mpc8308 Freescale Semiconductor, Inc, mpc8308 Datasheet - Page 19

• Manufacturer Part Number: mpc8308
• Description: Mpc8308 Powerquicc Ii Pro Processor Hardware Specification
• Manufacturer: Freescale Semiconductor, Inc

Figure 11
Freescale Semiconductor
At recommended operating conditions with LV
Clock cycle duration
Duty cycle for 1000Base-T
Duty cycle for 10BASE-T and 100BASE-TX
Rise time (20%–80%)
Fall time (20%–80%)
GTX_CLK125 reference clock period
GTX_CLK125 reference clock duty cycle
Notes:
1. Note that, in general, the clock reference symbol representation for this section is based on the symbols RGT to represent
2. This implies that PC board design requires clocks to be routed such that an additional trace delay of greater than 1.5 ns is
3. For 10 and 100 Mbps, t
4. Duty cycle may be stretched/shrunk during speed changes or while transitioning to a received packet's clock domains as long
5. Duty cycle reference is 0.5*LV
6. This symbol is used to represent the external GTX_CLK125 and does not follow the original symbol naming convention.
RGMII timing. For example, the subscript of t
(R) and fall (F) times follows the clock symbol that is being represented. For symbols representing skews, the subscript is
skew (SK) followed by the clock that is being skewed (RGT).
added to the associated clock signal.
as the minimum duty cycle is not violated and stretching occurs for no more than three t
between.
(At Transmitter)
shows the RGMII AC timing and multiplexing diagrams.
RXD[8:5][3:0]
RXD[7:4][3:0]
TXD[8:5][3:0]
TXD[7:4][3:0]
GTX_CLK
(At PHY)
(At PHY)
RX_CTL
RX_CLK
TX_CLK
TX_CTL
3
MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 1
RGT
4, 5
Figure 11. RGMII AC Timing and Multiplexing Diagrams
scales to 400 ns ± 40 ns and 40 ns ± 4 ns, respectively.
Table 25. RGMII AC Timing Specifications (continued)
DD
DD
RXD[3:0]
TXD[3:0]
RXD[4]
TXD[4]
of 2.5 V ± 5%.
TXEN
RXDV
3, 5
RGT
represents the RGMII receive (RX) clock. Note also that the notation for rise
RXD[8:5]
RXD[7:4]
TXD[8:5]
TXD[7:4]
RXERR
TXERR
RXD[9]
TXD[9]
t
t
t
G125H
RGTH
RGTH
t
t
t
RGTR
t
RGTF
G12
RGT
/t
/t
/t
RGT
RGT
G125
6
t
t
SKRGT
SKRGT
t
RGTH
7.2
Ethernet: Three-Speed Ethernet, MII Management
45
40
47
—
—
—
RGT
t
8.0
8.0
of the lowest speed transitioned
50
50
—
—
—
RGT
t
t
SKRGT
SKRGT
0.75
0.75
8.8
55
60
53
—
ns
ns
ns
ns
%
%
%
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