Ultra Fast USB 2.0
Chapter 10 AC Specifications
10.1Oscillator/Clock
Crystal: Parallel Resonant, Fundamental Mode, 24 MHz ± 100 ppm.
External Clock: 50% Duty cycle ± 10%, 24 MHz ± 100 ppm, Jitter < 100 ps rms.
XTAL1
(CS1 =
CB + CXTAL )
C1
Crystal CL | 1Meg |
C2 | XTAL2 |
| |
| (CS2 = |
| CB + CXTAL ) |
Figure 10.1 Typical Crystal Circuit
Note: CB equals total board/trace capacitance.
(C1 + CS1) x (C2 + CS2)
CL =
(C1 + CS1 + C2 + CS2)
Figure 10.2 Formula to find value of C1 and C21
Revision 2.0 | 58 | SMSC USB2640/USB2641 |
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