SMB6F28AY Equivalent & Substitute Parts

Part Overview

The SMB6F28AY is a unidirectional transient voltage suppressor (TVS) diode manufactured by STMicroelectronics, designed for surface mount applications in automotive-grade circuits. This component operates with a 28V reverse standoff voltage and provides 45.4V clamping at peak pulse current, delivering 600W peak pulse power dissipation. The device is qualified to AEC-Q101 automotive standards and packaged in DO-221AA SMBflat configuration.

The SMB6F28AY carries a Last Time Buy product status, indicating discontinued production. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs and field replacements.

Substiute Parts

SMB6F28AY

STMicroelectronicsIn Stock: 756SMB6F28AY Datasheet

Current PartRFQ

SM6F28AY

STMicroelectronicsIn Stock: 868SM6F28AY Datasheet

MFR RecommendedRFQ

SMA6T30AY

STMicroelectronicsIn Stock: 978SMA6T30AY Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMB6F28AY is determined by the following critical electrical and mechanical parameters:

Voltage Parameters: Reverse standoff voltage (28V nominal), breakdown voltage minimum (31.1V), and clamping voltage at peak pulse current must remain within acceptable design tolerances to ensure proper transient suppression without affecting normal circuit operation.

Current and Power Ratings: Peak pulse current capacity and peak pulse power dissipation (600W) define the device's ability to handle transient events. Substitute parts must maintain or exceed these specifications.

Package and Mounting: Surface mount configuration and physical footprint compatibility determine mechanical interchangeability. Package type transitions (SMBflat to SOD128Flat or SMA) require circuit board redesign.

Automotive Qualification: AEC-Q101 certification is mandatory for automotive-grade applications. All substitute parts must maintain this qualification level.

Operating Temperature Range: The -55°C to 175°C junction temperature range is critical for automotive environments. Substitute parts must support this full range or demonstrate equivalent thermal performance.

Two substitute categories are identified:

1. Manufacturer Recommended Equivalent (SM6F28AY): Maintains identical voltage specifications and automotive qualification with package variation (SOD128Flat).

2. Similar Specification Alternative (SMA6T30AY): Provides comparable voltage suppression with different package form factor (SMA/DO-214AC) and slightly lower standoff voltage (25.6V).

Parameter Comparison

Engineering Selection Recommendations

SM6F28AY (Manufacturer Recommended Equivalent)

The SM6F28AY is the manufacturer-recommended substitute for the SMB6F28AY. This part maintains identical voltage specifications (28V reverse standoff, 31.1V breakdown minimum) and automotive AEC-Q101 qualification. The device operates across the full -55°C to 175°C temperature range required for automotive applications. The primary difference is package configuration: SM6F28AY uses SOD128Flat instead of SMBflat. This substitution requires printed circuit board redesign to accommodate the different footprint. The part is currently in Active production status with 793 units in stock, ensuring long-term availability.

SMA6T30AY (Similar Specification Alternative)

The SMA6T30AY provides an alternative suppression solution with comparable electrical performance. This part operates at a slightly lower reverse standoff voltage (25.6V versus 28V) and breakdown voltage (28.5V minimum versus 31.1V). The clamping voltage is higher at 53.5V, and peak pulse current capacity is significantly greater at 75A. The device maintains AEC-Q101 automotive qualification and 600W peak pulse power rating. Operating temperature range is -40°C to 150°C, which is narrower than the main part. The SMA package (DO-214AC) differs from both the main part and the recommended equivalent, requiring circuit board redesign. This part is in Active production status with 886 units in stock.

Selection between these substitutes depends on circuit board layout constraints and thermal environment specifications. The SM6F28AY is preferred when SMBflat footprint compatibility is achievable. The SMA6T30AY is suitable for applications where the lower standoff voltage and higher current capacity are acceptable and where SMA package integration is feasible.

Frequently Asked Questions (FAQ)

Q: Can SM6F28AY be used as a direct replacement for SMB6F28AY without circuit board modification?

A: No. While SM6F28AY maintains identical electrical specifications, the package differs (SOD128Flat versus SMBflat). Circuit board redesign is required to accommodate the different footprint and lead configuration.

Q: What is the primary difference between SMB6F28AY and SMA6T30AY?

A: The primary differences are package type (SMBflat versus SMA/DO-214AC), reverse standoff voltage (28V versus 25.6V), and peak pulse current capacity (13.8A versus 75A). The SMA6T30AY has higher clamping voltage (53.5V versus 45.4V) and narrower operating temperature range (-40°C to 150°C versus -55°C to 175°C).

Q: Are all three parts automotive-qualified?

A: Yes. SMB6F28AY, SM6F28AY, and SMA6T30AY all carry AEC-Q101 automotive qualification and are suitable for automotive-grade circuit protection applications.

Q: Why does the SMB6F28AY have Last Time Buy status?

A: Last Time Buy status indicates the manufacturer has discontinued production of this part number. Existing inventory is available for final orders, but long-term supply is not guaranteed. Transition to an active substitute part is recommended for new designs.

Q: Can SMA6T30AY be used in applications requiring the full -55°C to 175°C temperature range?

A: No. SMA6T30AY operates only to -40°C minimum and 150°C maximum junction temperature. Applications requiring the full -55°C to 175°C range must use SMB6F28AY or SM6F28AY.

Q: What does the voltage rating difference between SMB6F28AY (28V standoff) and SMA6T30AY (25.6V standoff) mean for circuit protection?

A: The standoff voltage determines the threshold at which the TVS diode begins to conduct. A lower standoff voltage (25.6V) means the SMA6T30AY will begin suppressing transients at a lower voltage level. This difference must be evaluated against the specific circuit's normal operating voltage and transient suppression requirements.

Q: Are there RoHS compliance differences between these parts?

A: SM6F28AY and SMA6T30AY are both ROHS3 Compliant. SMB6F28AY RoHS status is not specified in the provided data. All three parts are REACH Unaffected.

Q: What is the significance of the different peak pulse current measurements (10/1000µs versus 8/20µs)?

A: These represent different pulse waveform standards used for testing. The 10/1000µs waveform (SMB6F28AY: 13.8A) and 8/20µs waveform (SM6F28AY: 68A, SMA6T30AY: 75A) measure current capacity under different transient conditions. Direct numerical comparison between these measurements is not valid due to the different test standards.