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SA40A Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts
Part Overview
The SA40A is a unidirectional Zener-type transient voltage suppressor diode manufactured by onsemi, designed for general-purpose overvoltage protection applications. The device features a 40V reverse standoff voltage with a 64.5V maximum clamping voltage and 7.8A peak pulse current capability in a through-hole DO-15 package. The SA40A is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Voltage - Reverse Standoff (Typ) | 40 | V |
| Voltage - Breakdown (Min) | 44.4 | V |
| Voltage - Clamping (Max) @ Ipp | 64.5 | V |
| Current - Peak Pulse (10/1000µs) | 7.8 | A |
| Power - Peak Pulse | 500 | W |
| Type | Zener | — |
| Unidirectional Channels | 1 | — |
| Mounting Type | Through Hole | — |
| Package / Case | DO-204AC, DO-15, Axial | — |
| Applications | General Purpose | — |
Substitute Part Grouping Explanation
Substitution eligibility for the SA40A is determined by the following critical parameters:
- Voltage Rating Match: Reverse standoff voltage of 40V, breakdown minimum of 44.4V, and clamping voltage maximum of 64.5V
- Current Capability: Peak pulse current of 7.8A to 7.9A (minor tolerance variation acceptable)
- Power Dissipation: 500W peak pulse power rating
- Package Compatibility: Through-hole axial configuration (DO-15 or DO-204AC equivalent)
- Unidirectional Operation: Single-channel Zener diode topology
- Application Class: General-purpose transient suppression
Substitute parts are categorized as Direct Equivalents (identical electrical and mechanical specifications with different manufacturers or packaging) and Similar Alternatives (matching voltage and current parameters with variations in package type, current capability, or power rating).
Parameter Comparison
| Part Number | Manufacturer | Voltage - Reverse Standoff (V) | Voltage - Clamping (V) | Current - Peak Pulse (A) | Power - Peak Pulse (W) | Package | Product Status | Operating Temperature (°C) |
|---|---|---|---|---|---|---|---|---|
| SA40A | onsemi | 40 | 64.5 | 7.8 | 500 | DO-15 | Obsolete | — |
| SA40A-AP | Micro Commercial Co | 40 | 64.5 | 7.9 | 500 | DO-15 | Active | -55 to 175 |
| SA40A-BP | Micro Commercial Co | 40 | 64.5 | 7.9 | 500 | DO-15 | Active | -55 to 175 |
| SA40A-E3/54 | Vishay General Semiconductor - Diodes Division | 40 | 64.5 | 7.8 | 500 | DO-204AC (DO-15) | Active | -55 to 175 |
| SA40AHE3/54 | Vishay General Semiconductor - Diodes Division | 40 | 64.5 | 7.8 | 500 | DO-204AC (DO-15) | Active | -55 to 175 |
| P5KE40A-AP | Micro Commercial Co | 40 | 64.5 | 7.8 | 500 | DO-15 | Active | -65 to 175 |
| P5KE40A-BP | Micro Commercial Co | 40 | 64.5 | 7.8 | 500 | DO-15 | Active | -65 to 175 |
| P5KE40A-TP | Micro Commercial Co | 40 | 64.5 | 7.8 | 500 | DO-15 | Active | -65 to 175 |
| SA40A | Taiwan Semiconductor Corporation | 40 | 64.5 | 8.1 | 500 | DO-204AC (DO-15) | Active | -55 to 175 |
| SA40A-TP | Micro Commercial Co | 40 | 64.5 | 7.9 | 500 | DO-15 | Active | -55 to 175 |
| SLD40U-017 | Littelfuse Inc. | 40 | 64.5 | 79.1 | 5000 | P600 | Active | -55 to 175 |
Engineering Selection Recommendations
Direct Equivalents (Recommended Primary Substitutes):
SA40A-AP, SA40A-BP, and SA40A-TP from Micro Commercial Co are direct functional equivalents with active product status. These parts maintain identical voltage ratings (40V standoff, 64.5V clamping) and current specifications (7.9A peak pulse) in the same DO-15 package. All three are REACH compliant and suitable for immediate substitution in existing designs.
SA40A-E3/54 and SA40AHE3/54 from Vishay General Semiconductor are functionally equivalent with identical electrical parameters. SA40AHE3/54 carries AEC-Q101 automotive qualification, making it suitable for automotive-grade applications. Both are available in DO-204AC (DO-15 equivalent) packaging and carry RoHS3 compliance.
SA40A from Taiwan Semiconductor Corporation is functionally equivalent with a marginally higher peak pulse current specification (8.1A versus 7.8A), providing additional design margin. This part is RoHS3 compliant and available in DO-204AC packaging.
Similar Alternatives (Extended Capability):
P5KE40A-AP, P5KE40A-BP, and P5KE40A-TP from Micro Commercial Co maintain identical voltage and current specifications but offer an extended operating temperature range (-65°C to 175°C versus -55°C to 175°C). These parts are suitable for applications requiring lower temperature operation.
SLD40U-017 from Littelfuse Inc. is a higher-power alternative with identical voltage ratings but significantly elevated current capability (79.1A peak pulse) and power dissipation (5kW). This part uses a P600 package and carries AEC-Q101 automotive qualification. Selection of this part is appropriate only when higher transient current handling is required.
Frequently Asked Questions (FAQ)
Q: Can SA40A-AP be used as a direct replacement for the obsolete SA40A?
A: Yes. SA40A-AP from Micro Commercial Co is a direct equivalent with matching 40V standoff voltage, 64.5V clamping voltage, and 7.9A peak pulse current in the same DO-15 package. The 0.1A current difference is within acceptable tolerance for general-purpose transient suppression applications.
Q: What is the difference between SA40A-E3/54 and SA40AHE3/54?
A: Both parts are electrically identical with 40V standoff, 64.5V clamping, and 7.8A peak pulse current in DO-204AC packaging. SA40AHE3/54 carries AEC-Q101 automotive qualification and is supplied in tape-and-reel packaging, while SA40A-E3/54 is supplied in cut-tape packaging. Selection depends on packaging requirements and automotive compliance needs.
Q: Why would SLD40U-017 be selected over other substitutes?
A: SLD40U-017 is selected only when the application requires higher transient current handling (79.1A versus 7.8A) and greater power dissipation capability (5kW versus 500W). The P600 package accommodates this higher power rating. Standard SA40A replacement applications do not require this elevated capability.
Q: Are all substitute parts RoHS compliant?
A: Vishay parts (SA40A-E3/54, SA40AHE3/54) and Taiwan Semiconductor SA40A are explicitly RoHS3 compliant. Micro Commercial Co parts (SA40A-AP, SA40A-BP, SA40A-TP, P5KE40A series) and Littelfuse SLD40U-017 are REACH compliant. Verify specific RoHS requirements with component datasheets for your application.
Q: Can P5KE40A series parts be used interchangeably with SA40A?
A: Yes, for voltage and current specifications. P5KE40A-AP, P5KE40A-BP, and P5KE40A-TP maintain identical 40V standoff, 64.5V clamping, and 7.8A peak pulse ratings. The extended temperature range (-65°C to 175°C) makes these parts suitable for applications requiring lower temperature operation compared to standard SA40A substitutes.
Q: What packaging considerations apply when substituting SA40A?
A: The original SA40A uses DO-15 axial through-hole packaging. Direct substitutes maintain this package type. Vishay alternatives (SA40A-E3/54, SA40AHE3/54) and Taiwan Semiconductor SA40A use DO-204AC packaging, which is mechanically and electrically equivalent to DO-15. SLD40U-017 uses P600 packaging and is suitable only for applications where higher power dissipation justifies the package change.
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