SMSC USB2513i - Manual (Page 17)

Industrial Temperature Rated USB 2.0 High-Speed 3-Port Hub Controller
Datasheet
SMSC USB2513i 17 Revision 1.98 (11-19-07)
DATASHEET
I/OSD12 Open drain...12mA sink with Schmitt trigger, and must meet I2C-Bus Specification
Version 2.1 requirements.
ICLKx XTAL clock input.
OCLKx XTAL clock output.
I-R RBIAS.
I/O-U Analog Input/Output Defined in USB specification.
AIO Analog Input/Output.
Table 3.4 USB2514 Buffer Type Descriptions (continued)
BUFFER DESCRIPTION