MPC8640DEC datasheet(38/140 Pages) FREESCALE

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MPC8640 and MPC8640D Integrated Host Processor Hardware Specifications, Rev. 1

Freescale Semiconductor

Ethernet: Enhanced Three-Speed Ethernet (eTSEC), MII Management

A timing diagram for TBI receive appears in Figure 18.

Figure 18. TBI Single-Clock Mode Receive AC Timing Diagram

8.2.6

RGMII and RTBI AC Timing Specifications

Table 34 presents the RGMII and RTBI AC timing specifications.

Table 34. RGMII and RTBI AC Timing Specifications

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

Parameter/Condition

Symbol 1

Min

Typ

Max

Unit

Data to clock output skew (at transmitter)

tSKRGT

–500

500

Data to clock input skew (at receiver) 2

tSKRGT

1.0

—

2.8

Clock period duration 3

tRGT

5,6

7.2

8.0

8.8

Duty cycle for 10BASE-T and 100BASE-TX 3, 4

tRGTH/tRGT

Rise time (20%–80%)

tRGTR

—

0.75

Fall time (80%–20%)

tRGTF

—

0.75

Notes:

1. Note that, in general, the clock reference symbol representation for this section is based on the symbols RGT to

represent RGMII and RTBI timing. For example, the subscript of tRGT represents the TBI (T) receive (RX) clock. Note

also that the notation for rise (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).

2. This implies that PC board design will require clocks to be routed such that an additional trace delay of greater than

1.5 ns will be added to the associated clock signal.

3. For 10 and 100 Mbps, tRGT scales to 400 ns ± 40 ns and 40 ns ± 4 ns, respectively.

4. Duty cycle may be stretched/shrunk during speed changes or while transitioning to a received packet's clock domains

as long as the minimum duty cycle is not violated and stretching occurs for no more than three tRGT of the lowest speed

transitioned between.

5. Guaranteed by characterization

6. ±100 ppm tolerance on RX_CLK frequency

tTRR

tTRRH

tTRRF

tTRRR

RX_CLK

RCG[9:0]

valid data

tTRRDXKH

tTRRDVKH

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