The MF72 series 5D-5 is a directly heated, power-type negative temperature coefficient thermistor specifically designed for suppressing startup inrush current in electronic devices. Upon power-up, the device provides a high initial resistance to limit capacitor charging current. Self-heating then rapidly reduces the resistance to a residual resistance of 0.35Ω, ensuring steady-state, low-power operation.
The device's rated zero-power resistance is 5Ω ±20%, tested at 1.5VDC at 25°C. The material constant B value reaches 2700K ±10%, ensuring stable temperature response. A thermal time constant of approximately 20 seconds and a dissipation factor of approximately 6mW/°C, multiplied by 120mJ/°C, provide excellent surge protection. A maximum steady-state current of 1A supports a 150μF capacitive load in a 240V system or a 560μF load in a 120V system.
The compact 7mm diameter and 5mm thickness design, combined with low residual resistance, extend device life and simplify circuit protection. With an operating temperature range of -40°C to +150°C, it's suitable for high-reliability applications such as switching power supplies, UPS systems, electronic ballasts, and lighting equipment.
The MF72 series 5D-5 utilizes a phenolic resin package and CP wire leads. It's available in four configurations: inward-curved, outward-curved, side-curved, and straight-lead.