SMA4F58AY Equivalent & Substitute Parts

Part Overview

The SMA4F58AY is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by STMicroelectronics, designed for surface mount applications in automotive-grade circuits. This component provides transient overvoltage protection with a 58V reverse standoff voltage and 121V maximum clamping voltage at peak pulse current.

The SMA4F58AY is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this TVS diode specification.

Substiute Parts

SMA4F58AY

STMicroelectronicsIn Stock: 5224SMA4F58AY Datasheet

Current PartRFQ

SM4T68AY

STMicroelectronicsIn Stock: 5349SM4T68AY Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMA4F58AY is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Voltage - Reverse Standoff: 58V nominal
• Voltage - Clamping (Max) @ Ipp: 121V
• Current - Peak Pulse (8/20µs): 19A
• Power - Peak Pulse: 400W
• Unidirectional channel configuration (1 channel)
• Zener diode type

Mechanical & Environmental Criteria:

• Surface mount packaging (SMA or SMAflat variants)
• Automotive grade classification
• AEC-Q101 qualification
• Operating temperature range compatibility
• Moisture Sensitivity Level 1

Compliance & Supply Status:

• Active product status preferred for long-term availability
• REACH and RoHS compliance status
• Automotive qualification maintenance

The SM4T68AY qualifies as a substitute based on matching electrical performance specifications, automotive-grade certification, AEC-Q101 qualification, and active product status. Package variation (SMA vs. SMAflat) represents a mechanical difference that requires PCB layout verification but does not affect electrical function.

Parameter Comparison

Engineering Selection Recommendations

Substitution Feasibility:

The SM4T68AY is a direct electrical substitute for the SMA4F58AY based on matching voltage ratings, current handling, power dissipation, and automotive qualification standards. Both components maintain AEC-Q101 certification and identical MSL ratings.

Considerations for Implementation:

1. Package Transition: The substitute uses DO-214AC (SMA) packaging versus the original DO-221AC (SMAflat) packaging. PCB footprint verification is required to confirm mechanical compatibility with existing board designs. Lead geometry differences between SMA and SMAflat variants may necessitate layout modifications.

2. Operating Temperature Range: The SM4T68AY specifies a maximum junction temperature of 150°C compared to the SMA4F58AY maximum of 175°C. Applications operating near the upper thermal limit of the original part require thermal analysis to confirm the substitute remains within acceptable operating conditions.

3. Product Status: The SM4T68AY maintains active product status with STMicroelectronics, ensuring long-term availability and supply chain continuity compared to the obsolete SMA4F58AY.

4. Compliance Alignment: Both components maintain identical REACH and RoHS compliance status, supporting regulatory requirements without modification.

Selection Criteria:

• Select SM4T68AY when PCB layout can accommodate SMA (DO-214AC) footprint and operating temperatures remain below 150°C junction temperature.
• Verify thermal performance through simulation or testing if the application approaches the 150°C maximum junction temperature limit.
• Confirm mechanical fit with existing PCB designs prior to production implementation.

Frequently Asked Questions (FAQ)

Q: Can the SM4T68AY directly replace the SMA4F58AY without circuit modifications?

A: Electrical substitution is direct based on identical voltage ratings, current capacity, and power dissipation specifications. However, mechanical compatibility requires verification. The package change from SMAflat (DO-221AC) to SMA (DO-214AC) may require PCB footprint adjustment. Thermal analysis is recommended if the application operates near 150°C junction temperature.

Q: What is the difference between SMA and SMAflat packaging?

A: SMA (DO-214AC) and SMAflat (DO-221AC) are both surface mount packages for TVS diodes but differ in lead geometry and footprint dimensions. SMAflat features flat leads optimized for specific PCB layouts, while SMA uses standard lead configuration. PCB design files must be reviewed to confirm compatibility with the substitute package.

Q: Why does the SM4T68AY have a lower maximum operating temperature than the SMA4F58AY?

A: The SM4T68AY specifies a maximum junction temperature of 150°C versus 175°C for the SMA4F58AY. This difference reflects design or qualification variations between the two parts. Applications must verify that peak junction temperatures remain below 150°C under worst-case operating conditions.

Q: Are both parts automotive-grade with identical certifications?

A: Yes. Both the SMA4F58AY and SM4T68AY carry automotive-grade classification and AEC-Q101 qualification. REACH and RoHS compliance status are identical, supporting automotive and industrial applications without regulatory modification.

Q: What should be verified before implementing the SM4T68AY as a substitute?

A: Verification steps include: (1) PCB footprint compatibility with SMA (DO-214AC) package, (2) thermal analysis confirming junction temperatures remain below 150°C, (3) mechanical fit validation with existing assembly processes, and (4) functional testing in the target application circuit to confirm performance equivalence.

Q: Is the SM4T68AY available in the same packaging format as the original part?

A: No. The SM4T68AY is supplied in Tape & Reel (TR) format with SMA (DO-214AC) packaging, while the SMA4F58AY used SMAflat (DO-221AC) packaging. Packaging format and reel specifications may differ, requiring supply chain and assembly process adjustments.

Q: Can the SM4T68AY be used in applications requiring the full 175°C operating range?

A: The SM4T68AY is rated to 150°C maximum junction temperature. Applications requiring operation above 150°C must either maintain the original SMA4F58AY through inventory management or identify alternative TVS diodes with higher temperature ratings. Thermal modeling is required to determine if the 150°C limit is acceptable for the specific application.