SA40-B Equivalent & Substitute Parts

Part Overview

The SA40-B is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for transient overvoltage protection in telecom applications. This component features a 40V reverse standoff voltage with a 64.5V maximum clamping voltage and 7.9A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package.

The SA40-B is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for systems utilizing this TVS diode specification.

Substiute Parts

SA40-B

Littelfuse Inc.In Stock: 705SA40-B Datasheet

Current PartRFQ

SA40A

Taiwan Semiconductor CorporationIn Stock: 1177SA40A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA40-B TVS diode is determined by electrical and mechanical parameter equivalence. The following criteria establish valid substitution:

Electrical Parameters (Critical):

• Voltage - Reverse Standoff (Typ): 40V
• Voltage - Breakdown (Min): 44.4V
• Voltage - Clamping (Max) @ Ipp: 64.5V
• Power - Peak Pulse: 500W

Mechanical Parameters (Critical):

• Package / Case: DO-204AC (DO-15) Axial
• Mounting Type: Through Hole
• Unidirectional Channels: 1

Functional Parameters (Critical):

• Type: Zener
• Category: Transient Voltage Suppressors (TVS)

The SA40A, manufactured by Taiwan Semiconductor Corporation, meets all critical electrical and mechanical parameters. Variations in peak pulse current (7.9A vs. 8.1A) and operating temperature range remain within acceptable substitution tolerance for this component category, as the clamping voltage and power dissipation specifications are maintained.

Parameter Comparison

Engineering Selection Recommendations

SA40A (Taiwan Semiconductor Corporation) - Active Status

The SA40A is the primary substitute for the obsolete SA40-B. This component maintains electrical equivalence across all critical voltage and power parameters. The SA40A is classified as Active product status, ensuring ongoing availability and supply chain support.

Compliance certifications for the SA40A include ROHS3 Compliant and REACH Unaffected status, meeting current regulatory requirements. The component is available in Tape & Reel (TR) packaging with 1144 units in current inventory.

The SA40A exhibits a marginally higher peak pulse current specification (8.1A versus 7.9A), which represents improved performance capability within the same thermal and voltage envelope. The operating temperature range of -55°C to 175°C covers the upper operational boundary of the SA40-B and is suitable for general-purpose and telecom applications.

Frequently Asked Questions (FAQ)

Q: Can the SA40A directly replace the SA40-B in existing designs?

A: Yes. The SA40A meets all critical electrical parameters (40V standoff, 44.4V breakdown minimum, 64.5V clamping maximum, 500W peak pulse power) and maintains identical mechanical compatibility through the DO-204AC (DO-15) axial through-hole package. Both components are unidirectional Zener-type TVS diodes with single channels.

Q: What is the significance of the peak pulse current difference (7.9A vs. 8.1A)?

A: The SA40A provides 8.1A peak pulse current compared to the SA40-B's 7.9A specification. This represents enhanced current handling capability within the same voltage clamping and power dissipation envelope. This difference does not restrict substitution; the SA40A performs within or exceeds the original specification.

Q: Are there packaging differences between SA40-B and SA40A?

A: Both components use the DO-204AC (DO-15) axial through-hole package. The SA40-B was supplied in standard packaging, while the SA40A is available in Tape & Reel (TR) format. The physical component dimensions and pin configuration remain identical, ensuring direct mechanical compatibility on printed circuit boards.

Q: What is the operating temperature range difference?

A: The SA40-B operates from -65°C to 175°C (TJ), while the SA40A operates from -55°C to 175°C (TJ). The SA40A's lower temperature limit of -55°C covers the majority of industrial and telecom applications. If operation below -55°C is required, the SA40-B specification must be maintained.

Q: Are there compliance or regulatory differences?

A: The SA40-B is RoHS Compliant. The SA40A is ROHS3 Compliant and REACH Unaffected, representing current regulatory standards. Both components carry EAR99 ECCN classification and 8541.10.0080 HTSUS code. The SA40A's enhanced compliance status supports modern supply chain and environmental requirements.

Q: What is the availability status of each component?

A: The SA40-B is classified as Obsolete with 651 units in current inventory. The SA40A is classified as Active with 1144 units in current inventory, ensuring long-term supply chain support and design continuity for new production.