MPC8544E datasheet(32/117 Pages) FREESCALE

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MPC8544E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 5

Freescale Semiconductor

Enhanced Three-Speed Ethernet (eTSEC), MII Management

8.5.2

GMII AC Timing Specifications

This section describes the GMII transmit and receive AC timing specifications.

8.5.2.1

GMII Transmit AC Timing Specifications

Table 30 provides the GMII transmit AC timing specifications.

Figure 13 shows the GMII transmit AC timing diagram.

Figure 13. GMII Transmit AC Timing Diagram

Table 30. GMII Transmit AC Timing Specifications

At recommended operating conditions with L/TVDD of 3.3 V ± 5% or 2.5 V ± 5%

Parameter/Condition

Symbol1

Min

Typ

Max

Unit

Notes

GTX_CLK clock period

tGTX

—

8.0

—ns—

GTX_CLK to GMII data TXD[7:0], TX_ER, TX_EN delay

tGTKHDX

0.2

—

5.0

GTX_CLK data clock rise time (20%-80%)

tGTXR

——

1.0

—

GTX_CLK data clock fall time (80%-20%)

tGTXF

——

1.0

—

Notes:

1. The symbols used for timing specifications 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, tGTKHDV symbolizes GMII transmit timing

(GT) with respect to the tGTX 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, tGTKHDX symbolizes GMII transmit timing (GT) with respect to the tGTX 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 tGTX 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. Data valid tGTKHDV to GTX_CLK Min setup time is a function of clock period and max hold time (Min setup = cycle time – Max

delay).

GTX_CLK

TXD[7:0]

tGTKHDX

tGTX

tGTXH

tGTXR

tGTXF

tGTKHDV

TX_EN

TX_ER

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