ROV20-121K Equivalent & Substitute Parts

Part Overview

The ROV20-121K is a 120V disc varistor manufactured by Littelfuse Inc., rated for 6.5 kA surge current with 64J energy absorption capacity. This through-hole component is designed for transient voltage suppression in industrial and commercial applications. The part is currently obsolete, making equivalent substitutes necessary for ongoing system maintenance and new designs requiring compatible performance characteristics.

Key Parameters

Parameter	Value
Varistor Voltage (Typical)	120 V
Varistor Voltage Range	108 V – 132 V
Current - Surge	6.5 kA
Maximum AC Volts	75 V
Maximum DC Volts	100 V
Energy Absorption	64 J
Operating Temperature Range	-40°C to 125°C
Mounting Type	Through Hole
Package / Case	Disc 20mm
Number of Circuits	1
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Varistor voltage rating (108 V – 132 V nominal 120 V)
Surge current capacity (minimum 6.5 kA)
Maximum AC and DC voltage ratings (75 V AC / 100 V DC)
Through-hole mounting configuration
Operating temperature range compatibility
RoHS3 compliance and regulatory status

Substitute parts are grouped into two categories based on surge current capacity and physical package dimensions:

Category A (Direct Electrical Equivalents): Parts with 6.5 kA surge rating and identical electrical specifications. These include MOV-20D121K, MOV-20D121KTR, and VDRS20W075BSE. Physical package dimensions vary slightly (20mm to 22.50mm disc), but all maintain through-hole mounting compatibility.

Category B (Enhanced Performance Alternative): ERZ-V20D121 provides higher surge current capacity (10 kA) and increased energy absorption (85J) while maintaining the same voltage rating and operating parameters. This part is suitable for applications requiring additional transient protection margin.

Parameter Comparison

Parameter	ROV20-121K (Littelfuse)	MOV-20D121K (Bourns)	MOV-20D121KTR (Bourns)	ERZ-V20D121 (Panasonic)	VDRS20W075BSE (Vishay)
Varistor Voltage (Typ)	120 V	120 V	120 V	120 V	120 V
Varistor Voltage Range	108–132 V	108–132 V	108–132 V	108–132 V	108–132 V
Current - Surge	6.5 kA	6.5 kA	6.5 kA	10 kA	6.5 kA
Maximum AC Volts	75 V	75 V	75 V	75 V	75 V
Maximum DC Volts	100 V	100 V	100 V	100 V	100 V
Energy Absorption	64 J	55 J	55 J	85 J	64 J
Operating Temperature	-40°C to 125°C	-40°C to 105°C	-40°C to 105°C	-40°C to 85°C	-40°C to 85°C
Package / Case	Disc 20mm	Disc 20mm	Disc 20mm	Disc 21.5mm	Disc 22.50mm
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

MOV-20D121K and MOV-20D121KTR from Bourns Inc. are functionally equivalent to the ROV20-121K. Both maintain 6.5 kA surge capacity, 120V nominal rating, and through-hole disc configuration. MOV-20D121KTR is supplied in tape and reel packaging, while MOV-20D121K is supplied in bulk. Both are active products with ROHS3 compliance and extended temperature range to 105°C.

VDRS20W075BSE from Vishay Beyschlag/Draloric/BC Components provides electrical equivalence with identical surge current and energy absorption specifications. Physical package diameter is 22.50mm compared to 20mm, requiring verification of PCB layout clearance. Operating temperature range is limited to 85°C.

For Enhanced Protection Applications:

ERZ-V20D121 from Panasonic Electronic Components offers increased surge current capacity (10 kA) and energy absorption (85J) while maintaining the 120V nominal rating and all voltage compliance parameters. Physical package diameter is 21.5mm. Operating temperature range is limited to 85°C. This part is suitable for applications requiring additional transient suppression margin beyond the original 6.5 kA specification.

Compliance and Regulatory Status:

All substitute parts maintain ROHS3 compliance, REACH unaffected status, and EAR99 export classification consistent with the original ROV20-121K.

Frequently Asked Questions (FAQ)

Q: Can MOV-20D121K directly replace ROV20-121K in existing designs?

A: Yes. MOV-20D121K provides identical electrical specifications including 120V nominal rating, 6.5 kA surge capacity, and 64J energy absorption. Physical package dimensions (20mm disc) are identical. No circuit modifications are required.

Q: What is the difference between MOV-20D121K and MOV-20D121KTR?

A: Both parts are electrically identical. MOV-20D121K is supplied in bulk packaging, while MOV-20D121KTR is supplied in tape and reel format. Selection depends on assembly process requirements and volume handling.

Q: Why does ERZ-V20D121 have higher surge current (10 kA) than the original part?

A: ERZ-V20D121 is designed with enhanced transient suppression capability. The 10 kA rating provides additional protection margin. All voltage parameters remain identical to the ROV20-121K, making it suitable for applications requiring increased surge protection without circuit redesign.

Q: Are there physical package considerations when substituting VDRS20W075BSE?

A: Yes. VDRS20W075BSE uses a 22.50mm disc package compared to 20mm for the ROV20-121K. PCB layout and mounting hole spacing must be verified for compatibility. Electrical performance is equivalent.

Q: What is the operating temperature limitation for Panasonic ERZ-V20D121?

A: ERZ-V20D121 operates from -40°C to 85°C, compared to -40°C to 125°C for the original ROV20-121K. Applications requiring operation above 85°C should use MOV-20D121K (rated to 105°C) or verify thermal environment compatibility.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts (MOV-20D121K, MOV-20D121KTR, ERZ-V20D121, and VDRS20W075BSE) are ROHS3 compliant and REACH unaffected, matching the regulatory status of the original ROV20-121K.

Q: Which substitute part should be selected for new designs?

A: MOV-20D121K from Bourns Inc. is recommended for new designs. It provides direct electrical and mechanical equivalence, is an active product with extended temperature range (105°C), and offers the best long-term availability and supply chain stability.

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