SMA4F40AY Equivalent & Substitute Parts

Part Overview

The SMA4F40AY 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 40V reverse standoff voltage and 84V maximum clamping voltage at peak pulse current.

The SMA4F40AY is classified as an obsolete product. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this component.

Substiute Parts

SMA4F40AY

STMicroelectronicsIn Stock: 10797SMA4F40AY Datasheet

Current PartRFQ

SM4T47AY

STMicroelectronicsIn Stock: 4476SM4T47AY Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMA4F40AY is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

• Voltage - Reverse Standoff: 40V (Max)
• Voltage - Breakdown (Min): 44.4V
• Voltage - Clamping (Max) @ Ipp: 84V
• Current - Peak Pulse (8/20µs): 27A
• Power - Peak Pulse: 400W
• Type: Zener, Unidirectional (1 channel)

Mechanical & Environmental Criteria:

• Mounting Type: Surface Mount
• Grade: Automotive
• Qualification: AEC-Q101
• Moisture Sensitivity Level: 1 (Unlimited)

Packaging Consideration: The SMA4F40AY is supplied in Tape & Reel (TR) packaging with SMAflat package configuration (DO-221AC). Substitute parts may utilize alternative surface mount packages (SMA, DO-214AC) provided electrical parameters remain equivalent.

The SM4T47AY meets all electrical and environmental criteria and is qualified as an active substitute. This part maintains identical voltage and current specifications while offering improved product status and supply availability.

Parameter Comparison

Engineering Selection Recommendations

SM4T47AY as Primary Substitute:

The SM4T47AY is the qualified substitute for the obsolete SMA4F40AY. This recommendation is based on the following engineering factors:

Electrical Equivalence: All critical electrical parameters are identical, including reverse standoff voltage (40V), breakdown voltage (44.4V), clamping voltage (84V), peak pulse current (27A), and peak pulse power (400W).

Compliance & Certification: Both parts maintain automotive-grade classification and AEC-Q101 qualification, ensuring compatibility with automotive supply chain requirements and quality standards.

Product Status: The SM4T47AY is classified as an active product with confirmed inventory availability (4446 pcs), providing supply chain continuity for the obsolete SMA4F40AY.

Environmental & Regulatory Alignment: Both parts share identical moisture sensitivity levels (MSL 1), REACH status (REACH Unaffected), and ECCN classification (EAR99).

Package Consideration: The SM4T47AY utilizes DO-214AC (SMA) packaging versus the SMA4F40AY's DO-221AC (SMAflat) packaging. Both are surface mount configurations suitable for automated assembly. PCB layout and footprint modifications may be required to accommodate the different package geometry.

Operating Temperature: The SM4T47AY operates across -55°C to 150°C (TJ), compared to the SMA4F40AY's -55°C to 175°C (TJ). For applications requiring operation above 150°C, alternative substitutes must be evaluated.

Frequently Asked Questions (FAQ)

Q: Can the SM4T47AY directly replace the SMA4F40AY without circuit modifications?

A: The SM4T47AY provides electrical equivalence across all critical parameters (voltage, current, power ratings). However, the different package configuration (DO-214AC versus DO-221AC) requires PCB footprint verification and potential layout adjustments. Electrical circuit operation remains unchanged.

Q: What is the significance of the different operating temperature ranges?

A: The SMA4F40AY operates to 175°C (TJ), while the SM4T47AY operates to 150°C (TJ). For applications with maximum junction temperatures exceeding 150°C, the SM4T47AY is not suitable. Verify application thermal requirements before substitution.

Q: Are both parts automotive-qualified?

A: Yes. Both the SMA4F40AY and SM4T47AY carry automotive-grade classification and AEC-Q101 qualification, meeting automotive supply chain and reliability standards.

Q: What packaging differences exist between these parts?

A: The SMA4F40AY uses DO-221AC (SMAflat) packaging with flat leads, while the SM4T47AY uses DO-214AC (SMA) packaging. Both are surface mount configurations. Physical dimensions and PCB footprints differ; design verification is required.

Q: Why is the SMA4F40AY classified as obsolete?

A: Product obsolescence is determined by manufacturer lifecycle decisions. The SM4T47AY, as an active product from the same manufacturer with equivalent electrical specifications, provides continuity for applications requiring this functionality.

Q: Are there compliance or regulatory differences between these parts?

A: No. Both parts share identical REACH status (REACH Unaffected), ECCN classification (EAR99), and moisture sensitivity levels (MSL 1). Regulatory and compliance requirements are equivalent.

Q: What inventory status should be considered for production planning?

A: The SMA4F40AY has 10,736 pcs in stock (obsolete status). The SM4T47AY has 4,446 pcs in stock (active status). For long-term production requirements, the active status of SM4T47AY provides greater supply chain stability.