The **CMK-R033** is a specific surface-mount (SMD) power resistor, typically part of the **CMK Series** manufactured by companies like **KOA Speer** or **Susumu**. It is designed for high-precision current sensing. --- ### 1. Part Number Breakdown The part number follows a standard convention in electronics: | Segment | Meaning | Detail | | :--- | :--- | :--- | | **CMK** | Series Name | Metal Plate Current Sense Resistor | | **R033** | Resistance Value | **0.033 Ohms** (or 33 milliohms) | ### 2. Technical Specifications The "R033" is not just a resistor; it is a specialized component used to measure current flow by monitoring the voltage drop across it ($V = I \times R$). | Feature | Typical Specification | | :--- | :--- | | **Resistance** | $33\text{ m}\Omega$ (0.033 $\Omega$) | | **Power Rating** | Generally 1W to 2W (depending on package size) | | **Tolerance** | $\pm1\%$ or $\pm5\%$ | | **Construction** | Metal Plate / Shunt | | **TCR** | Low Temperature Coefficient (e.g., $\pm50\text{ ppm/}^\circ\text{C}$) | --- ### 3. Key Characteristics * **Low Resistance:** Because it is used for sensing, the resistance is kept very low to minimize power loss ($P = I^2R$) and heat generation. * **High Stability:** These parts are made of special alloys (like Manganin or Ni-Cr) to ensure the resistance does not change significantly as the component heats up. * **Flame Retardancy:** The molded or metal plate construction is usually designed to be flameproof. ### 4. Common Applications The CMK-R033 is found in circuits where monitoring power consumption is critical: 1. **Battery Management Systems (BMS):** Measuring charge and discharge currents in laptops or EVs. 2. **DC-DC Converters:** Providing feedback for over-current protection. 3. **Motor Control:** Detecting the load on a motor to prevent stalling or burnout. 4. **Power Supplies:** Regulating output current. --- ### 5. Identification Example On a circuit board, this part usually looks like a small rectangular black or green block with "R033" printed on the top. ```text _________________ | | | R033 | <-- Marking for 0.033 Ohms |_________________| [Solder] [Solder] ```