ALSC AS7C251MNTD18A

December 2004
AS7C251MNTD18A
®
2.5V 1M x 18 Pipelined SRAM with NTDTM
Features
•
•
•
•
•
•
•
•
•
Organization: 1,048,576 words × 18 bits
NTD™architecture for efficient bus operation
Fast clock speeds to 166 MHz
Fast clock to data access: 3.5/3.8 ns
Fast OE access time: 3.5/3.8 ns
Fully synchronous operation
Asynchronous output enable control
Available in 100-pin TQFP package
Individual byte write and global write
•
•
•
•
•
•
Clock enable for operation hold
Multiple chip enables for easy expansion
2.5V core power supply
Self-timed write cycles
Interleaved or linear burst modes
Snooze mode for standby operation
Logic block diagram
20
A[19:0]
D
Address
register
burst logic
Q
20
CLK
D
Q
Write delay
addr. registers
CE0
CE1
CE2
20
CLK
R/W
Control
logic
BWa
BWb
CLK
LBO
ZZ
DQ [a,b]
Write Buffer
ADV / LD
CLK
18
D
1M x 18
SRAM
array
18
Data Q
input
register
18
CLK
18
18
CLK
CEN
CLK
Output
register
OE
18
OE
DQ [a,b]
Selection guide
-166
-133
Units
6
7.5
ns
Maximum clock frequency
166
133
MHz
Maximum clock access time
3.5
3.8
ns
Maximum operating current
290
270
mA
Maximum standby current
85
75
mA
Maximum CMOS standby current (DC)
40
40
mA
Minimum cycle time
12/23/04, v.2.2
Alliance Semiconductor
P. 1 of 18
Copyright © Alliance Semiconductor. All rights reserved.
AS7C251MNTD18A
®
16 Mb 2.5V Synchronous SRAM products list1,2
Org
1MX18
512KX32
512KX36
1MX18
512KX32
512KX36
1MX18
512KX32
512KX36
1MX18
512KX32
512KX36
1MX18
512KX32
512KX36
Part Number
AS7C251MPFS18A
AS7C25512PFS32A
AS7C25512PFS36A
AS7C251MPFD18A
AS7C25512PFD32A
AS7C25512PFD36A
AS7C251MFT18A
AS7C25512FT32A
AS7C25512FT36A
AS7C251MNTD18A
AS7C25512NTD32A
AS7C25512NTD36A
AS7C251MNTF18A
AS7C25512NTF32A
AS7C25512NTF36A
Mode
PL-SCD
PL-SCD
PL-SCD
PL-DCD
PL-DCD
PL-DCD
FT
FT
FT
NTD-PL
NTD-PL
NTD-PL
NTD-FT
NTD-FT
NTD-FT
Speed
166/133 MHz
166/133 MHz
166/133 MHz
166/133 MHz
166/133 MHz
166/133 MHz
7.5/8.5/10 ns
7.5/8.5/10 ns
7.5/8.5/10 ns
166/133 MHz
166/133 MHz
166/133 MHz
7.5/8.5/10 ns
7.5/8.5/10 ns
7.5/8.5/10 ns
1 Core Power Supply: VDD = 2.5V + 0.125V
2 I/O Supply Voltage: VDDQ = 2.5V + 0.125V
PL-SCD
PL-DCD
FT
NTD1-PL
NTD-FT
:
:
:
:
:
Pipelined Burst Synchronous SRAM - Single Cycle Deselect
Pipelined Burst Synchronous SRAM - Double Cycle Deselect
Flow-through Burst Synchronous SRAM
Pipelined Burst Synchronous SRAM with NTDTM
Flow-through Burst Synchronous SRAM with NTDTM
1. NTD: No Turnaround Delay. NTDTM is a trademark of Alliance Semiconductor Corporation. All trademarks mentioned in this document are the property
of their respective owners.
12/23/04, v.2.2
Alliance Semiconductor
P. 2 of 18
AS7C251MNTD18A
®
Pin assignment
91
90
89
88
87
86
85
84
83
82
81
TQFP 14 x 20mm
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
A
NC
NC
VDDQ
VSSQ
NC
DQPa
DQa7
DQa6
VSSQ
VDDQ
DQa5
DQa4
VSS
NC
VDD
ZZ
DQa3
DQa2
VDDQ
VSSQ
DQa1
DQa0
NC
NC
VSSQ
VDDQ
NC
NC
NC
LBO
A
A
A
A
A1
A0
NC
NC
VSS
VDD
NC
NC
A
A
A
A
A
A
A
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
VDDQ
VSSQ
NC
NC
DQb0
DQb1
VSSQ
VDDQ
DQb2
DQb3
NC
VDD
NC
VSS
DQb4
DQb5
VDDQ
VSSQ
DQb6
DQb7
DQPb
NC
VSSQ
VDDQ
NC
NC
NC
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
92
NC
NC
NC
100
99
98
97
96
95
94
93
A
A
CE0
CE1
NC
NC
BWb
BWa
CE2
VDD
VSS
CLK
R/W
CEN
OE
ADV/LD
A
A
A
A
100-pin TQFP - top view
12/23/04, v.2.2
Alliance Semiconductor
P. 3 of 18
AS7C251MNTD18A
®
Functional description
The AS7C251MNTD18A family is a high performance CMOS 16-Mbit synchronous Static Random Access Memory (SRAM) organized as
1,048,576 words × 18 bits and incorporates a LATE LATE Write.
This variation of the 16Mb+ synchronous SRAM uses the No Turnaround Delay (NTD™) architecture, featuring an enhanced write
operation that improves bandwidth over pipelined burst devices. In a normal pipelined burst device, the write data, command, and address
are all applied to the device on the same clock edge. If a read command follows this write command, the system must wait for two 'dead'
cycles for valid data to become available. These dead cycles can significantly reduce overall bandwidth for applications requiring random
access or read-modify-write operations.
NTD™ devices use the memory bus more efficiently by introducing a write latency which matches the two-cycle pipelined or one-cycle
flow-through read latency. Write data is applied two cycles after the write command and address, allowing the read pipeline to clear. With
NTD™, write and read operations can be used in any order without producing dead bus cycles.
Assert R/W low to perform write cycles. Byte write enable controls write access to specific bytes, or can be tied low for full 18 bit writes.
Write enable signals, along with the write address, are registered on a rising edge of the clock. Write data is applied to the device two clock
cycles later. Unlike some asynchronous SRAMs, output enable OE does not need to be toggled for write operations; it can be tied low for
normal operations. Outputs go to a high impedance state when the device is de-selected by any of the three chip enable inputs. In pipelined
mode, a two cycle deselect latency allows pending read or write operations to be completed.
Use the ADV (burst advance) input to perform burst read, write and deselect operations. When ADV is high, external addresses, chip select, R/W
pins are ignored, and internal address counters increment in the count sequence specified by the LBO control. Any device operations, including
burst, can be stalled using the CEN=1, the clock enable input.
The AS7C251MNTD18A operates with a 2.5V ± 5% power supply for the device core (VDD). These devices are available in a 100-pin
TQFP package.
TQFP capacitance
Parameter
Input capacitance
I/O capacitance
Symbol
CIN*
CI/O*
Test conditions
VIN = 0V
VOUT = 0V
Min
-
Max
5
7
Unit
pF
pF
* Guaranteed not tested
TQFP thermal resistance
Description
Thermal resistance
(junction to ambient)1
Thermal resistance
(junction to top of case)1
Conditions
Test conditions follow standard test methods
and procedures for measuring thermal
impedance, per EIA/JESD51
1–layer
Symbol
θJA
4–layer
θJA
Typical
40
22
θJC
8
Units
°C/W
°C/W
°C/W
1 This parameter is sampled
12/23/04, v.2.2
Alliance Semiconductor
P. 4 of 18
AS7C251MNTD18A
®
Signal descriptions
Signal
I/O
Properties Description
CLK
I
CLOCK
CEN
I
SYNC
Clock enable. When de-asserted high, the clock input signal is masked.
A, A0, A1
Clock. All inputs except OE, LBO, and ZZ are synchronous to this clock.
I
SYNC
Address. Sampled when all chip enables are active and ADV/LD is asserted.
I/O
SYNC
Data. Driven as output when the chip is enabled and OE is active.
CE0, CE1,
CE2
I
SYNC
Synchronous chip enables. Sampled at the rising edge of CLK, when ADV/LD is asserted.
Are ignored when ADV/LD is high.
ADV/LD
I
SYNC
Advance or Load. When sampled high, the internal burst address counter will increment in
the order defined by the LBO input value. When low, a new address is loaded.
R/W
I
SYNC
A high during LOAD initiates a READ operation. A low during LOAD initiates a WRITE
operation. Is ignored when ADV/LD is high.
BW[a,b]
I
SYNC
Byte write enables. Used to control write on individual bytes. Sampled along with WRITE
command and BURST WRITE.
OE
I
ASYNC
Asynchronous output enable. I/O pins are not driven when OE is inactive.
LBO
I
STATIC
Selects Burst mode. When tied to VDD or left floating, device follows interleaved Burst order. When
driven Low, device follows linear Burst order. This signal is internally pulled High.
ZZ
I
ASYNC
Snooze. Places device in low power mode; data is retained. Connect to GND if unused.
NC
-
-
DQ[a,b]
No connects.
Snooze Mode
SNOOZE MODE is a low current, power-down mode in which the device is deselected and current is reduced to ISB2. The duration of
SNOOZE MODE is dictated by the length of time the ZZ is in a High state.
The ZZ pin is an asynchronous, active high input that causes the device to enter SNOOZE MODE.
When the ZZ pin becomes a logic High, ISB2 is guaranteed after the time tZZI is met. After entering SNOOZE MODE, all inputs except ZZ
is disabled and all outputs go to High-Z. Any operation pending when entering SNOOZE MODE is not guaranteed to successfully complete.
Therefore, SNOOZE MODE (READ or WRITE) must not be initiated until valid pending operations are completed. Similarly, when exiting
SNOOZE MODE during tPUS, only a DESELECT or READ cycle should be given while the SRAM is transitioning out of SNOOZE
MODE.
12/23/04, v.2.2
Alliance Semiconductor
P. 5 of 18
AS7C251MNTD18A
®
Burst order
Interleaved burst order (LBO = 1)
Linear burst order (LBO = 0)
A1A0
A1A0
A1A0
A1A0
Starting address
0 0
0 1
1 0
1 1
A1A0
A1A0
A1A0
A1A0
Starting Address
0 0
0 1
1 0
1 1
First increment
0 1
0 0
1 1
1 0
First increment
0 1
1 0
1 1
0 0
Second increment
1 0
1 1
0 0
0 1
Second increment
1 0
1 1
0 0
0 1
Third increment
1 1
1 0
0 1
0 0
Third increment
1 1
0 0
0 1
1 0
Synchronous truth table[5,6,7,8,9,11]
CE0
CE1 CE2 ADV/LD R/W
BWn
OE
CEN
Address
source
CLK
Operation
DQ
H
X
X
L
X
X
X
L
NA
L to H
DESELECT Cycle
High-Z
X
X
H
L
X
X
X
L
NA
L to H
DESELECT Cycle
High-Z
X
L
X
L
X
X
X
L
NA
L to H
DESELECT Cycle
High-Z
X
X
X
H
X
X
X
L
NA
L to H
CONTINUE DESELECT Cycle
High-Z
L
H
L
L
H
X
L
L
READ Cycle (Begin Burst)
Q
X
X
X
H
X
X
L
L
READ Cycle (Continue Burst)
Q
L
H
L
L
H
X
H
L
X
X
X
H
X
X
H
L
L
H
L
L
L
L
X
L
X
X
X
H
X
L
X
L
L
H
L
L
L
H
X
L
X
X
X
H
X
H
X
L
X
X
X
X
X
X
X
H
External L to H
Next
L to H
External L to H NOP/DUMMY READ (Begin Burst) High-Z
Next
L to H
External L to H
Next
L to H
DUMMY READ (Continue Burst)
L to H
1,10
2
High-Z 1,2,10
D
3
WRITE CYCLE (Continue Burst)
D
1,3,10
High-Z
2,3
WRITE ABORT (Continue Burst)
High-Z
1,2,3,
10
INHIBIT CLOCK
-
4
Current L to H
Key: X = Don’t Care, H = HIGH, L = LOW. BWn = H means all byte write signals (BWa, BWb, BWc, and BWd) are HIGH. BWn = L means one or
more byte write signals are LOW.
Notes:
1 CONTINUE BURST cycles, whether READ or WRITE, use the same control inputs. The type of cycle performed (READ or WRITE) is chose in the initial
BEGIN BURST cycle. A CONINUE DESELECT cycle can only be entered if a DESELECT CYCLE is executed first.
2 DUMMY READ and WRITE ABORT cycles can be considered NOPs because the device performs no external operation. A WRITE ABORT means a
WRITE command is given, but no operation is performed.
3 OE may be wired LOW to minimize the number of control signal to the SRAM. The device will automatically turn off the output drivers during a WRITE
cycle. OE may be used when the bus turn-on and turn-off times do not meet an application’s requirements.
4 If an INHIBIT CLOCK command occurs during a READ operation, the DQ bus will remain active (Low-Z). If it occurs during a WRITE cycle, the bus will
remain in High-Z. No WRITE operations will be performed during the INHIBIT CLOCK cycle.
5 BWa enables WRITEs to byte “a” (DQa pins); BWb enables WRITEs to byte “b” (DQb pins); BWc enables WRITEs to byte “c” (DQc pins); BWd
enables WRITEs to byte “d” (DQd pins).
6 All inputs except OE and ZZ must meet setup and hold times around the rising edge (LOW to HIGH) of CLK.
7 Wait states are inserted by setting CEN HIGH.
8 This device contains circuitry that will ensure that the outputs will be in High-Z during power-up.
9 The device incorporates a 2-bit burst counter. Address wraps to the initial address every fourth BURST CYCLE.
10 The address counter is incremented for all CONTINUE BURST cycles.
11 ZZ pin is always Low in this truth table.
12/23/04, v.2.2
1
WRITE CYCLE (Begin Burst)
External L to H NOP/WRITE ABORT (Begin Burst)
Next
Notes
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P. 6 of 18
AS7C251MNTD18A
®
State diagram for NTD SRAM
Burst
Read
Read
Read
Ds
el
Re
ad
Dsel
d
ea
Dsel
el
Ds
ite
Wr
Burst
Write
Burst
Dsel
W
rit
e
Burst
Dsel
R
Write
Read
Write
Write
Burst
Read
Burst
Write
Burst
Absolute maximum ratings
Parameter
Symbol
Min
Max
Unit
VDD, VDDQ
–0.3
+3.6
V
Input voltage relative to GND (input pins)
VIN
–0.3
VDD + 0.3
V
Power supply voltage relative to GND
Input voltage relative to GND (I/O pins)
VIN
–0.3
VDDQ + 0.3
V
Power dissipation
PD
–
1.8
W
DC output current
IOUT
–
50
mA
Storage temperature
Tstg
–65
+150
oC
Temperature under bias (junction)
Tbias
–65
+150
o
C
Stresses greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only, and functional
operation of the device at these or any other conditions outside those indicated in the operational sections of this specification is not implied. Exposure to
absolute maximum rating conditions may affect reliability.
Recommended operating conditions
Parameter
Symbol
Min
Nominal
Max
Unit
Supply voltage for inputs
VDD
2.375
2.5
2.625
V
Supply voltage for I/O
VDDQ
2.375
2.5
2.625
V
Vss
0
0
0
V
Ground supply
12/23/04, v.2.2
Alliance Semiconductor
P. 7 of 18
AS7C251MNTD18A
®
DC electrical characteristics
Parameter
Sym
Conditions
Min
Max
Unit
current†
|ILI|
VDD = Max, 0V < VIN < VDD
-2
2
µA
Output leakage current
|ILO|
OE ≥ VIH, VDD = Max, 0V < VOUT < VDDQ
-2
2
µA
Input high (logic 1) voltage
VIH
Address and control pins
1.7*
VDD+0.3
V
I/O pins
1.7*
VDDQ+0.3
V
Input low (logic 0) voltage
VIL
Address and control pins
-0.3**
0.7
V
I/O pins
-0.3**
0.7
V
Output high voltage
VOH
IOH = –4 mA, VDDQ = 2.375V
1.7
–
V
Output low voltage
VOL
IOL = 8 mA, VDDQ = 2.625V
–
0.7
V
Input leakage
† LBO and ZZ pins have an internal pull-up or pull-down, and input leakage = ±10 µA.
*V max < VDD +1.5V for pulse width less than 0.2 X t
IH
CYC
**
VIL min = -1.5 for pulse width less than 0.2 X tCYC
IDD operating conditions and maximum limits
Parameter
Operating power supply current1
Sym
ICC
ISB
Standby power supply current
Conditions
CE0 < VIL, CE1 > VIH, CE2 < VIL, f = fMax,
IOUT = 0 mA, ZZ < VIL
All VIN ≤ 0.2V or > VDD – 0.2V, Deselected,
f = fMax, ZZ < VIL
-166
-133
Unit
290
270
mA
85
75
ISB1
Deselected, f = 0, ZZ < 0.2V,
all VIN ≤ 0.2V or ≥ VDD – 0.2V
40
40
ISB2
Deselected, f = fMax, ZZ ≥ VDD – 0.2V,
all VIN ≤ VIL or ≥ VIH
40
40
mA
1 ICC given with no output loading. ICC increases with faster cycle times and greater output loading.
12/23/04, v.2.2
Alliance Semiconductor
P. 8 of 18
AS7C251MNTD18A
®
Timing characteristics over operating range
-166
Parameter
-133
Notes1
Sym
Min
Max
Min
Max
Unit
Clock frequency
FMAX
–
166
–
133
MHz
Cycle time
tCYC
6
–
7.5
–
ns
Clock access time
tCD
–
3.5
–
3.8
ns
Output enable low to data valid
tOE
–
3.5
–
3.8
ns
Clock high to output low Z
tLZC
0
–
0
–
ns
2, 3, 4
Data output invalid from clock high
tOH
1.5
–
1.5
–
ns
2
Output enable low to output low Z
tLZOE
0
–
0
–
ns
2, 3, 4
Output enable high to output high Z
tHZOE
–
3.5
–
3.8
ns
2, 3, 4
Clock high to output high Z
tHZC
–
3.5
–
3.8
ns
2, 3, 4
Output enable high to invalid output
tOHOE
0
–
0
–
ns
Clock high pulse width
tCH
2.4
–
2.4
–
ns
5
Clock low pulse width
tCL
2.3
–
2.4
–
ns
5
Address and Control setup to clock high
tAS
1.5
–
1.5
–
ns
6
Data setup to clock high
tDS
1.5
–
1.5
–
ns
6
Write setup to clock high
tWS
1.5
–
1.5
–
ns
6, 7
Chip select setup to clock high
tCSS
1.5
–
1.5
–
ns
6, 8
Address hold from clock high
tAH
0.5
–
0.5
–
ns
6
Data hold from clock high
tDH
0.5
–
0.5
–
ns
6
Write hold from clock high
tWH
0.5
–
0.5
–
ns
6, 7
Chip select hold from clock high
tCSH
0.5
–
0.5
–
ns
6, 8
Clock enable setup to clock high
tCENS
1.5
–
1.5
–
ns
6
Clock enable hold from clock high
tCENH
0.5
–
0.5
–
ns
6
ADV setup to clock high
tADVS
1.5
–
1.5
–
ns
6
ADV hold from clock high
tADVH
0.5
–
0.5
–
ns
6
1 See “Notes” on page 15
Snooze Mode Electrical Characteristics
Description
Current during Snooze Mode
ZZ active to input ignored
ZZ inactive to input sampled
ZZ active to SNOOZE current
ZZ inactive to exit SNOOZE current
12/23/04, v.2.2
Conditions
Symbol
ZZ > VIH
ISB2
tPDS
tPUS
tZZI
tRZZI
Alliance Semiconductor
Min
Max
Units
40
mA
cycle
cycle
cycle
cycle
2
2
2
0
P. 9 of 18
AS7C251MNTD18A
®
Key to switching waveforms
Rising input
don’t care
Falling input
Undefined
Timing waveform of read cycle
tCH
tCL
tCYC
CLK
tCES tCEH
CEN
tAS
Address
tAH
A1
A2
A3
tWS tWH
R/W
tWS tWH
BWn
tCSH
CE0,CE2
CE1
tADVS tADVH
ADV/LD
OE
tOE
tLZOE
Dout
tHZOE
Q(A1)
tHLZC
Q(A2Y‘10)
Q(A2)
Q(A2Y‘11)
Q(A2Y‘01)
Read
Q(A1)
12/23/04, v.2.2
DSEL
Read
Q(A2)
Continue
Read
Q(A2Y‘01)
Continue
Read
Q(A2Y‘10)
Continue
Read
Q(A2Y‘11)
Alliance Semiconductor
Q(A3)
Inhibit
Clock
Read
Q(A3)
Continue
Read
Q(A3Y‘01)
P. 10 of 18
AS7C251MNTD18A
®
Timing waveform of write cycle
tCH
tCL
tCYC
CLK
tCES tCEH
CEN
tAS
Address
tAH
A1
A2
A3
R/W
BWn
tCSH
CE0,CE2
CE1
tADVS tADVH
ADV/LD
OE
tDS
D(A1)
Din
tHZOE
Dout
Q(n-2)
D(A3)
D(A2Y‘01)
D(A2Y‘10)
D(A2Y‘11)
Q(n-1)
Write
D(A1)
12/23/04, v.2.2
tDH
D(A2)
DSEL
Write
D(A2)
Continue
Write
D(A2Y‘01)
Continue
Write
D(A2Y‘10)
Continue
Write
D(A2Y‘11)
Alliance Semiconductor
Inhibit
Clock
Write
D(A3)
Continue
Write
D(A3Y‘01)
P. 11 of 18
AS7C251MNTD18A
®
Timing waveform of read/write cycle
tCH
tCL
tCYC
CLK
tCENS
tCENH
CEN
CE1
tCSS
tCSH
CE0, CE2
tADVS
tADVH
ADV/LD
tWS
tWH
tWS
tWH
tAS
tAH
R/W
BWn
ADDRESS
A1
A3
A2
A4
A6
A5
A7
tCD
tDS tDH
D/Q
D(A1)
tLZC
D(A2)
D(A2Ý01)
tOH
tOE
Q(A3)
Q(A4)
tHZC
Q(A4Ý01)
D(A5)
Q(A6)
tHZOE
tLZOE
OE
Command
Write
D(A1)
Write
D(A2)
Burst
Write
D(A2Ý01)
Read
Q(A3)
Read
Q(A4)
Burst
Read
Q(A4Ý01)
Write
D(A5)
Read
Q(A6)
Write
D(A7)
DSEL
Note: Ý = XOR when LBO = high/no connect. Ý = ADD when LBO = low. BW[a:d] is don’t care.
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NOP, stall and deselect cycles
CLK
CEN
CE1
CE0, CE2
ADV/LD
R/W
BWn
Address
A2
A1
Q(A1)
D/Q
Command
Read
Q(A1)
Burst
Q(A1Ý01)
STALL
Q(A1Ý01)
Burst
Q(A1Ý10)
A3
D(A2)
Q(A1Ý10)
DSEL
Burst
DSEL
Write
D(A2)
Burst
NOP
D(A2Ý01)
Burst
D(A2Ý10)
Write
NOP
D(A3)
Note: Ý = XOR when LBO = high/no connect; Ý = ADD when LBO = low. OE is low.
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Timing waveform of snooze mode
CLK
tPUS
ZZ setup cycle
ZZ recovery cycle
ZZ
tZZI
Isupply
ISB2
tRZZI
All inputs
(except ZZ)
Deselect or Read Only
Deselect or Read Only
Normal
operation
Cycle
Dout
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High-Z
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AC test conditions
• Output load: see Figure B, except for tLZC, tLZOE, tHZOE, tHZC, see Figure C.
• Input pulse level: GND to 2.5V. See Figure A.
Thevenin equivalent:
• Input rise and fall time (measured at 0.25V and 2.25V): 2 ns. See Figure A.
• Input and output timing reference levels: 1.25V.
+2.5V
+2.5V
Z0 = 50Ω
90%
90%
10%
GND
50Ω
DOUT
VL = VDDQ/2
30 pF*
10%
Figure A: Input waveform
Figure B: Output load (A)
319Ω/1667Ω
DOUT
5 pF*
353Ω/1538Ω
GND *including scope
and jig capacitance
Figure C: Output load(B)
Notes:
1) For test conditions, see “AC test conditions”, Figures A, B, C
2) This parameter measured with output load condition in Figure C.
3) This parameter is sampled, but not 100% tested.
4) tHZOE is less than tLZOE and tHZC is less than tLZC at any given temperature and voltage.
5) tCH measured high above VIH and tCL measured as low below VIL
6) This is a synchronous device. All addresses must meet the specified setup and hold times for all rising edges of CLK. All other synchronous inputs must
meet the setup and hold times with stable logic levels for all rising edges of CLK when chip is enabled.
7) Write refers to R/W and BW[a,b].
8) Chip select refers to CE0, CE1, and CE2.
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Package dimensions
100-pin quad flat pack (TQFP)
A1
A2
b
c
D
E
e
Hd
He
L
L1
α
Hd
D
TQFP
Min
Max
0.05
0.15
1.35
1.45
0.22
0.38
0.09
0.20
13.90 14.10
19.90 20.10
0.65 nominal
15.85 16.15
21.80 22.20
0.45
0.75
1.00 nominal
0°
7°
Dimensions in millimeters
b
e
He E
α
c
L1
A1 A2
L
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Ordering information
Package &Width
TQFP x18
–166 MHz
–133 MHz
AS7C251MNTD18A-166TQC
AS7C251MNTD18A-133TQC
AS7C251MNTD18A-166TQI
AS7C251MNTD18A-133TQI
Note:
Add suffix ‘N’ to the above part number for Lead Free Parts (Ex. AS7C251MNTD18A-166TQCN)
Part numbering guide
AS7C
25
1M
NTD
18
A
–XXX
TQ
C/I
X
1
2
3
4
5
6
7
8
9
10
1. Alliance Semiconductor SRAM prefix
2. Operating voltage: 25 = 2.5V
3. Organization: 1M
4. NTD™ = No Turn-Around Delay. Pipelined mode
5. Organization: 18 = x 18
6. Production version: A = first production version
7. Clock speed (MHz)
8. Package type: TQ = TQFP
9. Operating temperature: C = commercial (0° C to 70° C); I = industrial (-40° C to 85° C)
10. N = Lead free part
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P. 17 of 18
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®
Alliance Semiconductor Corporation
2575, Augustine Drive,
Santa Clara, CA 95054
Tel: 408 - 855 - 4900
Fax: 408 - 855 - 4999
www.alsc.com
Copyright © Alliance Semiconductor
All Rights Reserved
Part Number: AS7C251MNTD18A
Document Version: v.2.2
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