SA43-B Transient Voltage Suppressor (TVS) Equivalent & Substitute Parts

Part Overview

The SA43-B is a unidirectional Zener-type transient voltage suppressor diode manufactured by Littelfuse Inc., designed for telecom applications. This component features a 43V reverse standoff voltage with a 69.4V maximum clamping voltage and 7.3A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package format.

The SA43-B is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support legacy system maintenance and repairs.

Substiute Parts

SA43-B

Littelfuse Inc.In Stock: 1020SA43-B Datasheet

Current PartRFQ

SA43A

Fairchild SemiconductorIn Stock: 300340SA43A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of TVS diodes is determined by electrical parameter equivalence and mechanical compatibility. The SA43-B can be substituted with parts that maintain identical or functionally equivalent specifications across the following critical parameters:

Electrical Equivalence Criteria:

• Voltage - Reverse Standoff (Typ): 43V
• Voltage - Breakdown (Min): 47.8V
• Voltage - Clamping (Max) @ Ipp: 69.4V
• Current - Peak Pulse (10/1000µs): 7.3A
• Power - Peak Pulse: 500W
• Type: Zener, Unidirectional (1 channel)

Mechanical Compatibility Criteria:

• Package / Case: DO-204AC (DO-15) axial through-hole configuration
• Mounting Type: Through Hole

Substitute parts must satisfy all electrical parameters and maintain the same physical package format to ensure direct board-level compatibility without circuit redesign or PCB modification.

Parameter Comparison

Engineering Selection Recommendations

SA43A (Fairchild Semiconductor) - Direct Substitute

The SA43A is a direct electrical and mechanical equivalent to the SA43-B. Both components share identical voltage ratings, current specifications, power dissipation, package format, and unidirectional Zener topology. Both parts are classified as obsolete and carry RoHS compliance certifications (RoHS and ROHS3 respectively).

The SA43A exhibits a narrower operating temperature range (-55°C to 175°C versus -65°C to 175°C for the SA43-B). This difference is relevant only for applications requiring operation below -55°C. For standard telecom and general-purpose applications operating within the -55°C to 175°C envelope, the SA43A provides full functional equivalence.

The SA43A is available in significantly higher inventory quantities (300,300 pieces) compared to the SA43-B (962 pieces), making it the preferred substitute for ongoing supply requirements.

Frequently Asked Questions (FAQ)

Q: Can the SA43A directly replace the SA43-B without circuit modification?

A: Yes. The SA43A is electrically and mechanically equivalent. Both components feature identical voltage ratings (43V standoff, 69.4V clamping), current specifications (7.3A peak pulse), power dissipation (500W), and package format (DO-204AC axial through-hole). Direct board-level substitution is possible without PCB redesign.

Q: What is the significance of the operating temperature range difference?

A: The SA43-B operates from -65°C to 175°C, while the SA43A operates from -55°C to 175°C. The SA43A has a 10°C narrower lower temperature limit. For applications requiring operation below -55°C, the SA43-B is required. For standard operating environments, this difference is not a limiting factor.

Q: Are both parts RoHS compliant?

A: Yes. The SA43-B carries RoHS compliance certification, and the SA43A carries ROHS3 compliance certification. Both meet environmental and hazardous substance restrictions applicable to their respective certification standards.

Q: Why is the SA43A preferred despite being from a different manufacturer?

A: The SA43A is preferred due to superior supply availability (300,300 pieces in stock versus 962 pieces for the SA43-B) and complete electrical equivalence. Both parts are obsolete, making inventory availability a critical selection factor for ongoing support and maintenance applications.

Q: Can these parts be used interchangeably in new designs?

A: Both the SA43-B and SA43A are classified as obsolete products. Neither part is recommended for new design implementations. New designs should specify current-production TVS diodes with equivalent electrical specifications and modern package options.

Q: What package format do these parts use?

A: Both the SA43-B and SA43A use the DO-204AC package format, also designated as DO-15. This is an axial through-hole package with leads on opposite ends, suitable for insertion into PCB holes and wave soldering or hand soldering processes.