1SMA18CAT3 Equivalent & Substitute Parts

Part Overview

The 1SMA18CAT3 is a transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface mount applications. This component features an 18V reverse standoff voltage with a 29.2V maximum clamping voltage and 13.7A peak pulse current capability in a DO-214AC (SMA) package. The part is currently classified as obsolete, making identification of active equivalent and substitute parts essential for ongoing design support and procurement.

Substiute Parts

1SMA18CAT3

onsemiIn Stock: 7341SMA18CAT3 Datasheet

Current PartRFQ

SMAJ18CA

MDDIn Stock: 72275SMAJ18CA Datasheet

DirectRFQ

SMAJ18CA

MDDIn Stock: 72275SMAJ18CA Datasheet

DirectRFQ

SMAJ18CA

MDDIn Stock: 72275SMAJ18CA Datasheet

DirectRFQ

SMAJ18CA-TR

STMicroelectronicsIn Stock: 19566SMAJ18CA-TR Datasheet

DirectRFQ

SM4T21CAY

STMicroelectronicsIn Stock: 879SM4T21CAY Datasheet

SimilarRFQ

SMAJ18CA-13-F

Diodes IncorporatedIn Stock: 26151SMAJ18CA-13-F Datasheet

SimilarRFQ

SMAJ18CA-TP

Micro Commercial CoIn Stock: 998SMAJ18CA-TP Datasheet

SimilarRFQ

SMAJ18CAE3/TR13

Microchip TechnologyIn Stock: 871SMAJ18CAE3/TR13 Datasheet

SimilarRFQ

TV04A180JB-G

Comchip TechnologyIn Stock: 963TV04A180JB-G Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1SMA18CAT3 is determined by strict alignment of the following electrical and mechanical parameters:

Critical Matching Parameters:

• Voltage - Reverse Standoff (Typ): 18V
• Voltage - Breakdown (Min): 20V
• Voltage - Clamping (Max) @ Ipp: 29.2V
• Current - Peak Pulse (10/1000µs): 13.7A
• Power - Peak Pulse: 400W
• Package / Case: DO-214AC, SMA
• Mounting Type: Surface Mount
• Bidirectional Channels: 1

Substitute parts are grouped into two categories based on parameter alignment:

Category 1 - Direct Electrical & Mechanical Match (29.2V Clamp, 13.7A Ipp): Parts meeting all critical parameters with identical clamping voltage and peak pulse current specifications. These parts provide direct functional equivalence.

Category 2 - Electrical Variant (39.3V Clamp, 59A Ipp): Parts with the same reverse standoff and breakdown voltages but higher clamping voltage and peak pulse current ratings. These parts offer enhanced transient suppression capability within the same package and voltage class.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Performance):

SMAJ18CA-13-F (Diodes Incorporated) and TV04A180JB-G (Comchip Technology) provide direct functional equivalence to the 1SMA18CAT3 with matching 29.2V clamping voltage and 13.7A peak pulse current. Both parts are active products with ROHS3 compliance and extended operating temperature ranges (-55°C minimum vs. -65°C for the original). SMAJ18CA-13-F offers the widest temperature range at -55 to 150°C.

SMAJ18CA (MDD) matches all critical electrical parameters but operates at a reduced minimum temperature of -50°C, suitable for applications not requiring the full -65°C lower limit.

For Enhanced Performance (Higher Current Rating):

SMAJ18CAE3/TR13 (Microchip Technology) maintains the 29.2V clamping voltage while providing increased peak pulse current of 17.2A and 500W power dissipation. This part is suitable for applications requiring higher transient energy absorption within the same voltage class.

For Higher Clamping Voltage Applications:

SMAJ18CA-TR (STMicroelectronics) and SM4T21CAY (STMicroelectronics) feature 39.3V clamping voltage with 59A peak pulse current capability. These parts are appropriate only when higher clamping voltage is acceptable for the circuit design. SM4T21CAY includes AEC-Q101 automotive qualification.

Compliance Consideration:

All substitute parts listed are ROHS3 compliant, addressing the RoHS non-compliance status of the obsolete 1SMA18CAT3. Selection should prioritize active product status and compliance requirements for new designs.

Frequently Asked Questions (FAQ)

Q: Can SMAJ18CA-TR or SM4T21CAY be used as direct replacements for 1SMA18CAT3?

A: These parts share the same 18V reverse standoff and 20V breakdown voltages but feature 39.3V clamping voltage versus 29.2V for the original. They are not direct replacements. Use only if circuit design permits higher clamping voltage.

Q: What is the primary difference between SMAJ18CA-13-F and TV04A180JB-G?

A: Both parts match the 1SMA18CAT3 electrical specifications (29.2V clamp, 13.7A Ipp). The primary difference is manufacturer: Diodes Incorporated versus Comchip Technology. Both are active, ROHS3 compliant, and suitable for direct replacement.

Q: Why does SMAJ18CAE3/TR13 have higher current and power ratings?

A: SMAJ18CAE3/TR13 is rated for 17.2A peak pulse current and 500W power dissipation compared to 13.7A and 400W for the 1SMA18CAT3. This represents a higher-performance variant within the same voltage class, providing greater transient suppression capability.

Q: Is the operating temperature range difference significant?

A: The 1SMA18CAT3 operates from -65°C to 150°C. Most active substitutes operate from -55°C minimum. For applications requiring -65°C operation, SMAJ18CAE3/TR13 and SMAJ18CA-TP support this lower limit. Verify application requirements before selection.

Q: Are all substitute parts available in the same DO-214AC (SMA) package?

A: Yes. All listed substitute parts use DO-214AC (SMA) surface mount packaging, ensuring mechanical and footprint compatibility with the original 1SMA18CAT3.

Q: What is the significance of RoHS3 compliance on substitute parts?

A: The original 1SMA18CAT3 is RoHS non-compliant. All active substitute parts listed are ROHS3 compliant, meeting current environmental and regulatory requirements for new product designs and procurement.