SMF18AT1G Equivalent & Substitute Parts

Part Overview

The SMF18AT1G is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features an 18V reverse standoff voltage with a 29.2V maximum clamping voltage and 6.8A peak pulse current capability in a SOD-123FL package. The part is currently listed as obsolete, necessitating identification of active equivalent and substitute components that maintain electrical and mechanical compatibility for new designs or production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	20	V
Voltage - Clamping (Max) @ Ipp	29.2	V
Current - Peak Pulse (10/1000µs)	6.8	A
Power - Peak Pulse	200	W
Type	Zener	-
Unidirectional Channels	1	-
Mounting Type	Surface Mount	-
Operating Temperature Range	-55 to 150	°C (TJ)
RoHS Status	ROHS3 Compliant	-
Moisture Sensitivity Level	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution of the SMF18AT1G is determined by strict electrical parameter matching within the SMF series TVS diode family. The primary substitution criteria are:

Critical Parameters for Direct Substitution:

Voltage - Reverse Standoff: 18V (typ)
Voltage - Clamping (Max) @ Ipp: 29.2V
Current - Peak Pulse: 6.8A
Power - Peak Pulse: 200W
Type: Unidirectional Zener
Mounting: Surface Mount SOD-123F package family

Direct Equivalents maintain identical electrical specifications and differ only in packaging format (tape & reel vs. bulk) or manufacturer variant designation. These parts are pin-compatible and electrically interchangeable without circuit modification.

Alternative Voltage Ratings (SMF11A through SMF17A) represent different standoff voltage classes within the same SMF series. These parts share the same 200W peak pulse power rating, surface-mount SOD-123F package footprint, and general-purpose TVS application profile, but operate at different voltage thresholds. Selection of alternative voltage ratings requires circuit-level voltage protection requirements to be re-evaluated.

Parameter Comparison

Part Number	Manufacturer	VWM (V)	V(BR) Min (V)	VC Max @ Ipp (V)	Ipp (A)	Package	Status
SMF18AT1G	Littelfuse Inc.	18	20	29.2	6.8	SOD-123FL	Obsolete
SMF18A	MDD	18	20	29.2	6.8	SOD-123F / SMF	Active
SMF18A-T13	Littelfuse Inc.	18	20	29.2	6.8	SOD-123F	Active
SMF18A-E3-08	Vishay General Semiconductor	18	20	29.2	6.8	DO-219AB (SMF)	Active
SMF18A-TP	Micro Commercial Co	18	20	29.2	6.8	SOD-123FL	Active
SMF13A	Diotec Semiconductor	13	14.4	21.5	9.3	SOD-123F	Active
SMF15A	MDD	15	16.7	24.4	8.2	SOD-123F / SMF	Active
SMF16A	MDD	16	17.8	26	7.7	SOD-123F / SMF	Active
SMF17A	Diotec Semiconductor	17	18.9	27.6	7.25	SOD-123F	Active
SMF11A	MDD	11	12.2	18.2	11	SOD-123F / SMF	Active
SMF12A	MDD	12	13.3	19.9	10.1	SOD-123F / SMF	Active

Engineering Selection Recommendations

Direct Replacement (Identical Electrical Specifications):

SMF18A, SMF18A-T13, SMF18A-E3-08, and SMF18A-TP are electrically equivalent to the obsolete SMF18AT1G. All maintain 18V reverse standoff voltage, 29.2V clamping voltage, and 6.8A peak pulse current. Selection among these direct equivalents should be based on:

Availability and lead time from active manufacturers (MDD, Littelfuse Inc., Vishay, Micro Commercial Co)
Package format compatibility with existing PCB assembly processes (SOD-123F vs. DO-219AB)
Compliance certifications: all listed equivalents maintain ROHS3 compliance and REACH unaffected status
Moisture sensitivity level: all direct equivalents rated MSL 1 (Unlimited)

Alternative Voltage Ratings (SMF11A, SMF12A, SMF13A, SMF15A, SMF16A, SMF17A):

These parts share identical package footprint (SOD-123F surface mount), 200W peak pulse power rating, and general-purpose TVS application classification. However, each operates at a different voltage threshold. Selection of an alternative voltage rating requires verification that the circuit protection requirements can be met by the different standoff and clamping voltages. These alternatives are suitable only when circuit design permits operation at the specified voltage class.

All substitute parts listed maintain active product status, ROHS3 compliance, and MSL 1 rating, ensuring long-term availability and environmental regulatory compliance.

Frequently Asked Questions (FAQ)

Q: Can SMF18A directly replace SMF18AT1G without circuit modification?

A: Yes. SMF18A maintains identical electrical specifications: 18V reverse standoff, 29.2V clamping voltage, 6.8A peak pulse current, and 200W peak pulse power. The part is pin-compatible in SOD-123F package footprint. No circuit modification is required.

Q: What is the difference between SMF18A-T13 and SMF18A-TP?

A: Both are electrically identical 18V TVS diodes with 29.2V clamping voltage and 6.8A peak pulse current. SMF18A-T13 is manufactured by Littelfuse Inc. in tape & reel packaging. SMF18A-TP is manufactured by Micro Commercial Co, also in tape & reel format. Selection depends on supplier availability and procurement preference.

Q: Can SMF17A be used instead of SMF18AT1G?

A: SMF17A operates at 17V reverse standoff with 27.6V clamping voltage, compared to SMF18AT1G's 18V standoff and 29.2V clamping. While both share the same SOD-123F package and 200W power rating, the lower voltage threshold of SMF17A may not provide adequate protection in circuits designed for 18V standoff operation. Use only if circuit protection requirements permit operation at the lower voltage class.

Q: What is the package difference between SMF18A-E3-08 and other SMF18A variants?

A: SMF18A-E3-08 uses DO-219AB package (Vishay eSMP® designation), while most other SMF18A variants use SOD-123F package. Both are surface-mount packages with identical electrical performance. PCB footprint compatibility must be verified before substitution.

Q: Are all listed substitutes ROHS3 compliant?

A: Yes. All direct equivalents (SMF18A, SMF18A-T13, SMF18A-E3-08, SMF18A-TP) and alternative voltage ratings (SMF11A through SMF17A) maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory compliance for new designs and production continuity.

Q: What is the operating temperature range difference between SMF18AT1G and SMF18A-E3-08?

A: SMF18AT1G operates from -55°C to 150°C (TJ). SMF18A-E3-08 operates from -65°C to 175°C (TJ), providing extended temperature range capability. Both are suitable for general-purpose applications; the extended range of SMF18A-E3-08 offers additional margin for high-temperature environments.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message