Littelfuse V18ZS3 Equivalent & Substitute Parts

Part Overview

The Littelfuse V18ZS3 is an 18 V, 1 kA disc varistor designed for transient voltage suppression in through-hole applications. This component operates across a temperature range of -55°C to 85°C and is housed in a 14mm disc package. The V18ZS3 carries an obsolete product status, making identification of functionally equivalent alternatives essential for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value
Varistor Voltage (Typical)	18 V
Varistor Voltage Range	16.2 V (Min) – 19.8 V (Max)
Current - Surge	1 kA
Energy Absorption	4.6 J
Maximum DC Volts	14 V
Maximum AC Volts	10 V
Operating Temperature	-55°C to 85°C
Mounting Type	Through Hole
Package / Case	Disc 14mm
Capacitance @ 1 MHz	18870 pF
Number of Circuits	1
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the V18ZS3 is determined by strict equivalence across all critical electrical and mechanical parameters. The following criteria define valid substitutes:

Varistor voltage range: 16.2 V (Min) to 19.8 V (Max)
Surge current rating: 1 kA
Energy absorption: 4.6 J
Maximum DC voltage: 14 V
Maximum AC voltage: 10 V
Operating temperature range: -55°C to 85°C
Mounting configuration: Through Hole
Physical package: Disc 14mm
Capacitance @ 1 MHz: 18870 pF
Number of circuits: 1

All substitute parts listed maintain identical electrical performance and mechanical compatibility. Packaging format differences (bulk versus tape & reel) do not affect functional equivalence. Series designation variations (ZS, ZT, ZU) reflect internal manufacturing classifications within Littelfuse but do not alter component performance within the specified parameter envelope.

Parameter Comparison

Part Number	Manufacturer	Series	Status	Packaging	Varistor Voltage (Typ)	Surge Current	Energy	Max DC V	Max AC V	Temp Range	Package	RoHS	Inventory
V18ZS3	Littelfuse Inc.	ZS	Obsolete	Bulk	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	947 Pcs
V18ZS3P	Littelfuse Inc.	ZS	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	655 Pcs
V18ZS3PX2855	Littelfuse Inc.	ZS	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	866 Pcs
V18ZT3P	Littelfuse Inc.	ZT	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	680 Pcs
V18ZT3PX2855	Littelfuse Inc.	ZT	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	879 Pcs
V18ZU3P	Littelfuse Inc.	ZU	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	1083 Pcs
V18ZU3PX2855	Littelfuse Inc.	ZU	Active	Tape & Reel	18 V	1 kA	4.6 J	14 V	10 V	-55°C to 85°C	Disc 14mm	ROHS3	1096 Pcs

Engineering Selection Recommendations

All listed substitute parts maintain full electrical and mechanical equivalence to the V18ZS3. Selection among available options should be based on the following factors:

Product Status: The V18ZS3 is obsolete. All substitute parts carry active product status, ensuring long-term availability and manufacturing support. Active parts are recommended for new designs and ongoing production.

Packaging Considerations: The V18ZS3 is supplied in bulk packaging. Substitute parts V18ZS3P, V18ZT3P, V18ZU3P, and their X2855 variants are supplied in tape & reel format, suitable for automated assembly processes. Bulk-to-tape & reel conversion does not affect component performance.

Compliance: All parts maintain ROHS3 compliance and MSL 1 (unlimited moisture sensitivity level), ensuring compatibility with standard manufacturing and storage protocols.

Series Designation: Parts are available across ZS, ZT, and ZU series designations. These represent internal Littelfuse manufacturing classifications and do not affect functional performance within the specified parameter range.

Inventory Availability: V18ZU3P and V18ZU3PX2855 offer the highest current inventory levels (1083 and 1096 units respectively), supporting immediate procurement requirements.

Frequently Asked Questions (FAQ)

Q: Can V18ZS3P be used as a direct replacement for V18ZS3?

A: Yes. V18ZS3P is functionally equivalent to V18ZS3, with identical electrical parameters and mechanical form factor. The primary difference is packaging format: V18ZS3P is supplied in tape & reel configuration versus bulk for the original part. Both are suitable for through-hole assembly.

Q: What is the difference between V18ZS3P, V18ZT3P, and V18ZU3P?

A: These parts differ only in internal series designation (ZS, ZT, ZU). All three maintain identical electrical specifications, surge current ratings, energy absorption, operating temperature range, and physical package dimensions. Series designation does not affect component performance or compatibility.

Q: Are the X2855 variants functionally different from standard parts?

A: No. Parts designated with X2855 suffix (V18ZS3PX2855, V18ZT3PX2855, V18ZU3PX2855) are parametrically equivalent to their non-suffixed counterparts. The X2855 designation reflects manufacturing or traceability coding and does not alter electrical or mechanical characteristics.

Q: Is tape & reel packaging compatible with manual assembly?

A: Tape & reel packaging is optimized for automated pick-and-place assembly. Manual assembly is possible but requires manual component extraction from the tape carrier. For manual assembly workflows, bulk packaging may be more practical, though all substitute parts maintain identical component specifications.

Q: Do all substitute parts meet the same compliance standards?

A: Yes. All substitute parts carry ROHS3 compliance, MSL 1 rating, and identical ECCN and HTSUS classifications. Compliance profiles are uniform across all listed alternatives.

Q: What is the varistor voltage tolerance across all parts?

A: All parts maintain a varistor voltage range of 16.2 V (minimum) to 19.8 V (maximum), with a typical value of 18 V. This tolerance envelope is consistent across the V18ZS3 and all substitute parts.

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