SA28-B Equivalent & Substitute Parts

Part Overview

The SA28-B is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for telecom applications. This component features a 28V reverse standoff voltage with a 45.4V maximum clamping voltage and 11.2A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package. The SA28-B is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing system support and procurement requirements.

Substiute Parts

SA28-B

Littelfuse Inc.In Stock: 1078SA28-B Datasheet

Current PartRFQ

SA28A

Fairchild SemiconductorIn Stock: 6156SA28A Datasheet

DirectRFQ

SA28A-B

Littelfuse Inc.In Stock: 1217SA28A-B Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SA28-B TVS diode are qualified based on electrical and mechanical parameter equivalence. The critical parameters determining substitution compatibility are:

• Voltage - Reverse Standoff: 28V (Typ)
• Voltage - Clamping (Max) @ Ipp: 45.4V
• Current - Peak Pulse (10/1000µs): 11.2A
• Power - Peak Pulse: 500W
• Package / Case: DO-204AC (DO-15) Axial
• Mounting Type: Through Hole
• Type: Zener, Unidirectional (1 channel)

The identified substitute parts SA28A-B and SA28A maintain identical electrical specifications across all critical parameters and share the same physical package configuration, enabling direct functional replacement in circuit applications.

Parameter Comparison

Engineering Selection Recommendations

SA28A-B (Littelfuse Inc.) is the primary recommended substitute for the obsolete SA28-B. This part maintains identical electrical and mechanical specifications while offering active product status, ensuring long-term availability and supply chain continuity. The SA28A-B carries ROHS3 compliance certification and REACH unaffected status, meeting current regulatory requirements for electronic component procurement.

SA28A (Fairchild Semiconductor) provides an alternative substitute with equivalent electrical performance and DO-204AC package compatibility. This part is classified as obsolete; however, it remains electrically interchangeable with the SA28-B across all critical parameters. The SA28A carries ROHS3 compliance and is suitable for applications where Fairchild-sourced components are acceptable.

Both substitute parts exhibit identical voltage regulation characteristics (28V standoff, 45.4V clamping) and current handling capacity (11.2A peak pulse), enabling direct circuit replacement without design modification. The minor difference in operating temperature range (-55°C minimum for substitutes versus -65°C for the main part) does not affect functionality in standard telecom applications operating within the -55°C to 175°C envelope.

Frequently Asked Questions (FAQ)

Q: Can SA28A-B be used as a direct replacement for SA28-B in existing designs?

A: Yes. The SA28A-B provides identical electrical specifications (28V standoff, 45.4V clamping, 11.2A peak pulse current) and shares the same DO-204AC through-hole axial package. No circuit modifications are required for substitution.

Q: What is the difference between SA28A-B and SA28A?

A: Both parts are electrically equivalent with identical voltage and current ratings. The primary differences are manufacturer (Littelfuse vs. Fairchild) and product status (SA28A-B is active; SA28A is obsolete). SA28A-B is recommended for new procurement due to active status.

Q: Are there operating temperature differences between the substitute parts and the original SA28-B?

A: The SA28-B operates from -65°C to 175°C, while SA28A-B and SA28A operate from -55°C to 175°C. Both substitute parts cover the standard telecom operating range of -55°C to 175°C. Applications requiring operation below -55°C require evaluation of the reduced temperature specification.

Q: Do the substitute parts meet current compliance standards?

A: Yes. SA28A-B carries ROHS3 compliance and REACH unaffected status. SA28A carries ROHS3 compliance. Both meet current regulatory requirements for electronic component procurement.

Q: Is the DO-204AC package identical across all three parts?

A: Yes. The SA28-B, SA28A-B, and SA28A all use the DO-204AC (DO-15) axial through-hole package, ensuring mechanical and electrical compatibility on printed circuit boards without layout modifications.

Q: Can SA28A be used if SA28A-B is unavailable?

A: Yes. SA28A provides identical electrical performance and package compatibility. However, SA28A-B is preferred due to active product status, which typically ensures better long-term availability and supply chain support.