NTC and PTC Inrush Current Limiting Thermistors

March 16, 2017 by Power Pulse1595211359

Ametherm announced its product lineup for the Applied Power Electronics Conference and Exposition (APEC) 2017, taking place March 26-30 in Tampa, Florida. In booth 1426, the company will be showcasing a wide range of its leading NTC and PTC inrush current limiting thermistors for reliable circuit protection in high-power, high-voltage applications.

Highlighted Ametherm inrush current limiters at APEC 2017 will include the company's MS35 series of NTC thermistors for applications such as solar inverters, battery chargers, and dc-dc converters. Designed to withstand high input energy from 500J to 900J and steady-state currents from 10A to 50A, the devices offer resistance from 0.5Ω to 20Ω and thermal time constants from 65 to 240 seconds. Featuring diameters of 37mm and 38mm and thickness down to 6.50mm, the thermistors handle the same amount of energy as power resistors in a smaller package, saving valuable circuit board space.

PTC circuit protection thermistors on display will include the ceramic CL20 series for pre-charge circuits, degaussing circuits, and heater applications. The devices deliver voltage ratings up to 750V and maximum energy ratings to 700J while offering four resistance values at 25 degrees C values from 7.0Ω to 100Ω to accommodate a variety of pre-charge times. These resistance values remain unchanged over the typical operating temperature range of -40 to +110 degrees C. Providing high reliability and stability in high-voltage applications, CL20 series thermistors can withstand hundreds of hits of maximum inrush current without degrading.

Ametherm will also highlight its MCL20 500100-A PTC circuit protection thermistor for applications such as welding equipment and plasma cutters with extremely high voltages from 480V to 930V. The device features a 680V voltage rating, handles a maximum inrush current of 20A at maximum peak voltage, and offers resistance at 25 degrees C of 50Ω. With a 19-mm diameter, 9-mm maximum profile, and 7.8-mm lead spacing, the MCL20 500100-A provides designers with a more compact and cost-effective alternative to combining a power resistor, relay, and timer on one circuit to achieve the same functionality.