MPC5553_07 datasheet(46/66 Pages) FREESCALE

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MPC5553 Microcontroller Data Sheet, Rev. 2.0

Electrical Characteristics

Freescale Semiconductor

3.14

Fast Ethernet AC Timing Specifications

Media Independent Interface (MII) Fast Ethernet Controller (FEC) signals use transistor-to-transistor logic

(TTL) signal levels compatible with devices operating at 3.3 V. The timing specifications for the MII FEC

signals are independent of the system clock frequency (part speed designation).

3.14.1

MII FEC Receive Signal Timing

FEC_RXD[3:0], FEC_RX_DV, FEC_RX_ER, and FEC_RX_CLK

The receive functions correctly up to an FEC_RX_CLK maximum frequency of 25 MHz plus one percent.

There is no minimum frequency requirement. The processor clock frequency must exceed four times the

FEC_RX_CLK frequency.

Table 28 lists MII FEC receive channel timings.

Figure 29 shows MII FEC receive signal timings listed in Table 28.

Figure 29. MII FEC Receive Signal Timing Diagram

Table 28. MII FEC Receive Signal Timing

Spec

Characteristic

Min

Max

Unit

FEC_RXD[3:0], FEC_RX_DV, FEC_RX_ER to FEC_RX_CLK setup

—

FEC_RX_CLK to FEC_RXD[3:0], FEC_RX_DV, FEC_RX_ER hold

—

FEC_RX_CLK pulse-width high

35%

65%

FEC_RX_CLK period

FEC_RX_CLK pulse-width low

35%

65%

FEC_RX_CLK period

FEC_RX_CLK (input)

FEC_RXD[3:0] (inputs)

FEC_RX_DV

FEC_RX_ER

MPC5553 Datasheet(PDF) 46 Page - Freescale Semiconductor, Inc