W3H64M72E-XSBX
White Electronic Designs
ADVANCED*
EXTENDED MODE REGISTER (EMR)
ꢀhe extended mode register controls functions beyond
those controlled by the mode register; these additional
functions are DTT enable/disable, output drive strength,
on die termination (ODꢀ) (Rꢀꢀ), postedAT, off-chip driver
impedance calibration (OCD), DQS# enable/disable,
RDQS/RDQS# enable/disable, and output disable/enable.
ꢀhese functions are controlled via the bits shown in
Figure 7. ꢀhe EMR is programmed via the TOAD MODE
(TM) 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.
ꢀhe 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 unspecified operation.
FIGURE 7 – EXTENDED MODE REGISTER 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
1
0
02 out
OCD Program
Posted CAS#
ODS DLL
MRS
RTT
RTT
RDQS DQS#
Outputs
Enabled
Disabled
E0
0
DLL Ena ble
Enable (Normal)
E12
0
Rtt (nominal)
RTT disabled
75Ω
E6 E2
1
1
0
0
1
1
0
1
0
1
Disable (Test/Debug)
Output Drive Strength
RDQ S Ena ble
150 Ω
E11
0
E1
0
No
50Ω
Full strength (18 Ω target)
1
Yes
1
Reduced strength (40 Ω target)
E10
0
DQ S# Ena ble
Posted CA S# A dditive Laten cy (AL)
E5 E4 E3
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
1
2
3
E9 E8 E7
OCD Operation
1
0
0
0
1
1
0
0
1
0
1
0
1
0
0
1
OCD not supported
Reserved
4
Reserved
Reserved
Reserved
Reserved
Reserved
1
OCD default state
Mo de Regi ster Set
Mode register set (MRS)
E16 E15 E14
0
1
0
1
0
0
0
0
0
0
1
1
Extended mode register (EMRS)
Extended mode register (EMRS2)
Extended mode register (EMRS3)
Note: 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, as detailed in the
initialization procedure.
2.. E13 (A13) is not used on this device.
White Electronic Designs Corp. reserves the right to change products or specifications without notice.
March 2006
Rev. 1
12
White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com
WEDC [ WHITE ELECTRONIC DESIGNS CORPORATION ]
