EtronTech
EM68C08CWAE
z Extended Mode Register Set (EMRS)
EMR(1)
The extended mode register(1) stores the data for enabling or disabling the DLL, output driver strength, ODT value
selection and additive latency. The default value of the extended mode register is not defined, therefore the
extended mode register must be written after power-up for proper operation. The extended mode register is written
by asserting LOW on CS#, RAS#, CAS#, WE#, BA1 and HIGH on BA0, while controlling the states of address pins
A0 ~ A13. The DDR2 SDRAM should be in all bank precharge with CKE already HIGH prior to writing into the
extended mode register. The mode register set command cycle time (tMRD) must be satisfied to complete the write
operation to the extended mode register. Mode register contents can be changed using the same command and
clock cycle requirements during normal operation as long as all banks are in the precharge state. A0 is used for
DLL enable or disable. A1 is used for enabling a half strength data-output driver. A3~A5 determine the additive
latency, A2 and A6 are used for ODT value selection, A7~A9 are used for OCD control, A10 is used for DQS#
disable and A11 is used for RDQS enable.
- DLL Enable/Disable: The DLL must be enabled for normal operation. DLL enable is required during power up
initialization, and upon returning to normal operation after having the DLL disabled. The DLL
is automatically disabled when entering self refresh operation and is automatically re-enabled
upon exit of self refresh operation. Any time the DLL is enabled (and subsequently reset),
200 clock cycles must occur before a Read command can be issued to allow time for the
internal clock to be synchronized with the external clock. Failing to wait for synchronization to
occur may result in a violation of the tAC or tDQSCK parameters.
Table 6-1. Extended Mode Register EMR (1) Bitmap
BA2 BA1 BA0 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 Address Field
0*3
0
1
0*3 Qoff
OCD program Rtt
Rtt
RDQS
DQS#
Additive Latency
D.I.C Extended Mode Register
DLL
BA1 BA0
MRS mode
MR
A6 A2
Rtt(NOMINAL)
ODT Disable
0
0
1
1
0
1
0
1
0
0
1
1
0
1
0
1
A0
DLL Enable
Enable
Ω
EMR(1)
EMR(2)
EMR(3)
75
0
1
Disable
Ω
150
Ω
50
A9
0
A8
0
A7 OCD Calibration Program
Output Driver
Impedance Control
Full strength
A1
OCD Calibration mode exit; maintain setting
Drive(1)
0
1
0
0
1
0
0
0
1
0
1
Drive(0)
Reduced strength
1
0
Adjust mode*1
1
1
OCD Calibration default*2
A5 A4 A3
Additive Latency
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
A12
0
Qoff *3
1
Output buffer enabled
Output buffer disabled
2
A10
DQS#
1
3
0
1
Enable
4
Disable
A11
0
RDQS Enable*4
5
6
Disable
Enable
1
Reserved
NOTE 1: When Adjust mode is issued, AL from previously set value must be applied.
NOTE 2: After setting to default, OCD calibration mode needs to be exited by setting A9-A7 to 000.
NOTE 3: Output disabled – DQs, DQSs, DQSs#.This feature is intended to be used during IDD characterization of read current.
NOTE 4: If RDQS is enabled, the DM function is disabled. RDQS is active for reads and do not care for writes.
Rev. 1.3
10
Oct. /2015
ETRON [ ETRON TECHNOLOGY, INC. ]
