SMSC USB2512Ai Manual do Utilizador descarregar pdf (Página 36)

Industrial Temperature Rated USB 2.0 Hi-Speed 2-Port Hub Controller

Datasheet

Revision 1.97 (08-11-08) 36 SMSC USB2512Ai

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

equals total board/trace capacitance.

Figure 6.2 Formula to find value of C

and C

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 I

C EEPROM:

Clock frequency is fixed at 60KHz ± 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

S1 =

+ C

XTAL

)

XTAL2

S2 =

+ C

XTAL

)

1Meg

Crystal

+ C

) x (C

+ C

)

+ C

)

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SMSC USB2512Ai Manual do Utilizador Página 36