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Tnetx4090 thunderswitch ii, Switch – Texas Instruments THUNDERSWITCH II TNETX4090 User Manual

Page 65

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TNETX4090

ThunderSWITCH II

9-PORT 100-/1000-MBIT/S ETHERNET

SWITCH

SPWS044E – DECEMBER 1997 – REVISED AUGUST 1999

65

POST OFFICE BOX 655303

DALLAS, TEXAS 75265

PMA and GMII clock (see Figure 20)

NO.

MIN

MAX

UNIT

1

tr(Mxx_GCLK)

Pulse width low, Mxx_RFCLK

2.5

ns

2

th(Mxx_GCLK)

Pulse width high, Mxx_RFCLK

2.5

ns

3

tw(Mxx_GCLK)

Cycle time, Mxx_RFCLK

8

ns

PMA and GMII clock (see Figure 20)

NO.

MIN

MAX

UNIT

1

tr(Mxx_GCLK) Rise time, Mxx_RFCLK

1

ns

2

tf(Mxx_GCLK) Fall time, Mxx_RFCLK

1

ns

3

Accuracy

100

PPM

duty cycle

40%

60%

† tr and tf are measured between 20% and 80%, VDD(3.3-V) = min, output load (GTCLK) = 20pf.

Mxx_RFCLK

1

2

3

Figure 20. GMII Clock