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USB 2.0 Hi-Speed 2-Port Hub Controller
Datasheet
Revision 1.96 (07-11-08) 36 SMSC USB2512A
DATASHEET
Chapter 6 AC Specifications
6.1 Oscillator/Clock
Crystal: Parallel Resonant, Fundamental Mode, 24 MHz ±350ppm.
External Clock: 50% Duty cycle ± 10%, 24 MHz ± 350ppm, Jitter < 100ps rms.
Figure 6.1 Typical Crystal Circuit
Note: C
B
equals total board/trace capacitance.
Figure 6.2 Formula to find value of C
1
and C
2
6.1.1 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 4.3).
6.1.2 I
2
C EEPROM:
Clock frequency is fixed at 60KHz ± 20%.
6.1.3 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
(C
S1 =
C
B
+ C
XTAL
)
XTAL2
(C
S2 =
C
B
+ C
XTAL
)
C
1
C
2
C
L
1Meg
Crystal
(C
1
+ C
S1
) x (C
2
+ C
S2
)
(C
1
+ C
S1
+ C
2
+ C
S2
)
C
L
=