SA85-B Equivalent & Substitute Parts

Part Overview

The SA85-B is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for transient overvoltage protection in telecom applications. This through-hole component operates with an 85V reverse standoff voltage and provides 137V maximum clamping voltage at peak pulse current. The SA85-B is classified as obsolete, necessitating identification of active equivalent parts to maintain design continuity and ensure ongoing component availability for production and field service applications.

Substiute Parts

SA85-B

Littelfuse Inc.In Stock: 713SA85-B Datasheet

Current PartRFQ

SA85A

Taiwan Semiconductor CorporationIn Stock: 1219SA85A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA85-B with the SA85A is based on electrical parameter equivalence within the SA series TVS diode family. Both components share identical specifications for the critical protection parameters: 85V reverse standoff voltage, 94.4V minimum breakdown voltage, and 137V maximum clamping voltage. Both devices maintain the same through-hole mounting configuration in DO-204AC (DO-15) axial package format, ensuring mechanical and electrical compatibility in existing PCB designs.

The substitution logic is determined by the following key parameters:

• Voltage - Reverse Standoff (Typ): 85V
• Voltage - Clamping (Max) @ Ipp: 137V
• Package / Case: DO-204AC (DO-15)
• Mounting Type: Through Hole
• Type: Zener, Unidirectional

Parameter Comparison

Engineering Selection Recommendations

The SA85A from Taiwan Semiconductor Corporation is a direct functional equivalent to the obsolete SA85-B. Selection of the SA85A is supported by the following factors:

Product Status: The SA85A maintains active product status, ensuring long-term availability and continued manufacturing support, whereas the SA85-B is obsolete and subject to inventory depletion.

Electrical Equivalence: Both devices operate at identical voltage protection thresholds (85V standoff, 137V clamping) and power dissipation ratings (500W peak pulse), confirming functional interchangeability in circuit protection applications.

Compliance: The SA85A meets ROHS3 compliance requirements and maintains EAR99 export classification identical to the SA85-B. Both components carry MSL Level 1 (Unlimited) moisture sensitivity ratings, indicating equivalent handling and storage requirements.

Package Compatibility: Both components utilize the DO-204AC (DO-15) axial through-hole package, enabling direct PCB footprint compatibility without design modification.

Peak Pulse Current: The SA85A provides 3.8A peak pulse current capacity, which exceeds the SA85-B specification of 3.7A, offering improved transient handling capability within the same thermal envelope.

Operating Temperature: The SA85A operates across -55°C to 175°C, which encompasses the primary operating range of the SA85-B (-65°C to 175°C). The SA85-B's extended lower temperature limit of -65°C is not required for general telecom applications.

Frequently Asked Questions (FAQ)

Q: Can the SA85A directly replace the SA85-B in existing designs?

A: Yes. The SA85A is electrically and mechanically equivalent to the SA85-B. Both components share identical voltage protection parameters (85V standoff, 137V clamping), power ratings (500W), and DO-204AC (DO-15) through-hole package configuration. No circuit modifications are required.

Q: What is the difference in peak pulse current between these parts?

A: The SA85A provides 3.8A peak pulse current capacity compared to the SA85-B's 3.7A specification. This 0.1A increase represents improved transient suppression capability and does not affect compatibility or circuit operation.

Q: Are there temperature range differences between the SA85-B and SA85A?

A: The SA85-B operates from -65°C to 175°C, while the SA85A operates from -55°C to 175°C. For standard telecom applications operating within -55°C to 175°C, both components are equivalent. Applications requiring operation below -55°C would require the SA85-B; however, the SA85-B is obsolete and unavailable.

Q: Do packaging and handling requirements differ between these parts?

A: No. Both components carry MSL Level 1 (Unlimited) moisture sensitivity ratings, indicating identical handling, storage, and reflow requirements. Both are RoHS compliant and carry EAR99 export classification.

Q: What is the availability status of each part?

A: The SA85-B is classified as obsolete with limited remaining inventory (685 pcs). The SA85A is active with robust inventory availability (1142 pcs), ensuring reliable supply for new production and field service applications.

Q: Are there any compliance or certification differences?

A: The SA85-B carries RoHS Compliance certification, while the SA85A carries ROHS3 Compliance certification. Both meet current regulatory requirements. Both components share identical ECCN (EAR99) and HTSUS (8541.10.0080) classifications.