CM2722 Datasheet | Steward

Overview A primary problem for the Firewire IEEE1394 and USB2.0 as with the USB1.1 port designer is mon mode noise conducted through the power and signal lines from various sources. EMI susceptibility on data/power lines is also a major concern. The use of a mon mode choke in this application will provide a plete low cost, effective, modular, filter solution. Steward’s CM2722 (for single and dual ports), CM3822 (for tri ports), and CM5022 (for quad ports) series of ponents have the lowest normal mode impedance in the industry and suppress a wide range of digital mon mode noise. Normal mode impedance is net circuit impedance i.e. the impedance seen by the differential signal. Discussion Firewire and USB2.0 is a serial data / power port providing a broad range of data and current loads. The initial USB industry specification called for a serial port which operates in a hybrid full duplex mode and a power port that operates up to 1 amp of current. This design has created several layers of EMI problems that must be corrected. Also, USB ponent performance requirements have been stretched beyond initial specifications which has caused field failures of 1 amp and even 3 amp rated ferrite chip beads. Firewire and USB2.0 have increased the expected design loading to a minimum of 4.0 amps to insure failure free operation. The source of most USB EMI problems is the two outside conductors in the connector for the power port. The primary problem is conducted mon mode noise on the power line and the best EMI solution is a mon mode choke. mon mode chokes have not traditionally been considered plete power and data line solutions because: 1. PROBLEM: Traditional mon mode choke geometry generates excessive normal mode impedance which causes failure in the transmission signal integrity due to excessive net differential impedance in line. This is exacerbated with Firewire and USB2.0 both of which are clocking at greater than 480 Mb/s, pared to USB1.1 which was operating @ 12Mb/s...