SA15ARLG Transient Voltage Suppressor - Equivalent & Substitute Parts

Part Overview

The SA15ARLG is a 15V Zener transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in through-hole applications. This part features a 24.4V maximum clamping voltage, 20.6A peak pulse current capability, and 500W peak pulse power rating in a DO-204AC (DO-15) axial package. The SA15ARLG is currently classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production and field replacements.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	15V
Voltage - Breakdown (Min)	16.7V
Voltage - Clamping (Max) @ Ipp	24.4V
Current - Peak Pulse (10/1000µs)	20.6A
Power - Peak Pulse	500W
Operating Temperature Range	-55°C ~ 150°C (TJ)
Mounting Type	Through Hole
Package / Case	DO-204AC, DO-15, Axial
Type	Zener
Unidirectional Channels	1

Substitute Part Grouping Explanation

Substitution eligibility for the SA15ARLG is determined by the following critical parameters:

Voltage - Reverse Standoff: 15V (nominal)
Voltage - Clamping (Max) @ Ipp: 24.4V (maximum allowable)
Current - Peak Pulse (10/1000µs): minimum 20.6A
Power - Peak Pulse: minimum 500W
Mounting Type: Through Hole
Package / Case: DO-204AC (DO-15) or equivalent axial configuration
Type: Zener, Unidirectional

Substitute parts are grouped into two categories:

Category A - Direct Electrical Equivalents (DO-204AC/DO-15 Package): Parts meeting all electrical parameters within the specified ranges, maintaining identical or superior performance characteristics in the same physical package form.

Category B - Higher Power Capability Alternatives (P600 Package): Parts with identical voltage specifications but significantly higher current and power ratings, suitable for applications requiring enhanced transient protection. These use a different physical package (P600) and require mechanical redesign.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Package / Case	Product Status
SA15ARLG	Littelfuse Inc.	15V	24.4V	20.6A	500W	-55°C ~ 150°C	DO-204AC (DO-15)	Obsolete
SA15A	Taiwan Semiconductor Corporation	15V	24.4V	21A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
SA15A-B	Littelfuse Inc.	15V	24.4V	20.9A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
SA15A-E3/73	Vishay General Semiconductor - Diodes Division	15V	24.4V	20.5A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
SA15A-TP	Micro Commercial Co	15V	24.4V	20.9A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
SA15AHE3/54	Vishay General Semiconductor - Diodes Division	15V	24.4V	20.5A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
SAC15-AP	Micro Commercial Co	15V	23.6V	20A	500W	-55°C ~ 175°C	DO-204AC (DO-15)	Active
P6KE18A	Fairchild Semiconductor	15.3V	25.2V	25A	600W	-50°C ~ 175°C	DO-204AC (DO-15)	Active
1N8157	Microchip Technology	15V	25.1V	5.98A	150W	-55°C ~ 175°C	Axial	Active
SLD15U-017	Littelfuse Inc.	15V	24.4V	209A	5000W (5kW)	-55°C ~ 175°C	P600	Active
SLD15U-017-B	Littelfuse Inc.	15V	24.4V	209A	5000W (5kW)	-55°C ~ 175°C	P600	Active

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

SA15A, SA15A-B, SA15A-E3/73, SA15A-TP, and SA15AHE3/54 are the preferred direct replacements for the SA15ARLG. All maintain identical voltage specifications (15V reverse standoff, 24.4V clamping), equivalent or superior current ratings (20.5A to 21A), and are active products with extended operating temperature ranges (-55°C to 175°C). These parts are available in the same DO-204AC (DO-15) axial package, requiring no circuit board modifications. All primary substitutes carry ROHS3 compliance and unlimited moisture sensitivity level (MSL 1).

Secondary Substitutes (Conditional Use):

SAC15-AP offers electrical compatibility with a slightly lower clamping voltage (23.6V) and current rating (20A), suitable for applications with less stringent transient protection requirements. P6KE18A provides enhanced performance with higher current (25A) and power (600W) ratings while maintaining the same package form, appropriate for circuits requiring additional margin. Both remain active products with full compliance certifications.

Higher Power Alternative (Package Change Required):

SLD15U-017 and SLD15U-017-B deliver significantly higher transient protection capability (209A peak pulse, 5kW peak power) with identical voltage specifications. These parts require mechanical redesign due to the P600 package form and are qualified to AEC-Q101 automotive standards, suitable for demanding industrial and automotive applications.

Not Recommended:

1N8157 exhibits insufficient current (5.98A) and power (150W) ratings relative to the SA15ARLG specification and is not suitable as a direct substitute.

Frequently Asked Questions (FAQ)

Q: Can SA15A be used as a direct replacement for SA15ARLG without circuit modifications?

A: Yes. SA15A maintains identical voltage specifications (15V reverse standoff, 24.4V clamping), equivalent current rating (21A vs. 20.6A), and uses the same DO-204AC (DO-15) axial package. No circuit board or layout changes are required. SA15A is an active product with extended temperature range (-55°C to 175°C).

Q: What is the difference between SA15A-B and SA15A-TP?

A: Both are electrically equivalent with 15V standoff voltage and 24.4V clamping. The primary difference is packaging: SA15A-B is supplied in bulk form, while SA15A-TP is supplied in tape and reel format. Selection depends on production volume and assembly process requirements.

Q: Why is the operating temperature range different between SA15ARLG (-55°C to 150°C) and its substitutes (-55°C to 175°C)?

A: The SA15ARLG is an obsolete part with a narrower temperature specification. Active substitute parts offer extended upper temperature limits (175°C), providing improved thermal margin and reliability. This represents an enhancement over the original specification.

Q: Can SLD15U-017 replace SA15ARLG in existing designs?

A: SLD15U-017 is electrically compatible (15V standoff, 24.4V clamping) but uses a different physical package (P600 vs. DO-15). Circuit board redesign is required. SLD15U-017 is appropriate only when higher transient protection capability (209A, 5kW) is needed and mechanical redesign is feasible.

Q: Is P6KE18A suitable for SA15ARLG replacement?

A: P6KE18A is electrically compatible with slightly higher voltage specifications (15.3V standoff, 25.2V clamping) and superior current/power ratings (25A, 600W). It maintains the same DO-204AC (DO-15) package and is suitable for applications requiring enhanced protection margin. No circuit modifications are required.

Q: What compliance certifications should I verify for substitute parts?

A: All recommended substitutes carry ROHS3 compliance and unlimited moisture sensitivity level (MSL 1). For automotive applications, SA15AHE3/54 and SLD15U-017 series carry AEC-Q101 qualification. Verify REACH status with your supplier for specific regulatory requirements.

Q: Why is 1N8157 not recommended as a substitute?

A: 1N8157 has insufficient current (5.98A) and power (150W) ratings compared to the SA15ARLG requirement (20.6A, 500W). It cannot provide equivalent transient protection and is unsuitable for direct replacement.

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