The part number **MEX-F-03221-R** refers to a high-precision, automotive-grade **NTC (Negative Temperature Coefficient) Thermistor** sensor assembly, typically manufactured by **Mitsubishi Materials Corporation** (now part of the ScioSense or similar specialty sensor groups). These components are designed for harsh environments where accurate temperature measurement is critical. --- ### 1. Technical Specifications The "MEX" series is known for its durability and moisture resistance. Below are the typical characteristics associated with this specific part: | Characteristic | Description | | :--- | :--- | | **Type** | NTC Thermistor (Resistance decreases as temperature increases) | | **Series** | MEX (Moisture-resistant, resin-coated) | | **Resistance at 25°C** | 3.2 kΩ (standard for the 03221 series) | | **B-Constant** | Typically ~3900K - 4000K (defines the curve slope) | | **Tolerance** | ±1% to ±3% (depending on specific binning) | | **Operating Temp Range** | -40°C to +125°C (Automotive Standard) | | **Compliance** | RoHS Compliant, Lead-Free | --- ### 2. Physical Construction The MEX-F-03221-R is built to withstand mechanical stress and chemical exposure: 1. **Sensing Element:** A high-stability ceramic semiconductor chip. 2. **Coating:** Encapsulated in a special **epoxy resin** (F-type) that provides superior insulation and protection against humidity. 3. **Leads:** Usually features radial tinned copper leads, sometimes insulated with a flexible sleeve for chassis mounting. 4. **Suffix "-R":** Generally indicates **Reel** packaging or specific **RoHS** compliance certification. --- ### 3. Common Applications Due to its reliability and specific resistance value (3.2k), it is frequently found in: * **Automotive Systems:** Evaporator temperature sensing in HVAC systems to prevent icing. * **Industrial Controls:** Overheat protection in power supplies or motor drives. * **Home Appliances:** Temperature monitoring in refrigerators or air conditioning units. --- ### 4. Resistance-Temperature Relationship As an NTC device, the resistance follows an exponential decay. If you are troubleshooting this part, you can use the **Steinhart-Hart equation** or a simplified B-parameter formula: ```python # Simplified resistance calculation formula (Python) import math def calculate_resistance(temp_c, r25, b_const): temp_k = temp_c + 273.15 t25_k = 25 + 273.15 resistance = r25 * math.exp(b_const * (1/temp_k - 1/t25_k)) return resistance # Example for MEX-F-03221-R at 50°C # res = calculate_resistance(50, 3200, 3950) ``` ---