RUSB090 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RUSB090 is a polymeric PTC (Positive Temperature Coefficient) resettable fuse manufactured by Littelfuse Inc. under the PolySwitch® series. This component is rated for 16V maximum voltage with a 900 mA hold current and is designed for through-hole radial mounting in disc configuration.

The RUSB090 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements for systems utilizing this component.

Substiute Parts

RUSB090

Littelfuse Inc.In Stock: 857RUSB090 Datasheet

Current PartRFQ

RUSBF090

Littelfuse Inc.In Stock: 1434RUSBF090 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the RUSB090 is determined by strict equivalence across the following critical parameters:

• Voltage rating: 16V maximum
• Current hold specification: 900 mA
• Current trip specification: 1.8 A
• Time to trip: 1.2 s
• Resistance characteristics: Initial minimum 70 mOhms, post-trip maximum 180 mOhms
• Mounting configuration: Through-hole radial disc
• Lead spacing: 0.199" (5.05mm)
• Polymeric PTC type classification

The RUSBF090 meets all electrical and mechanical parameters required for direct substitution. Both components share identical voltage, current, resistance, and temporal specifications, as well as matching physical form factors and lead configurations.

Parameter Comparison

Engineering Selection Recommendations

The RUSBF090 is the direct substitute for the obsolete RUSB090. Both components are manufactured by Littelfuse Inc. and share identical electrical specifications and mechanical form factors.

The RUSBF090 offers the advantage of active product status, ensuring ongoing availability and supply chain support. The RUSBF090 also provides ROHS3 compliance, whereas the RUSB090 is RoHS non-compliant. Both components maintain equivalent regulatory approvals from CSA, TUV, and UL/UR agencies.

Physical dimensions are functionally equivalent between the two parts, with negligible tolerance variations (0.118" W versus 0.122" T) that do not affect PCB layout or mechanical fit in standard through-hole applications.

Frequently Asked Questions (FAQ)

Q: Can RUSBF090 be used as a direct replacement for RUSB090 in existing designs?

A: Yes. The RUSBF090 meets all electrical and mechanical specifications of the RUSB090, including voltage rating, current hold and trip values, resistance characteristics, and physical form factor. Lead spacing and mounting configuration are identical.

Q: What is the difference between RUSB090 and RUSBF090?

A: The primary differences are product status and regulatory compliance. RUSB090 is obsolete; RUSBF090 is active. RUSBF090 is ROHS3 compliant, while RUSB090 is RoHS non-compliant. Electrical performance and physical dimensions are equivalent.

Q: Are there any dimensional concerns when substituting RUSBF090 for RUSB090?

A: No. Both components use identical lead spacing (0.199" / 5.05mm) and seated height (0.480" / 12.20mm). Thickness specifications differ minimally (0.118" versus 0.122"), which does not impact PCB assembly or mechanical clearance in standard applications.

Q: What certifications apply to RUSBF090?

A: RUSBF090 holds approvals from CSA, TUV, and UL. It is ROHS3 compliant and REACH unaffected. ECCN classification is EAR99.

Q: Is operating temperature specified for both parts?

A: Operating temperature is not specified for RUSB090. RUSBF090 is rated for -40°C to 85°C operation. Both components are suitable for standard industrial and consumer electronics applications within this temperature range.