The term **621-R** is frequently associated with specific electronic components, most notably high-precision resistors (specifically the 0.62 ohm value) or specific parts within the **TE Connectivity / Holsworthy** series or **Littelfuse** product lines. Below is a breakdown of the most common electronic parts identified by this designation. --- ### 1. High-Precision Resistors (RL73 Series) The most common reference for "621-R" in electronics is a **Low Ohmic Current Sense Resistor**. | Feature | Specification | | :--- | :--- | | **Common Value** | 0.62 Ohms (often marked as R62 or 621 on surface mount codes) | | **Type** | Thick Film or Metal Strip | | **Tolerance** | Usually ±1% or ±5% | | **Application** | Current sensing, power management, and feedback loops | ### 2. Littelfuse 621 Series (Fuses) In the context of circuit protection, the **621 series** refers to specialized high-voltage fuses. * **Type:** 5x20mm Glass or Ceramic Body. * **Voltage Rating:** Often rated up to 600V AC. * **Purpose:** Designed for high-energy applications where standard 250V fuses would fail. * **"R" Suffix:** Often denotes "RoHS Compliant" or a specific reel packaging. --- ### 3. Technical Identification Table If you are looking at a component labeled "621-R," it likely falls into one of these categories: | Component Category | Description | Common Use Case | | :--- | :--- | :--- | | **Resistor** | 620 Ohm (62 x 10^1) or 0.62 Ohm | Signal conditioning or current limiting. | | **Inductor** | 620 µH Inductor | Filtering in power supplies or RF circuits. | | **Fuse** | 621-R Series Protection | Heavy-duty industrial equipment protection. | | **Connector** | Circular or Modular Connectors | Specialized aerospace or industrial interfaces. | --- ### 4. Code Breakdown for SMD Resistors If "621" is printed on a small black surface-mount chip (SMD): ```text 621 = 62 (Significant Digits) + 1 (Multiplier: 10^1) 62 * 10 = 620 Ohms ``` *Note: If the R is placed between digits (e.g., 6R21), it signifies a decimal point (6.21 Ohms).* ---