SMSC FlexPWR LAN8720 - Manual (Page 60)

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
Section 4.7.2
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 1.5 5 ns
REFCLKO frequency 50 MHz
REFCLKO
Data Out -
RXD[1:0]
CRS_DV
Valid Data
T
11.1