DDR3(L) 4Gb SDRAM
NT5CB(C)512M8DN / NT5CB(C)256M16DP
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-enable upon exit of Self-Refresh
operation. Any time the DLL is enabled and subsequently reset, tDLLK 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 tDQSCK, tAON, or tAOF parameters. During
tDLLK, CKE must continuously be registered high. DDR3(L) SDRAM does not require DLL for any Write operation, expect
when RTT_WR is enabled and the DLL is required for proper ODT operation. For more detailed information on DLL Disable
operation in DLL-off Mode.
The direct ODT feature is not supported during DLL-off mode. The on-die termination resistors must be disabled by continu-
ously 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.
The dynamic ODT feature is not supported at DLL-off mode. User must use MRS command to set Rtt_WR, MR2 {A10, A9}
= {0, 0}, to disable Dynamic ODT externally.
Output Driver Impedance Control
The output driver impedance of the DDR3(L) SDRAM device is selected by MR1 (bit A1 and A5) as shown in MR1 definition
figure.
ODT Rtt Values
DDR3(L) SDRAM is capable of providing two different termination values (Rtt_Nom and Rtt_WR). The nominal termination
value Rtt_Nom is programmable in MR1. A separate value (Rtt_WR) may be programmable in MR2 to enable a unique Rtt
value when ODT is enabled during writes. The Rtt_WR value can be applied during writes even when Rtt_Nom is disabled.
Version 2.3
02/2017
22
Nanya Technology Cooperation ©
All Rights Reserved.
NANYA [ Nanya Technology Corporation. ]
