Difference between USB host & device when connected to the Intel PCH chipset
[W]hat is the difference between USB host &amp; device when they are connected to the Intel PCH chipset?


The USB host is like the "master": it initiates all communications on the bus and manages all transactions. The host can communicate with all devices.

A USB device is like a "slave": it only responds when initiated by the host. A device can only communicate with the host controller.

In your application, the host is going to be the computer itself. The devices are going to be, well, the devices that you attach to it (in other words, the USB peripherals).


  I would like to ask if there are any other controller out there which can replace USB3380.


Yes, of course there are other controller options. It sounds like controller that converts PCIe to USB would work for you. In order to help you to choose, we would need to know more details about your exact purposes or application. What are your requirements? What is your budget? What are your primary considerations? Et cetera.

Additionally, it's worth noting that Stack Exchange sites aren't really well suited as recommendation engines. You should be able to find other suitable devices just by searching the product inventory on a distributors' site, like DigiKey or Mouser. From there, you can obtain the data sheets for all controllers matching your requirements and compare them.

I would definitely recommend looking for an alternative to the USB3380 controller (unless you eliminate it entirely&mdash;see answer to next question), since it is, according to the manufacturer, no longer recommended for new designs. In other words, it is obsolete and is being phased out.


  [W]ithout a USB3380 controller, can I connect/design the USB device port directly to a Intel PCH chipset?


Yes, (nearly) all Intel PCH chipsets include at least one integrated USB host controller, supporting multiple USB devices. Using this USB host controller directly makes far more sense to me than obtaining USB via a separate PCIe bridge, and would allow you to eliminate a superfluous component.

Check the datasheet provided by Intel for your specific PCH chipset family/model (e.g., here for the ICH 9 series) to determine how many USB host controllers it provides, how many USB devices are supported by each of those host controllers, which pins to connect, and how to make use of them via software.