EPCOS ferrite disk selected for power receiver design

The EPCOS ferrite disk is a key component in the reference design supporting the LTC4120-based receiver. For this wireless power charging application, Linear Technology is using the ferrite like a lens to focus the magnetic flux into the receiver coil, instead of using it as a core. As a result the EPCOS ferrite disk acts as a flux collector so that the flux goes through the coil instead of out into space.

Based on the diameter of the receiver coil and the receive power design target, engineers at Linear Technology selected the new EPCOS ferrite disk, which offered the required diameter and power loss. “We needed certain characteristics from the ferrite material in order to collect the flux properly,” explains Brian Shaffer, Applications Manager at Linear Technology. “The EPCOS ferrite material makes a big difference. It is a unique application that promises to become prevalent now that wireless power technology is taking off.” Linear Technology has worked with TDK for many years. “Our working relationship is excellent,” said Shaffer. “We use TDK and EPCOS components in many of our products, and we appreciate the quality of the parts.”

The LTC4120 combines a wireless power receiver with a constant current and voltage battery charger. The wireless power module functions as the receive circuit component in a complete wireless power transmission system composed of Tx and Rx circuitry and coils. The wireless power module based on Linear Technology’s LTC4120 can be used for handheld devices, industrial and other sensors and applications, portable medical devices, and other small devices.

“We developed this ferrite disk for Linear Technology’s reference design,” said Chris Spadafora, Marketing Manager for EPCOS Ferrite Products, “and it is now available throughout the industry.” TDK offers a wide range of ferrite products in many shapes and sizes, including disks and plates.