1Gb : x4, x8, x16 DDR3 SDRAM
Op e ra t io n s
Ext e n d e d Te m p e ra t u re Usa g e
Micron’s DDR3 SDRAM support the optional extended temperature range of 0°C to 95°C,
T . Thus, the SRT and ASR options must be used at a minimum.
C
The extended temperature range DRAM must be refreshed externally at 2X (double
refresh) anytime the case temperature is above 85°C (and does not exceed 95°C). The
external refreshing requirement is accomplished by reducing the refresh period from
64ms to 32ms. However, self refresh mode requires either ASR or SRT to support the
extended temperature. Thus either ASR or SRT must be enabled when T is above 85°C
C
or self refresh cannot be used until the case temperature is at or below 85°C. Table 71
summarizes the two extended temperature options and Table 72 summarizes how the
two extended temperature options relate to one another.
Ta b le 71:
Fie ld
Se lf Re fre sh Te m p e ra t u re a n d Au t o Se lf Re fre sh De scrip t io n
MR2 Bit s
De scrip t io n
Self Refresh Temperature (SRT)
SRT
7
If ASR is disabled (MR2[6] = 0), SRT must be programmed to indicate TOPER during self refresh:
*MR2[7] = 0: Normal operating temperature range (0°C to 85°C)
*MR2[7] = 1: Extended operating temperature range (0°C to 95°C)
If ASR is enabled (MR2[7] = 1), SRT must be set to 0, even if the extended temperature range is
supported
*MR2[7] = 0: SRT is disabled
Auto Self Refresh (ASR)
ASR
6
When ASR is enabled, the DRAM automatically provides SELF REFRESH power management
functions, (refresh rate for all supported operating temperature values)
* MR2[6] = 1: ASR is enabled (M7 must = 0)
When ASR is not enabled, the SRT bit must be programmed to indicate TOPER during SELF REFRESH
operation
* MR2[6] = 0: ASR is disabled, must use manual self refresh temperature (SRT)
Ta b le 72:
Se lf Re fre sh Mo d e Su m m a ry
MR2[6] MR2[7]
Pe rm it t e d Op e ra t in g Te m p e ra t u re
Ra n g e fo r Se lf Re fre sh Mo d e
(ASR)
(SRT) SELF REFRESH Op e ra t io n
0
0
0
1
Self refresh mode is supported in the normal temperature range Normal (0°C to 85°C)
Self refresh mode is supported in normal and extended
temperature ranges; When SRT is enabled, it increases self
refresh power consumption
Normal and extended (0°C to 95°C)
1
1
0
1
Self refresh mode is supported in normal and extended
temperature ranges; Self refresh power consumption may be
temperature-dependent
Normal and extended (0°C to 95°C)
Illegal
PDF: 09005aef826aa906/Source: 09005aef82a357c3
1Gb_DDR3_4.fm - Rev. D 8/1/08 EN
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2006 Micron Technology, Inc. All rights reserved.
150
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