1Gb: x4, x8, x16 DDR3 SDRAM
Extended Temperature Usage
Extended Temperature Usage
Micron’s DDR3 SDRAM support the optional extended case temperature (TC) range of
±°C to 95°C. Thus, the SRT and ASR options must be used at a minimum.
The extended temperature range DRAM must be refreshed externally at 2x (double re-
fresh) anytime the case temperature is above 85°C (and does not exceed 95°C). The ex-
ternal refresh 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 TC is above 85°C or self
refresh cannot be used until TC is at or below 85°C. Table 09 summarizes the two exten-
ded temperature options and Table 8± summarizes how the two extended temperature
options relate to one another.
Table 79: Self Refresh Temperature and Auto Self Refresh Description
Field
Self Refresh Temperature (SRT)
SRT
MR2 Bits Description
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 func-
tions, (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)
Table 80: Self Refresh Mode Summary
MR2[6] MR2[7]
Permitted Operating Temperature
Range for Self Refresh Mode
(ASR)
(SRT) SELF REFRESH Operation
0
0
1
Self refresh mode is supported in the normal temperature
range
Normal (0°C to 85°C)
0
1
1
Self refresh mode is supported in normal and extended temper- Normal and extended (0°C to 95°C)
ature ranges; When SRT is enabled, it increases self refresh
power consumption
0
1
Self refresh mode is supported in normal and extended temper- Normal and extended (0°C to 95°C)
ature ranges; Self refresh power consumption may be tempera-
ture-dependent
Illegal
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1Gb_DDR3_SDRAM.pdf - Rev. L 03/13 EN
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182
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