SMA4F64AY Equivalent & Substitute Parts

Part Overview

The SMA4F64AY is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by STMicroelectronics, designed for surface mount applications in automotive-grade circuits. This component features a 64V reverse standoff voltage with a 134V maximum clamping voltage and 17A peak pulse current capability (8/20µs). The device is packaged in DO-221AC SMAflat configuration and meets AEC-Q101 automotive qualification standards.

The SMA4F64AY is classified as an obsolete product. 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

SMA4F64AY

STMicroelectronicsIn Stock: 11073SMA4F64AY Datasheet

Current PartRFQ

SM4T82AY

STMicroelectronicsIn Stock: 4656SM4T82AY Datasheet

MFR RecommendedRFQ

SM4T68AY

STMicroelectronicsIn Stock: 5349SM4T68AY Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMA4F64AY is determined by electrical and mechanical compatibility within the following parameters:

Primary Substitution Criteria:

• Unidirectional TVS diode topology (single channel)
• Automotive-grade classification with AEC-Q101 qualification
• Surface mount packaging (DO-214AC or DO-221AC)
• Voltage rating compatibility: reverse standoff voltage and clamping voltage within acceptable circuit operating ranges
• Peak pulse current capability: minimum 16A at 8/20µs pulse duration
• Peak pulse power rating: 400W
• Operating temperature range: minimum -55°C to 150°C

Substitute Classification:

MFR Recommended Substitute: SM4T82AY represents the manufacturer-recommended alternative, offering higher voltage ratings (70V reverse standoff, 146V clamping) with comparable current handling (16A) and identical peak power dissipation (400W). This part maintains active product status and full AEC-Q101 compliance.

Similar Substitute: SM4T68AY provides an alternative with lower voltage ratings (58V reverse standoff, 121V clamping) but enhanced current capability (19A) and identical peak power dissipation (400W). This part also maintains active product status and AEC-Q101 compliance.

Both substitute parts utilize the SM4TY TRANSIL™ series platform and are packaged in DO-214AC SMA configuration, which differs from the original SMAflat package but maintains surface mount compatibility.

Parameter Comparison

Engineering Selection Recommendations

SM4T82AY (MFR Recommended Substitute):

The SM4T82AY is the manufacturer-recommended substitute for the obsolete SMA4F64AY. This part maintains active product status, ensuring long-term availability and supply chain continuity. Both devices share identical peak pulse power ratings (400W) and comparable peak pulse current specifications (16A versus 17A). The SM4T82AY operates within a reduced temperature range (-55°C to 150°C versus -55°C to 175°C), which is acceptable for most automotive applications. The higher voltage ratings (70V reverse standoff, 146V clamping) provide enhanced protection margins in circuits where the original 64V standoff voltage was marginal. Full AEC-Q101 automotive qualification and RoHS3 compliance are maintained. Package transition from DO-221AC SMAflat to DO-214AC SMA requires PCB layout verification but maintains surface mount compatibility.

SM4T68AY (Similar Substitute):

The SM4T68AY provides an alternative substitute with lower voltage ratings (58V reverse standoff, 121V clamping) but enhanced peak pulse current capability (19A). This part is suitable for applications where the original circuit operates at lower voltage levels and where increased current handling capacity provides design margin. Active product status and full AEC-Q101 qualification are maintained. The reduced operating temperature range (-55°C to 150°C) applies equally to this substitute. Selection of this part requires confirmation that circuit voltage levels do not exceed the 58V reverse standoff specification.

Selection Basis:

Both substitute parts are manufactured by STMicroelectronics and maintain automotive-grade classification with AEC-Q101 qualification. The transition from obsolete to active product status ensures continued manufacturing support and supply availability. Electrical parameter compatibility is confirmed through peak pulse power equivalence (400W) and comparable current handling specifications. Compliance with REACH and EAR99 export classification is maintained across all three parts.

Frequently Asked Questions (FAQ)

Q: Why is the SMA4F64AY classified as obsolete?

A: The SMA4F64AY has reached end-of-life status in the manufacturer's product portfolio. STMicroelectronics has transitioned this design to the active SM4TY TRANSIL™ series platform, represented by the SM4T82AY and SM4T68AY alternatives.

Q: Can SM4T82AY directly replace SMA4F64AY without circuit modification?

A: SM4T82AY provides electrical substitution with higher voltage ratings (70V standoff versus 64V). Circuit operation is compatible provided the application voltage levels do not exceed the original 64V specification. PCB layout modification is required due to package transition from DO-221AC SMAflat to DO-214AC SMA, though both are surface mount configurations.

Q: What is the difference between the two substitute parts?

A: SM4T82AY offers higher voltage protection (70V standoff, 146V clamping) with slightly reduced current capability (16A). SM4T68AY provides lower voltage protection (58V standoff, 121V clamping) with enhanced current capability (19A). Both maintain 400W peak pulse power and AEC-Q101 qualification. Selection depends on circuit voltage and current requirements.

Q: Are the substitute parts automotive-qualified?

A: Both SM4T82AY and SM4T68AY maintain automotive-grade classification and AEC-Q101 qualification, identical to the original SMA4F64AY. Moisture sensitivity level (MSL 1, Unlimited) and REACH compliance are preserved.

Q: What is the operating temperature difference?

A: The original SMA4F64AY operates from -55°C to 175°C (TJ). Both substitute parts operate from -55°C to 150°C (TJ). This 25°C reduction in maximum junction temperature is acceptable for most automotive applications but requires verification for high-temperature circuit environments.

Q: How do the package differences affect PCB design?

A: The SMA4F64AY uses DO-221AC SMAflat leads, while both substitutes use DO-214AC SMA leads. Both are surface mount packages with different footprint geometries. PCB layout and solder pad dimensions require modification to accommodate the package transition. Electrical performance and mounting type (surface mount) remain compatible.

Q: Are there RoHS compliance differences?

A: The original SMA4F64AY does not specify RoHS status. Both substitute parts (SM4T82AY and SM4T68AY) are RoHS3 compliant, providing enhanced environmental compliance for new designs and manufacturing processes.

Q: Which substitute should be selected for new designs?

A: SM4T82AY is the manufacturer-recommended substitute and is appropriate for applications requiring voltage protection in the 64V to 70V range. SM4T68AY is suitable for lower voltage applications (58V range) where enhanced current handling provides design margin. Both parts ensure long-term supply availability through active product status.