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USB2412-DZK-TR

2-Port USB 2.0 Hi-Speed Hub Controller

SMSC -> Microchip 

Chapter 5 AC Specifications

2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

5.1

Oscillator/Crystal

Parallel Resonant, Fundamental Mode, 24 MHz ± 350 ppm.

XTALIN

(CS1 = CB1 + CXTAL1 )

C1

C0

Crystal CL

1M

C2

XTALOUT

(CS2 = CB2 + CXTAL2 )

Figure 5.1 Typical Crystal Circuit

SYMBOL

C0

CL

CB

CS

CXTAL

C1

C2

Table 5.1 Crystal Circuit Legend

DESCRIPTION

IN ACCORDANCE WITH

Crystal shunt capacitance

Crystal load capacitance

Total board or trace capacitance

Stray capacitance

Crystal manufacturer’s specification (See Note 5.1)

OEM board design

SMSC IC and OEM board design

XTAL pin input capacitance

Load capacitors installed on OEM

board

SMSC IC

Calculated values based on Figure 5.2, "Formula to Find the

Value of C1 and C2" (See Note 5.2)

C1 = 2 x (CL – C0) – CS1

Note 5.1

C2 = 2 x (CL – C0) – CS2

Figure 5.2 Formula to Find the Value of C1 and C2

C0 is usually included (subtracted by the crystal manufacturer) in the specification for CL

and should be set to 0 for use in the calculation of the capacitance formulas in Figure 5.2,

"Formula to Find the Value of C1 and C2". However, the PCB itself may present a parasitic

capacitance between XTALIN and XTALOUT. For an accurate calculation of C1 and C2,

take the parasitic capacitance between traces XTALIN and XTALOUT into account.

Note 5.2 Each of these capacitance values is typically approximately 18 pF.

Revision 1.3 (12-27-11)

20

DATASHEET

SMSC USB2412

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