SMB15F20A Equivalent & Substitute Parts

Part Overview

The SMB15F20A is a unidirectional transient voltage suppressor (TVS) diode manufactured by STMicroelectronics, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 20V reverse standoff voltage with a 32.4V maximum clamping voltage and 19.4A peak pulse current capability in the SMBflat package configuration.

The SMB15F20A is designated as Last Time Buy, indicating that STMicroelectronics has discontinued or will discontinue production. Identifying equivalent and substitute parts is necessary to ensure continued component availability for new designs, production runs, and field replacements.

Substiute Parts

SMB15F20A

STMicroelectronicsIn Stock: 1103SMB15F20A Datasheet

Current PartRFQ

SMCJ20A-TR

STMicroelectronicsIn Stock: 7968SMCJ20A-TR Datasheet

DirectRFQ

SM15T24A

STMicroelectronicsIn Stock: 20378SM15T24A Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMB15F20A is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

• Voltage - Reverse Standoff (Typ): Must be within the same voltage class (20V nominal)
• Voltage - Breakdown (Min): Must support the same or lower minimum breakdown threshold
• Voltage - Clamping (Max) @ Ipp: Must not exceed the original clamping specification to prevent overvoltage conditions
• Current - Peak Pulse: Must meet or exceed the original peak pulse current rating
• Power - Peak Pulse: Must support the required power dissipation level
• Type: Must be Zener-type TVS diode
• Unidirectional Channels: Must be single-channel configuration

Mechanical Compatibility Criteria:

• Mounting Type: Surface mount only
• Package / Case: SMBflat or equivalent SMC packages acceptable for board-level integration

Compliance & Status Criteria:

• RoHS3 Compliance: Required
• REACH Status: Must be unaffected
• Product Status: Active or Last Time Buy acceptable; discontinued parts are not suitable

The substitute parts SMCJ20A-TR and SM15T24A meet these criteria with higher peak pulse current ratings (234A) and increased power dissipation (1500W), providing enhanced protection capability while maintaining the same reverse standoff voltage class and clamping characteristics within acceptable limits.

Parameter Comparison

Engineering Selection Recommendations

SMCJ20A-TR Selection Criteria:

The SMCJ20A-TR is an active product with full STMicroelectronics support and availability. This part maintains the same 20V reverse standoff voltage and 22.2V minimum breakdown voltage as the SMB15F20A. The clamping voltage increases to 42.8V, which is acceptable for applications where higher transient suppression is beneficial. Peak pulse current capability increases to 234A with 1500W power dissipation, providing enhanced protection margin. The DO-214AB SMC package is a standard surface-mount configuration compatible with modern PCB assembly processes. Operating temperature range is -55 to 150°C, which is 25°C lower than the original part but remains suitable for most industrial and commercial applications. This part is supplied in Tape & Reel packaging for automated assembly.

SM15T24A Selection Criteria:

The SM15T24A is an active product with extensive inventory availability (20,300 pieces in stock). This part features a slightly higher reverse standoff voltage of 20.5V and minimum breakdown voltage of 22.8V, remaining within acceptable tolerance for 20V-class applications. Clamping voltage and peak pulse current specifications match the SMCJ20A-TR (42.8V and 234A respectively), with identical 1500W power dissipation. The DO-214AB SMC package provides the same mechanical compatibility. Operating temperature range is -55 to 150°C. This part is supplied in Cut Tape and Digi-Reel packaging options, offering flexibility for both manual and automated assembly processes.

Compliance & Regulatory Status:

Both substitute parts are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements. Both maintain MSL Level 1 (Unlimited) moisture sensitivity, eliminating special storage or handling requirements. Both are classified under the same HTSUS code (8541.10.0080) and ECCN (EAR99) as the original part.

Frequently Asked Questions (FAQ)

Q: Can the SMCJ20A-TR or SM15T24A be used as direct replacements for the SMB15F20A on existing PCBs?

A: Package compatibility must be verified. The SMB15F20A uses DO-221AA SMBflat leads, while both substitute parts use DO-214AB SMC packages. These packages have different footprints and pin configurations. PCB redesign or adapter solutions are required for direct board-level substitution. For new designs, the SMC package is recommended.

Q: What is the significance of the higher clamping voltage (42.8V) in the substitute parts compared to the original 32.4V?

A: The clamping voltage represents the maximum voltage across the TVS diode during transient suppression. The higher clamping voltage in substitute parts (42.8V vs. 32.4V) means the protected circuit will experience a higher peak voltage during a transient event. This is acceptable if the downstream components are rated for this voltage level. For applications with strict voltage limits, circuit-level analysis is required.

Q: Why do the substitute parts have significantly higher peak pulse current ratings (234A vs. 19.4A)?

A: The substitute parts are rated for 8/20µs pulse waveforms, which is a standard industrial surge test profile, while the original part is rated for 10/1000µs pulses. The 8/20µs waveform represents a faster, more severe transient event. The higher current rating reflects the increased energy handling capability of the larger SMC package. This provides additional protection margin for high-energy transient events.

Q: Are there any temperature-related limitations when substituting the SMB15F20A?

A: The original SMB15F20A operates from -55 to 175°C (TJ), while both substitute parts operate from -55 to 150°C (TJ). The 25°C reduction in maximum junction temperature may be a constraint for applications operating at elevated temperatures. Verify that the application's thermal environment does not exceed 150°C at the component junction.

Q: What packaging options are available for the substitute parts?

A: The SMCJ20A-TR is supplied in Tape & Reel (TR) packaging for automated pick-and-place assembly. The SM15T24A is available in both Cut Tape (CT) and Digi-Reel packaging options, providing flexibility for different assembly methods. Select packaging based on production volume and assembly equipment capabilities.

Q: Are both substitute parts equally suitable for all applications?

A: Both parts meet the same electrical and mechanical substitution criteria. Selection between SMCJ20A-TR and SM15T24A should be based on packaging preference, inventory availability, and lead time requirements. The SM15T24A has significantly higher inventory (20,300 pieces vs. 7,900 pieces), which may provide supply chain advantages for high-volume production.

Q: Do the substitute parts maintain the same RoHS and REACH compliance as the original part?

A: Yes. Both SMCJ20A-TR and SM15T24A are ROHS3 compliant and REACH unaffected, matching the compliance status of the SMB15F20A. Both parts maintain MSL Level 1 (Unlimited) moisture sensitivity classification, eliminating special storage requirements.