SMF26AT1 Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The SMF26AT1 is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. The device features a 26V reverse standoff voltage with a 42.1V maximum clamping voltage at peak pulse current of 4.8A, housed in a SOD-123FL package. The SMF26AT1 is classified as obsolete, necessitating identification of active equivalent and substitute parts for new designs and ongoing production requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	26	V
Voltage - Breakdown (Min)	28.9	V
Voltage - Clamping (Max) @ Ipp	42.1	V
Current - Peak Pulse (10/1000µs)	4.8	A
Power - Peak Pulse	200	W
Package / Case	SOD-123F	—
Mounting Type	Surface Mount	—
Operating Temperature	-55°C ~ 150°C	TJ
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the SMF26AT1 is determined by the following critical electrical and mechanical parameters:

Voltage - Reverse Standoff (Typ): Must match 26V to ensure proper circuit protection threshold
Voltage - Clamping (Max) @ Ipp: Must match 42.1V to maintain clamping performance
Current - Peak Pulse (10/1000µs): Must match 4.8A to ensure adequate transient suppression capability
Power - Peak Pulse: Must match 200W rating
Package / Case: Must be SOD-123F or SOD-123FL for mechanical and thermal compatibility
Mounting Type: Must be Surface Mount
Type: Must be Zener unidirectional TVS diode

The SMF26A-TP from Micro Commercial Co is a direct equivalent meeting all electrical and mechanical specifications. Additional substitute parts from the SMF series (SMF20A, SMF22A, SMF24A, SMF28A, SMF30A, SMF33A, SMF36A, SMF43A) provide alternative voltage ratings within the same product family and package format, suitable for applications requiring different protection thresholds.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Clamping (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Package	Product Status	RoHS Status
SMF26AT1	onsemi	26	42.1	4.8	200	SOD-123F	Obsolete	RoHS non-compliant
SMF26A-TP	Micro Commercial Co	26	42.1	4.8	200	SOD-123F	Active	ROHS3 Compliant
SMF20A	MDD	20	32.4	6.2	200	SOD-123F	Active	ROHS3 Compliant
SMF22A	MDD	22	35.5	5.6	200	SOD-123F	Active	ROHS3 Compliant
SMF24A	MDD	24	38.9	5.1	200	SOD-123F	Active	ROHS3 Compliant
SMF28A	MDD	28	45.4	4.4	200	SOD-123F	Active	ROHS3 Compliant
SMF30A	MDD	30	48.4	4.1	200	SOD-123F	Active	ROHS3 Compliant
SMF33A	Diotec Semiconductor	33	53.3	3.75	200	SOD-123F	Active	ROHS3 Compliant
SMF36A	MDD	36	58.1	3.44	200	SOD-123F	Active	ROHS3 Compliant
SMF43A	Diotec Semiconductor	43	69.4	2.88	200	SOD-123F	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement: SMF26A-TP from Micro Commercial Co is the primary equivalent for SMF26AT1. This part maintains identical electrical specifications (26V standoff, 42.1V clamping, 4.8A peak pulse) and package format while offering active product status and ROHS3 compliance, addressing the obsolescence of the original onsemi part.

Alternative Voltage Ratings: The SMF series parts (SMF20A through SMF43A) are suitable substitutes when circuit design permits deviation from the 26V protection threshold. Selection among these alternatives depends on the specific overvoltage protection requirement of the application. All listed alternatives are active products with ROHS3 compliance, providing improved supply chain availability and regulatory compliance compared to the obsolete SMF26AT1.

Compliance Considerations: The SMF26AT1 is RoHS non-compliant. All recommended substitute parts are ROHS3 compliant, meeting current regulatory requirements for electronic component procurement and manufacturing.

Frequently Asked Questions (FAQ)

Q: Can SMF26A-TP directly replace SMF26AT1 in existing designs?

A: Yes. SMF26A-TP provides identical electrical performance (26V standoff, 42.1V clamping, 4.8A peak pulse current, 200W power rating) and is housed in the same SOD-123F surface-mount package. The primary differences are active product status and ROHS3 compliance.

Q: What is the difference between SMF26A-TP and other SMF series parts?

A: SMF series parts differ in reverse standoff voltage rating, which determines the protection threshold. SMF26A-TP maintains the 26V rating of the original SMF26AT1. Other ratings (SMF20A, SMF22A, SMF24A, SMF28A, SMF30A, SMF33A, SMF36A, SMF43A) provide alternative protection levels with correspondingly different clamping voltages and peak pulse currents.

Q: Are all substitute parts compatible with SOD-123F footprints?

A: Yes. All listed substitute parts use SOD-123F or SOD-123FL packaging, ensuring mechanical and thermal compatibility with existing PCB layouts designed for the SMF26AT1.

Q: What packaging format is SMF26A-TP supplied in?

A: SMF26A-TP is supplied in Tape & Reel (TR) format, standard for high-volume surface-mount production. The SMF26AT1 original part did not specify packaging format in available documentation.

Q: Are there RoHS compliance differences among the substitute parts?

A: All listed substitute parts are ROHS3 compliant. The original SMF26AT1 is RoHS non-compliant. This compliance improvement is a key advantage of transitioning to active substitute parts.

Q: How do peak pulse current ratings affect part selection?

A: Peak pulse current (Ipp) indicates the maximum transient current the TVS diode can suppress. SMF26A-TP matches the original 4.8A rating. Alternative SMF series parts range from 2.88A to 6.2A. Selection must ensure the chosen part's Ipp rating meets or exceeds the maximum transient current expected in the protected circuit.

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