QT2022/32 - Data Sheet: DS3051
9 MDIO Interface
The management data input output (MDIO) interface provides a simple, two wire, serial interface to connect a sta-
tion management entity (STA) and a managed PHY for the purpose of controlling the PHY and gathering status
from the PHY. The management interface consists of the two wire physical interface, a frame format, a protocol
specification for exchanging the frames and a register set that can be read and written using these frames. The two
wires of the physical interface are the Management Data Clock (MDC) and the Management Data I/O (MDIO).
9.1 Management Data Clock (MDC)
The MDC is sourced by the Station Management entity to the PHY as the timing reference for transfer of informa-
tion on the MDIO signal. MDC is an aperiodic signal that has no maximum high or low times. Please see Table 61,
“MDIO AC Parameters,” on page 189 for minimum high and low times.
9.2 Management Data I/O (MDIO)
MDIO is a bidirectional signal between the PHY (QT2022/32) and the STA. It is used to transfer control and status
information. Data is always driven and sampled synchronously with respect to MDC.
9.3 MDIO Timing Relationship to MDC
MDIO is a bidirectional signal that can be sourced by the STA or the QT2022/32. When the STA sources the MDIO
signal, the STA shall provide a minimum of 10ns of setup time and a minimum of 10ns of hold time referenced to
the rising edge of MDC.
When the MDIO signal is sourced by the QT2022/32, it is sampled by the STA synchronously with respect to the
rising edge of MDC. Please see Table 61, “MDIO AC Parameters,” on page 189 for the clock output delay.
Figure 21: MDIO/MDC Timing
MDC
tsu=10ns min
MDIO
(STA Sourced)
Data Valid
thd=10ns min
MDC
MDIO
(PHY Sourced)
Data Valid
tpd = 0ns min, 300ns max
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