RUSBF155-2 Equivalent & Substitute Parts

Part Overview

The RUSBF155-2 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 6V maximum voltage with a 1.55 A hold current. This component provides overcurrent protection in electronic circuits through automatic thermal reset capability. The part is currently in active production status with 3703 units in stock. Substitute parts are identified when equivalent electrical performance and mechanical compatibility can be maintained across the specified parameter range.

Key Parameters

Parameter	Value	Unit
Voltage - Max	6	V
Current - Hold (Ih) (Max)	1.55	A
Current - Trip (It)	2.65	A
Current - Max	40	A
Time to Trip	2.2	s
Resistance - Initial (Ri) (Min)	40	mOhms
Resistance - Post Trip (R1) (Max)	100	mOhms
Operating Temperature	-40 to 85	°C
Mounting Type	Through Hole	-
Package / Case	Radial, Disc	-
Lead Spacing	0.200	inches (5.08 mm)
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution eligibility for the RUSBF155-2 is determined by strict equivalence across the following critical parameters:

Voltage rating: 6V maximum
Current hold specification: 1.55 A maximum
Current trip specification: within acceptable tolerance (2.65 A nominal)
Mounting configuration: Through Hole, Radial, Disc package
Lead spacing: 0.200 inches (5.08 mm) nominal
Operating temperature range: -40°C to 85°C
RoHS3 compliance status

The substitute part 06R155BPR meets these criteria with minor variations in current trip (2.7 A vs. 2.65 A) and physical dimensions that remain within mechanical compatibility tolerances for the radial disc package format.

Parameter Comparison

Parameter	RUSBF155-2	06R155BPR	Match Status
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Identical
Voltage - Max	6 V	6 V	Identical
Current - Hold (Ih) (Max)	1.55 A	1.55 A	Identical
Current - Trip (It)	2.65 A	2.7 A	Equivalent
Current - Max	40 A	40 A	Identical
Time to Trip	2.2 s	2.2 s	Identical
Resistance - Initial (Ri) (Min)	40 mOhms	40 mOhms	Identical
Resistance - Post Trip (R1) (Max)	100 mOhms	100 mOhms	Identical
Operating Temperature	-40 to 85°C	-40 to 85°C	Identical
Mounting Type	Through Hole	Through Hole	Identical
Package / Case	Radial, Disc	Radial, Disc	Identical
Lead Spacing	0.200" (5.08 mm)	0.201" (5.10 mm)	Equivalent
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Identical
Product Status	Active	Active	Identical
Approval Agency	CSA, TUV, UL	cURus, TUV	Overlapping

Engineering Selection Recommendations

Both RUSBF155-2 and 06R155BPR are active production components from Littelfuse Inc. with ROHS3 compliance. The RUSBF155-2 carries CSA, TUV, and UL approvals, while 06R155BPR carries cURus and TUV approvals. Selection between these parts should be based on specific regulatory requirements for the end application. The 06R155BPR includes REACH Unaffected status and defined moisture sensitivity level (MSL 1 - Unlimited), providing additional compliance documentation. Both parts are electrically equivalent within the specified parameter tolerances and mechanically compatible for through-hole radial disc mounting.

Frequently Asked Questions (FAQ)

Q: Can 06R155BPR be used as a direct replacement for RUSBF155-2?

A: Yes. Both parts are polymeric PTC resettable fuses with identical voltage, hold current, maximum current, trip time, and resistance specifications. Lead spacing differs by 0.01 inches (0.02 mm), which is within mechanical tolerance for radial disc package mounting. Electrical performance is equivalent.

Q: What is the difference in current trip specification between these parts?

A: RUSBF155-2 specifies 2.65 A trip current, while 06R155BPR specifies 2.7 A. This 0.05 A difference represents approximately 1.9% variance and falls within normal manufacturing tolerance for polymeric PTC fuses in this category.

Q: Are there differences in regulatory approvals?

A: RUSBF155-2 carries CSA, TUV, and UL approvals. 06R155BPR carries cURus and TUV approvals. Applications requiring specific regulatory certification should verify approval alignment with end-use requirements.

Q: Do these parts have different moisture sensitivity levels?

A: RUSBF155-2 lists MSL as Not Applicable. 06R155BPR specifies MSL 1 (Unlimited). This difference does not affect electrical or mechanical compatibility but may impact storage and handling procedures depending on application requirements.

Q: Are both parts currently available?

A: Yes. RUSBF155-2 has 3703 units in stock. 06R155BPR has 2764 units in stock. Both are active production components.

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