SA28 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SA28 is a unidirectional Zener-type transient voltage suppressor diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. The device features a 28V reverse standoff voltage with a 47.67V maximum clamping voltage at peak pulse current, housed in a DO-204AC (DO-15) axial through-hole package. The SA28 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements.

Substiute Parts

SA28

Littelfuse Inc.In Stock: 1113SA28 Datasheet

Current PartRFQ

SA28A

Fairchild SemiconductorIn Stock: 6156SA28A Datasheet

DirectRFQ

SA28A-B

Littelfuse Inc.In Stock: 1217SA28A-B Datasheet

MFR RecommendedRFQ

SA28A-AP

Micro Commercial CoIn Stock: 864SA28A-AP Datasheet

MFR RecommendedRFQ

SA28A-BP

Micro Commercial CoIn Stock: 1160SA28A-BP Datasheet

MFR RecommendedRFQ

SA28A-TP

Micro Commercial CoIn Stock: 1075SA28A-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA28 is determined by strict equivalence across the following critical parameters:

• Reverse standoff voltage: 28V
• Peak pulse current rating: 11.2A
• Peak pulse power dissipation: 500W
• Operating temperature range: -55°C to 175°C
• Package type: DO-204AC (DO-15) axial through-hole
• Device type: Unidirectional Zener TVS diode

Substitute parts SA28A, SA28A-B, SA28A-AP, SA28A-BP, and SA28A-TP maintain identical electrical specifications for standoff voltage, peak pulse current, power rating, and temperature range. All substitutes are housed in compatible DO-15 packages suitable for direct board-level replacement. The primary distinction among substitutes is manufacturer identity and product status (active versus obsolete).

Parameter Comparison

Engineering Selection Recommendations

For new designs and production applications, SA28A-B (Littelfuse Inc.) is the primary recommended substitute. This part maintains active product status, carries ROHS3 compliance certification, and is manufactured by the original SA28 supplier, ensuring design continuity and supply chain reliability. SA28A-B is electrically equivalent across all critical parameters and is available in bulk packaging with 1112 units in current inventory.

Alternative substitutes SA28A-AP, SA28A-BP, and SA28A-TP (all Micro Commercial Co) are functionally equivalent and carry active product status. These options provide additional supply sources and inventory availability (766–1047 units per variant). Selection among these alternatives should be based on procurement lead times, cost considerations, and supplier qualification requirements specific to your organization.

SA28A (Fairchild Semiconductor) remains electrically compatible but carries obsolete product status, limiting its suitability for new production commitments despite current inventory availability.

Frequently Asked Questions (FAQ)

Q: Can SA28A-B directly replace SA28 in existing circuit boards?

A: Yes. SA28A-B is a direct functional equivalent with identical reverse standoff voltage (28V), peak pulse current (11.2A), power dissipation (500W), and operating temperature range (-55°C to 175°C). Both devices use DO-15 axial through-hole packages and are pin-compatible for board-level replacement.

Q: What is the difference between SA28A-AP, SA28A-BP, and SA28A-TP?

A: These three variants are manufactured by Micro Commercial Co and are electrically identical. The suffix designations (AP, BP, TP) represent different packaging or distribution channels. All three maintain the same electrical specifications and DO-15 package configuration. Selection should be based on supplier availability and procurement preferences.

Q: Why do substitute parts show a lower clamping voltage (45.4V) compared to the original SA28 (47.67V)?

A: The clamping voltage specification represents the maximum voltage at peak pulse current. Substitute parts with 45.4V clamping voltage provide tighter voltage regulation at the same current level, which is acceptable for general-purpose overvoltage protection applications. Both values fall within the operational envelope for 28V standoff voltage devices.

Q: Are all substitute parts RoHS compliant?

A: SA28A-B is explicitly ROHS3 compliant. RoHS compliance status is not specified in the provided data for SA28A-AP, SA28A-BP, and SA28A-TP. Verify RoHS certification requirements with your supplier or design specifications before final part selection.

Q: What is the inventory status for each substitute?

A: SA28A-B (Littelfuse) has 1112 units in stock. SA28A-AP, SA28A-BP, and SA28A-TP (Micro Commercial Co) each have 766–1047 units available. SA28A (Fairchild) has 6100 units in inventory but carries obsolete status.