USB2227-NU-11

The USB2227 is a Bus-powered USB2.0 Flash Media Card Readers are enjoying an explosive growth due to the increasing popularity of digital photography and portable music players. The basic card formats now stand at four types, but all of these require the careful implementation of their power control. Historically, this is provided via discrete power FETs which are external to the card reader controller, and requires careful design and component selection to avoid several possible system issues. This paper addresses some of those issues. In addition, fourth generation controllers, such as SMSC’s USB2227 devices, integrate some of the power FETs internally to the controller itself, to further save system cost. The design of these integrated FETs must account for these issues also in order to obtain successful operation.