1. UTMI+
The UTMI+ standard contains progressive levels of technology support because the complexity
requirements for devices can vary widely. For example, in OTG devices, the complexity needed for the
host controller block is directly dependent on the targeted peripheral list. The different UTMI+ levels
allow the designer to implement an ASIC with the required complexity level without having to design in
unused logic.
The levels provide a layered support structure:
• Level 0 is fully compatible with UTMI.
• Level 1 adds support for USB OTG dual-role devices that generate high-speed (HS) and
full-speed (FS) traffic.
• Level 2 adds support for generating low-speed (LS) traffic towards LS devices that are directly
connected to the OTG device.
• Level 3 adds support for using USB 2.0 FS hubs in the system. It lets the host controller part of
the OTG dual-role dev