
WEDPN16M72VR-XBX
White Electronic Designs Corporation (602) 437-1520 www.whiteedc.com
7
NOTES:
1. CKE is HIGH for all commands shown except SELF REFRESH.
2. A0-11 define the op-code written to the Mode Register.
3. A0-12 provide row address, and BA0, BA1 determine which bank is made active.
4. A0-8 provide column address; A10 HIGH enables the auto precharge feature
(nonpersistent), while A10 LOW disables the auto precharge feature; BA0, BA1
determine which bank is being read from or written to.
5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH: All banks
precharged and BA0, BA1 are “Don’t Care.”
6. This command is AUTO REFRESH if CKE is HIGH; SELF REFRESH if CKE is LOW.
7. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care”
except for CKE.
8. Activates or deactivates the I/Os during WRITEs (zero-clock delay) and READs
(two-clock delay).
INPUTS
OUTPUT
OE
LE
CLK
A
Y
H
X
Z
L
X
L
X
H
L
H
I
L
H
I
H
L
H
L OR H
X
Y
0(1)
NAME (FUNCTION)
CS
RAS
CAS
WE
DQM
ADDR
I/Os
COMMAND INHIBIT (NOP)
H
X
NO OPERATION (NOP)
L
H
X
ACTIVE (Select bank and activate row) ( 3)
L
H
X
Bank/Row
X
READ (Select bank and column, and start READ burst) (4)
L
H
L
H
L/H 8
Bank/Col
X
WRITE (Select bank and column, and start WRITE burst) (4)
L
H
L
L/H 8
Bank/Col
Valid
BURST TERMINATE
L
H
L
X
Active
PRECHARGE (Deactivate row in bank or banks) ( 5)
L
H
L
X
Code
X
AUTO REFRESH or SELF REFRESH (Enter self refresh mode) (6, 7)
L
H
X
LOAD MODE REGISTER (2)
L
X
Op-Code
X
Write Enable/Output Enable (8)
–
L
–
Active
Write Inhibit/Output High-Z (8)
–
H
–
High-Z
TRUTH TABLE - COMMANDS AND DQM OPERATION (NOTE 1)
NOTES:
1. Output level before the indicated steady-state
input conditions were established.
REGISTER FUNCTION TABLE
COMMAND INHIBIT
The COMMAND INHIBIT function prevents new commands
from being executed by the SDRAM, regardless of whether
the CLK signal is enabled. The SDRAM is effectively dese-
lected. Operations already in progress are not affected.
The NO OPERATION (NOP) command is used to perform a
NOP to an SDRAM which is selected (CS is LOW). This
prevents unwanted commands from being registered during
idle or wait states. Operations already in progress are not
affected.
The Mode Register is loaded via inputs A0-11. See Mode
Register heading in the Register Definition section. The LOAD
NO OPERATION (NOP)
LOAD MODE REGISTER
MODE REGISTER command can only be issued when all banks
are idle, and a subsequent executable command cannot be
issued until tMRD is met.
The ACTIVE command is used to open (or activate) a row in a
particular bank for a subsequent access. The value on the BA0,
BA1 inputs selects the bank, and the address provided on
inputs A0-11 selects the row. This row remains active (or open)
for accesses until a PRECHARGE command is issued to that
bank. A PRECHARGE command must be issued before open-
ing a different row in the same bank.
The READ command is used to initiate a burst read access to
an active row. The value on the BA0, BA1 inputs selects the
bank, and the address provided on inputs A0-8 selects the
starting column location. The value on input A10 determines
whether or not AUTO PRECHARGE is used. If AUTO PRECHARGE
ACTIVE
READ