In addition to limiting the total average power used by the device, the USB specification limits the inrush current (i.e., that used to charge decoupling and filter capacitors) when the device is first connected. Otherwise, connecting a device could cause problems with the host's internal power. USB devices are also required to automatically enter ultra low-power suspend mode when the USB host is suspended. Nevertheless, many USB host interfaces do not cut off the power supply to USB devices when they are suspended. COUNT 4
QSN1 What does the USB specification limit? ANS1 the inrush current QSN2 When is the inrush current affected by the USB specification? ANS2 when the device is first connected QSN3 What are USB devices required to enter? ANS3 ultra low-power suspend mode when the USB host is suspended QSN4 Many USB host interfaces do not what? ANS4 cut off the power supply to USB devices when they are suspended