SMSC LAN8720 User Manual
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Revision 1.0 (05-28-09)
60
SMSC LAN8720/LAN8720i
DATASHEET
6.3
RMII 10/100Base-TX/RX Timings (50MHz REF_CLK OUT)
The 50MHz REF_CLK OUT timing applies to the case when LED/nINTSEL is pulled-low on the
LAN8720. In this mode, a 25MHz crystal or clock oscillator must be provided to the LAN8720. For
more information on 50MHz REF_CLK OUT mode, see
LAN8720. In this mode, a 25MHz crystal or clock oscillator must be provided to the LAN8720. For
more information on 50MHz REF_CLK OUT mode, see
6.3.1
RMII 100Base-T TX/RX Timings (50MHz REF_CLK OUT)
6.3.1.1
100M RMII Receive Timing (50MHz REF_CLK OUT)
Figure 6.6 100M RMII Receive Timing Diagram (50MHz REF_CLK OUT)
Table 6.6 100M RMII Receive Timing Values (50MHz REF_CLK OUT)
PARAMETER
DESCRIPTION
MIN
TYP
MAX
UNITS
NOTES
T11.1
Output delay from rising edge of
REFCLKO to receive signals
output valid
REFCLKO to receive signals
output valid
1.5
5
ns
REFCLKO frequency
50
MHz
REFCLKO
Data Out -
RXD[1:0]
CRS_DV
Valid Data
T
11.1