1KSMB39C Equivalent & Substitute Parts

Part Overview

The 1KSMB39C is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for telecom applications. This bidirectional zener diode operates with a reverse standoff voltage of 33.3V and provides clamping protection at 53.9V with a peak pulse current rating of 18.6A. The device is packaged in a surface-mount DO-214AA (SMB) configuration and rated for automotive-grade applications.

The 1KSMB39C carries an obsolete product status. Identifying equivalent substitute parts ensures design continuity and maintains supply chain reliability for applications requiring identical electrical and mechanical specifications.

Substiute Parts

1KSMB39C

Littelfuse Inc.In Stock: 7311KSMB39C Datasheet

Current PartRFQ

1KSMB39CA

Taiwan Semiconductor CorporationIn Stock: 39471KSMB39CA Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1KSMB39C is determined by strict equivalence across the following electrical and mechanical parameters:

• Voltage Rating Match: Reverse standoff voltage of 33.3V, breakdown voltage minimum of 37.1V, and clamping voltage maximum of 53.9V must be identical
• Current Handling: Peak pulse current of 18.6A (10/1000µs pulse) must be maintained
• Power Dissipation: Peak pulse power rating of 1000W must be equivalent
• Package Compatibility: DO-214AA (SMB) surface-mount package required for PCB layout compatibility
• Diode Type: Zener-type bidirectional TVS diode with single channel configuration
• Mechanical Fit: Surface-mount technology with identical footprint and lead configuration

The 1KSMB39CA meets all substitution criteria as a direct electrical and mechanical equivalent.

Parameter Comparison

Engineering Selection Recommendations

The 1KSMB39CA is a direct functional substitute for the obsolete 1KSMB39C. Both devices share identical electrical specifications across all critical parameters: voltage ratings, current handling, power dissipation, and package configuration.

Product Status Consideration: The 1KSMB39C is obsolete, while the 1KSMB39CA maintains active product status with higher inventory availability (3889 units in stock versus 642 units for the original part). This availability differential supports long-term supply chain stability.

Compliance Alignment: Both parts maintain RoHS compliance. The 1KSMB39CA carries ROHS3 certification and REACH Unaffected status, providing enhanced regulatory documentation for applications requiring strict environmental compliance tracking.

Operating Temperature: The 1KSMB39CA extends the upper operating temperature limit to 175°C compared to the 1KSMB39C at 150°C. The lower temperature limit increases from -65°C to -55°C. For applications operating within the original -65°C to 150°C range, the 1KSMB39CA remains fully qualified.

Packaging Format: The 1KSMB39CA is supplied in Tape & Reel (TR) format, suitable for automated assembly processes. The original part packaging specification was not provided; verify packaging requirements for your manufacturing process.

Frequently Asked Questions (FAQ)

Q: Can the 1KSMB39CA be used as a direct replacement for the 1KSMB39C in existing designs?

A: Yes. The 1KSMB39CA is electrically and mechanically equivalent across all specified parameters. No circuit modifications are required. Both devices feature identical voltage ratings (33.3V standoff, 53.9V clamp), current handling (18.6A peak pulse), and DO-214AA surface-mount packaging.

Q: What is the difference in operating temperature range between these parts?

A: The 1KSMB39C operates from -65°C to 150°C, while the 1KSMB39CA operates from -55°C to 175°C. For applications within the original -65°C to 150°C specification, the 1KSMB39CA is fully qualified. If your application requires operation below -55°C, the original part specification must be maintained.

Q: Are there any compliance or certification differences?

A: Both parts are RoHS compliant. The 1KSMB39CA carries ROHS3 certification and REACH Unaffected status, providing additional regulatory documentation. The original 1KSMB39C was specified as automotive-grade; verify that your application's automotive qualification requirements are met by the 1KSMB39CA if this is a critical specification.

Q: What packaging formats are available?

A: The 1KSMB39C packaging format was not specified in the original documentation. The 1KSMB39CA is supplied in Tape & Reel (TR) format for automated assembly. Confirm that TR packaging is compatible with your manufacturing process, or contact the supplier for alternative packaging options.

Q: Are both parts in stock?

A: The 1KSMB39C has 642 units in stock (obsolete status). The 1KSMB39CA has 3889 units in stock (active status). The substitute part offers significantly higher availability for immediate procurement and future reorders.

Q: What is the moisture sensitivity level for these parts?

A: Both the 1KSMB39C and 1KSMB39CA carry MSL 1 (Unlimited) rating, indicating no moisture sensitivity restrictions. Standard handling and storage procedures apply without special moisture control requirements.