Specifications

98 Intel
®
Atom™ processor CE4100 Ref# 420826
Platform Design Guide
Intel Confidential
8.2.1.3 USB Power Sequence
With more and more USB devices used for different purposes, there is a potential issue that
a USB device might not be detected during power cycles. Intel recommends adding a delay
circuit or designing the power sequence circuit in the USB power interface to prevent this
issue.
On the development platform, the PIC (external microcontroller) is used to control the
PIC_USB_EN# signals, which are used to enable 5V VBUS_USB power rails on USB
connectors. The design is to make sure the USB controller core power is ready before the
USB devices connected to USB port are active.
Figure 8-8. Design Example