The **LOR3-R0075-D** is a high-precision, low-resistance current sense resistor. It belongs to the **LOR Series** (Low Ohmic Resistors), typically manufactured by companies like **LOHM** or similar precision component specialists. These resistors are designed for power management and current sensing applications where accuracy and heat dissipation are critical. --- ### 1. Part Number Breakdown Understanding the alphanumeric code helps identify its specific electrical characteristics: | Code Segment | Meaning | Value / Description | | :--- | :--- | :--- | | **LOR3** | Series/Power Rating | LOR Series, 3 Watts power rating | | **R0075** | Resistance Value | 0.0075 $\Omega$ (or 7.5 m$\Omega$) | | **D** | Tolerance | $\pm$ 0.5% | --- ### 2. Technical Specifications The following table outlines the typical performance parameters for this component: | Feature | Specification | | :--- | :--- | | **Resistance** | 7.5 m$\Omega$ | | **Power Rating** | 3 Watts (at 70°C) | | **Tolerance** | $\pm$ 0.5% (High Precision) | | **Temperature Coefficient (TCR)** | Typically $\pm$ 50ppm/°C to $\pm$ 100ppm/°C | | **Construction** | Metal Plate / Shunt Type | | **Operating Temperature** | -55°C to +170°C | --- ### 3. Key Electronic Functions The LOR3-R0075-D is primarily used for **Current Sensing** via Ohm's Law ($V = I \times R$). * **Low Ohmic Value:** At 7.5 m$\Omega$, it minimizes "Insertion Loss." This means it does not waste much power as heat, preserving the efficiency of the circuit. * **High Power Dissipation:** The 3W rating allows it to handle significant current. For example, at 3W, this resistor can theoretically handle a continuous current of approximately **20 Amperes**. * **Kelvin Connection Compatibility:** Often used in 4-terminal layouts to eliminate the resistance of the PCB traces from the measurement. --- ### 4. Common Applications * **Battery Management Systems (BMS):** Monitoring charge and discharge cycles in Lithium batteries. * **DC-DC Converters:** Providing feedback loops for current mode control. * **Motor Control:** Detecting over-current conditions to protect industrial motors. * **Power Supplies:** Precise regulation of output current in server or telecommunication equipment. --- ### 5. Footprint and Mounting These parts are usually **Surface Mount Devices (SMD)**. Because they deal with high currents, the "Land Pattern" (the copper pads on the PCB) must be large enough to act as a heatsink to prevent the component from desoldering itself under heavy loads.