The **P-A35-R** refers to a specific series of **NTC (Negative Temperature Coefficient) Thermistors**, commonly produced by manufacturers like Thinking Electronic. These components are thermal resistors whose resistance value decreases as the temperature increases. Below is a breakdown of the electronic specifications and characteristics of this component. --- ### 1. Technical Specifications The "P-A35-R" designation usually belongs to the **Power NTC** category, designed specifically for inrush current limiting. | Parameter | Typical Value / Description | |:---|:---| | **Type** | NTC Thermistor (Negative Temperature Coefficient) | | **Material** | Metal Oxide Ceramic | | **Coating** | Silicone or Phenolic Resin (usually green or black) | | **Resistance at 25°C ($R_{25}$)** | Varies by sub-model (commonly 5Ω to 50Ω) | | **Max Steady State Current** | Up to 4.0A - 7.0A (depending on body size) | | **Operating Temperature** | -40°C to +200°C | | **Lead Style** | Radial Leaded (Through-hole) | --- ### 2. Key Functions The P-A35-R is primarily used as an **Inrush Current Limiter (ICL)**. * **Cold State (High Resistance):** When the device is first turned on, the thermistor is cold and has a high resistance. This prevents a massive "surge" of electricity from damaging sensitive components like bridge rectifiers or filter capacitors. * **Hot State (Low Resistance):** As current flows through it, the part heats up due to Joule heating ($P = I^2R$). This causes its resistance to drop significantly, allowing the circuit to operate efficiently with minimal power loss. --- ### 3. Application Areas These parts are found in the input stage of power electronics: 1. **Switching Mode Power Supplies (SMPS):** To protect the input filter capacitors. 2. **Electric Motors:** To soften the start-up current of AC motors. 3. **LED Drivers:** Preventing fuse-blow during initial power-up. 4. **Transformers:** Reducing the magnetic inrush current. --- ### 4. Part Number Breakdown (Typical) While naming conventions vary slightly by manufacturer, the code generally follows this logic: | Segment | Meaning | |:---:|:---| | **P** | Power Type Thermistor | | **A** | Series / Shape designation (often Disk shape) | | **35** | Diameter of the disk (e.g., 3.5mm or a size code) | | **R** | RoHS Compliant / Radial Lead configuration | --- ### 5. Circuit Symbol In a schematic, it is represented as a resistor with a diagonal line and often a '-t°' or 'NTC' label: ```text ---[ NTC ]--- ```