In Pulse's shielded drum core inductor, an additional ferrite cylinder is located around the outside of the two discs which guides the flux between the discs through the cylinder. The discrete air gap is the combination of the gaps between each end disc and the ferrite cylinder. Because the additional ferrite cylinder keeps the flux in a controlled path, shielded drum-core inductors are better for applications where the stray flux of the unshielded drum core may interfere with nearby noise-sensitive electronics or where electromagnetic interference (EMI) is a concern. The shielded drum-core inductor has a higher inductance for the same number of wire turns than the unshielded inductor due to the smaller air gap and higher permeability of the ferrite cylinder.
Applications that use drum core inductors include:
- Catalog power modules
- Computer equipment - notebook computers, hard disk drives, video graphic cards, small printers
- Telecom equipment - modems, mobile phones, set-top-boxes
- Consumer electronics - game stations, digital cameras, PDAs, LCD displays and TVs, CD players