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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
SMSC LAN8720/LAN8720i 63 Revision 1.0 (05-28-09)
DATASHEET
6.3.2.2 10M RMII Transmit Timing (50MHz REF_CLK OUT)
6.4 RMII CLKIN Requirements
Figure 6.9 10M RMII Transmit Timing Diagram (50MHz REF_CLK OUT)
Table 6.9 10M RMII Transmit Timing Values (50MHz REF_CLK OUT)
PARAMETER DESCRIPTION MIN TYP MAX UNITS NOTES
T14.1 Transmit signals required setup to
rising edge of REFCLKO
7ns
T14.2 Transmit signals required hold
after rising edge of REFCLKO
2.5 ns
CLKIN frequency 50 MHz
Table 6.10 RMII CLKIN (REF_CLK) Timing Values
PARAMETER DESCRIPTION MIN TYP MAX UNITS NOTES
CLKIN frequency 50 MHz
CLKIN Frequency Drift ± 50 ppm
CLKIN Duty Cycle 40 60 %
CLKIN Jitter 150 psec p-p – not RMS
REFCLKO
Data In -
TXD[1:0]
T
14.1
TX_EN
T
14.2
Valid Data