SMSC USB2513i - Manual (Page 18)

Industrial Temperature Rated USB 2.0 High-Speed 3-Port Hub Controller
Datasheet
Revision 1.98 (11-19-07) 18 SMSC USB2513i
DATASHEET
Chapter 4 Configuration Options
4.1 3-Port Hub
SMSC’s USB 2.0 3-Port Hub is fully specification compliant to the Universal Serial Bus Specification
Revision 2.0 April 27, 2000 (12/7/2000 and 5/28/2002 Errata). Please reference Chapter 10 (Hub
Specification) for general details regarding Hub operation and functionality.
For performance reasons, the 3-Port Hub provides 1 Transaction Translator (TT) per port (defined as
Multi-TT configuration), divided into 4 non-periodic buffers per TT.
4.1.1 Hub Configuration Options
The SMSC Hub supports a large number of features (some are mutually exclusive), and must be
configured in order to correctly function when attached to a USB host controller. There are three
principal ways to configure the hub: SMBus, EEPROM, or by internal default settings (with or without
pin strapping option over-rides). In all cases, the configuration method will be determined by the
CFG_SEL2, CFG_SEL1 and CFG_SEL0 pins immediately after RESET_N negation.
4.1.1.1 Power Switching Polarity
The selection of active state “polarity” for the PRTPWR pins is made by a strapping option only (the
PRTPWR_POL pin).
Note: If PRTPWR_POL is not an available pin on the package, the hub will support active high power
controllers only!
4.1.2 VBus Detect
According to Section 7.2.1 of the USB 2.0 Specification, a downstream port can never provide power
to its D+ or D- pull-up resistors unless the upstream port’s VBUS is in the asserted (powered) state.
The VBUS_DET pin on the Hub monitors the state of the upstream VBUS signal and will not pull-up
the D+ resistor if VBUS is not active. If VBUS goes from an active to an inactive state (Not Powered),
Hub will remove power from the D+ pull-up resistor within 10 seconds.
4.2 36 QFN and 48 QFN Feature Differences
Table 4.1 36 QFN and 48 QFN Feature Differences
36 QFN 48 QFN FEATURE
N/A Available 48MHz clock input mode
N/A Available External 1.8V regulators
N/A Available Port LED Indicators
N/A Available Port Swap Strapping Options
Available N/A Only Active High Port Power Control is supported in 36 QFN package
Available N/A Boost Default Level is used; see Table 4.2, "Internal Default, EEPROM and
SMBus Register Memory Map"