Ethernet: Three-Speed,10/100, MII Management
Table 23. GMII Transmit AC Timing Specifications (continued)
At recommended operating conditions with LV
DD
of 3.3 V ± 5%, or LV
DD
=2.5V ± 5%.
Parameter/Condition
GTX_CLK data clock rise and fall time
Symbol
1
t
GTXR
, t
GTXF 2,4
Min
—
Typ
—
Max
1.0
Unit
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, t
GTKHDV
symbolizes GMII transmit timing (GT) with respect to the t
GTX
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, t
GTKHDX
symbolizes GMII
transmit timing (GT) with respect to the t
GTX
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 t
GTX
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.
shows the GMII transmit AC timing diagram.
t
GTX
GTX_CLK
t
GTXH
TXD[7:0]
TX_EN
TX_ER
t
GTKHDX
t
GTKHDV
t
GTXF
t
GTXR
Figure 6. GMII Transmit AC Timing Diagram
8.2.1.2
GMII Receive AC Timing Specifications
Table 24. GMII Receive AC Timing Specifications
provides the GMII receive AC timing specifications.
At recommended operating conditions with LV
DD
of 3.3 V ± 5%, or LV
DD
=2.5V ± 5%.
Parameter/Condition
RX_CLK clock period
RX_CLK duty cycle
RXD[7:0], RX_DV, RX_ER setup time to RX_CLK
RXD[7:0], RX_DV, RX_ER hold time to RX_CLK
Symbol
1
t
GRX
t
GRXH
/t
GRX
t
GRDVKH
t
GRDXKH
Min
—
40
2.0
0.5
Typ
8.0
—
—
—
Max
—
60
—
—
Unit
ns
ns
ns
ns
MPC8540 Integrated Processor Hardware Specifications, Rev. 4
24
Freescale Semiconductor
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
