SMSC USB2250 User Manual
Ultra Fast USB 2.0 Multi-Slot Flash Media Controller
Datasheet
SMSC USB2250/50i/51/51i
33
Revision 1.1 (05-29-08)
DATASHEET
Chapter 8 AC Specifications
8.1
Oscillator/Clock
Crystal: Parallel Resonant, Fundamental Mode, 24 MHz
± 100ppm.
External Clock: 50% Duty cycle
± 10%, 24/48 MHz ± 100ppm, Jitter < 100ps rms.
Figure 8.1 Typical Crystal Circuit
Note: C
B
equals total board/trace capacitance.
Figure 8.2 Formula to Find Value of C
1
and C
2
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
=