W949D6DB Datasheet, PDF (18/60 Pages) Winbond – Standard Self Refresh Mode

W949D6DB / W949D2DB
7.5 Status Register Read
Status Register Read (SRR) is an optional feature in JEDEC, and it is implemented in this device. With
SRR, a method is defined to read registers from the device. The encoding for an SRR command is the
same as a MRS with BA[1:0]=“01”. The address pins (A[n:0]) encode which register is to be read.
Currently only one register is defined at A[n:0]=0. The sequence to perform an SRR command is as
follows:
 All reads/writes must be completed
 All banks must be closed
 MRS with BA=01 is issued (SRR)
 Wait tSRR
 Read issued to any bank/page
 CAS latency cycles later the device returns the registers data as it would a normal read
 The next command to the device can be issued tSRC after the Read command was issued.
The burst length for the SRR read is always fixed to length 2.
7.5.1 SRR Register Definition
Default: (A[n:0] = 0)
X
16 15 13 12 11 10 8 7
43
0 ^{Rising Edge of DQ Bus}
Reserved(0)
Density
DT
DW
Refresh
Rate
Revision
Identification
Manufacturer
Identification
SRR Register 0
DQ15 DQ14 DQ13 Density
0
0
0
128
0
0
1
256
0
1
0
512
0
1
1
1024
1
0
0
2048
1
0
1 Reserved
1
1
0 Reserved
1
1
1
64
DQ3 DQ2 DQ1 DQ0 Manufacturer
1
0
0
0
Winbond
DQ12 Device Type
0
LPDDR
1
Reserved
DQ11
0
1
DW
16 bits
32 bits
DQ10 DQ9
1
1
1
1
1
0
1
0
0
1
0
1
0
0
DQ8
1
0
1
0
1
0
x
Refresh Rate
0.25 (See Note 2)
0.25
0.5
1
2
4
4 (See Note 3)
DQ7:4 Revision ID
(See Note 1)
Note 1 : The manufacture’s revision number
starts at ‘0000’ and increments by ‘0001’ each
time a change in the manufacturer’s specification
(AC timings, or feature set), IBIS (pull up or pull
down characteristics), or process occurs.
Note 2 : High temperature out of range - no refresh rate can guarantee functionality.
Note 3 : Low temperature out of range.
Note 4 : The refresh rate multiplier is based on the memory’s temperature sensor.
Note 5 : Required average periodic refresh interval = tREFI * multiplier.
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Publication Release Date: Oct. 08, 2014
Revision: A01-003