K7A401800M
Document Title
256Kx18-Bit Synchronous Pipelined Burst SRAM
256Kx18 Synchronous SRAM
Revision History
Rev. No.
0.0
0.1
History
Initial draft
Change DC characteristics V
DD
condition from V
DD
=3.3V+10%/-5% Change
Input/output leackage currant from
±1µA
to
±2µA
Modify Read timing & Power down cycle timing.
Change I
SB2
value from 30mA to 20mA.
Remove DC characteristics I
SB1
- L ver. & I
SB2
- L ver .
Remove Low power version.
Change Undershoot spec
from -3.0V(pulse width
≤
20ns) to -2.0V(pulse width
≤
t
CYC
/2)
Add Overshoot spec 4.6V((pulse width
≤
t
CYC
/2)
Change V
IH
max from 5.5V to V
DD
+0.5V
Change I
SB2
value from 20mA to 30mA.
Change V
DD
condition from V
DD
=3.3V+10%/-5% to V
DD
=3.3V+0.3V/-0.165V.
Modify DC characteristics( Input Leakage Current test Conditions)
form V
DD
=V
SS to
V
DD
to Max.
Final spec Release
Add V
DDQ
Supply voltage( 3.3V I/O)
Draft Date
February. 02. 1998
February. 12. 1998
Remark
Preliminary
Preliminary
0.2
April. 14. 1998
Preliminary
0.3
May. 13. 1998
Preliminary
0.4
May. 14.1998
Preliminary
1.0
2.0
May. 15. 1998
Mar. 31. 1999
Final
Final
The attached data sheets are prepared and approved by SAMSUNG Electronics. SAMSUNG Electronics CO., LTD. reserve the right to change the
specifications. SAMSUNG Electronics will evaluate and reply to your requests and questions on the parameters of this device. If you have any ques-
tions, please contact the SAMSUNG branch office near your office, call or contact Headquarters.
-1-
March 1999
Rev 2.0
K7A401800M
256Kx18 Synchronous SRAM
256Kx18-Bit Synchronous Pipelined Burst SRAM
FEATURES
• Synchronous Operation.
• 2 Stage Pipelined Operation With 4 Burst
• On-Chip Address Counter.
• Self-Timed Write Cycle.
• On-Chip Address and Control Registers.
• V
DD
=3.3V+0.3V/-0.165V Power Supply.
• V
DDQ
Supply Voltage 3.3V+0.3V/-0.165V for 3.3V I/O
or 2.5V+0.4V/-0.125V for 2.5V I/O.
• 5V Tolerant Inputs except I/O Pins.
• Byte Writable Function.
• Global Write Enable Controls a full bus-width write.
• Power Down State via ZZ Signal.
• LBO Pin allows a choice of either a interleaved burst or a lin-
ear burst.
• Three Chip Enables for simple depth expansion with No Data
Contention ; 2 cycle Enable, 1 cycle Disable.
• Asynchronous Output Enable Control.
• ADSP, ADSC, ADV Burst Control Pins.
• TTL-Level Three-State Output.
• 100-TQFP-1420A
GENERAL DESCRIPTION
The K7A401800M is a 4,718,592 bits Synchronous Static Ran-
dom Access Memory designed for high performance second
level cache of pentium and Power PC based system.
It is organized as 256K words of 18 bits. And it integrates
address and control registers, a 2-bit burst address counter and
added some new functions for high performance cache RAM
applications; GW, BW, LBO, ZZ.
Write cycles are internally self-timed and synchronous.
Full bus-width write is done by GW, and each byte write is per-
formed by the combination of WEx and BW when GW is high.
And with CS
1
high, ADSP disable to support address pipelining.
Burst cycle can be initiated with either the address status pro-
cessor(ADSP) or address status cache controller(ADSC)
inputs. Subsequent burst addresses are generated internally in
the system′s burst sequence and are controlled by the burst
address advance(ADV) input.
LBO pin is DC operated and determines burst sequence (linear
or interleaved).
ZZ pin controls Power Down State and reduces Stand-by cur-
rent regardless of CLK.
The K7A401800M is fabricated using SAMSUNG′s high perfor-
mance CMOS technology and is available in a 100pin TQFP.
Multiple power and ground pins are utilized to minimize ground
bounce.
FAST ACCESS TIMES
Parameter
Cycle Time
Clock Access Time
Output Enable Access Time
Symbol -16 -15 -14 -11 Unit
t
CYC
t
CD
t
OE
6.0 6.7 7.2 8.5
3.5 3.8 4.0 4.0
3.5 3.8 4.0 4.0
ns
ns
ns
LOGIC BLOCK DIAGRAM
CLK
LBO
ADV
ADSC
BURST CONTROL
LOGIC
CONTROL
REGISTER
BURST
ADDRESS
COUNTER
A′
0
~
A′
1
256Kx18
MEMORY
ARRAY
A
0
~
A
1
A
0
~
A
17
ADDRESS
REGISTER
A
2
~
A
17
ADSP
CS
1
CS
2
CS
2
GW
BW
WEa
WEb
OE
ZZ
DQa
0
~ DQb
7
DQPa ~ DQPb
DATA-IN
REGISTER
CONTROL
REGISTER
CONTROL
LOGIC
OUTPUT
REGISTER
BUFFER
-2-
March 1999
Rev 2.0
K7A401800M
PIN CONFIGURATION
(TOP VIEW)
256Kx18 Synchronous SRAM
ADSC
ADSP
WEb
WEa
ADV
83
N.C.
N.C.
CLK
CS
1
CS
2
CS
2
V
DD
GW
V
SS
BW
OE
A
6
A
7
A
8
82
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
81
A
9
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
N.C.
N.C.
V
SS
N.C.
N.C.
V
DD
A
5
A
4
A
3
A
2
A
1
A
0
A
11
A
12
A
13
A
14
A
15
A
16
PIN NAME
SYMBOL
A
0
- A
17
PIN NAME
Address Inputs
TQFP PIN NO.
32,33,34,35,36,37,
44,45,46,47,48,49,
50,80,81,82,99,100
83
84
85
89
98
97
92
93,94
86
88
87
64
31
SYMBOL
V
DD
V
SS
N.C.
PIN NAME
Power Supply(+3.3V)
Ground
No Connect
TQFP PIN NO.
15,41,65,91
17,40,67,90
1,2,3,6,7,14,16,25,28,29,
30,38,39,42,43,51,52,53,
56,57,66,75,78,79,95,96
58,59,62,63,68,69,72,73
8,9,12,13,18,19,22,23
74,24
4,11,20,27,54,61,70,77
5,10,21,26,55,60,71,76
ADV
ADSP
ADSC
CLK
CS
1
CS
2
CS
2
WEx
OE
GW
BW
ZZ
LBO
Burst Address Advance
Address Status Processor
Address Status Controller
Clock
Chip Select
Chip Select
Chip Select
Byte Write Inputs
Output Enable
Global Write Enable
Byte Write Enable
Power Down Input
Burst Mode Control
LBO
DQa
0
~a
7
DQb
0
~b
7
DQPa, Pb
V
DDQ
V
SSQ
Data Inputs/Outputs
Output Power Supply
(2.5V or 3.3V)
Output Ground
-3-
A
17
50
N.C.
N.C.
N.C.
V
DDQ
V
SSQ
N.C.
N.C.
DQb
0
DQb
1
V
SSQ
V
DDQ
DQb
2
DQb
3
N.C.
V
DD
N.C.
V
SS
DQb
4
DQb
5
V
DDQ
V
SSQ
DQb
6
DQb
7
DQPb
N.C.
V
SSQ
V
DDQ
N.C.
N.C.
N.C.
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
28
29
30
100 Pin TQFP
(20mm x 14mm)
A
10
N.C.
N.C.
V
DDQ
V
SSQ
N.C.
DQPa
DQa
7
DQa
6
V
SSQ
V
DDQ
DQa
5
DQa
4
V
SS
N.C.
V
DD
ZZ
DQa
3
DQa
2
V
DDQ
V
SSQ
DQa
1
DQa
0
N.C.
N.C.
V
SSQ
V
DDQ
N.C.
N.C.
N.C.
March 1999
Rev 2.0
K7A401800M
FUNCTION DESCRIPTION
256Kx18 Synchronous SRAM
The K7A401800M is a synchronous SRAM designed to support the burst address accessing sequence of the Pentium and Power
PC based microprocessor. All inputs(with the exception of OE, LBO and ZZ) are sampled on rising clock edges. The start and dura-
tion of the burst access is controlled by ADSP, ADSC, ADV and Chip Select pins.
The accesses are enabled with the chip select signals and output enabled signals. Wait states are inserted into the access with
ADV.
When ZZ is pulled high, the SRAM will enter a Power Down State. At this time, internal state of the SRAM is preserved. When ZZ
returns to low, the SRAM normally operates after 2 cycles of wake up time. ZZ pin is pulled down internally.
Read cycles are initiated with ADSP(regardless of WEx and ADSC) using the new external address clocked into the on-chip
address register whenever ADSP is sampled low, the chip selects are sampled active, and the output buffer is enabled with OE. In
read operation the data of cell array accessed by the current address, registered in the Data-out registers by the positive edge of
CLK, are carried to the Data-out buffer by the next positive edge of CLK. The data, registered in the Data-out buffer, are projected to
the output pins. ADV is ignored on the clock edge that samples ADSP asserted, but is sampled on the subsequent clock edges. The
address increases internally for the next access of the burst when WEx are sampled High and ADV is sampled Low. And ADSP is
blocked to control signals by disabling CS
1
.
All byte write is done by GW (regardless of BW and WEx.), and each byte write is performed by the combination of BW and WEx
when GW is High.
Write cycles are performed by disabling the output buffers with OE and asserting WEx. WEx are ignored on the clock edge that sam-
ples ADSP Low, but are sampled on the subsequent clock edges. The output buffers are disabled when WEx are sampled
Low(regaedless of OE). Data is clocked into the data input register when WEx sampled Low. The address increases internally to the
next address of burst, if both WEx and ADV are sampled Low. Individual byte write cycles are performed by any one or more byte
write enable signals(WEa or WEb) sampled low. The WEa controls DQa
0
~ DQa
7
and DQPa, WEb controls DQb
0
~ DQb
7
and
DQPb. Read or write cycle may also be initiated with ADSC, instead of ADSP. The differences between cycles initiated with ADSC
and ADSP as are follows;
ADSP must be sampled high when ADSC is sampled low to initiate a cycle with ADSC.
WEx are sampled on the same clock edge that sampled ADSC low(and ADSP high).
Addresses are generated for the burst access as shown below, The starting point of the burst sequence is provided by the external
address. The burst address counter wraps around to its initial state upon completion. The burst sequence is determined by the state
of the LBO pin. When this pin is Low, linear burst sequence is selected. And when this pin is High, Interleaved burst sequence is
selected.
BURST SEQUENCE TABLE
LBO PIN
HIGH
First Address
Case 1
A
1
0
0
1
1
A
0
0
1
0
1
A
1
0
0
1
1
Case 2
A
0
1
0
1
0
A
1
1
1
0
0
Case 3
A
0
0
1
0
1
(Interleaved Burst)
Case 4
A
1
1
1
0
0
A
0
1
0
1
0
Fourth Address
BURST SEQUENCE TABLE
LBO PIN
LOW
First Address
Case 1
A
1
0
0
1
1
A
0
0
1
0
1
A
1
0
1
1
0
Case 2
A
0
1
0
1
0
A
1
1
1
0
0
Case 3
A
0
0
1
0
1
A
1
1
0
0
1
(Linear Burst)
Case 4
A
0
1
0
1
0
Fourth Address
Note :
1. LBO pin must be tied to High or Low, and Floating State must not be allowed.
-4-
March 1999
Rev 2.0
K7A401800M
TRUTH TABLES
SYNCHRONOUS TRUTH TABLE
CS
1
H
L
L
L
L
L
L
L
X
H
X
H
X
H
X
H
CS
2
X
L
X
L
X
H
H
H
X
X
X
X
X
X
X
X
CS
2
X
X
H
X
H
L
L
L
X
X
X
X
X
X
X
X
ADSP ADSC
X
L
L
X
X
L
H
H
H
X
H
X
H
X
H
X
L
X
X
L
L
X
L
L
H
H
H
H
H
H
H
H
ADV
X
X
X
X
X
X
X
X
L
L
L
L
H
H
H
H
WRITE
X
X
X
X
X
X
L
H
H
H
L
L
H
H
L
L
CLK
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
↑
256Kx18 Synchronous SRAM
ADDRESS ACCESSED
N/A
N/A
N/A
N/A
N/A
External Address
External Address
External Address
Next Address
Next Address
Next Address
Next Address
Current Address
Current Address
Current Address
Current Address
OPERATION
Not Selected
Not Selected
Not Selected
Not Selected
Not Selected
Begin Burst Read Cycle
Begin Burst Write Cycle
Begin Burst Read Cycle
Continue Burst Read Cycle
Continue Burst Read Cycle
Continue Burst Write Cycle
Continue Burst Write Cycle
Suspend Burst Read Cycle
Suspend Burst Read Cycle
Suspend Burst Write Cycle
Suspend Burst Write Cycle
Notes :
1. X means "Don′t Care".
2. The rising edge of clock is symbolized by
↑.
3. WRITE = L means Write operation in WRITE TRUTH TABLE.
WRITE = H means Read operation in WRITE TRUTH TABLE.
4. Operation finally depends on status of asynchronous input pins(ZZ and OE).
WRITE TRUTH TABLE
GW
H
H
H
H
H
L
BW
H
L
L
L
L
X
WEa
X
H
L
H
L
X
WEb
X
H
H
L
L
X
OPERATION
READ
READ
WRITE BYTE a
WRITE BYTE b
WRITE ALL BYTEs
WRITE ALL BYTEs
Notes :
1. X means "Don′t Care".
2. All inputs in this table must meet setup and hold time around the rising edge of CLK(↑).
ASYNCHRONOUS TRUTH TABLE
(See Notes 1 and 2)
:
OPERATION
Sleep Mode
Read
Write
Deselected
ZZ
H
L
L
L
L
OE
X
L
H
X
X
I/O STATUS
High-Z
DQ
High-Z
Din, High-Z
High-Z
Notes
1. X means "Don′t Care".
2. ZZ pin is pulled down internally
3. For write cycles that following read cycles, the output buffers must be
disabled with OE, otherwise data bus contention will occur.
4. Sleep Mode means power down state of which stand-by current does
not depend on cycle time.
5. Deselected means power down state of which stand-by current
depends on cycle time.
-5-
March 1999
Rev 2.0
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