SMF36AT1 Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The SMF36AT1 is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. With a 36V reverse standoff voltage and 58.1V maximum clamping voltage at 3.4A peak pulse current, this component provides 200W peak pulse power dissipation in a SOD-123FL package.

The SMF36AT1 is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs and field replacements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	36	V
Voltage - Breakdown (Min)	40	V
Voltage - Clamping (Max) @ Ipp	58.1	V
Current - Peak Pulse (10/1000µs)	3.4	A
Power - Peak Pulse	200	W
Operating Temperature Range	-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 SMF36AT1 is determined by the following critical electrical parameters:

Voltage - Reverse Standoff (Typ): 36V nominal operating voltage
Voltage - Clamping (Max) @ Ipp: 58.1V maximum clamp voltage at peak pulse current
Current - Peak Pulse (10/1000µs): 3.4A peak pulse rating
Power - Peak Pulse: 200W dissipation capability
Package / Case: SOD-123F or equivalent surface-mount form factor
Type: Unidirectional Zener diode

Substitute parts are classified into two categories:

Direct Equivalent: Parts with identical electrical specifications (36V standoff, 58.1V clamp, 3.4A Ipp, 200W peak pulse) and compatible packaging.

Similar Alternatives: Parts within the SMF series with different voltage ratings (20V to 43V standoff) that maintain the same 200W peak pulse power rating and surface-mount package compatibility. These are suitable for applications requiring different voltage protection levels.

Parameter Comparison

Part Number	Manufacturer	Standoff Voltage (V)	Breakdown Min (V)	Clamp Voltage (V)	Peak Pulse Current (A)	Peak Pulse Power (W)	Package	Product Status	RoHS Status
SMF36AT1	onsemi	36	40	58.1	3.4	200	SOD-123F	Obsolete	Non-compliant
SMF36A-E3-08	Vishay General Semiconductor	36	40	58.1	3.4	200	DO-219AB (SMF)	Active	ROHS3 Compliant
SMF20A	MDD	20	22.2	32.4	6.2	200	SOD-123F / SMF	Active	ROHS3 Compliant
SMF22A	MDD	22	24.4	35.5	5.6	200	SOD-123F / SMF	Active	ROHS3 Compliant
SMF24A	MDD	24	26.7	38.9	5.1	200	SOD-123F / SMF	Active	ROHS3 Compliant
SMF26A	EVVO Semi	26	28.9	42.1	4.8	200	SOD-123F	Active	ROHS3 Compliant
SMF28A	MDD	28	31.1	45.4	4.4	200	SOD-123F / SMF	Active	ROHS3 Compliant
SMF30A	MDD	30	33.3	48.4	4.1	200	SOD-123F / SMF	Active	ROHS3 Compliant
SMF33A	Diotec Semiconductor	33	36.7	53.3	3.75	200	SOD-123F	Active	ROHS3 Compliant
SMF43A	Diotec Semiconductor	43	47.8	69.4	2.88	200	SOD-123F	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: SMF36A-E3-08 (Vishay General Semiconductor)

The SMF36A-E3-08 is the direct electrical equivalent to the SMF36AT1, matching all critical parameters: 36V standoff voltage, 58.1V clamping voltage, 3.4A peak pulse current, and 200W peak pulse power. This part is in active production status with ROHS3 compliance, making it the preferred choice for new designs and direct replacement applications. The DO-219AB (SMF) package is mechanically and electrically compatible with the original SOD-123F footprint.

Alternative Selections Based on Application Requirements

For applications where voltage protection levels differ from 36V, the SMF series alternatives provide equivalent power handling and surface-mount compatibility:

SMF33A (Diotec Semiconductor): Suitable for 33V protection circuits. Closest voltage rating to the original 36V specification with 3.75A peak pulse current.
SMF30A (MDD): Appropriate for 30V protection applications with 4.1A peak pulse current.
SMF28A (MDD): Suitable for 28V protection circuits with 4.4A peak pulse current.
SMF26A (EVVO Semi): For 26V protection applications with 4.8A peak pulse current.
SMF24A (MDD): Appropriate for 24V protection circuits with 5.1A peak pulse current.
SMF22A (MDD): Suitable for 22V protection applications with 5.6A peak pulse current.
SMF20A (MDD): For 20V protection circuits with 6.2A peak pulse current.
SMF43A (Diotec Semiconductor): For higher voltage protection at 43V with 2.88A peak pulse current.

All substitute parts maintain the 200W peak pulse power rating and surface-mount package format. Selection should be based on the specific voltage protection requirement of the target application circuit.

Frequently Asked Questions (FAQ)

Q: Can SMF36A-E3-08 be used as a direct replacement for SMF36AT1?

A: Yes. The SMF36A-E3-08 is electrically identical to the SMF36AT1 across all critical parameters: 36V standoff voltage, 58.1V clamping voltage, 3.4A peak pulse current, and 200W peak pulse power. The DO-219AB (SMF) package is compatible with SOD-123F footprints. The primary advantage is active production status and ROHS3 compliance.

Q: What is the difference between the SMF36AT1 and lower-voltage alternatives like SMF30A or SMF28A?

A: The primary difference is the reverse standoff voltage and corresponding clamping voltage. The SMF36AT1 protects circuits at 36V nominal, while SMF30A protects at 30V and SMF28A at 28V. All maintain identical 200W peak pulse power dissipation. Selection depends on the actual voltage level requiring protection in your circuit.

Q: Are all substitute parts in the same package?

A: Most substitute parts use SOD-123F or compatible SMF packages suitable for surface-mount assembly. The SMF36A-E3-08 uses DO-219AB (SMF), which is mechanically and electrically equivalent to SOD-123F. Verify package compatibility with your PCB footprint before selection.

Q: Why is the SMF36AT1 listed as obsolete?

A: The SMF36AT1 has been discontinued by onsemi. The SMF36A-E3-08 from Vishay General Semiconductor serves as the active production equivalent, ensuring continued availability and compliance with current regulatory standards.

Q: Do all substitute parts meet RoHS compliance?

A: The SMF36AT1 is RoHS non-compliant. All active substitute parts listed (SMF36A-E3-08, SMF20A through SMF43A) are ROHS3 compliant, meeting current environmental and regulatory requirements for new designs.

Q: Can I use a higher-voltage part like SMF43A in a 36V circuit?

A: No. Using a higher-voltage TVS diode (SMF43A at 43V standoff) in a 36V circuit will not provide adequate protection. The clamping voltage (69.4V for SMF43A) exceeds safe limits for 36V-rated components. Always select a TVS diode with standoff voltage matching or slightly below your circuit's nominal voltage.

Q: What is the significance of the peak pulse current rating?

A: Peak pulse current (Ipp) indicates the maximum transient current the TVS diode can safely conduct during a surge event. The SMF36AT1 and SMF36A-E3-08 both handle 3.4A peak pulse current. Lower-voltage alternatives (SMF20A to SMF30A) have higher Ipp ratings (6.2A down to 4.1A) due to lower clamping voltages, while higher-voltage alternatives (SMF43A) have lower Ipp ratings (2.88A).

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