W3H128M72E-XSBX / W3H128M72E-XNBX
is programmed again or the device loses power. Reprogramming
the EMR will not alter the contents of the memory array, provided
it is performed correctly.
EXTENDED MODE REGISTER 2
The extended mode register 2 (EMR2) controls functions beyond
those controlled by the mode register. Currently all bits in EMR2
are reserved except for E7, as shown in Figure 8. The EMR2
is programmed via the LM command and will retain the stored
information until it is programmed again or the device loses power.
Reprogramming the EMR will not alter the contents of the memory
array, provided it is performed correctly.
EMR3 must be loaded when all banks are idle and no bursts are
in progress, and the controller must wait the specified time tMRD
before initiating any subsequent operation. Violating either of these
requirements could result in unspecified operation.
COMMAND TRUTH TABLE
The following table provides a quick reference of DDR2 SDRAM
available commands, including CKE power-down modes, and
bank-to-bank commands.
Bit E7 (A7) must be programmed as"1" to provide a faster refresh
rate on devices if the junction temperature (TJ) exceeds 85°C but
doesn't exceed 95°C. Refer to operating junction temperature
limits in "DC operating conditions" table. Self refresh function is
not available for military grade devices.
EMR2 must be loaded when all banks are idle and no bursts are
in progress, and the controller must wait the specified time tMRD
before initiating any subsequent operation. Violating either of these
requirements could result in unspecified operation.
EXTENDED MODE REGISTER 3
The extended mode register 3 (EMR3) controls functions beyond
those controlled by the mode register. Currently, all bits in EMR3
are reserved, as shown in Figure 9. The EMR3 is programmed
via the LM command and will retain the stored information until it
FIGURE 9 – EXTENDED MODE REGISTER 3 (EMR3) DEFINITION
BA2
BA1 BA0 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 Address bus
Extended mode
register (Ex)
16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
0
1
0
0
MRS
0
0
0
0
0
0
0
0
0
0
0
0
0
E15 E14
Mode Register Set
Mode register (MR)
0
0
1
1
0
1
0
1
Extended mode register (EMR)
Extended mode register (EMR2)
Extended mode register (EMR3)
13
4163.12E-0716-ss-W3H128M72E-XSBX / XNBX
Mercury Corp. - Memory and Storage Solutions • (602) 437-1520 • www.mrcy.com
MERCURY [ MERCURY UNITED ELECTRONICS INC ]
