The code **L4-R39-10** typically refers to a specific configuration of an **NTC (Negative Temperature Coefficient) Thermistor**, a component whose resistance decreases as the temperature increases. Below is a detailed breakdown of the electronic specifications, naming convention, and common applications for this part. --- ### 1. Specification Breakdown The alphanumeric string follows a standard industry format for power NTC thermistors (often manufactured by brands like Shibaura or similar electronic component firms). | Segment | Meaning | Detail | | :--- | :--- | :--- | | **L4** | Series/Body Style | Often denotes a leaded disc-type thermistor with a specific physical size (approx. 4mm-5mm diameter). | | **R39** | Resistance Value | The resistance at 25°C ($R_{25}$). "39" typically indicates **3.9k Ohms** or **39 Ohms** depending on the manufacturer's multiplier. | | **10** | Tolerance | Indicates a **±10%** tolerance in the resistance value. | --- ### 2. Technical Characteristics As an NTC thermistor, the L4-R39-10 possesses the following electronic traits: * **Sensitivity:** High sensitivity to temperature changes, making it ideal for sensing or circuit protection. * **B-Value:** This component will have a specific "B-constant" (usually between 3000K and 4500K) which defines the slope of the resistance-temperature curve. * **Thermal Time Constant:** Because of its small size (L4), it has a fast response time to environmental temperature shifts. * **Dissipation Constant:** The amount of power required to raise the component's temperature by 1°C. --- ### 3. Common Applications These parts are widely used in consumer electronics and industrial power supplies for: 1. **Temperature Sensing:** Monitoring the heat of CPUs, battery packs, or power transistors. 2. **Temperature Compensation:** Offsetting the temperature-induced drift of other components (like crystal oscillators or LCDs). 3. **Inrush Current Limiting:** If used in the power input stage, it limits the initial surge of current when a device is turned on. --- ### 4. Circuit Symbol and Implementation In a schematic, it is represented by a resistor symbol with a diagonal line and a "$-t^\circ$" or "NTC" label. ```spice * Typical Voltage Divider usage VCC ---- [ R1 ] ----+---- [ NTC L4-R39-10 ] ---- GND | ADC Input (MCU) ``` *As the temperature rises, the NTC resistance drops, lowering the voltage at the ADC input pin.*