SAMSUNG K4S560432E-TC75

SDRAM 256Mb E-die (x4, x8, x16)
CMOS SDRAM
256Mb E-die SDRAM Specification
Revision 1.5
May 2004
* Samsung Electronics reserves the right to change products or specification without notice.
Rev. 1.5 May 2004
SDRAM 256Mb E-die (x4, x8, x16)
CMOS SDRAM
Revision History
Revision 1.0 (May. 2003)
- First release.
Revision 1.1 (June. 2003)
- Correct Typo
Revision 1.2 (June. 2003)
- Added 166MHz speed bin in x16
Revision 1.3 (September. 2003)
- Corrected typo in ordering information.
Revision 1.4 (February, 2004)
- Corrected typo.
Revision 1.5 (May, 2004)
Added Note 5. sentense of tRDL parameter
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
16M x 4Bit x 4 Banks / 8M x 8Bit x 4 Banks / 4M x 16Bit x 4 Banks SDRAM
FEATURES
• JEDEC standard 3.3V power supply
• LVTTL compatible with multiplexed address
• Four banks operation
• MRS cycle with address key programs
-. CAS latency (2 & 3)
-. Burst length (1, 2, 4, 8 & Full page)
-. Burst type (Sequential & Interleave)
• All inputs are sampled at the positive going edge of the system clock.
• Burst read single-bit write operation
• DQM (x4,x8) & L(U)DQM (x16) for masking
• Auto & self refresh
• 64ms refresh period (8K Cycle)
GENERAL DESCRIPTION
The K4S560432E / K4S560832E / K4S561632E is 268,435,456 bits synchronous high data rate Dynamic RAM organized as 4 x
16,777,216 words by 4 bits / 4 x 8,388,608 words by 8bits / 4 x 4,194,304 words by 16bits, fabricated with SAMSUNG's high performance CMOS technology. Synchronous design allows precise cycle control with the use of system clock I/O transactions are possible
on every clock cycle. Range of operating frequencies, programmable burst length and programmable latencies allow the same device to
be useful for a variety of high bandwidth, high performance memory system applications.
Ordering Information
Part No.
Orgainization
Max Freq.
K4S560432E-TC(L)75
64M x 4
133MHz (CL=3)
K4S560832E-TC(L)75
32M x 8
133MHz (CL=3)
K4S561632E-TC(L)60/75
16M x 16
166MHz (CL=3)
Interface
Package
LVTTL
54pin TSOP(II)
Organization
Row Address
Column Address
64Mx4
A0~A12
A0-A9, A11
32Mx8
A0~A12
A0-A9
16Mx16
A0~A12
A0-A8
Row & Column address configuration
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
Package Physical Dimension
0~8°C
#1
#27
10.16
0.400
0.125+0.075
-0.035
0.005+0.003
-0.001
22.62
MAX
0.891
22.22
0.875
0.10
MAX
0.004
(
0.71
)
0.028
+0.10
0.30 -0.05
0.012 +0.004
-0.002
± 0.10
0.21
0.008
± 0.004
± 0.05
± 0.002
1.00
0.039
0.80
0.0315
± 0.10
± 0.004
( 0.50 )
0.020
#28
11.76±0.20
0.463±0.008
#54
0.45~0.75
0.018~0.030
0.25
TYP
0.010
1.20
MAX
0.047
0.05
MIN
0.002
54Pin TSOP(II) Package Dimension
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
FUNCTIONAL BLOCK DIAGRAM
I/O Control
Data Input Register
LWE
LDQM
Bank Select
16M x 4 / 8M x 8 / 4M x 16
16M x 4 / 8M x 8 / 4M x 16
Output Buffer
16M x 4 / 8M x 8 / 4M x 16
Sense AMP
Row Decoder
ADD
Row Buffer
Refresh Counter
DQi
Column Decoder
Col. Buffer
LCBR
LRAS
Address Register
CLK
16M x 4 / 8M x 8 / 4M x 16
Latency & Burst Length
LCKE
Programming Register
LRAS
LCBR
LWE
LCAS
LWCBR
LDQM
Timing Register
CLK
CKE
CS
RAS
CAS
WE
L(U)DQM
* Samsung Electronics reserves the right to change products or specification without notice.
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
PIN CONFIGURATION (Top view)
x8
x16
x4
VDD
VDD
VDD
DQ0
DQ0
N.C
VDDQ
VDDQ
VDDQ
DQ1
N.C
N.C
DQ2
DQ1
DQ0
VSSQ
VSSQ
VSSQ
DQ3
N.C
N.C
DQ4
DQ2
N.C
VDDQ
VDDQ
VDDQ
DQ5
N.C
N.C
DQ6
DQ3
DQ1
VSSQ
VSSQ
VSSQ
DQ7
N.C
N.C
VDD
VDD
VDD
LDQM
N.C
N.C
WE
WE
WE
CAS
CAS
CAS
RAS
RAS
RAS
CS
CS
CS
BA0
BA0
BA0
BA1
BA1
BA1
A10/AP A10/AP A10/AP
A0
A0
A0
A1
A1
A1
A2
A2
A2
A3
A3
A3
VDD
VDD
VDD
x4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
VSS
N.C
VSSQ
N.C
DQ3
VDDQ
N.C
N.C
VSSQ
N.C
DQ2
VDDQ
N.C
VSS
N.C/RFU
DQM
CLK
CKE
A12
A11
A9
A8
A7
A6
A5
A4
VSS
x8
VSS
DQ7
VSSQ
N.C
DQ6
VDDQ
N.C
DQ5
VSSQ
N.C
DQ4
VDDQ
N.C
VSS
N.C/RFU
DQM
CLK
CKE
A12
A11
A9
A8
A7
A6
A5
A4
VSS
x16
VSS
DQ15
VSSQ
DQ14
DQ13
VDDQ
DQ12
DQ11
VSSQ
DQ10
DQ9
VDDQ
DQ8
VSS
N.C/RFU
UDQM
CLK
CKE
A12
A11
A9
A8
A7
A6
A5
A4
VSS
54Pin TSOP
(400mil x 875mil)
(0.8 mm Pin pitch)
PIN FUNCTION DESCRIPTION
Pin
Name
Input Function
CLK
System clock
Active on the positive going edge to sample all inputs.
CS
Chip select
Disables or enables device operation by masking or enabling all inputs except
CLK, CKE and DQM
CKE
Clock enable
Masks system clock to freeze operation from the next clock cycle.
CKE should be enabled at least one cycle prior to new command.
Disable input buffers for power down in standby.
A0 ~ A12
Address
Row/column addresses are multiplexed on the same pins.
Row address : RA0 ~ RA12,
Column address : (x4 : CA0 ~ CA9,CA11), (x8 : CA0 ~ CA9), (x16 : CA0 ~ CA8)
BA0 ~ BA1
Bank select address
Selects bank to be activated during row address latch time.
Selects bank for read/write during column address latch time.
RAS
Row address strobe
Latches row addresses on the positive going edge of the CLK with RAS low.
Enables row access & precharge.
CAS
Column address strobe
Latches column addresses on the positive going edge of the CLK with CAS low.
Enables column access.
WE
Write enable
Enables write operation and row precharge.
Latches data in starting from CAS, WE active.
DQM
Data input/output mask
Makes data output Hi-Z, tSHZ after the clock and masks the output.
Blocks data input when DQM active.
DQ0 ~ N
Data input/output
Data inputs/outputs are multiplexed on the same pins.
(x4 : DQ0 ~ 3), (x8 : DQ0 ~ 7), (x16 : DQ0 ~ 15)
VDD/VSS
Power supply/ground
Power and ground for the input buffers and the core logic.
VDDQ/VSSQ
Data output power/ground
Isolated power supply and ground for the output buffers to provide improved noise
immunity.
N.C/RFU
No connection
/reserved for future use
This pin is recommended to be left No Connection on the device.
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
ABSOLUTE MAXIMUM RATINGS
Symbol
Value
Unit
Voltage on any pin relative to Vss
Parameter
VIN, VOUT
-1.0 ~ 4.6
V
Voltage on VDD supply relative to Vss
VDD, VDDQ
-1.0 ~ 4.6
V
TSTG
-55 ~ +150
°C
Storage temperature
Power dissipation
PD
1
W
Short circuit current
IOS
50
mA
Note : Permanent device damage may occur if "ABSOLUTE MAXIMUM RATINGS" are exceeded.
Functional operation should be restricted to recommended operating condition.
Exposure to higher than recommended voltage for extended periods of time could affect device reliability.
DC OPERATING CONDITIONS
Recommended operating conditions (Voltage referenced to VSS = 0V, TA = 0 to 70°C)
Parameter
Supply voltage
Symbol
Min
Typ
Max
Unit
VDD, VDDQ
3.0
3.3
3.6
V
Note
Input logic high voltage
VIH
2.0
3.0
VDD+0.3
V
Input logic low voltage
VIL
-0.3
0
0.8
V
2
Output logic high voltage
VOH
2.4
-
-
V
IOH = -2mA
Output logic low voltage
VOL
-
-
0.4
V
IOL = 2mA
ILI
-10
-
10
uA
3
Input leakage current
1
Notes : 1. VIH (max) = 5.6V AC. The overshoot voltage duration is ≤ 3ns.
2. VIL (min) = -2.0V AC. The undershoot voltage duration is ≤ 3ns.
3. Any input 0V ≤ VIN ≤ VDDQ.
Input leakage currents include Hi-Z output leakage for all bi-directional buffers with Tri-State outputs.
CAPACITANCE
(VDD = 3.3V, TA = 23°C, f = 1MHz, VREF =1.4V ± 200 mV)
Pin
Clock
RAS, CAS, WE, CS, CKE, DQM
Symbol
Min
Max
Unit
CCLK
2.5
3.5
pF
CIN
2.5
3.8
pF
Address
CADD
2.5
3.8
pF
(x4 : DQ0 ~ DQ3), (x8 : DQ0 ~ DQ7), (x16 : DQ0 ~ DQ15)
COUT
4.0
6.0
pF
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
DC CHARACTERISTICS (x4, x8)
(Recommended operating condition unless otherwise noted, TA = 0 to 70°C)
Parameter
Operating current
(One bank active)
Precharge standby current in
power-down mode
Precharge standby current in
non power-down mode
Active standby current in
power-down mode
Active standby current in
non power-down mode
(One bank active)
Symbol
ICC1
ICC2P
75
Burst length = 1
tRC ≥ tRC(min)
IO = 0 mA
80
CKE ≤ VIL(max), tCC = 10ns
2
ICC2PS CKE & CLK ≤ VIL(max), tCC = ∞
ICC2N
ICC2NS
ICC3P
20
CKE ≥ VIH(min), CLK ≤ VIL(max), tCC = ∞
Input signals are stable
10
CKE ≤ VIL(max), tCC = 10ns
6
ICC3PS CKE & CLK ≤ VIL(max), tCC = ∞
ICC3N
ICC3NS
Note
mA
1
mA
mA
6
CKE ≥ VIH(min), CS ≥ VIH(min), tCC = 10ns
Input signals are changed one time during 20ns
25
mA
CKE ≥ VIH(min), CLK ≤ VIL(max), tCC = ∞
Input signals are stable
25
mA
100
mA
1
ICC4
IO = 0 mA
Page burst
4banks Activated.
tCCD = 2CLKs
Refresh current
ICC5
tRC ≥ tRC(min)
ICC6
Unit
mA
2
CKE ≥ VIH(min), CS ≥ VIH(min), tCC = 10ns
Input signals are changed one time during 20ns
Operating current
(Burst mode)
Self refresh current
Version
Test Condition
CKE ≤ 0.2V
180
mA
2
C
3
mA
3
L
1.5
mA
4
Notes : 1. Measured with outputs open.
2. Refresh period is 64ms.
3. K4S5604(08)32E-TC
4. K4S5604(08)32E-TL
5. Unless otherwise noticed, input swing level is CMOS(VIH/VIL=VDDQ/VSSQ).
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
DC CHARACTERISTICS (x16)
(Recommended operating condition unless otherwise noted, TA = 0 to 70°C)
Parameter
Operating current
(One bank active)
Precharge standby current in
power-down mode
Precharge standby current in
non power-down mode
Active standby current in
power-down mode
Active standby current in
non power-down mode
(One bank active)
Symbol
ICC1
ICC2P
ICC2PS
ICC2N
ICC2NS
ICC3P
ICC3PS
ICC3N
ICC3NS
Version
Test Condition
Burst length = 1
tRC ≥ tRC(min)
IO = 0 mA
60
75
140
90
Unit Note
mA
CKE ≤ VIL(max), tCC = 10ns
2
CKE & CLK ≤ VIL(max), tCC = ∞
2
CKE ≥ VIH(min), CS ≥ VIH(min), tCC = 10ns
Input signals are changed one time during 20ns
20
CKE ≥ VIH(min), CLK ≤ VIL(max), tCC = ∞
Input signals are stable
10
CKE ≤ VIL(max), tCC = 10ns
6
CKE & CLK ≤ VIL(max), tCC = ∞
6
CKE ≥ VIH(min), CS ≥ VIH(min), tCC = 10ns
Input signals are changed one time during 20ns
25
mA
CKE ≥ VIH(min), CLK ≤ VIL(max), tCC = ∞
Input signals are stable
25
mA
1
mA
mA
mA
Operating current
(Burst mode)
ICC4
IO = 0 mA
Page burst
4banks Activated.
tCCD = 2CLKs
170
130
mA
1
Refresh current
ICC5
tRC ≥ tRC(min)
200
180
mA
2
Self refresh current
ICC6
CKE ≤ 0.2V
C
3
mA
3
L
1.5
mA
4
Notes : 1. Measured with outputs open.
2. Refresh period is 64ms.
3. K4S561632E-TC
4. K4S561632E-TL
5. Unless otherwise noticed, input swing level is CMOS(VIH/VIL=VDDQ/VSSQ).
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
AC OPERATING TEST CONDITIONS (VDD = 3.3V ± 0.3V, TA = 0 to 70°C)
Parameter
Value
AC input levels (Vih/Vil)
2.4/0.4
V
1.4
V
tr/tf = 1/1
ns
1.4
V
Input timing measurement reference level
Input rise and fall time
Output timing measurement reference level
Output load condition
Unit
See Fig. 2
3.3V
Vtt = 1.4V
1200Ω
50Ω
VOH (DC) = 2.4V, IOH = -2mA
VOL (DC) = 0.4V, IOL = 2mA
Output
870Ω
Z0 = 50Ω
Output
50pF
50pF
(Fig. 1) DC output load circuit
(Fig. 2) AC output load circuit
OPERATING AC PARAMETER
(AC operating conditions unless otherwise noted)
Parameter
Symbol
Version
60
75
Unit
Note
1
Row active to row active delay
tRRD(min)
12
15
ns
RAS to CAS delay
tRCD(min)
18
20
ns
1
Row precharge time
tRP(min)
18
20
ns
1
tRAS(min)
42
ns
1
Row active time
tRAS(max)
45
100
us
65
Row cycle time
tRC(min)
Last data in to row precharge
tRDL(min)
2
Last data in to Active delay
tDAL(min)
2 CLK + tRP
-
5
Last data in to new col. address delay
tCDL(min)
1
CLK
2
Last data in to burst stop
tBDL(min)
1
CLK
2
tCCD(min)
1
CLK
3
ea
4
Col. address to col. address delay
Number of valid output data
60
CAS latency=3
CAS latency=2
2
-
1
ns
1
CLK
2,5
Notes : 1. The minimum number of clock cycles is determined by dividing the minimum time required with clock cycle time
and then rounding off to the next higher integer.
2. Minimum delay is required to complete write.
3. All parts allow every cycle column address change.
4. In case of row precharge interrupt, auto precharge and read burst stop.
5. In 100MHz and below 100MHz operating conditions, tRDL=1CLK and tDAL=1CLK + 20ns is also supported.
SAMSUNG recommends tRDL=2CLK and tDAL=2CLK + tRP.
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
AC CHARACTERISTICS (AC operating conditions unless otherwise noted)
Parameter
Symbol
CAS latency=3
CLK cycle time
CAS latency=2
CLK to valid
output delay
CAS latency=3
Output data
hold time
CAS latency=3
CAS latency=2
60
Min
6
tCC
-
tSAC
75
Max
1000
Min
7.5
10
Max
Unit
Note
ns
1
ns
1,2
ns
2
1000
5
5.4
-
6
2.5
3
-
3
tCH
2.5
2.5
ns
3
CLK low pulse width
tCL
2.5
2.5
ns
3
Input setup time
tSS
1.5
1.5
ns
3
Input hold time
tSH
1
0.8
ns
3
tSLZ
1
ns
2
CAS latency=2
CLK high pulse width
CLK to output in Low-Z
CAS latency=3
CLK to output in Hi-Z
CAS latency=2
tOH
tSHZ
1
5
5.4
-
6
ns
Notes : 1. Parameters depend on programmed CAS latency.
2. If clock rising time is longer than 1ns, (tr/2-0.5)ns should be added to the parameter.
3. Assumed input rise and fall time (tr & tf) = 1ns.
If tr & tf is longer than 1ns, transient time compensation should be considered,
i.e., [(tr + tf)/2-1]ns should be added to the parameter.
DQ BUFFER OUTPUT DRIVE CHARACTERISTICS
Parameter
Symbol
Condition
Min
Output rise time
trh
Measure in linear
region : 1.2V ~ 1.8V
Output fall time
tfh
Output rise time
Output fall time
Typ
Max
Unit
Notes
1.37
4.37
Volts/ns
3
Measure in linear
region : 1.2V ~ 1.8V
1.30
3.8
Volts/ns
3
trh
Measure in linear
region : 1.2V ~ 1.8V
2.8
3.9
5.6
Volts/ns
1,2
tfh
Measure in linear
region : 1.2V ~ 1.8V
2.0
2.9
5.0
Volts/ns
1,2
Notes : 1. Rise time specification based on 0pF + 50 Ω to VSS, use these values to design to.
2. Fall time specification based on 0pF + 50 Ω to VDD, use these values to design to.
3. Measured into 50pF only, use these values to characterize to.
4. All measurements done with respect to VSS.
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
IBIS SPECIFICATION
100MHz/133MHz Pull-up
0
IOH Characteristics (Pull-up)
(V)
3.45
3.3
3.0
2.6
2.4
2.0
1.8
1.65
1.5
1.4
1.0
0.0
0.0
-21.1
-34.1
-58.7
-67.3
-73.0
-77.9
-80.8
-88.6
-93.0
100MHz
133MHz
Max
I (mA)
-2.4
-27.3
-74.1
-129.2
-153.3
-197.0
-226.2
-248.0
-269.7
-284.3
-344.5
-502.4
0.5
1
1.5
2
2.5
3
3.5
0
-100
-200
mA
Voltage
100MHz
133MHz
Min
I (mA)
-300
-400
-500
-600
Voltage
IOH Min (100MHz/133MHz)
IOH Max (66 and 100MHz/133MHz)
100MHz/133MHz Pull-down
IOL Characteristics (Pull-down)
(V)
0.0
0.4
0.65
0.85
1.0
1.4
1.5
1.65
1.8
1.95
3.0
3.45
100MHz
133MHz
Min
I (mA)
0.0
27.5
41.8
51.6
58.0
70.7
72.9
75.4
77.0
77.6
80.3
81.4
100MHz
133MHz
Max
I (mA)
0.0
70.2
107.5
133.8
151.2
187.7
194.4
202.5
208.6
212.0
219.6
222.6
250
200
150
mA
Voltage
100
50
0
0
0.5
1
1.5
2
2.5
3
3.5
Voltage
IOL Min (100MHz/133MHz)
IOL Max (100MHz/133MHz)
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
Minimum VDD clamp current
(Referenced to VDD)
VDD Clamp @ CLK, CKE, CS, DQM & DQ
I (mA)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.23
1.34
3.02
5.06
7.35
9.83
12.48
15.30
18.31
20
15
mA
VDD (V)
0.0
0.2
0.4
0.6
0.7
0.8
0.9
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
10
5
0
0
1
2
3
Voltage
I (mA)
Minimum VSS clamp current
VSS Clamp @ CLK, CKE, CS, DQM & DQ
I (mA)
-57.23
-45.77
-38.26
-31.22
-24.58
-18.37
-12.56
-7.57
-3.37
-1.75
-0.58
-0.05
0.0
0.0
0.0
0.0
-3
-2
-1
0
0
-10
-20
mA
VSS (V)
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
-0.9
-0.8
-0.7
-0.6
-0.4
-0.2
0.0
-30
-40
-50
-60
Voltage
I (mA)
Rev. 1.5 May 2004
CMOS SDRAM
SDRAM 256Mb E-die (x4, x8, x16)
SIMPLIFIED TRUTH TABLE
Command
Register
CKEn-1
Mode register set
Auto refresh
Refresh
Entry
Self
refresh
(V=Valid, X=Don't care, H=Logic high, L=Logic low)
H
H
CKEn
CS
RAS
CAS
WE
DQM
X
L
L
L
L
X
OP code
L
L
L
H
X
X
X
X
H
L
L
H
H
H
H
X
X
X
X
L
L
H
H
X
V
H
X
L
H
L
H
X
V
H
X
L
H
L
L
X
V
H
X
L
H
H
L
X
H
X
L
L
H
L
X
Entry
H
L
H
X
X
X
L
V
V
V
Exit
L
H
X
X
X
X
Entry
H
L
Exit
L
H
L
H
Bank active & row addr.
H
Read &
column address
Write &
column address
Exit
Auto precharge disable
Auto precharge enable
Auto precharge disable
Auto precharge enable
Burst stop
Precharge
Bank selection
All banks
Clock suspend or
active power down
BA0,1
Precharge power down mode
DQM
H
No operation command
H
H
X
X
X
L
H
H
H
H
X
X
X
V
V
V
L
X
X
H
X
X
X
L
H
H
H
X
A10/AP
A0 ~ A9
A11, A12
Note
1,2
3
3
3
3
Row address
L
Column
address
H
L
Column
address
H
X
V
L
X
H
4
4,5
4
4,5
6
X
X
X
X
X
X
V
X
X
X
7
Notes : 1. OP Code : Operand code
A0 ~ A12 & BA0 ~ BA1 : Program keys. (@ MRS)
2. MRS can be issued only at all banks precharge state.
A new command can be issued after 2 CLK cycles of MRS.
3. Auto refresh functions are as same as CBR refresh of DRAM.
The automatical precharge without row precharge command is meant by "Auto".
Auto/self refresh can be issued only at all banks precharge state.
4. BA0 ~ BA1 : Bank select addresses.
If both BA0 and BA1 are "Low" at read, write, row active and precharge, bank A is selected.
If BA0 is "High" and BA1 is "Low" at read, write, row active and precharge, bank B is selected.
If BA0 is "Low" and BA1 is "High" at read, write, row active and precharge, bank C is selected.
If both BA0 and BA1 are "High" at read, write, row active and precharge, bank D is selected.
If A10/AP is "High" at row precharge, BA0 and BA1 is ignored and all banks are selected.
5. During burst read or write with auto precharge, new read/write command can not be issued.
Another bank read/write command can be issued after the end of burst.
New row active of the associated bank can be issued at tRP after the end of burst.
6. Burst stop command is valid at every burst length.
7. DQM sampled at positive going edge of a CLK and masks the data-in at the very CLK (Write DQM latency is 0),
but makes Hi-Z state the data-out of 2 CLK cycles after. (Read DQM latency is 2)
Rev. 1.5 May 2004