SA33 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SA33 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features a 33V reverse standoff voltage with a 55.97V maximum clamping voltage and 9.6A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package. The SA33 is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support, maintenance, and component sourcing.

Substiute Parts

SA33

Littelfuse Inc.In Stock: 766SA33 Datasheet

Current PartRFQ

SA33A

Fairchild SemiconductorIn Stock: 21325SA33A Datasheet

DirectRFQ

P6KE39A

Taiwan Semiconductor CorporationIn Stock: 18061P6KE39A Datasheet

MFR RecommendedRFQ

SA33A-AP

Micro Commercial CoIn Stock: 902SA33A-AP Datasheet

MFR RecommendedRFQ

SA33A-BP

Micro Commercial CoIn Stock: 1012SA33A-BP Datasheet

MFR RecommendedRFQ

SA33A-TP

Micro Commercial CoIn Stock: 3421SA33A-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SA33 TVS diode are qualified based on the following electrical and mechanical parameters:

• Reverse standoff voltage within the 33V specification
• Breakdown voltage minimum in the range of 34.79V to 37.1V
• Clamping voltage (maximum @ Ipp) between 53.3V and 55.97V
• Peak pulse current capability of 9.4A or greater
• Peak pulse power rating of 500W or greater
• Unidirectional zener diode topology
• Through-hole axial package configuration (DO-15 / DO-204AC)
• RoHS3 compliance

The substitute parts identified maintain electrical performance within acceptable operating margins while preserving package compatibility and environmental compliance requirements.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: P6KE39A (Taiwan Semiconductor Corporation)

The P6KE39A is the manufacturer-recommended substitute for the SA33. This part maintains active product status, ensuring long-term availability and supply chain stability. It exceeds the original specification with 11.2A peak pulse current and 600W peak pulse power, providing enhanced transient protection margin. RoHS3 compliance and REACH unaffected status confirm environmental regulatory alignment. Cut Tape (CT) packaging supports automated assembly processes.

Secondary Recommendations: SA33A-TP, SA33A-AP, SA33A-BP (Micro Commercial Co)

These Micro Commercial Co variants provide direct electrical equivalence to the SA33 with active product status. The SA33A-TP in Cut Tape packaging is preferred for production environments. SA33A-AP and SA33A-BP in Bulk packaging support component stocking and manual assembly workflows. All three variants maintain the original 9.6A peak pulse current and 500W power rating with identical clamping voltage characteristics. Operating temperature range (-55°C to 175°C) matches the original specification.

Tertiary Option: SA33A (Fairchild Semiconductor)

The SA33A provides electrical compatibility with slightly reduced peak pulse current (9.4A versus 9.6A). Obsolete product status limits future availability. This option is suitable only when existing inventory must be consumed or when other substitutes are unavailable.

Frequently Asked Questions (FAQ)

Q: Can the P6KE39A directly replace the SA33 in existing designs?

A: Yes. The P6KE39A maintains the same reverse standoff voltage (33V nominal), clamping voltage range (53.9V maximum), and through-hole DO-15 axial package configuration. The higher peak pulse current (11.2A) and power rating (600W) provide additional protection margin without affecting circuit compatibility.

Q: What is the difference between SA33A-TP, SA33A-AP, and SA33A-BP?

A: These three Micro Commercial Co parts are electrically identical. The suffix designates packaging format: TP = Cut Tape (CT), AP = Bulk, BP = Bulk. Selection depends on assembly method and inventory management requirements. Cut Tape is standard for automated pick-and-place assembly; Bulk packaging supports manual assembly and component stocking.

Q: Are all substitute parts RoHS3 compliant?

A: The P6KE39A and SA33A-TP are explicitly RoHS3 compliant. SA33A-AP and SA33A-BP do not specify RoHS status in available documentation. For applications requiring RoHS3 certification, P6KE39A or SA33A-TP are the recommended selections.

Q: Does the SA33A from Fairchild Semiconductor remain a viable substitute despite obsolete status?

A: The SA33A is electrically compatible but carries obsolete product status, which may limit future availability. It is suitable for applications where existing inventory exists or when other substitutes are temporarily unavailable. For new designs or long-term production, active-status alternatives (P6KE39A or Micro Commercial Co variants) are preferred.

Q: What operating temperature range applies to all substitute parts?

A: The SA33, SA33A-TP, SA33A-AP, and SA33A-BP all specify -55°C to 175°C operating temperature range. The SA33A (Fairchild) and P6KE39A do not specify operating temperature in available documentation. For temperature-critical applications, confirm operating range with the component manufacturer or distributor.

Q: Can these TVS diodes be used interchangeably in power line protection circuits?

A: No. All listed parts specify "Power Line Protection: No." These components are rated for general-purpose transient suppression only and are not suitable for direct power line protection applications. Consult application-specific TVS diode datasheets for power line rated alternatives.