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SDRAM Controller
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
9-20
Freescale Semiconductor
9.10.3
SDRAM Refresh Timing
shows refresh-cycle timing. As in
, during a
PRECHARGE
ALL
command (T1), the
SDRAM writes all of its on-chip RAM page buffers into the SDRAM array. SDTR[RP] determines the
number of dead cycles after a precharge. Note that self refresh occurs during T3. In refresh state, SDRAM
cannot accept any other command.
Figure 9-13. SDRAM Refresh Cycle
T0
T1
T2
T3
T4
T5
T6
T7
T8
T9
SDCLK
SDADR[13:0]
A10_PRECHG
SDBA[1:0]
SDCS
RAS0
SDWE
Precharge
All Banks
NOP
Auto
Refresh
CAS0
SDCLKE
(H)
Next Command
t
RC