Datasheet
EMR(2)
The extended mode register (2) controls refresh related features. The default value of the extended mode register
(2
)
is not defined, therefore the extended mode register (2) must be written after power-up for proper operation. T
he
extended mode register(2) is written by asserting LOW on CS#, RAS#, CAS#, WE#, HIGH on BA1 and LOW on
BA0
, while controlling the states of address pins A0 ~ A13. The DDR2 SDRAM should be in all bank precharge wit
h
CK
E already HIGH prior to writing into the extended mode register (2). The mode register set command cycle tim
e
(t
MRD
) must be satisfied to complete the write operation to the extended mode register (2). 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.
Table 7. Extended Mode Register EMR(2) Bitmap
BA2
BA1
BA0
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Address Field
0
*1
1
0
0
*1
SRF
0
*1
DCC
PASR
*3
Extended Mode Register(2)
A7
High Temperature Self-Refresh Rate Enable
0
Disable
1
Enable
*2
BA1
BA0
MRS mode
A3
DCC Enable (Optional)
*4
0
0
MR
0
Disable
0
1
EMR(1)
1
Enable
1
0
EMR(2)
1
1
EMR(3)
A2
A1
A0
Partial Array Self Refresh for 8 Banks (Optional)
0
0
0
Full array
0
0
1
Half Array (BA[2:0]=000,001,010&011)
0
1
0
Quarter Array (BA[2:0]= 000&001)
0
1
1
1/8 array (BA[2:0]=000)
1
0
0
3/4 array (BA[2:0]=010,011,100,101,110&111)
1
0
1
Half array (BA[2:0]= 100,101,110&111)
1
1
0
Quarter array (BA[2:0]= 110&111)
1
1
1
1/8 array (BA[2:0]=111)
NOTE 1: BA2 and A4-A6, A8-A13 is reserved for future use and must be set to 0 when programming the EMR(2).
NOTE 2: Due to the migration nature, user needs to ensure the DRAM part supports higher than 85
∞
C Tcase temperature
self-refresh entry. If the high temperature self-refresh mode is supported then controller can set the EMRS2[A7] bit
to enable the self-refresh rate in case of higher than 85
∞
C temperature self-refresh operation.
NOTE 3: If PASR (Partial Array Self Refresh) is enabled, data located in areas of the array beyond the specified location will
be lost if self refresh is entered. Data integrity will be maintained if t
REF
conditions are met and no Self Refresh
command is issued.
NOTE 4: DCC (Duty Cycle Corrector) implemented, user may be given the controllability of DCC thru EMR (2) [A3] bit.
AS4C128M16D2A-25BCN
AS4C128M16D2A-25BIN
Confidential
- 12/63 -
Rev.1.0 Dec 2015