LC18 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The LC18 is a unidirectional Zener-type transient voltage suppressor manufactured by Microchip Technology, designed for general-purpose overvoltage protection applications. This through-hole component operates across an extended temperature range of -65°C to 175°C and features a 1500W peak pulse power rating. The part is currently in active production status with 1030 units available in bulk packaging.

Equivalent and substitute parts are identified to address component availability, packaging preferences, compliance requirements, or regional sourcing needs while maintaining functional compatibility within specified electrical parameters.

Substiute Parts

LC18

Microchip TechnologyIn Stock: 1074LC18 Datasheet

Current PartRFQ

LCE15A

Littelfuse Inc.In Stock: 2372LCE15A Datasheet

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LCE18A

Littelfuse Inc.In Stock: 1007LCE18A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LC18 are qualified based on the following electrical and mechanical criteria:

Primary Substitution Criteria:

• Voltage - Reverse Standoff (Typ): 15V to 18V range
• Voltage - Clamping (Max) @ Ipp: 24.4V to 32.2V range
• Current - Peak Pulse (10/1000µs): Minimum 46A
• Power - Peak Pulse: 1500W (1.5kW)
• Mounting Type: Through Hole
• Type: Zener, Unidirectional
• Applications: General Purpose

Identified Substitutes:

LCE18A (Littelfuse Inc.) qualifies as a direct functional equivalent with matching 18V reverse standoff voltage and 1500W peak pulse power. The clamping voltage of 29.2V remains within acceptable tolerance, and peak pulse current of 51A exceeds the minimum requirement. Package format differs (DO-201 vs. DO-202AA), requiring mechanical verification for board layout compatibility.

LCE15A (Littelfuse Inc.) qualifies as a lower-voltage alternative with 15V reverse standoff. The 24.4V clamping voltage and 61A peak pulse current provide functional protection in applications where the lower voltage threshold is acceptable. This substitute is suitable for circuits with lower transient voltage exposure.

Parameter Comparison

Engineering Selection Recommendations

LC18 (Microchip Technology): Select this part for applications requiring the original specification with DO-13 package form factor. The extended lower temperature limit of -65°C provides advantage in extreme cold environments. Note that RoHS non-compliance may restrict use in regulated markets or OEM applications with RoHS mandates.

LCE18A (Littelfuse Inc.): This substitute provides voltage-matched performance (18V standoff) with improved clamping characteristics (29.2V vs. 32.2V) and higher peak pulse current (51A vs. 46A). ROHS3 compliance enables use in regulated supply chains. Package transition from DO-13 to DO-201 requires PCB layout verification. Operating temperature minimum of -55°C is suitable for most industrial and commercial applications.

LCE15A (Littelfuse Inc.): This lower-voltage substitute is appropriate for circuits with transient exposure below 18V. The superior peak pulse current rating (61A) and improved clamping voltage (24.4V) provide enhanced protection margin in lower-voltage systems. ROHS3 compliance and active production status support long-term availability. Package compatibility with DO-201 format must be confirmed for mechanical fit.

Frequently Asked Questions (FAQ)

Q: Can LCE18A directly replace LC18 without circuit modification?

A: LCE18A provides electrical equivalence with matching 18V reverse standoff voltage and 1500W power rating. However, the package format differs (DO-201 vs. DO-202AA). Direct PCB substitution requires verification that the DO-201 axial lead spacing and dimensions accommodate the existing footprint. Electrical performance is compatible without circuit changes.

Q: What is the functional difference between LCE18A and LCE15A?

A: LCE18A maintains the 18V reverse standoff voltage of the original LC18, providing identical trigger threshold for overvoltage events. LCE15A operates at 15V standoff, triggering protection at lower voltage levels. Selection depends on the maximum allowable transient voltage in the protected circuit. Both share identical 1500W peak pulse power and through-hole mounting.

Q: Are the Littelfuse LCE series parts compatible with the original Microchip LC18 application?

A: Both LCE18A and LCE15A are compatible for general-purpose transient voltage suppression applications. Compatibility is determined by matching the reverse standoff voltage to the circuit's protection threshold and confirming that peak pulse current and clamping voltage specifications meet application requirements. Package form factor must be verified for mechanical fit.

Q: Why does LCE18A show lower clamping voltage (29.2V) than LC18 (32.2V)?

A: Clamping voltage variation within the same voltage class reflects manufacturing tolerance and design differences between manufacturers. The 29.2V clamping voltage of LCE18A is within acceptable range for 18V class TVS diodes and provides improved transient suppression compared to the LC18 specification. This represents a performance advantage rather than a limitation.

Q: What is the impact of RoHS compliance on part selection?

A: LC18 is RoHS non-compliant, while both LCE18A and LCE15A are ROHS3 compliant. RoHS compliance is mandatory for products sold into European markets and many OEM supply chains. If RoHS compliance is required, LCE series substitutes are necessary. If RoHS status is not a constraint, LC18 remains available.

Q: Can LCE15A be used in an 18V circuit designed for LC18?

A: LCE15A operates at 15V reverse standoff, which is 3V lower than the LC18 design point. This substitute is suitable only if the circuit can tolerate protection activation at 15V instead of 18V. Use LCE15A only when the lower voltage threshold aligns with circuit protection requirements. For circuits requiring 18V threshold, use LCE18A.

Q: What are the temperature operating range implications for substitute selection?

A: LC18 operates from -65°C to 175°C, while both LCE substitutes operate from -55°C to 175°C. The 10°C difference in minimum temperature is not significant for most industrial and commercial applications. If operation below -55°C is required, LC18 is the only option. For standard temperature ranges, LCE series parts are fully compatible.