DDR and DDR2 SDRAM
Table 19. DDR SDRAM Output AC Timing Specifications (continued)
At recommended operating conditions.
Parameter
MDQS epilogue end
Symbol
1
t
DDKHME
Min
–0.6
Max
0.6
Unit
ns
Notes
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,
t
DDKHAS
symbolizes DDR timing (DD) for the time t
MCK
memory clock reference (K) goes from the high (H) state until outputs
(A) are setup (S) or output valid time. Also, t
DDKLDX
symbolizes DDR timing (DD) for the time t
MCK
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 t
DDKHMH
follows the symbol conventions described in note 1. For example, t
DDKHMH
describes the DDR timing (DD)
from the rising edge of the MCK[n] clock (KH) until the MDQS signal is valid (MH). t
DDKHMH
can be modified through control
of the MDQS override bits (called WR_DATA_DELAY) in the TIMING_CFG_2 register. This will typically be set to the same
delay as in DDR_SDRAM_CLK_CNTL[CLK_ADJUST]. The timing parameters listed in the table assume that these 2
parameters have been set to the same adjustment value. See the
MPC8548E PowerQUICC™ III Integrated Processor
Reference Manual
for a description and understanding of 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 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 t
DDKHMP
follows the
symbol conventions described in note 1.
NOTE
For the ADDR/CMD setup and hold specifications in
it is
assumed that the clock control register is set to adjust the memory clocks by
1/2 applied cycle.
shows the DDR SDRAM output timing for the MCK to MDQS skew measurement (t
DDKHMH
).
MCK[n]
MCK[n]
t
MCK
t
DDKHMHmax)
= 0.6 ns
MDQS
t
DDKHMH(min)
= –0.6 ns
MDQS
Figure 3. Timing Diagram for tDDKHMH
MPC8548E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 6
Freescale Semiconductor
23
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
