W3H128M72E-XSBX / W3H128M72E-XNBX
EXTENDED MODE REGISTER (EMR)
The extended mode register controls functions beyond those
controlled by the mode register; these additional functions are DLL
enable/disable, output drive strength, on die termination (ODT),
posted AL, off-chip driver impedance calibration (OCD), DQS#
enable/disable, RDQS/RDQS# enable/disable, and output disable/
enable. These functions are controlled via the bits shown in Figure
7. The EMR is programmed via the LOAD MODE (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.
The EMR 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 an unspecified operation.
FIGURE 7 – EXTENDED MODE REGISTER DEFINITION
BA2 BA1 BA0A13 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
1
0
RDQS DQS# OCD Program RTT Posted CAS# RTT ODS DLL
out
0
MRS
0
E0
DLL Enable
E12 Outputs
E6 E2 RTT (nominal)
0
1
0
1
Enabled
Disabled
Enable (Normal)
R
TT disabled
75Ω
0
0
1
1
0
1
0
1
Disable (Test/Debug)
E11 RDQS Enable
E1
Output Drive Strength
Full strength (18Ω target)
150Ω
0
1
No
50Ω
0
1
Yes
Reduced strength (40Ω target)
E10 DQS# Enable
E5 E4 E3 Posted CAS# Additive Latency (AL)
0
1
Enable
Disable
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
2
E9 E8 E7 OCD Operation1
3
0
0
0
1
1
0
0
1
0
1
0
1
0
0
1
OCD exit
Reserved
Reserved
Reserved
4
5
6
Reserved
Enable OCD defaults
E15 E14
Mode Register Set
Mode register set (MRS)
0
1
0
1
0
0
1
1
Extended mode register (EMR)
Extended mode register (EMRS2)
Extended mode register (EMRS3)
NOTES:
1.
During initialization, all three bits must be set to "1" for OCD default state, then must be set to "0" before
initialization is finished.
10
4163.12E-0716-ss-W3H128M72E-XSBX / XNBX
Mercury Corp. - Memory and Storage Solutions • (602) 437-1520 • www.mrcy.com
MERCURY [ MERCURY UNITED ELECTRONICS INC ]
