The **S-10-R** typically refers to a specific series of **NTC (Negative Temperature Coefficient) Thermistors**, often manufactured by companies like SEMITEC or used as inrush current limiters in power supplies. Below is a detailed breakdown of the electronic characteristics and specifications of this component. --- ### 1. Component Overview An NTC thermistor is a variable resistor whose resistance decreases as its temperature increases. The "S" designation usually implies a power-type thermistor designed to handle high current surges during the initial power-on phase of a device. ### 2. Technical Specifications The "10-R" part of the model number typically indicates the **Resistance at 25°C**. | Parameter | Typical Value | Description | | :--- | :--- | :--- | | **Resistance (R25)** | 10 $\Omega$ | Resistance value at ambient room temperature (25°C). | | **Tolerance** | ±15% to ±20% | The allowable deviation from the nominal resistance. | | **Max. Steady State Current** | 2.0A - 3.0A | The maximum continuous current the part can handle. | | **Thermal Dissipation Constant** | ~11 mW/°C | Heat required to raise the part's temperature by 1°C. | | **Operating Temperature** | -40°C to +160°C | The functional range of the component. | --- ### 3. How It Works (Inrush Current Limiting) The S-10-R is primarily used to protect sensitive electronics from "Inrush Current." 1. **Cold State (Power On):** When the device is first turned on, the S-10-R is at room temperature. Its resistance is high (10 ohms). This limits the initial surge of electricity. 2. **Heating Up:** As current flows through the thermistor, it generates heat (Joule heating). 3. **Hot State (Steady Operation):** As it gets hot, its resistance drops significantly (often to less than 1 ohm). This allows the circuit to operate efficiently with minimal power loss across the thermistor. ### 4. Common Applications * **Switching Power Supplies (SMPS):** Protecting bridge rectifiers and filter capacitors. * **LED Drivers:** Preventing sparks or fuse blows during startup. * **Motor Starters:** Smoothing the initial torque and current draw. * **CRT Monitors/TVs:** Deperming circuits (older technology). ### 5. Circuit Symbol and Package In a schematic, the S-10-R is represented as a resistor with a diagonal line and a `-t` or `NTC` label. ```text Standard NTC Symbol _ _ -----|_|/_----- / -t ``` --- **Safety Note:** Because these components function by getting hot, they should be placed away from heat-sensitive components (like electrolytic capacitors) on a PCB.