Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
5.5.4.3
RMII CLKIN Requirements
Table 5.11 RMII CLKIN (REF_CLK) Timing Values
PARAMETER
MIN
TYP
MAX
UNITS
NOTES
CLKIN frequency
50
MHz
ppm
%
CLKIN Frequency Drift
CLKIN Duty Cycle
CLKIN Jitter
± 50
60
40
150
psec
p-p – not RMS
5.5.5
SMI Timing
This section specifies the SMI timing of the device. Please refer to Section 3.5, "Serial Management
Interface (SMI)," on page 28 for additional details.
tclkp
tclkh tclkl
MDC
tohold
tval
tohold
MDIO
(Data-Out)
tsu tihold
MDIO
(Data-In)
Figure 5.6 SMI Timing
Table 5.12 SMI Timing Values
SYMBOL
DESCRIPTION
MIN
MAX
UNITS
NOTES
tclkp
tclkh
tclkl
MDC period
400
ns
ns
ns
ns
MDC high time
MDC low time
160 (80%)
160 (80%)
MDIO (read from PHY) output valid from rising
edge of MDC
300
tval
tohold
tsu
MDIO (read from PHY) output hold from rising
edge of MDC
0
ns
ns
ns
MDIO (write to PHY) setup time to rising edge
of MDC
10
10
MDIO (write to PHY) input hold time after rising
edge of MDC
tihold
SMSC LAN8720A/LAN8720Ai
73
Revision 1.4 (08-23-12)
DATASHEET