SA85A Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SA85A is an active Littelfuse Inc. TVS diode designed for transient voltage suppression in general-purpose applications. This unidirectional Zener diode features an 85V reverse standoff voltage with a 137V maximum clamping voltage and 3.7A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package. The SA85A is ROHS3 compliant and rated for operating temperatures from -55°C to 175°C. Equivalent substitute parts are identified based on matching critical electrical parameters including clamping voltage, package type, and thermal operating range to ensure functional interchangeability in circuit protection applications.

Substiute Parts

SA85A

Littelfuse Inc.In Stock: 1048SA85A Datasheet

Current PartRFQ

P6KE100A

Fairchild SemiconductorIn Stock: 18965P6KE100A Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SA85A are identified based on the following critical parameters that determine functional interchangeability:

• Voltage - Clamping (Max) @ Ipp: Must match at 137V to ensure equivalent transient suppression performance
• Package / Case: Must be DO-204AC or DO-15 axial through-hole to maintain mechanical and electrical compatibility
• Type: Must be Zener diode for consistent suppression characteristics
• Unidirectional Channels: Must be 1 channel for single-direction protection
• Mounting Type: Must be through-hole for PCB compatibility
• Operating Temperature Range: Must support the application's thermal requirements

The P6KE100A from Fairchild Semiconductor meets these substitution criteria with matching clamping voltage (137V), identical package type (DO-15/DO-204AC), and compatible thermal operating range (-55°C to 150°C).

Parameter Comparison

Engineering Selection Recommendations

Both the SA85A and P6KE100A are active products with equivalent clamping voltage performance (137V) and identical package configurations (DO-15/DO-204AC through-hole axial). The P6KE100A offers higher peak pulse current (4.4A vs 3.7A) and peak pulse power (600W vs 500W), providing additional margin in transient suppression applications. The SA85A maintains a higher maximum operating temperature (175°C vs 150°C), which may be required for high-temperature environments. Both devices are ROHS3 compliant and carry EAR99 ECCN classification. Selection between these parts should be based on specific application requirements regarding operating temperature limits and available current/power headroom.

Frequently Asked Questions (FAQ)

Q: Can the P6KE100A directly replace the SA85A in existing designs?

A: Yes, the P6KE100A is functionally equivalent for transient voltage suppression. Both devices share identical clamping voltage (137V), package type (DO-15/DO-204AC), and mounting configuration (through-hole axial). The primary difference is the reverse standoff voltage (100V vs 85V) and operating temperature range. Verify that your circuit's standoff voltage requirement aligns with the P6KE100A's 100V specification.

Q: What is the significance of the clamping voltage match?

A: The clamping voltage (137V maximum @ Ipp) is the critical parameter determining transient suppression performance. Both parts clamp at identical voltage levels, ensuring equivalent protection of downstream circuitry from voltage transients.

Q: Are there thermal considerations when substituting these parts?

A: The SA85A operates to 175°C while the P6KE100A operates to 150°C. If your application requires operation above 150°C, the SA85A is the appropriate choice. For applications within the 150°C limit, both parts are thermally compatible.

Q: Do these parts require different PCB footprints?

A: No. Both the SA85A and P6KE100A use identical DO-15 (DO-204AC) axial through-hole packages, requiring no PCB layout modifications for substitution.

Q: What does the reverse standoff voltage difference mean for circuit protection?

A: The reverse standoff voltage (85V for SA85A, 100V for P6KE100A) is the maximum voltage the diode can withstand without conducting. The P6KE100A's higher standoff voltage may be suitable for circuits with higher nominal operating voltages, while the SA85A is optimized for lower-voltage applications.