k4d263238a-gc50 Samsung Semiconductor, Inc., k4d263238a-gc50 Datasheet - Page 10

• Manufacturer Part Number: k4d263238a-gc50
• Description: 1m X 32bit X 4 Banks Double Data Rate Synchronous Ram With Bi-directional Data Strobe And Dll
• Manufacturer: Samsung Semiconductor, Inc.

K4D26323RA-GC
EXTENDED MODE REGISTER SET(EMRS)
RFU
BA
strength. The default value of the extended mode register is not defined, therefore the extened mode register
must be written after power up for enabling or disabling DLL. The extended mode register is written by assert-
ing low on CS, RAS, CAS, WE and high on BA0(The DDR SDRAM should be in all bank precharge with CKE
already high prior to writing into the extended mode register). The state of address pins A0, A2 ~ A5, A7 ~ A11
and BA1 in the same cycle as CS, RAS, CAS and WE going low are written in the extended mode register. A1
and A6 are used for setting driver strength to normal, weak or matched impedance. Two clock cycles are
required to complete the write operation in the extended mode register. The mode register contents can be
changed using the same command and clock cycle requirements during operation as long as all banks are in
the idle state. A0 is used for DLL enable or disable. "High" on BA0 is used for EMRS. All the other address
pins except A0,A1,A6 and BA0 must be set to low for proper EMRS operation. Refer to the table for specific
codes.
The extended mode register stores the data for enabling or disabling DLL and selecting output driver
1
*1 : RFU(Reserved for future use) should stay "0" during EMRS cycle.
BA
0
1
BA
1
0
0
EMRS
A
A
MRS
11
n
~ A
0
A
10
RFU
A
9
0
0
1
1
A
A
6
8
Figure 7. Extended Mode Register set
* VDD / VDDQ=2.8V *
0
1
0
1
A
1
A
7
D.I.C
Output Driver Impedence Control
A
6
Weak
N/A
N/A
N/A
- 10 -
A
5
A
4
RFU
Do not use
Do not use
Do not use
A
60%
3
A
2
128M DDR SDRAM
D.I.C
A
1
Rev. 2.0 (Jan. 2003)
A
DLL
0
1
A
0
0
DLL Enable
Address Bus
Extended
Mode Register
Disable
Enable