Littelfuse V18ZT2 Equivalent & Substitute Parts

Part Overview

The Littelfuse V18ZT2 is an 18 V, 500 A transient voltage suppressor varistor in a 10mm disc through-hole package. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The V18ZT2 series provides transient voltage suppression across a single circuit with 1.5 J energy rating and operates across the temperature range of -55°C to 85°C. Substitute parts maintain identical electrical and mechanical specifications while offering active product status and improved availability.

Key Parameters

Parameter	Value
Varistor Voltage (Typical)	18 V
Varistor Voltage Range	16.2 V (Min) to 19.8 V (Max)
Current - Surge	500 A
Energy Rating	1.5 J
Maximum AC Volts	10 V
Maximum DC Volts	14 V
Number of Circuits	1
Capacitance @ 1 MHz	5300 pF
Operating Temperature Range	-55°C to 85°C
Mounting Type	Through Hole
Package / Case	Disc 10mm
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the V18ZT2 are qualified based on strict electrical and mechanical parameter matching. All substitute parts maintain identical varistor voltage specifications (16.2 V minimum to 19.8 V maximum, 18 V typical), surge current rating (500 A), energy rating (1.5 J), capacitance (5300 pF @ 1 MHz), temperature range (-55°C to 85°C), and physical package (Disc 10mm through-hole).

Substitutes are differentiated by series designation (ZT, ZS, ZU) and packaging format. The V18ZT2P represents a direct packaging equivalent with tape and reel format. The V18ZS2P and V18ZU2P series parts are parametric equivalents from alternative Littelfuse series, maintaining all critical electrical parameters. Parts designated with the X2855 suffix indicate alternative tape and reel configurations. All substitute parts carry active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment.

Parameter Comparison

Part Number	Series	Packaging	Product Status	Varistor Voltage (Typ)	Surge Current	Energy	Operating Temp	Inventory (Pcs)
V18ZT2	ZT	Disc 10mm	Obsolete	18 V	500 A	1.5 J	-55°C to 85°C	1013
V18ZT2P	ZT	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	1021
V18ZS2P	ZS	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	1013
V18ZS2PX2855	ZS	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	915
V18ZT2PX2855	ZT	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	897
V18ZU2P	ZU	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	678
V18ZU2PX2855	ZU	Tape & Reel (TR)	Active	18 V	500 A	1.5 J	-55°C to 85°C	700

Engineering Selection Recommendations

For applications currently using the obsolete V18ZT2, the V18ZT2P is the primary direct substitute, maintaining identical series designation with active product status and equivalent electrical performance. This part is available in tape and reel packaging format, suitable for automated assembly processes.

The V18ZS2P and V18ZU2P represent parametric equivalents from alternative Littelfuse series. These parts deliver identical electrical specifications and thermal performance, with the distinction being series-level design variations. Selection between ZS and ZU series should be based on existing design validation and supply chain preferences.

All substitute parts carry ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), ensuring regulatory alignment and simplified handling requirements. Parts designated with the X2855 suffix provide alternative tape and reel configurations with equivalent electrical performance.

Frequently Asked Questions (FAQ)

Q: Can V18ZT2P be used as a direct replacement for V18ZT2?

A: Yes. The V18ZT2P maintains identical electrical parameters (18 V typical varistor voltage, 500 A surge current, 1.5 J energy) and physical package (Disc 10mm through-hole). The primary difference is packaging format (tape and reel versus bulk) and active product status.

Q: What is the difference between ZT, ZS, and ZU series parts?

A: All three series (ZT, ZS, ZU) deliver identical electrical specifications for this voltage and current rating. Series designation reflects internal design variations within the Littelfuse product line. Selection can be based on supply availability and existing design validation.

Q: Are parts with the X2855 suffix electrically equivalent?

A: Yes. The X2855 designation indicates an alternative tape and reel configuration. Electrical parameters, thermal performance, and compliance certifications remain identical to non-X2855 variants.

Q: What packaging format should be selected for new designs?

A: Tape and reel (TR) packaging is standard for automated assembly. All active substitute parts are available in tape and reel format. Bulk disc packaging is limited to the obsolete V18ZT2.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed carry ROHS3 compliance and are REACH unaffected, ensuring regulatory alignment for current manufacturing standards.

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

A: All parts carry MSL 1 (Unlimited), indicating no moisture sensitivity restrictions. Standard handling procedures apply without special drying or storage requirements.

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