Integrated USB 2.0 Compatible 4-Port Hub
Datasheet
SMSC USB2504/USB2504A 13 Revision 2.3 (08-27-07)
DATASHEET
SERIAL PORT INTERFACE
Serial Data/SMB
Data
SDA/SMBDATA IOSD12 (Serial Data)/(SMB Data) signal.
Serial Clock/SMB
Clock
SCL/SMBCLK IOSD12 (Serial Clock)/(SMB Clock) signal.
Configuration
Programming
Select
CFG_SEL0 IOSD12 This multifunction pin is read on the rising edge of
RESET_N negation and will determine the hub
configuration method as described in Table 4.2.
Configuration
Programming
Select
CFG_SEL1 I This pin is read on the rising edge of RESET_N (see the
applicable RESET_N timing table in Section 5.6.1) and will
determine the hub configuration method as described in
Table 4.2.
Configuration
Programming
Select
CFG_SEL2 I This pin is read on the rising edge of RESET_N negation
and will determine the hub configuration method as
described in Table 4.2.
Table 4.2 SMBus or EEPROM Interface Behavior
CFG_SEL2 CFG_SEL1 CFG_SEL0 SMBus or EEPROM interface behavior.
X 0 0 Configured as an SMBus slave for external download of user-
defined descriptors. SMBus slave address is 0101100
X 0 1 Configured as an SMBus slave for external download of user-
defined descriptors. SMBus slave address is 0101101
0 1 0 Internal Default Configuration
1 1 0 Internal Default Configuration via strapping options.
X 1 1 2-wire (I2C) EEPROMS are supported,
Table 4.3 Miscellaneous Pins
NAME SYMBOL TYPE FUNCTION
Crystal
Input/External
Clock Input
XTAL1/
CLKIN
ICLKx 24MHz crystal or external clock input.
This pin connects to either one terminal of the crystal or
to an external 24MHz clock when a crystal is not used.
Crystal Output XTAL2 OCLKx 24MHz Crystal
This is the other terminal of the crystal, or left
unconnected when an external clock source is used to
drive XTAL1/CLKIN. It must not be used to drive any
external circuitry other than the crystal circuit.
Clock Input
Enable
CLKIN_EN I Clock In Enable:
Low = XTAL1 and XTAL2 pins configured for use with
external crystal
High = XTAL1 pin configured as CLKIN, and must be
driven by an external CMOS clock.
Table 4.1 4-Port Hub Pin Descriptions (continued)
NAME SYMBOL TYPE FUNCTION
