USB 2.0 High-Speed 4-Port Hub Controller
Datasheet
4.4.4
Slave Device Time-Out
According to the SMBus Specification, V1.0 devices in a transfer can abort the transfer in progress
and release the bus when any single clock low interval exceeds 25ms (TTIMEOUT, MIN). Devices that
have detected this condition must reset their communication and be able to receive a new START
condition no later than 35ms (TTIMEOUT, MAX).
Note: Some simple devices do not contain a clock low drive circuit; this simple kind of device typically
resets its communications port after a start or stop condition. The Slave Device Time-Out must
be implemented.
4.4.5
4.4.6
4.4.7
Stretching the SCLK Signal
The Hub supports stretching of the SCLK by other devices on the SMBus. The Hub does not stretch
the SCLK.
SMBus Timing
The SMBus Slave Interface complies with the SMBus AC Timing Specification. See the SMBus timing
in the “Timing Diagram” section.
Bus Reset Sequence
The SMBus Slave Interface resets and returns to the idle state upon a START field followed
immediately by a STOP field.
4.4.8
SMBus Alert Response Address
The SMBALERT# signal is not supported by the Hub.
4.4.8.1
Undefined Registers
The registers shown in Table 4.2 are the defined registers in the Hub. Reads to undefined registers
return 00h. Writes to undefined registers have no effect and do not return an error.
4.4.8.2
Reserved Registers
Unless otherwise instructed, only a ‘0’ may be written to all reserved registers or bits.
4.5
Default Configuration Option:
The SMSC Hub can be configured via its internal default configuration. (please see Section 4.3.1,
"Internal Register Set (Common to EEPROM and SMBus)" for specific details on how to enable default
configuration.)
Please refer to Table 4.2 for the internal default values that are loaded when this option is selected.
4.6
Default Strapping Options:
The USB2514 can be configured via a combination of internal default values and pin strap options.
Please see Table 3.1 and Table 3.2 for specific details on how to enable the default/pin-strap
configuration option.
The strapping option pins only cover a limited sub-set of the configuration options. The internal default
values will be used for the bits & registers that are not controlled by a strapping option pin. Please
refer to Table 4.2 for the internal default values that are loaded when this option is selected.
Revision 1.92 (05-08-07)
SMSC USB2514
DATA3S4HEET
SMSC [ SMSC CORPORATION ]
