SMF24AT1 Equivalent & Substitute Parts

Part Overview

The SMF24AT1 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection applications. It features a 24V reverse standoff voltage with a 38.9V maximum clamping voltage and 5.1A peak pulse current capability in a surface-mount SOD-123FL package. The part is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	24V
Voltage - Breakdown (Min)	26.7V
Voltage - Clamping (Max) @ Ipp	38.9V
Current - Peak Pulse (10/1000µs)	5.1A
Power - Peak Pulse	200W
Operating Temperature Range	-55°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Package / Case	SOD-123F
Type	Zener
Unidirectional Channels	1

Substitute Part Grouping Explanation

Substitution for the SMF24AT1 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Voltage - Reverse Standoff (Typ): 24V
Voltage - Breakdown (Min): 26.7V
Voltage - Clamping (Max) @ Ipp: 38.9V
Current - Peak Pulse (10/1000µs): 5.1A
Power - Peak Pulse: 200W
Type: Zener
Unidirectional Channels: 1

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount
Package / Case: SOD-123F or equivalent footprint

Direct Substitutes maintain identical electrical specifications and package compatibility. Similar Parts operate within the same product family but with different voltage ratings; these are suitable only when circuit design permits voltage deviation.

Parameter Comparison

Part Number	Manufacturer	Standoff Voltage	Breakdown Voltage (Min)	Clamping Voltage (Max)	Peak Pulse Current	Package	Product Status	RoHS Status
SMF24AT1	onsemi	24V	26.7V	38.9V	5.1A	SOD-123FL	Obsolete	Non-compliant
SMF24A-E3-08	Vishay General Semiconductor - Diodes Division	24V	26.7V	38.9V	5.1A	DO-219AB (SMF)	Active	ROHS3 Compliant
SMF24A-TP	Micro Commercial Co	24V	26.7V	38.9V	5.1A	SOD-123FL	Active	ROHS3 Compliant
SMF20A	MDD	20V	22.2V	32.4V	6.2A	SOD-123F / SMF	Active	ROHS3 Compliant
SMF22A	MDD	22V	24.4V	35.5V	5.6A	SOD-123F / SMF	Active	ROHS3 Compliant
SMF26A	EVVO Semi	26V	28.9V	42.1V	4.8A	SOD-123FL	Active	ROHS3 Compliant
SMF28A	MDD	28V	31.1V	45.4V	4.4A	SOD-123F / SMF	Active	ROHS3 Compliant
SMF30A	MDD	30V	33.3V	48.4V	4.1A	SOD-123F / SMF	Active	ROHS3 Compliant
SMF33A	Diotec Semiconductor	33V	36.7V	53.3V	3.75A	SOD-123F	Active	ROHS3 Compliant
SMF36A	MDD	36V	40V	58.1V	3.44A	SOD-123F	Active	ROHS3 Compliant
SMF43A	Diotec Semiconductor	43V	47.8V	69.4V	2.88A	SOD-123F	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Substitutes (Identical Electrical Specifications):

SMF24A-E3-08 and SMF24A-TP are direct electrical equivalents to the SMF24AT1. Both maintain the 24V standoff voltage, 38.9V clamping voltage, and 5.1A peak pulse current. SMF24A-TP preserves the original SOD-123FL package footprint, enabling direct board-level replacement. SMF24A-E3-08 uses the DO-219AB (SMF) package, which is electrically equivalent but requires PCB layout verification for mechanical fit. Both substitute parts are active products with ROHS3 compliance, addressing the obsolescence and regulatory status of the original part.

Similar Parts (Voltage-Variant Family Members):

SMF20A, SMF22A, SMF26A, SMF28A, SMF30A, SMF33A, SMF36A, and SMF43A are members of the SMF TVS diode family with different voltage ratings. These parts are suitable substitutes only when circuit design permits operation at alternative voltage thresholds. Selection among these variants depends on the specific overvoltage protection requirement of the application. All similar parts are active products with ROHS3 compliance and surface-mount packaging compatible with SOD-123F footprints.

Frequently Asked Questions (FAQ)

Q: Can SMF24A-TP be used as a direct replacement for SMF24AT1?

A: Yes. SMF24A-TP is electrically identical to SMF24AT1 with matching standoff voltage (24V), clamping voltage (38.9V), and peak pulse current (5.1A). Both use the SOD-123FL package, enabling direct PCB substitution without layout modification.

Q: What is the difference between SMF24A-E3-08 and SMF24A-TP?

A: Both parts are electrical equivalents with identical voltage and current ratings. The primary difference is packaging: SMF24A-E3-08 uses DO-219AB (SMF) while SMF24A-TP uses SOD-123FL. Verify PCB footprint compatibility before selection.

Q: Can I use SMF26A instead of SMF24AT1?

A: SMF26A has a higher standoff voltage (26V vs. 24V) and clamping voltage (42.1V vs. 38.9V). Substitution is possible only if the circuit design accommodates these higher voltage thresholds. Lower peak pulse current (4.8A vs. 5.1A) may also affect transient suppression performance.

Q: Why is SMF24AT1 listed as obsolete?

A: The SMF24AT1 is no longer manufactured by onsemi. Direct substitutes SMF24A-TP and SMF24A-E3-08 are active products from alternative manufacturers, ensuring long-term availability and supply chain continuity.

Q: Are all substitute parts RoHS compliant?

A: SMF24A-TP and SMF24A-E3-08 are ROHS3 compliant. The original SMF24AT1 is RoHS non-compliant. All similar parts in the SMF family are ROHS3 compliant.

Q: What operating temperature range should I verify for substitution?

A: SMF24AT1 operates from -55°C to 150°C (TJ). SMF24A-TP extends to -65°C to 175°C (TA), providing wider thermal coverage. SMF24A-E3-08 operates from -65°C to 175°C (TJ). Verify application requirements before selection.

Q: Can I mix different SMF voltage variants in the same circuit?

A: No. Each TVS diode variant is designed for a specific voltage protection threshold. Mixing variants with different standoff voltages will result in inconsistent overvoltage protection across the circuit. Use identical part numbers or verified direct equivalents only.

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