MPC8308 datasheet(13/88 Pages) FREESCALE

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MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 0

Freescale Semiconductor

DDR2 SDRAM

Figure 5 shows the DDR2 SDRAM output timing for the MCK to MDQS skew measurement

(tDDKHMH).

Figure 5. Timing Diagram for tDDKHMH

MDQS preamble start

tDDKHMP

–0.5

× t

MCK – 0.6

–0.5

× t

MCK + 0.6

MDQS epilogue end

tDDKHME

–0.6

0.6

Notes:

1. The symbols used for timing specifications follow the pattern of 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. Output hold time can be read as DDR timing

(DD) from the rising or falling edge of the reference clock (KH or KL) until the output went invalid (AX or DX). For example,

tDDKHAS symbolizes DDR timing (DD) for the time tMCK memory clock reference (K) goes from the high (H) state until outputs

(A) are setup (S) or output valid time. Also, tDDKLDX symbolizes DDR timing (DD) for the time tMCK memory clock reference

(K) goes low (L) until data outputs (D) are invalid (X) or data output hold time.

2. All MCK/MCK referenced measurements are made from the crossing of the two signals ±0.1 V.

3. ADDR/CMD includes all DDR SDRAM output signals except MCK/MCK, MCS, and MDQ/MECC/MDM/MDQS.

4. Note that tDDKHMH follows the symbol conventions described in note 1. For example, tDDKHMH describes the DDR timing (DD)

from the rising edge of the MCK[n] clock (KH) until the MDQS signal is valid (MH). tDDKHMH can be modified through control

of the DQSS override bits in the TIMING_CFG_2 register. This is typically set to the same delay as the clock adjust in the

CLK_CNTL register. The timing parameters listed in the table assume that these 2 parameters have been set to the same

adjustment value. For a description and understanding of the timing modifications enabled by use of these bits, see the

MPC8308 PowerQUICC II Pro Processor Reference Manual.

5. Determined by maximum possible skew between a data strobe (MDQS) and any corresponding bit of data (MDQ), ECC

(MECC), or data mask (MDM). The data strobe should be centered inside of the data eye at the pins of the microprocessor.

6. All outputs are referenced to the rising edge of MCK[n] at the pins of the microprocessor. Note that tDDKHMP follows the

symbol conventions described in note 1.

Table 18. DDR2 SDRAM Output AC Timing Specifications (continued)

Parameter

Symbol 1

Min

Max

Unit

Notes

MDQS

MCK[n]

tMCK

tDDKHMHmax) = 0.6 ns

tDDKHMH(min) = –0.6 ns

MDQS

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