SMA6J18A-TP Equivalent & Substitute Parts

Part Overview

The SMA6J18A-TP is an 18V unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Micro Commercial Co, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 29.2V maximum clamping voltage and 20.5A peak pulse current capability in a DO-214AC (SMA) package. The part is active in production with ROHS3 compliance and unlimited moisture sensitivity rating. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, supply chain considerations, or design flexibility needs.

Substiute Parts

SMA6J18A-TP

Micro Commercial CoIn Stock: 3823SMA6J18A-TP Datasheet

Current PartRFQ

SM4T21AY

STMicroelectronicsIn Stock: 2947SM4T21AY Datasheet

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SMA5J18A-E3/5A

Vishay General Semiconductor - Diodes DivisionIn Stock: 8567SMA5J18A-E3/5A Datasheet

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SMA5J18A-E3/61

Vishay General Semiconductor - Diodes DivisionIn Stock: 8181SMA5J18A-E3/61 Datasheet

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SMAJ18A

MDDIn Stock: 15558SMAJ18A Datasheet

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SMAJ18A-TR

STMicroelectronicsIn Stock: 30613SMAJ18A-TR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SMA6J18A-TP is determined by the following critical parameters:

• Voltage Rating Match: Reverse standoff voltage of 18V and breakdown voltage minimum of 20V
• Package Compatibility: DO-214AC (SMA) surface-mount package required for PCB footprint alignment
• Clamping Voltage: Maximum clamping voltage at Ipp must not exceed 29.2V to maintain circuit protection integrity
• Peak Pulse Current: Minimum 20.5A capability at 10/1000µs pulse profile
• Thermal Performance: Operating temperature range must support application requirements
• Compliance: ROHS3 compliance and MSL rating of 1 (Unlimited)

Substitute parts are grouped into two categories based on electrical performance characteristics:

Category A - Direct Electrical Equivalents (Clamping voltage 29.2V, Peak current 13.7A–17.1A): SMA5J18A-E3/5A, SMA5J18A-E3/61, SMAJ18A. These parts maintain identical clamping voltage and are suitable for applications where peak current requirements are within their specified range.

Category B - Higher Performance Variants (Clamping voltage 39.3V, Peak current 59A): SM4T21AY, SMAJ18A-TR. These parts provide enhanced transient suppression capability with higher peak current handling and are suitable for more demanding protection scenarios.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Identical Clamping Voltage)

SMA5J18A-E3/5A and SMA5J18A-E3/61 from Vishay General Semiconductor are functionally equivalent to SMA6J18A-TP with matching 29.2V clamping voltage. Both parts are active products with ROHS3 compliance. The primary consideration is the reduced peak pulse current (17.1A versus 20.5A) and lower maximum operating temperature (150°C versus 175°C). These parts are suitable when the application peak current requirement does not exceed 17.1A and operating temperature remains below 150°C.

SMAJ18A from MDD maintains the 29.2V clamping voltage specification with further reduced peak pulse current (13.7A) and lower power dissipation (400W). This part is appropriate for lower-current transient protection scenarios.

For Enhanced Protection (Higher Clamping Voltage)

SM4T21AY and SMAJ18A-TR from STMicroelectronics provide higher peak pulse current capability (59A) and are qualified to AEC-Q101 automotive standards. The 39.3V clamping voltage is higher than the SMA6J18A-TP specification. These parts are suitable for applications requiring greater transient suppression margin or higher peak current handling. Both maintain ROHS3 compliance and operate across -55°C to 150°C temperature range.

All substitute parts maintain DO-214AC (SMA) package compatibility, surface-mount configuration, and ROHS3 compliance with unlimited moisture sensitivity rating.

Frequently Asked Questions (FAQ)

Q: Can SMA5J18A-E3/5A replace SMA6J18A-TP in all applications?

A: SMA5J18A-E3/5A is suitable when the application peak transient current does not exceed 17.1A and operating temperature remains below 150°C. The 29.2V clamping voltage matches the original specification. If the application requires 20.5A peak current capability or operation above 150°C, this substitute is not appropriate.

Q: What is the difference between SM4T21AY and SMAJ18A-TR?

A: Both parts are from STMicroelectronics with identical electrical specifications (18V standoff, 39.3V clamping, 59A peak current). The primary difference is packaging: SM4T21AY is supplied in Tape & Reel format, while SMAJ18A-TR is available in Cut Tape and Digi-Reel format. Electrical performance and compliance are equivalent.

Q: Why does SMAJ18A have lower peak current than SMA6J18A-TP?

A: SMAJ18A from MDD is designed for lower-current transient protection applications. The 13.7A peak pulse current specification reflects its intended use case. Selection should be based on actual circuit transient current requirements rather than maximum available rating.

Q: Are all substitute parts compatible with the same PCB footprint?

A: Yes. All substitute parts use the DO-214AC (SMA) package with identical mechanical dimensions and pin configuration. PCB footprint compatibility is maintained across all listed alternatives.

Q: Which substitute part has the widest operating temperature range?

A: SMA6J18A-TP maintains the widest operating temperature range (-55°C to 175°C). All substitute parts operate within -55°C to 150°C or -50°C to 150°C ranges. Application thermal requirements should determine if the reduced upper temperature limit is acceptable.

Q: Do all parts meet the same compliance standards?

A: All listed parts are ROHS3 compliant with MSL rating of 1 (Unlimited). SM4T21AY and SMAJ18A-TR carry additional AEC-Q101 automotive qualification. Compliance requirements should be verified against specific application standards.