V maximum clamping voltage and 1A peak pulse current capability in a DO-214AC (SMA) package.

The SMAJ250 is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this component.

Substiute Parts

SMAJ250

Littelfuse Inc.In Stock: 912SMAJ250 Datasheet

Current PartRFQ

SMAJ250A

MeritekIn Stock: 5445SMAJ250A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMAJ250 is determined by the following critical parameters:

• Voltage Rating: Reverse standoff voltage of 250V and breakdown voltage minimum of 264.6V
• Clamping Voltage: Maximum clamping voltage at peak pulse current (Ipp)
• Peak Pulse Current: 1A capability at 10/1000µs pulse duration
• Power Dissipation: 400W peak pulse power rating
• Package Compatibility: DO-214AC (SMA) surface-mount package
• Electrical Type: Unidirectional zener TVS diode
• Compliance: ROHS3 compliance and MSL 1 rating

The SMAJ250A from Meritek meets these substitution criteria. It maintains the same 250V reverse standoff voltage, DO-214AC package, surface-mount configuration, and zener type. The clamping voltage (405V) and peak pulse current (990mA) remain within acceptable operational parameters for general-purpose TVS applications, with equivalent 400W peak pulse power rating and ROHS3 compliance.

Parameter Comparison

Engineering Selection Recommendations

The SMAJ250A (Meritek) qualifies as a direct substitute for the obsolete SMAJ250 (Littelfuse) based on the following criteria:

Electrical Compatibility: Both devices maintain identical 250V reverse standoff voltage and 1A peak pulse current specification. The SMAJ250A exhibits a lower maximum clamping voltage (405V versus 425.25V), which provides improved transient suppression performance. The breakdown voltage minimum of 279V in the SMAJ250A remains within acceptable tolerance for general-purpose TVS applications.

Package and Mounting: Both components utilize the DO-214AC (SMA) surface-mount package, ensuring direct PCB footprint compatibility without design modification.

Compliance and Reliability: Both parts maintain ROHS3 compliance and MSL 1 (unlimited moisture sensitivity) ratings, supporting equivalent reliability and environmental standards. The SMAJ250A is classified as active product status, ensuring continued availability and supply chain support.

Temperature Operating Range: The SMAJ250A operates across -55°C to 150°C, compared to the SMAJ250's -65°C to 150°C range. Applications requiring operation below -55°C require design review.

Frequently Asked Questions (FAQ)

Q: Can the SMAJ250A directly replace the SMAJ250 without PCB modification?

A: Yes. Both components share identical DO-214AC (SMA) package geometry and surface-mount footprint. No PCB layout changes are required for mechanical or electrical integration.

Q: What is the significance of the clamping voltage difference between SMAJ250 (425.25V) and SMAJ250A (405V)?

A: The SMAJ250A's lower clamping voltage indicates superior transient suppression performance. It clamps overvoltage transients to a lower peak level, providing enhanced protection for downstream circuitry. This represents an improvement over the original SMAJ250 specification.

Q: Are there temperature range limitations when substituting the SMAJ250A?

A: The SMAJ250A operates from -55°C to 150°C, compared to the SMAJ250's -65°C to 150°C range. Applications requiring operation below -55°C ambient temperature must be evaluated for thermal performance impact.

Q: Do both parts meet the same compliance and environmental standards?

A: Yes. Both the SMAJ250 and SMAJ250A are ROHS3 compliant with MSL 1 (unlimited) moisture sensitivity ratings. They meet equivalent environmental and regulatory requirements for general-purpose applications.

Q: What is the peak pulse current difference between these devices?

A: The SMAJ250 is rated for 1A peak pulse current, while the SMAJ250A is rated for 990mA. This 10mA difference is negligible for general-purpose TVS applications and does not affect functional substitution.

Q: Is the SMAJ250A currently available for procurement?

A: Yes. The SMAJ250A is classified as active product status with documented inventory availability, ensuring reliable supply chain access compared to the obsolete SMAJ250.