1SMC75AT3G Equivalent & Substitute Parts

Part Overview

The 1SMC75AT3G is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 75V reverse standoff voltage with 121V maximum clamping voltage and 12.4A peak pulse current capability in a DO-214AB (SMC) package. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and field replacement requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	75	V
Voltage - Breakdown (Min)	83.3	V
Voltage - Clamping (Max) @ Ipp	121	V
Current - Peak Pulse (10/1000µs)	12.4	A
Power - Peak Pulse	1500	W
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Operating Temperature Range	-65 to 150	°C
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the 1SMC75AT3G are categorized based on strict electrical parameter matching within the TVS diode classification. The primary substitution criteria are:

Critical Matching Parameters:

Voltage - Reverse Standoff: 75V
Voltage - Clamping (Max) @ Ipp: 121V
Voltage - Breakdown (Min): 83.3V
Package / Case: DO-214AB (SMC)
Mounting Type: Surface Mount
Unidirectional configuration with single channel

Substitution Categories:

Direct Equivalents (1:1 Replacement): Parts maintaining identical electrical specifications and 12.4A peak pulse current, including SMCJ75A (Meritek) and SMCJ75A-HR, SMCJ75A-HRA, SMCJ75A-HRAT7 (Littelfuse). These provide pin-for-pin compatibility with no circuit redesign required.

Higher Current Capacity Alternatives: Parts with elevated peak pulse current ratings (24.8A or 41.4A) while maintaining voltage parameters, including SMDJ75A, SMDJ75A-T7, 5.0SMDJ75A, and 5.0SMDJ75A-T7. These provide enhanced transient energy absorption capability and are suitable for applications requiring increased protection margin.

All substitute parts maintain DO-214AB (SMC) package geometry, surface-mount compatibility, and compliance certifications (ROHS3, REACH Unaffected, EAR99).

Parameter Comparison

Part Number	Manufacturer	VWM (V)	VC (V)	Ipp (A)	Power (W)	Temp Range (°C)	Status
1SMC75AT3G	Littelfuse	75	121	12.4	1500	-65 to 150	Obsolete
SMCJ75A	Meritek	75	121	12.4	1500	-55 to 150	Active
SMCJ75A-HR	Littelfuse	75	121	12.4	1500	-65 to 150	Active
SMCJ75A-HRA	Littelfuse Inc.	75	121	12.4	1500	-65 to 150	Active
SMCJ75A-HRAT7	Littelfuse Inc.	75	121	12.4	1500	-65 to 150	Active
SMDJ75A	Alpha & Omega Semiconductor Inc.	75	121	24.8	3000	-55 to 150	Active
SMDJ75A-T7	Littelfuse Inc.	75	121	24.8	3000	-65 to 150	Active
5.0SMDJ75A	Taiwan Semiconductor Corporation	75	121	41.4	5000	-55 to 175	Active
5.0SMDJ75A-T7	Littelfuse Inc.	75	121	41.4	5000	-65 to 150	Active

Engineering Selection Recommendations

For Direct Replacement (No Circuit Modification):

SMCJ75A-HR, SMCJ75A-HRA, and SMCJ75A-HRAT7 (all Littelfuse) are preferred direct substitutes. These maintain the original 12.4A peak pulse current, 1500W power rating, and -65 to 150°C operating range. All three variants are active products with ROHS3 compliance and MSL 1 rating. SMCJ75A-HRAT7 includes tape & reel packaging for automated assembly. SMCJ75A (Meritek) provides an alternative direct equivalent with identical electrical specifications but operates over -55 to 150°C and is available in higher inventory (18,835 pcs).

For Enhanced Protection Margin:

SMDJ75A-T7 (Littelfuse) doubles the peak pulse current to 24.8A and power dissipation to 3000W while maintaining voltage parameters and -65 to 150°C range. This variant is suitable for applications requiring increased transient energy absorption without circuit redesign, as the DO-214AB package and voltage characteristics remain unchanged.

For Maximum Protection Capability:

5.0SMDJ75A-T7 (Littelfuse) provides the highest current capacity at 41.4A and 5000W power rating, maintaining all voltage specifications and -65 to 150°C operating range. This option is appropriate for high-energy transient environments where superior clamping performance is required.

All recommended substitutes maintain ROHS3 compliance, REACH unaffected status, and EAR99 classification consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can SMCJ75A (Meritek) be used as a direct replacement for 1SMC75AT3G?

A: Yes. SMCJ75A maintains identical voltage parameters (75V standoff, 121V clamping), peak pulse current (12.4A), power rating (1500W), and DO-214AB package. The operating temperature range is -55 to 150°C versus the original -65 to 150°C. For applications operating above -55°C, this substitution is electrically and mechanically compatible.

Q: What is the difference between SMCJ75A-HR, SMCJ75A-HRA, and SMCJ75A-HRAT7?

A: All three are Littelfuse products with identical electrical specifications (75V, 121V, 12.4A, 1500W, -65 to 150°C). The suffix designations indicate packaging and series variants. SMCJ75A-HRAT7 includes tape & reel packaging suitable for automated pick-and-place assembly. Selection depends on packaging requirements and inventory availability.

Q: Can I use SMDJ75A-T7 instead of 1SMC75AT3G without modifying the circuit?

A: Yes. SMDJ75A-T7 maintains all voltage specifications and DO-214AB package geometry. The increased peak pulse current (24.8A versus 12.4A) and power rating (3000W versus 1500W) provide enhanced protection without requiring circuit changes. This substitution is suitable for applications where additional transient margin is beneficial.

Q: Are higher current variants (SMDJ75A, 5.0SMDJ75A) pin-compatible with the original 1SMC75AT3G?

A: Yes. All substitute parts use the DO-214AB (SMC) package with identical pin configuration and footprint. Higher current variants differ only in internal die design and power dissipation capability, not in external dimensions or electrical interface.

Q: What is the inventory status of substitute parts?

A: SMCJ75A (Meritek) has the highest availability at 18,835 pcs. Littelfuse variants range from 774 to 2,200 pcs. SMDJ75A and higher-current options have lower inventory (679 to 1,900 pcs). Availability should be confirmed with suppliers for production requirements.

Q: Do all substitute parts meet the same compliance requirements as 1SMC75AT3G?

A: Yes. All listed substitutes are ROHS3 compliant, REACH unaffected, and classified as EAR99. Moisture sensitivity level is MSL 1 (unlimited) for all variants, matching the original part's environmental specifications.

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