2Gb: x4, x8, x16 DDR3 SDRAM - Micron
2Gb: x4, x8, x16 DDR3 SDRAM - Micron
2Gb: x4, x8, x16 DDR3 SDRAM - Micron
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Mode Register 2 (MR2)<br />
Figure 55: Mode Register 2 (MR2) Definition<br />
The mode register 2 (MR2) controls additional features and functions not available in<br />
the other mode registers. These addional functions are CAS WRITE latency (CWL), AU-<br />
TO SELF REFRESH (ASR), SELF REFRESH TEMPERATURE (SRT), and DYNAMIC ODT<br />
(R TT(WR)). These functions are controlled via the bits shown in the figure below. MR2 is<br />
programmed via the MRS command and will retain the stored information until it is<br />
programmed again or the device loses power. Reprogramming the MR2 register will not<br />
alter the contents of the memory array, provided it is reprogrammed correctly. The MR2<br />
register must be loaded when all banks are idle and no data bursts are in progress, and<br />
the controller must wait the specified time t MRD and t MOD before initiating a subsequent<br />
operation.<br />
M16 M15<br />
0 0<br />
0 1<br />
1 0<br />
1 1<br />
CAS WRITE Latency (CWL)<br />
Mode Register<br />
Mode register set 0 (MR0)<br />
Mode register set 1 (MR1)<br />
Mode register set 2 (MR2)<br />
Mode register set 3 (MR3)<br />
M10 M9<br />
0 0<br />
0 1<br />
1 0<br />
1 1<br />
BA2 BA1 BA0 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0<br />
15 14<br />
0 01 17 16<br />
0 1 1<br />
Dynamic ODT<br />
(R TT(WR) )<br />
RTT(WR) disabled<br />
RZQ/4 (60� NOM)<br />
RZQ/2 (120� NOM)<br />
Reserved<br />
13<br />
0 1<br />
12 11 10 9 8 7 6 5 4 3 2 1 0<br />
ASR CWL<br />
2<br />
01 01 01 01 01 01 RTT(WR) SRT<br />
M7 Self Refresh Temperature<br />
0 Normal (0°C to 85°C)<br />
1 Extended (0°C to 95°C)<br />
Auto Self Refresh<br />
M6 (Optional)<br />
0 Disabled: Manual<br />
1 Enabled: Automatic<br />
<strong>2Gb</strong>: <strong>x4</strong>, <strong>x8</strong>, <strong>x16</strong> <strong>DDR3</strong> <strong>SDRAM</strong><br />
Mode Register 2 (MR2)<br />
Address bus<br />
Mode register 2 (MR2)<br />
CAS Write Latency (CWL)<br />
5 CK ( tCK � 2.5ns)<br />
6 CK (2.5ns > tCK � 1.875ns)<br />
7 CK (1.875ns > tCK � 1.5ns)<br />
8 CK (1.5ns > tCK � 1.25ns)<br />
9 CK (1.25ns > tCK � 1.07ns)<br />
10 CK (1.071ns > t M5 M4 M3<br />
0 0 0<br />
0 0 1<br />
0 1 0<br />
0 1 1<br />
1 0 0<br />
1 0 1<br />
CK � 0.938ns)<br />
1 1 0<br />
Reserved<br />
1 1 1<br />
Reserved<br />
Notes: 1. MR2[17, 14:11, 8, and 2:0] are reserved for future use and must all be programmed to 0.<br />
2. On die revision A, ASR is not available; MR2[6] must be programmed to 0 and, if operating<br />
in self refresh mode above 85°C, MR2[7] (SRT) must be used.<br />
CAS write latency (CWL) is defined by MR2[5:3] and is the delay, in clock cycles, from<br />
the releasing of the internal write to the latching of the first data in. CWL must be correctly<br />
set to the corresponding operating clock frequency (see Figure 55). The overall<br />
WRITE latency (WL) is equal to CWL + AL (Figure 53 (page 139)).<br />
PDF: 09005aef826aaadc<br />
<strong>2Gb</strong>_<strong>DDR3</strong>_<strong>SDRAM</strong>.pdf – Rev. P 2/12 EN 143 <strong>Micron</strong> Technology, Inc. reserves the right to change products or specifications without notice.<br />
� 2006 <strong>Micron</strong> Technology, Inc. All rights reserved.