MT41J256M8 Datasheet, PDF (143/211 Pages) Micron Technology – MT41J512M4 – 64 Meg x 4 x 8 Banks

2Gb: x4, x8, x16 DDR3 SDRAM
Mode Register 2 (MR2)
Figure 56: CAS WRITE Latency
CK#
CK
Command
T0
ACTIVE n
DQS, DQS#
DQ
T1
T2
T6
T11
WRITE n
NOP
t_{RCD (MIN)}
AL = 5
NOP
NOP
CWL = 6
WL = AL + CWL = 11
T12
T13
T14
NOP
NOP
NOP
DI
DI
DI
DI
n
n+1
n+2
n+3
Indicates break
in time scale
Transitioning Data
Don’t Care
AUTO SELF REFRESH (ASR)
Mode register MR2[6] is used to disable/enable the ASR function. When ASR is disabled,
the self refresh mode’s refresh rate is assumed to be at the normal 85°C limit (some-
times referred to as 1x refresh rate). In the disabled mode, ASR requires the user to en-
sure the DRAM never exceeds a case temperature ( T_C) of 85°C while in self refresh, un-
less the user enables the SRT function when T_C is between 85°C and 95°C.
Enabling ASR assumes the DRAM self refresh rate is changed automatically from 1x to
2x when T_C exceeds 85°C. This enables the user to operate the DRAM beyond the stand-
ard 85°C limit up to the optional extended temperature range of 95°C while in self re-
fresh mode.
The standard self refresh current test specifies test conditions for normal T_C (85°C) only,
meaning that if ASR is enabled, the standard self refresh current specifications do not
apply (see Extended Temperature Usage (page 179)).
SELF REFRESH TEMPERATURE (SRT)
Mode register MR2[7] is used to disable/enable the SRT function. When SRT is disabled,
the self refresh mode’s refresh rate is assumed to be at the normal 85°C limit (some-
times referred to as 1x refresh rate). In the disabled mode, SRT requires the user to en-
sure the DRAM never exceeds a T_C of 85°C while in self refresh mode, unless the user
enables ASR.
When SRT is enabled, the DRAM self refresh is changed internally from 1x to 2x, regard-
less of T_C. This enables the user to operate the DRAM beyond the standard 85°C limit up
to the optional extended temperature range of 95°C while in self refresh mode. The
standard self refresh current test specifies test conditions for normal T_C (85°C) only,
meaning that if SRT is enabled, the standard self refresh current specifications do not
apply (see Extended Temperature Usage (page 179)).
PDF: 09005aef826aaadc
2Gb_DDR3_SDRAM.pdf - Rev. Q 04/13 EN
143
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