RM cores were designed for use in high Q, high stability fi lter inductors.
Their shape allows economic utilization of surface area on the PCB. The range is standardized in IEC 431 and is available worldwide from many suppliers. The sizes are based on the standard PCB grid distance. RM 5, for instance, fi ts on a board space of 5 x 5 modules of 2.5 mm grid. Coil formers and clips were optimized for automated winding and mounting.
The slots provide suffi cient space for leads of windings. Magnetic shielding is not as good as with P-cores, but still
effective.
