SA51A Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SA51A is a unidirectional Zener-type transient voltage suppressor diode manufactured by onsemi in the DO-204AC (DO-15) axial package. This component is designed for general-purpose transient voltage suppression applications with a 51V reverse standoff voltage and 82.4V maximum clamping voltage at peak pulse current. The SA51A is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and component procurement.

Key Parameters

Parameter	Value
Reverse Standoff Voltage (Typ)	51V
Breakdown Voltage (Min)	56.7V
Clamping Voltage (Max) @ Ipp	82.4V
Peak Pulse Current (10/1000µs)	6.1A
Peak Pulse Power	500W
Type	Zener
Unidirectional Channels	1
Mounting Type	Through Hole
Package / Case	DO-204AC, DO-15, Axial
Operating Temperature Range	-55°C ~ 150°C (TJ)
Applications	General Purpose

Substitute Part Grouping Explanation

Substitution for the SA51A is determined by strict equivalence across the following electrical and mechanical parameters:

Reverse standoff voltage: 51V (Typ)
Breakdown voltage: 56.7V (Min)
Clamping voltage: 82.4V (Max) @ Ipp
Peak pulse current: 6.1A minimum (10/1000µs)
Peak pulse power: 500W
Zener type, unidirectional configuration
Through-hole axial package (DO-204AC / DO-15)
General-purpose application category

Substitute parts are grouped into two categories:

Direct Equivalents: Parts with identical electrical specifications and active product status, differing only in packaging format (Cut Tape, Tape & Reel) or manufacturer source.

Similar Equivalents: Parts meeting all core electrical parameters with minor variations in peak pulse current (6.3A vs 6.1A) or operating temperature range, maintaining functional compatibility within the specified application envelope.

Parameter Comparison

Part Number	Manufacturer	Standoff Voltage (V)	Breakdown Voltage (V)	Clamping Voltage (V)	Peak Pulse Current (A)	Peak Pulse Power (W)	Operating Temp (°C)	Package	Product Status
SA51A	onsemi	51	56.7	82.4	6.1	500	-55 ~ 150	DO-204AC (Axial)	Obsolete
SA51A-E3/54	Vishay	51	56.7	82.4	6.1	500	-55 ~ 175	DO-204AC (CT)	Active
SA51AHE3/54	Vishay	51	56.7	82.4	6.1	500	-55 ~ 175	DO-204AC (TR)	Active
P5KE51A-AP	Micro Commercial Co	51	56.7	82.4	6.1	500	-65 ~ 175	DO-15 (Axial)	Active
P5KE51A-BP	Micro Commercial Co	51	56.7	82.4	6.1	500	-65 ~ 175	DO-15 (Axial)	Active
P5KE51A-TP	Micro Commercial Co	51	56.7	82.4	6.1	500	-65 ~ 175	DO-15 (Axial)	Active
SA51A	Taiwan Semiconductor Corporation	51	56.7	82.4	6.3	500	-55 ~ 175	DO-204AC (TR)	Active

Engineering Selection Recommendations

Primary Recommendation: SA51A-E3/54 (Vishay) or SA51AHE3/54 (Vishay)

The Vishay TransZorb® SA51A-E3/54 and SA51AHE3/54 are direct electrical equivalents with active product status and ROHS3 compliance. Both parts maintain identical voltage and current specifications while offering extended operating temperature range (-55°C to 175°C vs -55°C to 150°C). The SA51AHE3/54 includes AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade reliability.

Secondary Recommendation: P5KE51A-AP, P5KE51A-BP, or P5KE51A-TP (Micro Commercial Co)

These Micro Commercial Co parts meet all core electrical parameters with extended lower temperature rating (-65°C vs -55°C). All three variants are active products with identical specifications; selection between AP, BP, and TP variants depends on specific packaging and supply chain requirements.

Alternative: SA51A (Taiwan Semiconductor Corporation)

The Taiwan Semiconductor Corporation SA51A variant is electrically compatible with a marginally higher peak pulse current specification (6.3A vs 6.1A), providing additional design margin. This part is active with ROHS3 compliance and extended temperature range.

Frequently Asked Questions (FAQ)

Q: Can I substitute the obsolete onsemi SA51A with any of these alternatives?

A: Yes. All listed substitute parts maintain the critical electrical parameters: 51V standoff voltage, 56.7V minimum breakdown voltage, 82.4V maximum clamping voltage, and 6.1A peak pulse current. All are through-hole axial packages compatible with the original footprint.

Q: What is the difference between SA51A-E3/54 and SA51AHE3/54?

A: Both are Vishay equivalents with identical electrical specifications. SA51A-E3/54 is supplied in Cut Tape (CT) packaging, while SA51AHE3/54 is supplied in Tape & Reel (TR) format. SA51AHE3/54 includes AEC-Q101 automotive qualification. Selection depends on packaging requirements and application grade.

Q: Are the Micro Commercial Co P5KE51A variants interchangeable?

A: Yes. P5KE51A-AP, P5KE51A-BP, and P5KE51A-TP are electrically identical. The suffix designates different packaging or supply chain variants. All meet the same electrical specifications and operating temperature range (-65°C to 175°C).

Q: Does the Taiwan Semiconductor Corporation SA51A have any advantages?

A: The Taiwan Semiconductor Corporation SA51A offers a slightly higher peak pulse current rating (6.3A vs 6.1A), providing additional design margin in transient suppression applications. It maintains all other specifications and is ROHS3 compliant.

Q: What compliance certifications should I verify for my application?

A: Vishay parts are ROHS3 compliant. The SA51AHE3/54 includes AEC-Q101 automotive qualification. All listed parts are REACH unaffected. Verify compliance requirements against your specific application and regional standards.

Q: Can I use these parts in high-temperature applications?

A: The original onsemi SA51A operates to 150°C. Vishay and Taiwan Semiconductor variants extend to 175°C. Micro Commercial Co parts extend to 175°C with lower temperature rating to -65°C. Select based on your specific operating temperature envelope.

Q: Are there any package compatibility concerns?

A: All parts use DO-204AC or DO-15 axial packages, which are mechanically and electrically compatible. Verify your PCB footprint accepts standard axial through-hole components. Packaging format (bulk, cut tape, tape & reel) affects supply and handling but not electrical performance.

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