Xerox WorkCentre Pro 412 Service Manual page 72

Circuit Description
5-3-6-2 SDRAM DRAM read timing (WorkCentre M15/M15i)
Basically the Extended Data Out DRAM is similar to Fast Page Mode DRAM. For FPM, the data are valid
only when the nCAS is active while reading the internal data, however, it has a latch that the data will
be continuously outputted even after the nCAS is inactivated.
While configuring the software, you must set the timing register of SFR considering the clock speed and
the DRAM spec.
0 1 2
CLOCK
CKE
*Note 1
CS
RAS
CAS
RAa RBb
ADDR
BA
0
BA
1
A /AP RAa RBb
10
CL=2
DQ
CL=3
WE
DQM
Row Active
(A-Bank)
Row Active
(B-Bank)
* Note : 1. CS can be don't cared when RAS, CAS and WE are hih at the clock high going dege.
2. To interrupt a burst read by row precharge, both the read and the precharge banks must be the
same.
5-34
3 4 5 6 7 8
CAa RCc CBb
RCc
QAa0 QAa1 QAa2
QAa0 QAa1
Read Read
(A-Bank) (B-Bank)
Row Acive
(C-Bank)
Precharge
(A-Bank)
9 10 11 12 13
HIGH
RDd CCc CDd
RDd
QBb0 QBb1 QBb2 QCc0 QCc1 QCc2
QAa2 QBb0 QBb1 QBb2 QCc0
Read Read
(C-Bank) (D-Bank)
Precharge
(D-Bank) (C-Bank)
Precharge
(B-Bank)
3/03 WorkCentre Pro 412, FaxCentre F12 &
14 15 16 17 18
*Note 2
QDd0 QDd1 QDd2
QCc1 QCc2 QDd0 QDd1 QDd2
Precharge
(D-Bank)
: Don't care
WorkCentre M15/M15i
19