Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.1 (04-26-10) 70 SMSC USB251x
DATASHEET
10.2 Ceramic Resonator
24 MHz ± 350 ppm
Figure 10.3 Ceramic Resonator Usage with SMSC IC
10.3 External Clock
50% Duty cycle ± 10%, 24 MHz ± 350 ppm, Jitter < 100 ps rms.
The external clock is recommended to conform to the signaling level designated in the JESD76-2
specification on 1.8 V CMOS Logic. XTALOUT should be treated as a no connect.
10.3.1 SMBus Interface
The SMSC Hub conforms to all voltage, power, and timing characteristics and specifications as set
forth in the SMBus 1.0 specification for Slave-Only devices (except as noted in Section 8.3, "SMBus
Slave Interface," on page 53.
10.3.2 I
2
C EEPROM
Clock frequency is fixed at 60 KHz ± 20%.
10.3.3 USB 2.0
The SMSC Hub conforms to all voltage, power, and timing characteristics and specifications as set
forth in the USB 2.0 specification. Please refer to the USB 2.0 specification for more information.
XTAL1
XTAL2
1 M
24 MHz
Ceramic
Resonator