Equivalent & Substitute Parts for 20LR450U

Part Overview

The 20LR450U is a polymeric PTC resettable fuse from Littelfuse's POLY-FUSE® LR series, rated for 20V maximum voltage with a 4.5A hold current. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing system support and component procurement. The part is designed for applications requiring automatic overcurrent protection with resettable functionality in strap mounting configurations.

Substiute Parts

20LR450U

LittelfuseIn Stock: 111220LR450U Datasheet

Current PartRFQ

MF-LR450

Bourns Inc.In Stock: 2156MF-LR450 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 20LR450U is determined by the following critical parameters:

• Voltage Rating: The substitute must support the maximum voltage requirement of 20V or higher
• Current - Hold (Ih): Must match or exceed 4.5A to maintain equivalent protection characteristics
• Current - Trip (It): Must match 8.9A for consistent overcurrent response
• Resistance Characteristics: Initial and post-trip resistance values must remain within specified ranges
• Operating Temperature Range: Must support -40°C to 85°C operation
• Package Type: Must be strap mounting configuration
• Physical Dimensions: Must be compatible with 25.00mm x 10.20mm footprint
• Regulatory Compliance: Must maintain cURus and TUV certifications with ROHS3 compliance

The MF-LR450 from Bourns Inc. is identified as a substitute part. However, the MF-LR450 is rated for 16V maximum voltage, which is below the 20V requirement of the 20LR450U. This voltage differential represents a critical parameter mismatch and must be evaluated against specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

The 20LR450U is obsolete, and the MF-LR450 is the identified substitute from Bourns Inc. with active product status. Both parts maintain identical regulatory certifications (cURus, TUV) and ROHS3 compliance. Physical dimensions are compatible within tolerance (25.00mm x 10.20mm versus 25.00mm x 10.21mm).

The primary distinction between these parts is the maximum voltage rating: 20V for the 20LR450U versus 16V for the MF-LR450. All other electrical parameters—hold current, trip current, resistance characteristics, and time to trip—are identical. The MF-LR450 is available in active inventory status, whereas the 20LR450U is obsolete.

Frequently Asked Questions (FAQ)

Q: Can the MF-LR450 directly replace the 20LR450U in all applications?

A: The MF-LR450 matches all electrical parameters except maximum voltage rating. The MF-LR450 is rated for 16V maximum, while the 20LR450U is rated for 20V. Substitution is valid only for applications operating at or below 16V.

Q: Are the physical dimensions compatible?

A: Yes. Both parts use strap mounting with dimensions of 25.00mm x 10.20mm (20LR450U) and 25.00mm x 10.21mm (MF-LR450), representing a negligible difference suitable for standard PCB layouts.

Q: Do both parts maintain the same regulatory certifications?

A: Yes. Both the 20LR450U and MF-LR450 carry cURus and TUV approvals and are ROHS3 compliant.

Q: What is the significance of the obsolete status of the 20LR450U?

A: Obsolete status indicates the part is no longer manufactured by Littelfuse. The MF-LR450 from Bourns Inc. is the active substitute with current manufacturing and inventory availability.

Q: Are the hold current and trip current values identical?

A: Yes. Both parts specify 4.5A hold current (Ih) and 8.9A trip current (It), ensuring equivalent overcurrent protection response characteristics.