Ethernet: Three-Speed,10/100, MII Management
Table 23. GMII Transmit AC Timing Specifications (continued)
At recommended operating conditions with LVDD of 3.3 V 5%, or LVDD=2.5V 5%.
Parameter/Condition
Symbol 1
Min
Typ
Max
Unit
2,4
GTX_CLK data clock rise and fall time
tGTXR, tGTXF
—
—
1.0
ns
Notes:
1. The symbols used for timing specifications herein follow the pattern t(first two letters of functional block)(signal)(state)
(reference)(state) for inputs and t(first two letters of functional block)(reference)(state)(signal)(state) for outputs. For example, tGTKHDV
symbolizes GMII transmit timing (GT) with respect to the tGTX clock reference (K) going to the high state (H) relative
to the time date input signals (D) reaching the valid state (V) to state or setup time. Also, tGTKHDX symbolizes GMII
transmit timing (GT) with respect to the tGTX clock reference (K) going to the high state (H) relative to the time date
input signals (D) going invalid (X) or hold time. Note that, in general, the clock reference symbol representation is
based on three letters representing the clock of a particular functional. For example, the subscript of tGTX represents
the GMII(G) transmit (TX) clock. For rise and fall times, the latter convention is used with the appropriate letter: R
(rise) or F (fall).
2.Signal timings are measured at 0.7 V and 1.9 V voltage levels.
3.Guaranteed by characterization.
4.Guaranteed by design.
Figure 6 shows the GMII transmit AC timing diagram.
tGTX
tGTXR
GTX_CLK
tGTXF
tGTXH
TXD[7:0]
TX_EN
TX_ER
tGTKHDX
tGTKHDV
Figure 6. GMII Transmit AC Timing Diagram
8.2.1.2 GMII Receive AC Timing Specifications
Table 24 provides the GMII receive AC timing specifications.
Table 24. GMII Receive AC Timing Specifications
At recommended operating conditions with LVDD of 3.3 V 5%, or LVDD=2.5V 5%.
Parameter/Condition
RX_CLK clock period
Symbol 1
Min
Typ
Max
Unit
tGRX
—
40
8.0
—
—
—
—
60
—
—
ns
ns
ns
ns
RX_CLK duty cycle
tGRXH/tGRX
tGRDVKH
tGRDXKH
RXD[7:0], RX_DV, RX_ER setup time to RX_CLK
RXD[7:0], RX_DV, RX_ER hold time to RX_CLK
2.0
0.5
MPC8540 Integrated Processor Hardware Specifications, Rev. 4
24
Freescale Semiconductor
FREESCALE [ Freescale ]
