SMSC USB2512 - Manual (Page 36)

USB 2.0 High-Speed 2-Port Hub Controller
Datasheet
SMSC USB2512 36 Revision 1.92 (11-28-07)
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 I2C EEPROM:
Frequency is fixed at 58.6KHz ± 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
=