1KSMB33C Equivalent & Substitute Parts

Part Overview

The 1KSMB33C is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features a 28.2V reverse standoff voltage, 47.99V maximum clamping voltage, and 21.9A peak pulse current capability in a DO-214AA (SMB) package. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

1KSMB33C

Littelfuse Inc.In Stock: 10451KSMB33C Datasheet

Current PartRFQ

1KSMB33CA

Taiwan Semiconductor CorporationIn Stock: 22281KSMB33CA Datasheet

DirectRFQ

P6SMB33CA

Eaton - Electronics DivisionIn Stock: 44383P6SMB33CA Datasheet

MFR RecommendedRFQ

SZP6SMB33CAT3G

LittelfuseIn Stock: 150219SZP6SMB33CAT3G Datasheet

MFR RecommendedRFQ

P6SMB33CAHE3_A/H

Vishay General Semiconductor - Diodes DivisionIn Stock: 2644P6SMB33CAHE3_A/H Datasheet

MFR RecommendedRFQ

SM6T33CA

STMicroelectronicsIn Stock: 30338SM6T33CA Datasheet

MFR RecommendedRFQ

SM6T33CA-E3/5B

Vishay General Semiconductor - Diodes DivisionIn Stock: 7382SM6T33CA-E3/5B Datasheet

MFR RecommendedRFQ

SMBJP6KE33CA-TP

Micro Commercial CoIn Stock: 50331SMBJP6KE33CA-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1KSMB33C is determined by the following critical parameters:

• Voltage - Reverse Standoff (Typ): 28.2V
• Voltage - Breakdown (Min): 29.75V minimum
• Package / Case: DO-214AA, SMB (surface mount)
• Bidirectional Channels: 1
• Type: Zener
• RoHS Compliance: ROHS3 Compliant

Substitute parts must maintain the same reverse standoff voltage (28.2V) and package form factor to ensure mechanical and electrical compatibility. The clamping voltage and peak pulse current may vary within acceptable ranges for the application, as these parameters define the protection characteristics rather than the substitution criteria. All listed substitutes meet the core voltage and package requirements.

Parameter Comparison

Engineering Selection Recommendations

Direct Replacement (Highest Compatibility): The 1KSMB33CA from Taiwan Semiconductor Corporation maintains identical reverse standoff voltage (28.2V), peak pulse current (21.9A), and power rating (1000W) as the original 1KSMB33C. This part is active and ROHS3 compliant, making it the preferred direct substitute for applications requiring equivalent electrical performance.

Active Alternatives with Reduced Power Handling: Parts including P6SMB33CA, SZP6SMB33CAT3G, SM6T33CA-E3/5B, and SMBJP6KE33CA-TP all maintain the critical 28.2V reverse standoff voltage and DO-214AA package compatibility. These substitutes feature reduced peak pulse current (13.1A to 13.3A) and power dissipation (600W), suitable for applications where the original 1kW rating is not required. All are active products with ROHS3 compliance.

Automotive-Grade Options: SZP6SMB33CAT3G and P6SMB33CAHE3_A/H are qualified to AEC-Q101 automotive standards with extended operating temperature ranges (-65°C to 150°C), providing enhanced reliability for automotive and harsh-environment applications.

Obsolete Part Consideration: P6SMB33CAHE3_A/H, while obsolete, remains available in inventory and maintains automotive qualification. This part should be selected only when automotive-grade performance is mandatory and active alternatives are insufficient.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with lower peak pulse current than the original 1KSMB33C? A: Yes, provided your application does not require the full 21.9A peak pulse current capability. The 1KSMB33CA maintains this rating, while alternatives (P6SMB33CA, SZP6SMB33CAT3G, SM6T33CA-E3/5B, SMBJP6KE33CA-TP) operate at 13.1A to 13.3A. Verify your circuit's transient current requirements before selecting a lower-rated substitute.

Q: Are all substitute parts compatible with the original DO-214AA (SMB) footprint? A: Yes. All listed substitutes use the DO-214AA (SMB) package, ensuring mechanical compatibility with existing PCB layouts and assembly processes.

Q: What is the significance of the 28.2V reverse standoff voltage in substitution? A: The reverse standoff voltage determines the normal operating point of the TVS diode. All substitutes maintain 28.2V to ensure the diode remains non-conducting under normal circuit conditions and activates at the same threshold as the original part.

Q: Which substitute offers the best long-term availability? A: The 1KSMB33CA and SMBJP6KE33CA-TP are active products with substantial inventory levels (2200 and 50240 units respectively), providing reliable long-term sourcing. SZP6SMB33CAT3G offers the highest inventory (150200 units) among active alternatives.

Q: Can I use an automotive-qualified substitute in non-automotive applications? A: Yes. Automotive-qualified parts (SZP6SMB33CAT3G, P6SMB33CAHE3_A/H) meet or exceed standard industrial specifications and are suitable for general-purpose applications. Their extended temperature range and additional qualification provide added margin.

Q: What is the difference between the clamping voltage values listed for different substitutes? A: Clamping voltage defines the maximum voltage across the diode during transient suppression. The original 1KSMB33C clamps at 47.99V, while most substitutes clamp at 45.7V. Lower clamping voltage provides tighter protection but requires verification that your circuit can tolerate this difference. SM6T33CA clamps at 59V, providing looser protection suitable for less sensitive applications.