1SMA33AT3 Equivalent & Substitute Parts

Part Overview

The 1SMA33AT3 is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by onsemi in the DO-214AC (SMA) surface mount package. This component is designed for general-purpose transient voltage suppression applications with a 33V reverse standoff voltage and 53.3V maximum clamping voltage at peak pulse current. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer Part Number	1SMA33AT3
Manufacturer	onsemi
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Unidirectional Channels	1
Voltage - Reverse Standoff (Typ)	33V
Voltage - Breakdown (Min)	36.7V
Voltage - Clamping (Max) @ Ipp	53.3V
Current - Peak Pulse (10/1000µs)	7.5A
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

Substitute parts for the 1SMA33AT3 are classified based on electrical parameter compatibility and package equivalence. The primary substitution criteria are:

Critical Parameters for Substitution:

Reverse standoff voltage: 33V (±tolerance)
Breakdown voltage minimum: 36.7V
Package type: DO-214AC (SMA) surface mount
Unidirectional configuration: 1 channel
Zener diode type

Substitution Categories:

Direct Equivalents maintain identical electrical specifications (53.3V clamping, 7.5A peak pulse current, 400W peak power) and are pin-compatible replacements:

SMAJ33A (MDD) — Active product status, RoHS3 compliant
SMAJ33A-13-F (Diodes Incorporated) — Active product status, RoHS3 compliant
SMAJ33A-TP (Micro Commercial Co) — Active product status, RoHS3 compliant

Compatible Alternatives share the same reverse standoff voltage and package but have different clamping voltage or peak pulse current specifications. These are suitable when the application can tolerate higher clamping voltages or peak current ratings:

SMAJ33AE3/TR13 (Microchip Technology) — 53.3V clamping, 9.4A peak pulse, 500W peak power
SMAJ33E3/TR13 (Microchip Technology) — 59V clamping, 8.5A peak pulse, 500W peak power
SMAJ33A-TR (STMicroelectronics) — 69.7V clamping, 33A peak pulse (8/20µs), 400W peak power
SMA6J33A-TR (STMicroelectronics) — 60.8V clamping, 57A peak pulse (8/20µs), 600W peak power

Package Variant uses different surface mount package but maintains electrical specifications:

PTVS33VS1UR,115 (Nexperia USA Inc.) — SOD-123W package, 53.3V clamping, 7.5A peak pulse, automotive grade AEC-Q101

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse	Power - Peak Pulse	Package / Case	Operating Temperature	Product Status	RoHS Status
1SMA33AT3	onsemi	33V	36.7V	53.3V	7.5A	400W	DO-214AC, SMA	-65°C ~ 150°C	Obsolete	RoHS non-compliant
SMAJ33A	MDD	33V	36.7V	53.3V	7.5A	400W	DO-214AC, SMA	-50°C ~ 150°C	Active	RoHS3 Compliant
SMAJ33A-13-F	Diodes Incorporated	33V	36.7V	53.3V	7.5A	400W	DO-214AC, SMA	-55°C ~ 150°C	Active	RoHS3 Compliant
SMAJ33A-TP	Micro Commercial Co	33V	36.7V	53.3V	7.5A	400W	DO-214AC, SMA	-55°C ~ 175°C	Active	RoHS3 Compliant
SMAJ33AE3/TR13	Microchip Technology	33V	36.7V	53.3V	9.4A	500W	DO-214AC, SMA	-65°C ~ 150°C	Active	RoHS3 Compliant
SMAJ33E3/TR13	Microchip Technology	33V	36.7V	59V	8.5A	500W	DO-214AC, SMA	-65°C ~ 150°C	Active	RoHS3 Compliant
SMAJ33A-TR	STMicroelectronics	33V	36.7V	69.7V	33A (8/20µs)	400W	DO-214AC, SMA	-55°C ~ 150°C	Active	RoHS3 Compliant
SMA6J33A-TR	STMicroelectronics	33V	36.7V	60.8V	57A (8/20µs)	600W	DO-214AC, SMA	-55°C ~ 175°C	Active	RoHS3 Compliant
PTVS33VS1UR,115	Nexperia USA Inc.	33V	36.7V	53.3V	7.5A	400W	SOD-123W	-55°C ~ 150°C	Active	RoHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Performance):

Select SMAJ33A-13-F (Diodes Incorporated), SMAJ33A-TP (Micro Commercial Co), or SMAJ33A (MDD) when the application requires exact electrical equivalence to the 1SMA33AT3. All three parts are active products with RoHS3 compliance, addressing the obsolescence and regulatory status of the original component. SMAJ33A-TP offers the widest operating temperature range (-55°C ~ 175°C), suitable for extended temperature applications.

For Higher Transient Energy Absorption:

Select SMAJ33AE3/TR13 or SMAJ33E3/TR13 (Microchip Technology) when the circuit can tolerate higher clamping voltages (53.3V or 59V respectively) and requires increased peak pulse power handling (500W). Both parts maintain the 33V reverse standoff voltage and DO-214AC package, with operating temperature range of -65°C ~ 150°C.

For High-Current Transient Protection:

Select SMAJ33A-TR or SMA6J33A-TR (STMicroelectronics) when the application requires significantly higher peak pulse current handling (33A or 57A respectively). These parts maintain the 33V reverse standoff voltage and DO-214AC package but feature higher clamping voltages. SMA6J33A-TR provides the highest power dissipation capability (600W) and extended temperature range (-55°C ~ 175°C).

For Automotive Applications:

Select PTVS33VS1UR,115 (Nexperia USA Inc.) when AEC-Q101 automotive qualification is required. This part maintains electrical equivalence to the 1SMA33AT3 but uses the SOD-123W package and includes automotive-grade certification.

Regulatory Compliance:

All recommended active substitutes are RoHS3 compliant, addressing the RoHS non-compliant status of the obsolete 1SMA33AT3. Verify specific RoHS requirements for your application region and supply chain.

Frequently Asked Questions (FAQ)

Q: Can SMAJ33A-TR be used as a direct replacement for 1SMA33AT3?

A: SMAJ33A-TR is electrically compatible in terms of reverse standoff voltage (33V) and package (DO-214AC, SMA), but features a higher clamping voltage (69.7V vs. 53.3V) and significantly higher peak pulse current (33A vs. 7.5A). It is suitable for applications where higher transient energy absorption is acceptable or beneficial. Circuit simulation or testing is necessary to confirm compatibility with specific application requirements.

Q: What is the difference between SMAJ33A and SMAJ33AE3/TR13?

A: Both parts share identical reverse standoff voltage (33V), breakdown voltage (36.7V), and clamping voltage (53.3V). The primary differences are peak pulse current (7.5A vs. 9.4A) and peak pulse power (400W vs. 500W). SMAJ33AE3/TR13 provides higher transient energy handling capability within the same package footprint.

Q: Why does PTVS33VS1UR,115 use a different package (SOD-123W) instead of DO-214AC?

A: PTVS33VS1UR,115 is offered in SOD-123W package, which is a smaller surface mount package than DO-214AC (SMA). This part is suitable only if the PCB layout can accommodate SOD-123W footprint. DO-214AC package variants (SMAJ33A, SMAJ33A-13-F, SMAJ33A-TP) are recommended for direct footprint compatibility.

Q: Are all substitute parts RoHS3 compliant?

A: Yes, all active substitute parts listed are RoHS3 compliant. The original 1SMA33AT3 is RoHS non-compliant. Substitution with any recommended part addresses regulatory compliance requirements for new designs and procurement.

Q: Can SMA6J33A-TR be used in space-constrained applications?

A: SMA6J33A-TR uses the same DO-214AC (SMA) package as the 1SMA33AT3, so footprint compatibility is maintained. However, the significantly higher peak pulse current (57A vs. 7.5A) and power dissipation (600W vs. 400W) may require thermal design considerations. Verify thermal management requirements for your specific application.

Q: What is the temperature range difference between substitute parts?

A: Operating temperature ranges vary among substitutes. SMAJ33AE3/TR13 and SMAJ33E3/TR13 support -65°C ~ 150°C (matching the original part). SMAJ33A-TP and SMA6J33A-TR extend to -55°C ~ 175°C. SMAJ33A (MDD) operates at -50°C ~ 150°C. Select based on your application's thermal requirements.

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