Hammond Manufacturing 621L Equivalent & Substitute Parts

Part Overview

The Hammond Manufacturing 621L is a 4.7 mH fixed unshielded wirewound inductor rated for 23 mA with 8.2 Ohm DC resistance and radial through-hole mounting. This component is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and production continuity. The 621L operates at a self-resonant frequency of 40 kHz with ±2% inductance tolerance.

Substiute Parts

621L

Hammond ManufacturingIn Stock: 1185621L Datasheet

Current PartRFQ

RL622-472K-RC

Bourns Inc.In Stock: 2769RL622-472K-RC Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 621L is determined by the following critical parameters:

• Inductance Value: Must be 4.7 mH to maintain circuit function
• Current Rating: Substitute must support the application's maximum current requirement; the 621L is rated for 23 mA
• DC Resistance: The 621L specifies 8.2 Ohm; substitutes with higher DCR will increase power dissipation
• Mounting Configuration: Through-hole radial mounting is required for mechanical compatibility
• Shielding: Unshielded construction matches the original specification
• Compliance: RoHS3 compliance ensures regulatory alignment

The Bourns RL622-472K-RC meets the core inductance requirement of 4.7 mH and maintains through-hole radial mounting. However, it exhibits higher current rating (50 mA), increased DC resistance (16 Ohm maximum), and wider inductance tolerance (±10%), which must be evaluated against application constraints.

Parameter Comparison

Engineering Selection Recommendations

The Bourns RL622-472K-RC is an active product with ROHS3 compliance, providing supply continuity for the obsolete Hammond 621L. Both components share identical inductance values and unshielded radial through-hole construction.

Selection of the RL622-472K-RC requires evaluation of the following differences:

• DC Resistance: The RL622-472K-RC exhibits 16 Ohm maximum DCR compared to the 621L's 8.2 Ohm, resulting in approximately double the resistive loss. Applications sensitive to power dissipation or operating efficiency must account for this increase.
• Inductance Tolerance: The RL622-472K-RC specifies ±10% tolerance versus the 621L's ±2%. Circuits requiring tight inductance control may require post-selection binning or circuit compensation.
• Current Rating: The RL622-472K-RC's 50 mA rating exceeds the 621L's 23 mA specification, providing margin for applications operating at or below the original current level.
• Physical Dimensions: The RL622-472K-RC measures 0.335" diameter by 0.433" height, differing from the 621L's 0.500" diameter by 0.290" height. PCB layout verification is required to confirm mechanical fit.

Frequently Asked Questions (FAQ)

Q: Can the Bourns RL622-472K-RC directly replace the Hammond 621L?

A: Direct replacement is possible if the application tolerates the increased DC resistance (16 Ohm vs. 8.2 Ohm) and wider inductance tolerance (±10% vs. ±2%). Physical dimensions differ, requiring PCB layout confirmation.

Q: What is the impact of the higher DC resistance in the RL622-472K-RC?

A: Higher DC resistance increases power dissipation in the inductor. For a 23 mA circuit, the 621L dissipates approximately 4.3 mW, while the RL622-472K-RC dissipates approximately 8.5 mW. Thermal performance and circuit efficiency must be reassessed.

Q: Are both components RoHS3 compliant?

A: Yes, both the Hammond 621L and Bourns RL622-472K-RC are ROHS3 compliant, meeting regulatory requirements for hazardous substance restrictions.

Q: Does the wider inductance tolerance of the RL622-472K-RC affect circuit performance?

A: The ±10% tolerance of the RL622-472K-RC compared to the ±2% of the 621L may impact circuits with tight frequency or impedance specifications. Circuit simulation or testing is necessary to determine acceptability for specific applications.

Q: What are the physical mounting differences?

A: The RL622-472K-RC is specified as a vertical cylinder package with smaller diameter (0.335" vs. 0.500") but greater height (0.433" vs. 0.290"). PCB footprint and clearance verification is required before implementation.