1SMA70AT3 Transient Voltage Suppressor (TVS) Diode – Equivalent & Substitute Parts

Part Overview

The 1SMA70AT3 is a unidirectional Zener-type transient voltage suppressor manufactured by onsemi in a surface-mount SMA (DO-214AC) package. This component is designed for general-purpose transient voltage suppression applications, offering a 70V reverse standoff voltage with a 113V maximum clamping voltage at peak pulse current of 4.6A. The part is currently classified as obsolete, making identification of active equivalent and substitute parts essential for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer Part Number	1SMA70AT3
Manufacturer	onsemi
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Unidirectional Channels	1
Voltage – Reverse Standoff (Typ)	70V
Voltage – Breakdown (Min)	77.8V
Voltage – Clamping (Max) @ Ipp	113V
Current – Peak Pulse (10/1000µs)	4.6A
Power – Peak Pulse	400W
Package / Case	DO-214AC, SMA
Mounting Type	Surface Mount
Operating Temperature	-65°C ~ 150°C (TJ)
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution of the 1SMA70AT3 is determined by strict electrical and mechanical parameter matching within the TVS diode category. The critical parameters that define substitutability are:

Electrical Parameters (Must Match or Exceed):

Voltage – Reverse Standoff: 70V (nominal)
Voltage – Breakdown (Min): 77.8V minimum
Voltage – Clamping (Max) @ Ipp: 113V maximum
Current – Peak Pulse (10/1000µs): 4.6A minimum
Power – Peak Pulse: 400W minimum
Unidirectional Channels: 1

Mechanical Parameters (Must Match):

Package / Case: DO-214AC (SMA)
Mounting Type: Surface Mount

Substitute parts are categorized into two groups:

Direct Substitutes: Parts with identical electrical specifications (70V standoff, 113V clamp, 4.6A peak pulse) in the same SMA package.

Similar Substitutes: Parts with comparable electrical performance within acceptable tolerance ranges but may differ in peak pulse current, clamping voltage, or operating temperature range. These require engineering evaluation for specific application requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage – Reverse Standoff (Typ)	Voltage – Breakdown (Min)	Voltage – Clamping (Max) @ Ipp	Current – Peak Pulse (10/1000µs)	Power – Peak Pulse	Package	Product Status	RoHS Status
1SMA70AT3	onsemi	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Obsolete	RoHS non-compliant
SMAJ70A	MDD	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
P4SMA82A	Eaton – Electronics Division	70.1V	77.9V	113V	3.6A	400W	DO-214AC, SMA	Active	RoHS Compliant
PTVS64VS1UR,115	Nexperia USA Inc.	64V	71.1V	103V	3.9A	400W	SOD-123W	Active	ROHS3 Compliant
SM4T82AY	STMicroelectronics	70V	77.8V	146V	16A (8/20µs)	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J70A-TR	STMicroelectronics	70V	77.8V	120V	27A (8/20µs)	600W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ70A-13-F	Diodes Incorporated	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ70A-M3/5A	Vishay General Semiconductor – Diodes Division	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ70A-M3/61	Vishay General Semiconductor – Diodes Division	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ70A-TP	Micro Commercial Co	70V	77.8V	113V	4.6A	400W	DO-214AC, SMA	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Substitutes (Identical Electrical & Mechanical Specifications):

The following parts provide direct substitution for the 1SMA70AT3 with identical 70V standoff, 77.8V breakdown, 113V clamping voltage, and 4.6A peak pulse current in DO-214AC (SMA) package:

SMAJ70A (MDD) – Active status, ROHS3 compliant
SMAJ70A-13-F (Diodes Incorporated) – Active status, ROHS3 compliant
SMAJ70A-M3/5A (Vishay General Semiconductor) – Active status, ROHS3 compliant, TransZorb® series
SMAJ70A-M3/61 (Vishay General Semiconductor) – Active status, ROHS3 compliant, TransZorb® series
SMAJ70A-TP (Micro Commercial Co) – Active status, ROHS3 compliant

All direct substitutes are currently in active production status and meet ROHS3 compliance requirements, addressing the RoHS non-compliance limitation of the obsolete 1SMA70AT3.

Similar Substitutes (Comparable Performance, Parameter Variations):

P4SMA82A (Eaton – Electronics Division) – 70.1V standoff, 113V clamp, 3.6A peak pulse. Marginal increase in peak pulse current. RoHS compliant.
SM4T82AY (STMicroelectronics) – 70V standoff, 146V clamp, 16A peak pulse (8/20µs). Higher clamping voltage and peak pulse current. AEC-Q101 automotive qualified. ROHS3 compliant.
SMA6J70A-TR (STMicroelectronics) – 70V standoff, 120V clamp, 27A peak pulse (8/20µs), 600W power rating. Significantly higher current and power handling. ROHS3 compliant.

Package Consideration:

PTVS64VS1UR,115 (Nexperia USA Inc.) uses SOD-123W package instead of SMA, making it unsuitable for direct PCB layout compatibility with the 1SMA70AT3 despite comparable electrical performance.

Frequently Asked Questions (FAQ)

Q: Can I use SMAJ70A as a direct replacement for 1SMA70AT3?

A: Yes. SMAJ70A provides identical electrical specifications (70V standoff, 113V clamp, 4.6A peak pulse) in the same DO-214AC (SMA) package. SMAJ70A is in active production and ROHS3 compliant, addressing the obsolescence and RoHS non-compliance of the original part.

Q: What is the difference between direct substitutes and similar substitutes?

A: Direct substitutes match all critical electrical parameters (standoff voltage, clamping voltage, peak pulse current) and package type. Similar substitutes maintain the same standoff voltage and package but may differ in clamping voltage, peak pulse current, or power rating. Similar substitutes require application-specific evaluation to confirm suitability.

Q: Why is package type critical for substitution?

A: The 1SMA70AT3 uses the DO-214AC (SMA) surface-mount package. Substitutes must use the same package to maintain PCB layout compatibility, trace routing, and thermal characteristics. Parts in different packages (such as SOD-123W) require PCB redesign and are not considered direct substitutes.

Q: Can I use SM4T82AY or SMA6J70A-TR instead of 1SMA70AT3?

A: These parts share the same 70V standoff voltage and SMA package but have higher clamping voltages (146V and 120V respectively) and significantly higher peak pulse currents (16A and 27A). They are suitable only if your application requires higher transient energy absorption. For circuits designed for 113V clamping and 4.6A peak pulse, use direct substitutes instead.

Q: Does the operating temperature range affect substitution?

A: The 1SMA70AT3 operates from -65°C to 150°C (TJ). Most direct substitutes operate from -55°C to 150°C (TJ), a narrower range at the lower temperature extreme. For applications requiring operation below -55°C, verify the specific substitute's temperature rating against system requirements.

Q: Are all substitute parts RoHS compliant?

A: All listed direct and similar substitutes are RoHS compliant (ROHS3 or RoHS Compliant status). The original 1SMA70AT3 is RoHS non-compliant. Substitution with any listed part addresses RoHS compliance requirements for new designs or product updates.

Q: What is the difference between SMAJ70A variants from different manufacturers?

A: SMAJ70A is offered by multiple manufacturers (MDD, Diodes Incorporated, Micro Commercial Co, Vishay) with identical electrical specifications and SMA packaging. Variants differ by manufacturer, packaging format (tape & reel designations), and internal quality certifications. All are functionally equivalent for the 1SMA70AT3 application.

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