The **LRMAP3920B-R001** is a high-power, low-resistance shunt resistor manufactured by **Welwyn (TT Electronics)**. It is specifically designed for current sensing applications where high precision and thermal stability are required. ### 1. Key Technical Specifications The following table outlines the core electrical and physical parameters of the component: | Parameter | Specification | | :--- | :--- | | **Resistance Value** | 0.001 $\Omega$ (1 m$\Omega$) | | **Power Rating** | Up to 5W (standard) / 10W (on specific thermal substrates) | | **Tolerance** | $\pm$ 1% | | **Temperature Coefficient (TCR)** | $\pm$ 50 ppm/°C | | **Package Size** | 3920 (Inch) / 10050 (Metric) | | **Construction** | Metal Alloy Element | | **Inductance** | < 3 nH | --- ### 2. Functional Characteristics #### High Power Dissipation The 3920 package is significantly larger than standard surface-mount resistors. This allows the part to dissipate heat effectively. When mounted on a PCB with large copper pads, it can handle up to **10 Watts**, making it ideal for power electronics. #### Kelvin (4-Terminal) Connection Capability While the physical part has two large terminals, the layout on the PCB is often designed using "Kelvin sensing" principles. This ensures that the voltage drop measured across the resistor is not affected by the resistance of the solder joints or the PCB traces. #### Low Thermal EMF The metal alloy construction minimizes the "Seebeck effect," where temperature gradients across different metals create parasitic voltages. This ensures that the current measurement remains accurate even as the component heats up. --- ### 3. Common Applications * **Battery Management Systems (BMS):** Monitoring charge and discharge cycles in Electric Vehicles (EVs) or large battery banks. * **Motor Control:** Sensing phase currents in industrial motor drives to prevent over-current conditions. * **Power Supplies:** Used in DC-DC converters and high-capacity switching power supplies. * **Inverters:** Essential for solar power and UPS systems to monitor AC output current. --- ### 4. Part Number Breakdown | Segment | Meaning | | :--- | :--- | | **LRMAP** | Low Resistance Metal Alloy Power | | **3920** | Physical dimensions (0.39 x 0.20 inches) | | **B** | Standard electron beam welded construction | | **R001** | Resistance value (R001 = 0.001 Ohms) |