SA54-B Transient Voltage Suppressor (TVS) Equivalent & Substitute Parts

Part Overview

The SA54-B is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse Inc., designed for telecom applications. This through-hole component operates across a temperature range of -65°C to 175°C and provides peak pulse power handling of 500W with a clamping voltage of 87.1V at peak pulse current.

The SA54-B carries an obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements for systems utilizing this TVS diode.

Substiute Parts

SA54-B

Littelfuse Inc.In Stock: 729SA54-B Datasheet

Current PartRFQ

SA54A

Taiwan Semiconductor CorporationIn Stock: 892SA54A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA54-B is determined by strict equivalence across the following critical parameters:

Voltage Parameters: Reverse standoff voltage (54V typical), breakdown voltage minimum (60V), and clamping voltage maximum at peak pulse current (87.1V) must remain identical to ensure proper transient suppression without circuit degradation.

Current Handling: Peak pulse current rating must meet or exceed the original specification (5.9A at 10/1000µs pulse width).

Power Dissipation: Peak pulse power rating must equal or exceed 500W to maintain thermal performance under transient events.

Package Compatibility: The substitute must utilize the DO-204AC (DO-15) axial through-hole package to ensure mechanical and electrical compatibility with existing PCB layouts.

Operating Temperature: The substitute must support the full operating temperature range or a range that encompasses the original specification (-65°C to 175°C).

Device Type: The substitute must be a unidirectional Zener-type TVS diode with a single channel configuration.

Parameter Comparison

Engineering Selection Recommendations

SA54A as Primary Substitute:

The SA54A from Taiwan Semiconductor Corporation qualifies as a functional substitute for the obsolete SA54-B. Both devices share identical voltage parameters (54V standoff, 60V breakdown minimum, 87.1V clamping maximum), equivalent power dissipation (500W peak pulse), and identical package configuration (DO-204AC through-hole axial).

The SA54A demonstrates superior peak pulse current capability (6A versus 5.9A), providing additional margin for transient suppression. Both components maintain RoHS compliance and unlimited moisture sensitivity classification (MSL 1).

Temperature Range Consideration:

The SA54A operates across -55°C to 175°C, which represents a narrower lower temperature bound compared to the SA54-B specification of -65°C to 175°C. Applications requiring operation below -55°C ambient or junction temperature must evaluate this limitation against system requirements.

Product Status Advantage:

The SA54A carries active product status, ensuring ongoing availability, manufacturing support, and supply chain continuity. This status contrasts with the SA54-B obsolete classification, making the SA54A the appropriate selection for new designs or sustained production requirements.

Packaging Consideration:

The SA54A is supplied in Tape & Reel (TR) packaging, whereas the SA54-B specification does not specify packaging format. Both utilize the identical DO-204AC (DO-15) component package, ensuring direct mechanical and electrical compatibility on PCB assemblies.

Frequently Asked Questions (FAQ)

Q: Can the SA54A directly replace the SA54-B in existing circuit designs?

A: The SA54A provides electrical and mechanical compatibility with the SA54-B across all critical transient suppression parameters: voltage ratings (54V standoff, 87.1V clamping), power dissipation (500W), and package format (DO-204AC through-hole). Direct substitution is supported for applications operating within the SA54A temperature range (-55°C to 175°C).

Q: What is the significance of the 0.1A higher peak pulse current rating on the SA54A?

A: The SA54A peak pulse current of 6A exceeds the SA54-B specification of 5.9A. This represents additional design margin and does not create incompatibility. The substitute provides equal or superior performance in transient suppression capability.

Q: Does the narrower operating temperature range of the SA54A affect substitution suitability?

A: The SA54A minimum operating temperature of -55°C (versus -65°C for the SA54-B) represents a design constraint. Applications requiring junction temperatures below -55°C must evaluate this specification against system environmental requirements. For applications within the -55°C to 175°C range, the SA54A operates within specification.

Q: Are there compliance or certification differences between the SA54-B and SA54A?

A: Both components maintain RoHS compliance. The SA54-B carries RoHS Compliant status, while the SA54A carries ROHS3 Compliant status, representing an updated compliance standard. Both devices maintain MSL 1 (unlimited moisture sensitivity) classification and EAR99 export control designation.

Q: What packaging format differences exist between these components?

A: The SA54A is supplied in Tape & Reel (TR) format, suitable for automated assembly processes. The SA54-B specification does not define packaging format. Both components utilize the identical DO-204AC (DO-15) axial through-hole package, ensuring compatibility with manual or automated PCB assembly methods.

Q: Why is the SA54-B classified as obsolete?

A: Obsolete product status indicates that the SA54-B is no longer manufactured or supported by Littelfuse Inc. The SA54A from Taiwan Semiconductor Corporation provides functional equivalence and active product status, ensuring sustained availability and manufacturing support.

Q: Can the SA54A be used in telecom applications originally designed for the SA54-B?

A: The SA54A specifications support general-purpose applications. The original SA54-B was designated for telecom applications. The SA54A electrical and thermal characteristics are compatible with telecom transient suppression requirements. Application-specific validation is determined by circuit design parameters rather than application category designation.