Ultra Fast USB 2.0 Multi-Format Flash Media Controller/USB Hub Combo

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 (10-03-08)

58

SMSC USB2640/USB2641

 

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