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SMAJ26 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts
Part Overview
The SMAJ26 is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse, designed for general-purpose overvoltage protection in surface-mount applications. The device features a 26V reverse standoff voltage with a 44.21V maximum clamping voltage at peak pulse current of 9.5A, packaged in the DO-214AC (SMA) form factor.
The SMAJ26 is classified as obsolete. Equivalent and substitute parts are available from multiple manufacturers with comparable or enhanced electrical characteristics, maintaining compatibility with the original design specifications while offering active product status and improved availability.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Voltage - Reverse Standoff (Typ) | 26 | V |
| Voltage - Breakdown (Min) | 27.36 | V |
| Voltage - Clamping (Max) @ Ipp | 44.21 | V |
| Current - Peak Pulse (10/1000µs) | 9.5 | A |
| Power - Peak Pulse | 400 | W |
| Operating Temperature Range | -65 to 150 | °C (TJ) |
| Package / Case | DO-214AC, SMA | — |
| Mounting Type | Surface Mount | — |
| RoHS Status | ROHS3 Compliant | — |
| Moisture Sensitivity Level | 1 (Unlimited) | — |
Substitute Part Grouping Explanation
Substitution of the SMAJ26 is determined by the following critical parameters:
- Reverse Standoff Voltage: 26V (all substitutes maintain this specification)
- Breakdown Voltage (Min): 27.36V to 28.9V range (acceptable variance for TVS diodes)
- Package / Case: DO-214AC (SMA) form factor (all substitutes use identical package)
- Mounting Type: Surface Mount (all substitutes are surface-mount compatible)
- Unidirectional Channels: 1 (all substitutes are single-channel devices)
- Type: Zener (all substitutes are Zener-type TVS diodes)
- RoHS Compliance: ROHS3 Compliant (all substitutes meet this requirement)
Substitute parts are grouped into two categories based on clamping voltage and peak pulse current characteristics:
Group A (Standard Performance): Clamping voltage 42.1V, peak pulse current 9.5A to 14.3A — direct functional equivalents with minimal performance variation.
Group B (Enhanced Performance): Clamping voltage 47.9V to 54.6V, peak pulse current 43A to 75A — higher energy absorption capability for demanding applications.
Parameter Comparison
| Part Number | Manufacturer | Voltage - Reverse Standoff (V) | Voltage - Breakdown Min (V) | Voltage - Clamping Max @ Ipp (V) | Current - Peak Pulse (A) | Power - Peak Pulse (W) | Operating Temp (°C) | Package | Product Status |
|---|---|---|---|---|---|---|---|---|---|
| SMAJ26 | Littelfuse | 26 | 27.36 | 44.21 | 9.5 | 400 | -65 to 150 | DO-214AC (SMA) | Obsolete |
| SMAJ26A | Meritek | 26 | 28.9 | 42.1 | 9.5 | 400 | -55 to 150 | DO-214AC (SMA) | Active |
| SZ1SMA26AT3G | Littelfuse Inc. | 26 | 28.9 | 42.1 | 9.5 | 400 | -65 to 150 | DO-214AC (SMA) | Active |
| SM4T30AY | STMicroelectronics | 26 | 28.9 | 54.6 | 43 (8/20µs) | 400 | -55 to 150 | DO-214AC (SMA) | Active |
| SMA6J26A-E3/5A | Vishay General Semiconductor | 26 | 28.9 | 47.9 | 75 (8/20µs) | 4000 | -55 to 150 | DO-214AC (SMA) | Active |
| SMA6J26A-E3/61 | Vishay General Semiconductor | 26 | 28.9 | 47.9 | 75 (8/20µs) | 4000 | -55 to 150 | DO-214AC (SMA) | Active |
| SMA6J26A-TP | Micro Commercial Co | 26 | 28.9 | 42.1 | 14.3 | 600 | -55 to 175 | DO-214AC (SMA) | Active |
| SMA6J26A-TR | STMicroelectronics | 26 | 28.9 | 47.9 | 75 (8/20µs) | 600 | -55 to 175 | DO-214AC (SMA) | Active |
| SMAJ26A-13-F | Diodes Incorporated | 26 | 28.9 | 42.1 | 9.5 | 400 | -55 to 150 | DO-214AC (SMA) | Active |
| SMAJ26A-TP | Micro Commercial Co | 26 | 28.9 | 42.1 | 9.5 | 400 | -55 to 175 | DO-214AC (SMA) | Active |
Engineering Selection Recommendations
Direct Equivalents (Group A): SMAJ26A (Meritek), SZ1SMA26AT3G (Littelfuse Inc.), SMAJ26A-13-F (Diodes Incorporated), and SMAJ26A-TP (Micro Commercial Co) provide electrical performance within the original SMAJ26 specification envelope. These parts maintain 26V reverse standoff voltage, 42.1V clamping voltage, and 9.5A peak pulse current. All are ROHS3 compliant with MSL 1 rating. SZ1SMA26AT3G and SMA6J26A-TP extend the operating temperature range to -65°C, matching the original device's lower temperature limit.
Enhanced Performance Alternatives (Group B): SMA6J26A-E3/5A, SMA6J26A-E3/61, and SMA6J26A-TR (Vishay and STMicroelectronics) offer higher clamping voltage (47.9V) and significantly increased peak pulse current (75A at 8/20µs pulse), with power dissipation up to 4000W. These are suitable for applications requiring greater transient energy absorption. SMA6J26A-TR extends operating temperature to -55 to 175°C. SM4T30AY (STMicroelectronics) provides 54.6V clamping with 43A peak pulse current and automotive-grade qualification (AEC-Q101).
All substitute parts maintain DO-214AC (SMA) package compatibility, surface-mount configuration, and ROHS3 compliance. Selection between Group A and Group B depends on circuit protection requirements and available board space for thermal dissipation.
Frequently Asked Questions (FAQ)
Q: Can SMAJ26A directly replace SMAJ26 in existing designs?
A: Yes. SMAJ26A maintains identical reverse standoff voltage (26V), comparable clamping voltage (42.1V vs. 44.21V), and equivalent peak pulse current (9.5A). The DO-214AC (SMA) package and surface-mount configuration are identical. Operating temperature range differs slightly (-55 to 150°C vs. -65 to 150°C), which is acceptable for most general-purpose applications.
Q: What is the difference between Group A and Group B substitutes?
A: Group A substitutes (SMAJ26A, SMAJ26A-13-F, SMAJ26A-TP, SZ1SMA26AT3G) maintain the original electrical performance with 42.1V clamping and 9.5A peak pulse current. Group B substitutes (SMA6J26A series, SM4T30AY) provide enhanced protection with higher clamping voltage (47.9V to 54.6V) and significantly increased peak pulse current (43A to 75A), suitable for high-energy transient environments.
Q: Are all substitutes RoHS compliant?
A: Yes. All listed substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level, matching the original SMAJ26 specification.
Q: Does package compatibility affect substitution?
A: No. All substitute parts use the DO-214AC (SMA) package in surface-mount configuration, ensuring PCB footprint and reflow soldering compatibility with the original SMAJ26 design.
Q: Which substitute offers the widest operating temperature range?
A: SMA6J26A-TP and SMA6J26A-TR extend the upper operating temperature to 175°C (compared to 150°C for the original SMAJ26), providing enhanced thermal margin in high-temperature environments.
Q: Are automotive-grade substitutes available?
A: Yes. SM4T30AY (STMicroelectronics) carries automotive-grade qualification (AEC-Q101) and is suitable for automotive and industrial applications requiring enhanced reliability standards.
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