SMSC FlexPWR LAN8720 - Manual (Page 63)

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 7 ns
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