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SMCJ24 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts
Part Overview
The SMCJ24 is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features a 24V reverse standoff voltage with a 40.85V maximum clamping voltage and 38.6A peak pulse current capability in a DO-214AB (SMC) package. The SMCJ24 is classified as obsolete; therefore, identifying functionally equivalent active alternatives is essential for ongoing design support and procurement continuity.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Voltage - Reverse Standoff (Typ) | 24 | V |
| Voltage - Breakdown (Min) | 25.29 | V |
| Voltage - Clamping (Max) @ Ipp | 40.85 | V |
| Current - Peak Pulse (10/1000µs) | 38.6 | A |
| Power - Peak Pulse | 1500 | W |
| Operating Temperature Range | -55 to 150 | °C |
| Package / Case | DO-214AB, SMC | — |
| Type | Zener | — |
| Unidirectional Channels | 1 | — |
| RoHS Status | ROHS3 Compliant | — |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) | — |
Substitute Part Grouping Explanation
Substitution eligibility for the SMCJ24 is determined by the following critical parameters:
- Voltage - Reverse Standoff: Must be 24V (nominal)
- Voltage - Breakdown (Min): Must be within the range 25.29V to 26.7V
- Voltage - Clamping (Max) @ Ipp: Must not exceed 43V
- Current - Peak Pulse (10/1000µs): Must be ≥38.6A
- Power - Peak Pulse: Must be ≥1500W
- Package / Case: Must be DO-214AB (SMC) or compatible surface-mount package
- Type: Must be Zener unidirectional
- RoHS & MSL Compliance: Must maintain ROHS3 compliance and MSL 1 rating
Substitute parts are grouped into two categories based on electrical performance:
Category A - Direct Electrical Equivalents (38.6A, 1500W): Parts with identical peak pulse current and power ratings, suitable for direct replacement in existing designs.
Category B - Enhanced Performance Alternatives (77.1A–77.2A, 3000W): Parts with doubled peak pulse current and power ratings, providing higher transient energy absorption capability while maintaining voltage parameters.
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) | Package | Status |
|---|---|---|---|---|---|---|---|---|
| SMCJ24 | Littelfuse Inc. | 24 | 25.29 | 40.85 | 38.6 | 1500 | DO-214AB (SMC) | Obsolete |
| SMCJ24A | EVVO Semi | 24 | 26.7 | 38.9 | 38.6 | 600 | DO-214AC (SMA) | Active |
| SZ1SMC24AT3G | Littelfuse Inc. | 24 | 26.7 | 38.9 | 38.6 | 1500 | DO-214AB (SMC) | Active |
| 3.0SMCJ24A-13 | Diodes Incorporated | 24 | 26.7 | 38.9 | 77.1 | 3000 | DO-214AB (SMC) | Active |
| SMCJ24A-13-F | Diodes Incorporated | 24 | 26.7 | 38.9 | 38.6 | 1500 | DO-214AB (SMC) | Active |
| SMCJ24AE3/TR13 | Microchip Technology | 24 | 26.7 | 38.9 | 38.6 | 1500 | DO-214AB (SMC) | Active |
| SMCJ24E3/TR13 | Microchip Technology | 24 | 26.7 | 43 | 34.9 | 1500 | DO-214AB (SMC) | Active |
| SMLJ24A | Bourns Inc. | 24 | 26.7 | 38.9 | 77.2 | 3000 | DO-214AB (SMC) | Active |
| SMLJ24A-TP | Micro Commercial Co | 24 | 26.7 | 38.9 | 77.2 | 3000 | DO-214AB (SMC) | Active |
Engineering Selection Recommendations
Primary Recommendation - Direct Replacement (Category A):
For applications requiring direct electrical and mechanical compatibility with the obsolete SMCJ24, select from the following active alternatives:
- SZ1SMC24AT3G (Littelfuse Inc.): Maintains original manufacturer continuity with identical 1500W power rating and DO-214AB package. Includes AEC-Q101 automotive qualification and REACH compliance documentation.
- SMCJ24AE3/TR13 (Microchip Technology): Equivalent electrical performance with 1500W rating in DO-214AB package. Active product status with full REACH compliance.
- SMCJ24A-13-F (Diodes Incorporated): Matches electrical specifications with 1500W power rating and DO-214AB package configuration.
Secondary Recommendation - Enhanced Performance (Category B):
For applications where increased transient energy absorption is beneficial without circuit redesign:
- 3.0SMCJ24A-13 (Diodes Incorporated): Doubles peak pulse current (77.1A) and power rating (3000W) while maintaining voltage parameters. Extended operating temperature range (-55°C to 175°C). DO-214AB package.
- SMLJ24A (Bourns Inc.): Provides 77.2A peak pulse current and 3000W power rating with identical voltage characteristics. DO-214AB package.
- SMLJ24A-TP (Micro Commercial Co): Equivalent to SMLJ24A with 77.2A current and 3000W power. Extended temperature range (-55°C to 175°C). DO-214AB package.
Not Recommended:
- SMCJ24E3/TR13 (Microchip Technology): Clamping voltage of 43V exceeds the original 40.85V specification, introducing higher voltage stress to protected circuits.
- SMCJ24A (EVVO Semi): Power rating of 600W is insufficient for the original 1500W specification and uses DO-214AC (SMA) package instead of DO-214AB (SMC).
Frequently Asked Questions (FAQ)
Q: Can SMCJ24A (EVVO Semi) be used as a direct replacement?
A: No. Although SMCJ24A matches the voltage parameters, its 600W power rating is significantly lower than the original 1500W specification. The DO-214AC (SMA) package also differs from the original DO-214AB (SMC) package, requiring PCB layout modifications.
Q: What is the difference between Category A and Category B substitutes?
A: Category A substitutes (38.6A, 1500W) provide electrical equivalence to the original SMCJ24. Category B substitutes (77.1A–77.2A, 3000W) offer doubled transient energy absorption capability. Category B parts are suitable only if circuit design permits the higher current handling and if thermal management is adequate.
Q: Is SMCJ24E3/TR13 compatible with the original SMCJ24?
A: No. The 43V clamping voltage exceeds the original 40.85V maximum, which may cause excessive voltage stress on protected components. This part is not suitable for direct replacement.
Q: Do all substitute parts maintain RoHS3 compliance?
A: Yes. All listed substitute parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity ratings, matching the original SMCJ24 environmental specifications.
Q: Which substitute offers the best package compatibility?
A: SZ1SMC24AT3G, SMCJ24AE3/TR13, SMCJ24A-13-F, 3.0SMCJ24A-13, SMLJ24A, and SMLJ24A-TP all use the DO-214AB (SMC) package, providing direct mechanical compatibility with the original SMCJ24 footprint.
Q: Can I use an enhanced performance part (Category B) in place of the original?
A: Yes, if circuit design permits. Enhanced performance parts (77.1A–77.2A, 3000W) provide superior transient protection and are backward-compatible with applications designed for the original 38.6A, 1500W specification. Verify that PCB thermal design accommodates the higher power dissipation.
Q: What is the inventory status of recommended substitutes?
A: SZ1SMC24AT3G (9,530 pcs), SMCJ24AE3/TR13 (1,144 pcs), SMCJ24A-13-F (7,725 pcs), 3.0SMCJ24A-13 (4,400 pcs), SMLJ24A (8,455 pcs), and SMLJ24A-TP (46,980 pcs) are all in active stock. SMLJ24A-TP offers the highest inventory availability.
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