SMF22AT1 Equivalent & Substitute Parts

Part Overview

The SMF22AT1 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 22V reverse standoff voltage with a 35.5V maximum clamping voltage and 5.6A peak pulse current capability in a SOD-123FL package. The part is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements.

Substiute Parts

SMF22AT1

onsemiIn Stock: 1037SMF22AT1 Datasheet

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SMF20A

MDDIn Stock: 91902SMF20A Datasheet

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SMF24A

MDDIn Stock: 27644SMF24A Datasheet

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SMF26A

EVVO SemiIn Stock: 131159SMF26A Datasheet

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SMF28A

MDDIn Stock: 20400SMF28A Datasheet

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SMF30A

MDDIn Stock: 23406SMF30A Datasheet

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SMF33A

Diotec SemiconductorIn Stock: 18867SMF33A Datasheet

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SMF36A

MDDIn Stock: 20906SMF36A Datasheet

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SMF43A

Diotec SemiconductorIn Stock: 17205SMF43A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMF22AT1 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Reverse standoff voltage within the application tolerance band
• Clamping voltage performance at specified peak pulse current
• Peak pulse current capability (10/1000µs waveform)
• Power dissipation rating (200W maintained across all candidates)
• Operating temperature range (-55°C to 150°C minimum)
• Unidirectional channel configuration (single channel)

Mechanical Compatibility Criteria:

• Surface-mount package type (SOD-123F / SOD-123FL)
• Pin-to-pin compatibility for direct PCB replacement

The substitute parts listed below maintain the same 200W peak pulse power rating and SOD-123F package footprint, enabling direct board-level substitution. Voltage ratings vary across the series to accommodate different circuit protection requirements while preserving the core TVS diode functionality.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Closest Electrical Match):

SMF24A and SMF26A represent the closest electrical equivalents to the SMF22AT1. Both maintain reverse standoff voltages within 2-4V of the original specification and deliver comparable clamping performance. SMF24A (MDD) and SMF26A (EVVO Semi) are both active products with ROHS3 compliance, addressing the regulatory limitations of the obsolete original part.

Extended Substitution Range:

SMF20A, SMF28A, SMF30A, SMF33A, SMF36A, and SMF43A provide alternative voltage ratings within the SMF series. Selection from this range depends on circuit-specific overvoltage thresholds. All listed substitutes maintain the 200W peak pulse power rating and SOD-123F package compatibility required for direct PCB replacement.

Compliance Considerations:

All substitute parts listed are ROHS3 compliant, addressing environmental and regulatory requirements that the obsolete SMF22AT1 does not meet. Operating temperature ranges are consistent across all candidates at -55°C to 150°C, with SMF33A and SMF43A rated to -50°C minimum.

Inventory and Availability:

Active product status across all substitutes ensures ongoing availability. Inventory levels range from 17,100 to 131,100 units across multiple manufacturers and distributors, supporting both prototype and production-volume requirements.

Frequently Asked Questions (FAQ)

Q: Can SMF24A directly replace SMF22AT1 on existing PCBs?

A: Yes. SMF24A maintains identical SOD-123FL package geometry and pin configuration. The 24V reverse standoff voltage is 2V higher than the original 22V specification, which is within typical circuit tolerance margins for general-purpose TVS applications. Verify that your circuit design accommodates the slightly higher clamping voltage (38.9V vs. 35.5V).

Q: What is the difference between SMF20A and SMF24A?

A: SMF20A has a lower reverse standoff voltage (20V) and higher peak pulse current (6.2A) compared to SMF24A (24V standoff, 5.1A peak current). Selection depends on whether your circuit requires lower or higher voltage threshold protection. Both are electrically and mechanically compatible with SMF22AT1.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance certification. The original SMF22AT1 is RoHS non-compliant, making substitution necessary for applications subject to RoHS regulations.

Q: Does package type affect substitution?

A: All substitute parts use SOD-123F or SOD-123FL packages, which are mechanically and electrically identical for TVS diode applications. Direct PCB footprint compatibility is maintained across all listed alternatives.

Q: What happens if I select a substitute with a higher voltage rating?

A: Higher voltage-rated TVS diodes (such as SMF36A or SMF43A) will clamp at higher voltage levels. This reduces protection effectiveness for lower-voltage circuits but may be appropriate for higher-voltage applications. Verify that your circuit design accommodates the selected clamping voltage.

Q: Can I use SMF33A or SMF43A as substitutes?

A: Yes, both are mechanically compatible. However, their operating temperature minimum is -50°C rather than -55°C. If your application requires -55°C operation, select from SMF20A, SMF24A, SMF26A, SMF28A, SMF30A, or SMF36A instead.