45F20R Equivalent & Substitute Parts Reference

Part Overview

The Ohmite 45F20R is a 20 Ohm ±1% 5W axial wirewound through-hole resistor from the Ohmicone® 40 series. This component is classified as Active and remains in production. Equivalent and substitute parts are identified when design requirements permit tolerance of minor variations in physical dimensions, temperature coefficients, or compliance certifications while maintaining core electrical performance specifications.

Substiute Parts

45F20R

OhmiteIn Stock: 99645F20R Datasheet

Current PartRFQ

45F20RE

OhmiteIn Stock: 88945F20RE Datasheet

DirectRFQ

ALSR0520R00FE12

Vishay DaleIn Stock: 1417ALSR0520R00FE12 Datasheet

DirectRFQ

RS00520R00FS73

Vishay DaleIn Stock: 1469RS00520R00FS73 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 45F20R is determined by the following core electrical and mechanical parameters:

• Resistance value: 20 Ohms (exact match required)
• Tolerance: ±1% (exact match required)
• Power rating: 5W (exact match required)
• Composition: Wirewound (exact match required)
• Package: Axial through-hole (exact match required)
• Termination count: 2 (exact match required)

Parts meeting these criteria are classified as direct substitutes. Variations in temperature coefficient, physical dimensions within acceptable assembly tolerances, operating temperature range, and compliance certifications do not preclude substitution when the core electrical specifications are identical.

Parameter Comparison

Engineering Selection Recommendations

All four parts—45F20R, 45F20RE, ALSR0520R00FE12, and RS00520R00FS73—meet the core electrical specifications for direct substitution: 20 Ohms ±1% at 5W with wirewound axial construction.

Selection between these parts should be based on:

• RoHS compliance requirements: 45F20RE and ALSR0520R00FE12 are RoHS compliant; 45F20R and RS00520R00FS73 are not.
• Operating temperature range: 45F20RE supports -55°C to 275°C; ALSR0520R00FE12 and RS00520R00FS73 support -65°C to 250°C.
• Temperature coefficient stability: 45F20R, 45F20RE, and RS00520R00FS73 specify ±20ppm/°C; ALSR0520R00FE12 specifies ±30ppm/°C.
• Physical dimensions: 45F20R and 45F20RE are 0.343" diameter; ALSR0520R00FE12 and RS00520R00FS73 are 0.312" diameter. Smaller dimensions may be advantageous in space-constrained layouts.
• Packaging format: 45F20RE is supplied in Bulk; ALSR0520R00FE12 is supplied in Bulk; RS00520R00FS73 is supplied in Cut Tape.

Frequently Asked Questions (FAQ)

Q: Can ALSR0520R00FE12 replace 45F20R in all applications?

A: ALSR0520R00FE12 meets all core electrical specifications (20 Ohms ±1% at 5W wirewound axial). Physical dimensions differ slightly (0.312" vs 0.343" diameter), which may affect board layout. Temperature coefficient is ±30ppm/°C versus ±20ppm/°C for the 45F20R. Operating temperature range is -65°C to 250°C versus unspecified for the 45F20R. Substitution is valid when these variations are acceptable to the design.

Q: What is the difference between 45F20R and 45F20RE?

A: Both are Ohmite 20 Ohm ±1% 5W axial wirewound resistors with identical electrical specifications and physical dimensions. The primary difference is RoHS compliance: 45F20RE is RoHS Compliant, while 45F20R is RoHS non-compliant. 45F20RE also specifies an operating temperature range of -55°C to 275°C.

Q: Are the Vishay Dale parts (ALSR0520R00FE12 and RS00520R00FS73) interchangeable?

A: Both Vishay Dale parts meet the core electrical specifications. ALSR0520R00FE12 is ROHS3 Compliant and supplied in Bulk; RS00520R00FS73 is RoHS non-compliant and supplied in Cut Tape. Temperature coefficient is ±30ppm/°C for ALSR0520R00FE12 and ±20ppm/°C for RS00520R00FS73. Physical dimensions are identical for both. Selection depends on compliance requirements and packaging format.

Q: Do physical dimension differences affect PCB assembly?

A: The Ohmite parts (45F20R and 45F20RE) are 0.343" diameter; the Vishay Dale parts (ALSR0520R00FE12 and RS00520R00FS73) are 0.312" diameter. Smaller diameter components may fit more easily in space-constrained designs. Verify that your PCB layout and mechanical clearances accommodate the selected part's dimensions.

Q: Which substitute part has the best compliance certifications?

A: ALSR0520R00FE12 carries ROHS3 Compliant status. 45F20RE is RoHS Compliant. Both meet modern compliance requirements. 45F20R and RS00520R00FS73 are RoHS non-compliant and should be selected only when compliance restrictions do not apply.