mpc5566 Freescale Semiconductor, Inc, mpc5566 Datasheet - Page 47

• Manufacturer Part Number: mpc5566
• Description: Mpc5566 High Performance Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

3.14.2
The transmitter functions correctly up to the FEC_TX_CLK maximum frequency of 25 MHz plus one
percent. There is no minimum frequency requirement. In addition, the processor clock frequency must
exceed twice the FEC_TX_CLK frequency.
The transmit outputs (FEC_TXD[3:0], FEC_TX_EN, FEC_TX_ER) can be programmed to transition
from either the rising- or falling-edge of TX_CLK, and the timing is the same in either case. These options
allow the use of non-compliant MII PHYs.
Refer to the Fast Ethernet Controller (FEC) chapter of the device reference manual for details of this option
and how to enable it.
Table 29
Figure 29
Freescale Semiconductor
Spec
5
6
7
8
FEC_TX_CLK to FEC_TXD[3:0], FEC_TX_EN, FEC_TX_ER invalid
FEC_TX_CLK to FEC_TXD[3:0], FEC_TX_EN, FEC_TX_ER valid
FEC_TX_CLK pulse-width high
FEC_TX_CLK pulse-width low
lists MII FEC transmit channel timings.
FEC_TXD[3:0] (outputs)
shows MII FEC transmit signal timings listed in
MII FEC Transmit Signal Timing
FEC_TXD[3:0], FEC_TX_EN, FEC_TX_ER, FEC_TX_CLK
FEC_TX_CLK (input)
FEC_TX_EN
FEC_TX_ER
Figure 29. MII FEC Transmit Signal Timing Diagram
Characteristic
Table 29. MII FEC Transmit Signal Timing
MPC5566 Microcontroller Data Sheet, Rev. 2.0
5
6
7
Table
29.
35%
35%
Min
—
5
8
65%
65%
Max
25
—
Electrical Characteristics
FEC_TX_CLK period
FEC_TX_CLK period
Unit
ns
ns
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