1KSMB18C Equivalent & Substitute Parts

Part Overview

The 1KSMB18C is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This bidirectional zener diode features a 15.3V reverse standoff voltage and 26.78V maximum clamping voltage with 39.2A peak pulse current capability in a DO-214AA (SMB) package. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and component procurement.

Substiute Parts

1KSMB18C

Littelfuse Inc.In Stock: 10401KSMB18C Datasheet

Current PartRFQ

1KSMB18CA

Taiwan Semiconductor CorporationIn Stock: 9791KSMB18CA Datasheet

DirectRFQ

P6SMB18CA-E3/5B

Vishay General Semiconductor - Diodes DivisionIn Stock: 978P6SMB18CA-E3/5B Datasheet

MFR RecommendedRFQ

P6SMB18CAHE3_A/H

Vishay General Semiconductor - Diodes DivisionIn Stock: 6086P6SMB18CAHE3_A/H Datasheet

MFR RecommendedRFQ

SM6T18CA-E3/52

Vishay General Semiconductor - Diodes DivisionIn Stock: 2130SM6T18CA-E3/52 Datasheet

MFR RecommendedRFQ

SM6T18CA-E3/5B

Vishay General Semiconductor - Diodes DivisionIn Stock: 4180SM6T18CA-E3/5B Datasheet

MFR RecommendedRFQ

SM6T18CAY

STMicroelectronicsIn Stock: 10399SM6T18CAY Datasheet

MFR RecommendedRFQ

SMBJP6KE18CA-TP

Micro Commercial CoIn Stock: 2699SMBJP6KE18CA-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1KSMB18C is determined by the following critical parameters:

• Voltage - Reverse Standoff (Typ): 15.3V
• Voltage - Clamping (Max) @ Ipp: 25.2V to 26.78V range
• Current - Peak Pulse (10/1000µs): 23.8A to 39.2A
• Package / Case: DO-214AA, SMB (surface mount)
• Mounting Type: Surface Mount
• RoHS Status: ROHS3 Compliant
• Moisture Sensitivity Level: 1 (Unlimited)

Substitute parts are grouped into two categories based on electrical performance and product status:

Category A - Direct Electrical Equivalents (Active Status): Parts with clamping voltages between 25.2V and 25.5V and peak pulse currents between 23.8A and 24.2A. These parts maintain the same reverse standoff voltage and package configuration.

Category B - Higher Performance Alternative (Active Status): Parts with elevated clamping voltage (32.5V) and significantly higher peak pulse current (123A at 8/20µs), suitable for applications requiring enhanced transient suppression capability while maintaining the same reverse standoff voltage and package.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Preferred):

1KSMB18CA (Taiwan Semiconductor Corporation) is the primary direct substitute. This part maintains identical reverse standoff voltage (15.3V), equivalent peak pulse current (39.2A), and matching power dissipation (1000W). It is currently in active production status and ROHS3 compliant. The extended operating temperature range (-55°C ~ 175°C) provides additional thermal margin compared to the original part.

For General-Purpose Applications:

P6SMB18CA-E3/5B, SM6T18CA-E3/52, SM6T18CA-E3/5B, and SMBJP6KE18CA-TP are suitable alternatives for applications where peak pulse current requirements do not exceed 24.2A and power dissipation is limited to 600W. All maintain the 15.3V reverse standoff voltage and DO-214AA package configuration. These parts are in active production status and ROHS3 compliant.

For Enhanced Transient Protection:

SM6T18CAY (STMicroelectronics) offers significantly higher peak pulse current (123A at 8/20µs) and is qualified to AEC-Q101 automotive standards. This part is suitable for applications requiring superior transient suppression capability while maintaining the same reverse standoff voltage and package. It is currently in active production status.

Avoid:

P6SMB18CAHE3_A/H is obsolete and should not be selected for new designs despite its technical compatibility.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a different clamping voltage?

A: Clamping voltage is a critical parameter for TVS diode selection. Substitute parts with clamping voltages between 25.2V and 26.78V are electrically compatible with the 1KSMB18C. Parts with significantly different clamping voltages (such as SM6T18CAY at 32.5V) alter the transient suppression characteristics and should only be used if the application circuit has been re-evaluated for the new clamping voltage.

Q: What is the difference between the 10/1000µs and 8/20µs pulse specifications?

A: These represent different test pulse waveforms used to characterize peak pulse current. The 10/1000µs waveform is standard for most TVS diodes, while 8/20µs is commonly used for automotive and industrial applications. Parts specified with different pulse waveforms may have different peak current ratings and should be selected based on the actual transient threat profile in the application.

Q: Are all substitute parts available in the same package?

A: Yes. All substitute parts listed are available in the DO-214AA (SMB) surface-mount package, ensuring mechanical and thermal compatibility with the original 1KSMB18C footprint.

Q: Which substitute part should I choose if my application requires the highest peak pulse current?

A: SM6T18CAY provides the highest peak pulse current at 123A (8/20µs). However, this part has a higher clamping voltage (32.5V) compared to the original 1KSMB18C (26.78V). Selection should be based on the specific transient threat profile and circuit requirements, not peak current alone.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed are ROHS3 compliant with Moisture Sensitivity Level 1 (Unlimited), matching the compliance profile of the original 1KSMB18C.

Q: Can I use 1KSMB18CA as a drop-in replacement?

A: Yes. The 1KSMB18CA is the closest electrical and mechanical equivalent to the 1KSMB18C, with identical reverse standoff voltage, equivalent peak pulse current, and matching power dissipation. It is currently in active production status and can be used as a direct replacement.