The MF72 series 12D-7 is a directly heated power negative temperature coefficient thermistor designed specifically for high-impedance surge current suppression. It provides a rated zero-power resistance of 12Ω ± 20% at startup, tested at 1.5VDC at 25°C, effectively limiting the charging current of large filter capacitors. Through self-heating, the resistance value steadily decreases to 0.82Ω residual resistance, optimizing the balance between startup protection and steady-state efficiency.
The material constant B value reaches 2700K ± 10%, ensuring consistent temperature response over a wide temperature range of -40°C to +150°C. Regarding thermal characteristics, the product of a thermal time constant of approximately 30 seconds and a dissipation factor of approximately 9mW/°C equals 270mJ/°C, providing reliable surge protection and supporting loads of 82μF capacitors in 240V systems or 330μF capacitors in 120V systems.
This device has passed IEC68-2-20/21 mechanical strength certification, meeting 1000-hour 1A load life test and 93% RH humidity resistance verification. It is suitable for applications such as high-impedance power modules, precision instrument power supply systems, industrial sensors, and outdoor security equipment, ensuring the long-term reliability of electronic systems under sudden load fluctuations.
The compact 9mm diameter x 5mm thick package utilizes phenolic resin and CP wire leads, and is compatible with four industry-standard lead configurations: inward-curved, outward-curved, side-curved, and straight-curved.