W632GU6NB
Publication Release Date: Aug. 20, 2018
Revision: A01
- 21 -
8.3.2
Mode Register MR1
The Mode Register MR1 stores the data for enabling or disabling the DLL, output driver strength,
Rtt_Nom impedance, additive latency, Write leveling enable and Qoff. The Mode Register 1 is written
by asserting low on CS#, RAS#, CAS#, WE#, high on BA0 and low on BA1 and BA2, while controlling
the states of address pins according to the Figure 6 below.
BA1
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
1
0
*
1
Rtt_Nom
BT
Rtt_Nom
Address Field
Mode Register 1
0
0
0
0
1
1
1
1
MR0
MR1
MR2
MR3
WR
AL
Qoff
0
*
1
0
*
1
Rtt_Nom
D.I.C
DLL
0
A0
1
Enable
Disable
Rtt_Nom disabled
RZQ/6
RZQ/12*
4
RZQ/4
RZQ/2
1
0
0
0
0
0
0
1
1
0
0
1
0
1
0
1
0
Output buffer enabled
Output buffer disabled
*2
1
0
Enabled
Disabled
BA0
A13
0
D.I.C
Level
0
*
1
0
0
1
1
0
1
0
1
0 (AL disabled)
Reserved
CL-1
CL-2
Reserved
Reserved
RZQ/8*
4
1
1
1
1
0
0
1
1
1
A5
0
0
1
1
A1
0
1
0
1
RZQ/6
Reserved
RZQ/7
Reserved
Note: RZQ = 240 ohms
Note: RZQ = 240 ohms
BA2
0
*
1
Output Driver
Impedance Control
A9
A6
A2
Rtt_Nom
*3
BA1
BA0
MR Select
A7
Write leveling enable
A12
Qoff
*2
DLL Enable
A4
A3
Additive Latency
Notes:
1. BA2, A8, A10, A11 and A13 are reserved for future use and must be programmed to
“0” during MRS.
2. Outputs disabled - DQs, DQSs, DQS#s.
3. In Write leveling Mode (MR1 A[7] = 1) with MR1 A[12]=1, all Rtt_Nom settings are allowed; in Write Leveling Mode (MR1 A[7]
= 1) with MR1 A[12]=0, only Rtt_Nom settings of RZQ/2, RZQ/4 and RZQ/6 are allowed.
4. If Rtt_Nom is used during Writes, only the values RZQ/2, RZQ/4 and RZQ/6 are allowed.
Figure 6
– MR1 Definition
8.3.2.1
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. During normal operation (DLL-on)
with MR1 (A0 = 0), 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, t
DLLK
clock cycles must occur before a Read or synchronous ODT 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 t
DQSCK
, t
AON
or t
AOF
parameters. During t
DLLK
,
CKE must continuously be registered high. DDR3L SDRAM does not require DLL for any Write
operation, except when Rtt_WR is enabled and the DLL is required for proper ODT operation. For more
detailed information on DLL Disable operation refer to section 8.6
on page 26.
The direct ODT feature is not supported during DLL-off mode. The on-die termination resistors must be
disabled by continuously registering the ODT pin low and/or by programming the Rtt_Nom bits
MR1{A9,A6,A2} to {0,0,0} via a mode register set command during DLL-off mode.