SMF43AT1 Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The SMF43AT1 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 43V reverse standoff voltage with a 69.4V maximum clamping voltage and 2.9A peak pulse current capability in a SOD-123FL package. The SMF43AT1 is classified as obsolete, necessitating identification of active equivalent and substitute components to maintain design continuity and ensure supply chain availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	43	V
Voltage - Breakdown (Min)	47.8	V
Voltage - Clamping (Max) @ Ipp	69.4	V
Current - Peak Pulse (10/1000µs)	2.9	A
Power - Peak Pulse	200	W
Operating Temperature	-55 to 150	°C (TJ)
Package / Case	SOD-123F	—
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the SMF43AT1 is determined by strict equivalence of electrical parameters within the TVS diode category. The primary substitution criteria are:

Reverse standoff voltage: 43V (nominal)
Breakdown voltage minimum: 47.8V
Clamping voltage maximum at Ipp: 69.4V
Peak pulse current: 2.9A
Peak pulse power: 200W
Package compatibility: SOD-123F / SOD-123FL
Mounting type: Surface Mount
Unidirectional configuration: Single channel

The SMF43A-TP manufactured by Micro Commercial Co is a direct electrical equivalent with identical voltage and current ratings. It maintains the same SOD-123FL package and provides active product status with improved RoHS3 compliance and extended operating temperature range (-65°C to 175°C).

Additional substitute parts in the SMF series (SMF20A through SMF36A) represent alternative voltage ratings within the same product family. These parts share identical package, mounting type, power rating, and general-purpose application profile but operate at different voltage levels. Selection among these alternatives depends on the specific circuit protection voltage requirement.

Parameter Comparison

Part Number	Manufacturer	VWM (V)	V(BR) Min (V)	V(CL) Max @ Ipp (V)	Ipp (A)	P(PP) (W)	Temp Range (°C)	Package	Status	RoHS
SMF43AT1	onsemi	43	47.8	69.4	2.9	200	-55 to 150 (TJ)	SOD-123FL	Obsolete	Non-compliant
SMF43A-TP	Micro Commercial Co	43	47.8	69.4	2.9	200	-65 to 175 (TA)	SOD-123FL	Active	ROHS3 Compliant
SMF20A	MDD	20	22.2	32.4	6.2	200	-55 to 150 (TJ)	SOD-123F / SMF	Active	ROHS3 Compliant
SMF22A	MDD	22	24.4	35.5	5.6	200	-55 to 150 (TJ)	SOD-123F / SMF	Active	ROHS3 Compliant
SMF24A	MDD	24	26.7	38.9	5.1	200	-55 to 150 (TJ)	SOD-123F / SMF	Active	ROHS3 Compliant
SMF26A	EVVO Semi	26	28.9	42.1	4.8	200	-55 to 150 (TJ)	SOD-123F	Active	ROHS3 Compliant
SMF28A	MDD	28	31.1	45.4	4.4	200	-55 to 150 (TJ)	SOD-123F / SMF	Active	ROHS3 Compliant
SMF30A	MDD	30	33.3	48.4	4.1	200	-55 to 150 (TJ)	SOD-123F / SMF	Active	ROHS3 Compliant
SMF33A	Diotec Semiconductor	33	36.7	53.3	3.75	200	-50 to 150 (TJ)	SOD-123F	Active	ROHS3 Compliant
SMF36A	MDD	36	40	58.1	3.44	200	-55 to 150	SOD-123F / SMF	Active	ROHS3 Compliant

Engineering Selection Recommendations

For direct replacement of the obsolete SMF43AT1, the SMF43A-TP from Micro Commercial Co is the primary equivalent. This part maintains identical electrical specifications (43V standoff, 69.4V clamping, 2.9A peak pulse) and SOD-123FL package compatibility. The SMF43A-TP offers superior product status (active), ROHS3 compliance, and extended operating temperature range (-65°C to 175°C ambient versus -55°C to 150°C junction for the original), providing enhanced reliability for new designs and production continuity.

For applications where the 43V protection voltage is not a strict requirement, alternative SMF series devices (SMF20A through SMF36A) provide equivalent mechanical compatibility and identical 200W power rating. Selection among these alternatives must be based on the specific circuit protection voltage requirement. All substitute options listed are active products with ROHS3 compliance and confirmed inventory availability.

Frequently Asked Questions (FAQ)

Q: Can SMF43A-TP be used as a direct replacement for SMF43AT1?

A: Yes. The SMF43A-TP is electrically equivalent with identical reverse standoff voltage (43V), breakdown voltage (47.8V minimum), clamping voltage (69.4V maximum), and peak pulse current (2.9A). Both use SOD-123FL packaging and surface-mount configuration. The SMF43A-TP is an active product with ROHS3 compliance and extended temperature range.

Q: What is the difference between SMF43AT1 and SMF43A-TP?

A: The primary differences are product status and compliance. SMF43AT1 is obsolete and RoHS non-compliant. SMF43A-TP is active, ROHS3 compliant, and operates across a wider temperature range (-65°C to 175°C ambient versus -55°C to 150°C junction). Electrical performance is identical.

Q: Can lower voltage SMF devices (SMF20A, SMF22A, SMF24A) substitute for SMF43AT1?

A: No. Lower voltage devices provide inadequate protection for circuits designed for 43V standoff voltage. Substitution requires matching the reverse standoff voltage specification. Lower voltage alternatives are suitable only for circuits with lower protection voltage requirements.

Q: Can higher voltage SMF devices (SMF36A) substitute for SMF43AT1?

A: No. Higher voltage devices will not trigger at the required 43V threshold, leaving the circuit unprotected. Substitution requires matching the reverse standoff voltage specification.

Q: Are all substitute parts compatible with existing PCB layouts?

A: Yes. All listed substitute parts use SOD-123F or SOD-123FL packaging with identical surface-mount footprints and pin configurations, ensuring direct PCB compatibility without layout modification.

Q: What is the inventory status of SMF43A-TP?

A: SMF43A-TP has 6131 pieces in stock as new original inventory, providing immediate availability for production and field replacement applications.

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