The MF72 series 3D-7 is a directly heated power negative temperature coefficient thermistor designed for high-precision inrush current suppression in electronic devices. This device provides a rated zero-power resistance of 3Ω±20% at circuit startup, tested at 1.5VDC at 25°C, effectively limiting capacitor charging current. Through self-heating, the resistance rapidly decreases to a residual resistance of 0.28Ω, ensuring steady-state low-power operation.
The material constant B value is 2600K±10%, ensuring stable response over the -40°C to +150°C operating temperature range. 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 excellent surge current resistance and supporting loads such as 100μF capacitors in 240V systems or 390μF capacitors in 120V systems.
This device has passed IEC68-2-20/21 mechanical strength certification, meeting 1000-hour load life testing and 93% RH humidity resistance testing requirements. It is suitable for demanding applications such as switching power supplies, UPS systems, inverters, electronic ballasts, and industrial heaters.
The MF72 series 3D-7 features a compact 9mm diameter and 5mm thickness design, a phenolic resin package, and CP wire leads. It is compatible with four mounting configurations: inward-curved, outward-curved, side-curved, and straight-leg.