FEC Electrical Characteristics
13 FEC Electrical Characteristics
This section provides the AC electrical specifications for the Fast Ethernet controller (FEC). Note that the
timing specifications for the MII signals are independent of system clock frequency (part speed
designation). Also, MII signals use TTL signal levels compatible with devices operating at either 5.0 V or
3.3 V.
13.1
MII Receive Signal Timing (MII_RXD[3:0], MII_RX_DV, MII_RX_ER,
MII_RX_CLK)
The receiver functions correctly up to a MII_RX_CLK maximum frequency of 25 MHz + 1%. There is no
minimum frequency requirement. In addition, the processor clock frequency must exceed the
MII_RX_CLK frequency – 1%.
provides information on the MII receive signal timing.
Table 29. MII Receive Signal Timing
Num
M1
M2
M3
M4
Characteristic
MII_RXD[3:0], MII_RX_DV, MII_RX_ER to MII_RX_CLK setup
MII_RX_CLK to MII_RXD[3:0], MII_RX_DV, MII_RX_ER hold
MII_RX_CLK pulse width high
MII_RX_CLK pulse width low
Min
5
5
35%
35%
Max
—
—
65%
65%
Unit
ns
ns
MII_RX_CLK
period
MII_RX_CLK
period
shows MII receive signal timing.
M3
MII_RX_CLK (Input)
M4
MII_RXD[3:0] (Inputs)
MII_RX_DV
MII_RX_ER
M1
M2
Figure 72. MII Receive Signal Timing Diagram
MPC860 PowerQUICC™ Family Hardware Specifications, Rev. 8
Freescale Semiconductor
67
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
