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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
SMSC LAN8720/LAN8720i 55 Revision 1.0 (05-28-09)
DATASHEET
Chapter 6 AC Electrical Characteristics
The timing diagrams and limits in this section define the requirements placed on the external signals
of the Phy.
6.1 Serial Management Interface (SMI) Timing
The Serial Management Interface is used for status and control as described in Section 4.14.
Figure 6.1 SMI Timing Diagram
Table 6.1 SMI Timing Values
PARAMETER DESCRIPTION MIN TYP MAX UNITS NOTES
T1.1 MDC minimum cycle time 400 ns
T1.2 MDC to MDIO (Read from PHY)
delay
030ns
T1.3 MDIO (Write to PHY) to MDC setup 10 ns
T1.4 MDIO (Write to PHY) to MDC hold 10 ns
Clock -
MDC
Data Out -
MDIO
T
1.2
Valid Data
(Read from PHY)
T
1.1
T
1.3
T
1.4
Data In -
MDIO
Valid Data
(Write to PHY)