DDR and DDR2 SDRAM
Table 20. DDR and DDR2 SDRAM Output AC Timing Specifications (continued)
At recommended operating conditions with GVDD of (1.8 or 2.5 V) 5%.
Parameter
Symbol 1
Min
Max
Unit
Notes
MDQS epilogue end
tDDKHME
–0.6
0.6
ns
6
Notes:
1. The symbols 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 goes 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
set up (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. For the
ADDR/CMD setup and hold specifications, it is assumed that the clock control register is set to adjust the memory clocks by
1/2 applied cycle.
4. 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 and 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 two parameters are set to the same adjustment value.
See the MPC8349EA PowerQUICC II Pro Integrated Host Processor Family Reference Manual for the timing modifications
enabled by use of these bits.
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 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.
Figure 6 shows the DDR SDRAM output timing for the MCK to MDQS skew measurement (t
).
DDKHMH
MCK[n]
MCK[n]
tMCK
tDDKHMHmax) = 0.6 ns
MDQS
tDDKHMH(min) = –0.6 ns
MDQS
Figure 6. Timing Diagram for t
DDKHMH
MPC8349EA PowerQUICC II Pro Integrated Host Processor Hardware Specifications, Rev. 13
Freescale Semiconductor
20
FREESCALE [ Freescale ]
