ROV20-681K Equivalent & Substitute Parts

Part Overview

The ROV20-681K is a 680 V, 6.5 kA disc varistor manufactured by Littelfuse Inc., designed for transient voltage suppression in through-hole applications. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The part operates across a temperature range of -40°C to 125°C and is housed in a 20mm disc package. Substitutes must maintain electrical equivalence in varistor voltage, surge current rating, and energy absorption while accommodating minor mechanical variations in package dimensions.

Key Parameters

Parameter	Value
Varistor Voltage (Typical)	680 V
Varistor Voltage Range	612 V – 748 V
Current - Surge	6.5 kA
Maximum AC Volts	420 V
Maximum DC Volts	560 V
Energy	344 J
Operating Temperature	-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 for the ROV20-681K is determined by strict equivalence in the following electrical parameters: varistor voltage (680 V nominal with 612–748 V tolerance band), maximum AC/DC voltage ratings (420 V AC, 560 V DC), and circuit configuration (single circuit, through-hole mounting). The surge current rating and energy absorption capacity are secondary selection criteria; substitutes with equal or higher ratings are acceptable. Package dimensions may vary within the disc form factor (20mm, 22.50mm, or 23mm) provided mechanical fit is verified in the target application. All substitutes must maintain ROHS3 compliance and operate within the specified temperature range or a subset thereof.

Parameter Comparison

Parameter	ROV20-681K (Littelfuse)	ERZ-V20D681 (Panasonic)	VDRS20W420BSE (Vishay)
Varistor Voltage (Typ)	680 V	680 V	680 V
Varistor Voltage (Min)	612 V	612 V	612 V
Varistor Voltage (Max)	748 V	748 V	748 V
Maximum AC Volts	420 V	420 V	420 V
Maximum DC Volts	560 V	560 V	560 V
Current - Surge	6.5 kA	7.5 kA	6.5 kA
Energy	344 J	382 J	344 J
Number of Circuits	1	1	1
Operating Temperature	-40°C to 125°C	-40°C to 85°C	-40°C to 85°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	Disc 20mm	Disc 22.50mm	Disc 23mm
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

Both ERZ-V20D681 (Panasonic) and VDRS20W420BSE (Vishay) are active product substitutes for the obsolete ROV20-681K. Selection between these two options depends on application-specific constraints:

The ERZ-V20D681 offers a higher surge current rating (7.5 kA versus 6.5 kA) and greater energy absorption (382 J versus 344 J), providing additional transient protection margin. However, its maximum operating temperature is limited to 85°C, compared to the original part's 125°C rating. This substitute is suitable for applications where ambient temperature does not exceed 85°C and enhanced surge protection is beneficial.

The VDRS20W420BSE maintains the exact surge current (6.5 kA) and energy rating (344 J) of the original ROV20-681K, ensuring direct electrical equivalence. Its operating temperature maximum of 85°C matches the ERZ-V20D681. This substitute is appropriate for direct replacement in applications where the original electrical specifications are the primary requirement.

Both substitutes are ROHS3 compliant and available in active production. Package dimension differences (20mm original versus 22.50mm and 23mm substitutes) must be evaluated for mechanical fit within the target PCB layout and enclosure constraints.

Frequently Asked Questions (FAQ)

Q: Can ERZ-V20D681 and VDRS20W420BSE be used interchangeably with ROV20-681K?

A: Both parts meet the core electrical requirements: 680 V nominal varistor voltage, 420 V maximum AC, 560 V maximum DC, and single-circuit through-hole configuration. Mechanical fit must be verified due to package diameter variations (20mm, 22.50mm, and 23mm). Operating temperature limits differ; applications requiring operation above 85°C are incompatible with both substitutes.

Q: What is the significance of the surge current difference between ERZ-V20D681 (7.5 kA) and the original ROV20-681K (6.5 kA)?

A: The ERZ-V20D681 provides higher transient energy absorption capacity. This is not a limitation but an enhancement; a substitute with equal or higher surge rating remains electrically compatible and may offer improved protection margins in high-transient environments.

Q: Are there temperature limitations when substituting with ERZ-V20D681 or VDRS20W420BSE?

A: Yes. Both substitutes are rated to -40°C to 85°C, whereas the original ROV20-681K operates to 125°C. Applications requiring sustained operation above 85°C cannot use these substitutes without thermal management modifications or alternative component selection.

Q: How do package dimension differences affect substitution?

A: The original ROV20-681K uses a 20mm disc package; ERZ-V20D681 uses 22.50mm, and VDRS20W420BSE uses 23mm. These are mechanical variations only and do not affect electrical performance. PCB layout and enclosure clearance must accommodate the larger diameter. Verify mounting hole spacing and component density constraints before design implementation.

Q: Are all three parts RoHS compliant?

A: Yes. ROV20-681K, ERZ-V20D681, and VDRS20W420BSE are all ROHS3 compliant. REACH status is unaffected for all three parts.

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