![Intel IXP45X Developer'S Manual Download Page 601](http://html1.mh-extra.com/html/intel/ixp45x/ixp45x_developers-manual_2073092601.webp)
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
601
Memory Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
15. The MCU may issue a
row-activate
command T
mrd
cycles after the
mode-register-set
command.
16. Software re-enables the refresh counter by setting the RFR to the required value.
The waveform in
illustrates the DDRI SDRAM initialization sequence.
If the DDRI SDRAM subsystem implements ECC (see
Section 11.2.3, “Error Correction
), then initialization software must initialize the entire memory array
with the IXP45X/IXP46X network processors. It is important that every memory
Figure 109. DDRI SDRAM Initialization Sequence (Controlled with Software)
B2452-02
VDD
VDDQ
VTT
(System*)
CK
CK_N
VREF
CKE
DM
A0-A9,
A11, A12
A10
BA0, BA1
DQS
DQ and CB
Power-up:
VDD and CK stable
Command
200µs
t
CH
t
CL
t
CK
t
MRD
t
MRD
t
RFC
t
RFC
t
MRD
t
RP
t
IS
t
IH
t
IS
t
IH
NOP
PRE
EMRS
MRS
MRS
PRE
AR
AR
ACT
t
IS
t
IH
200 cycles of CK**
t
IS
t
IH
CODE
CODE
CODE
RA
t
IS
t
IH
CODE
All Banks
High-Z
High-Z
BA1=L
BA1=L
BA1=L
CODE
CODE
RA
t
IS
t
IH
BA0=
H
BA0=
L
BA0=
L
RA
t
IS
t
IH
All Banks
t
VTD
LVCMOS Low Level
Notes:
*
VTT is not applied directly to the device, however t
VTD
must be greater than or equal to zero to avoid device latchup.
**
t
MRD
is required before any command can be applied and 200 cycles of CK are required before a Read command
can be applied.
The two Autorefresh commands may be moved to follow the first MRS, but precede the second Precharge All
command.
= Don't Care
Extended Mode
Register Set
Load Mode
Register, Reset DLL
Load Mode
Register
(with A8=L)