128K x 36, 256K x 18
IDT71V2556S/XS
3.3V Synchronous ZBT™ SRAMs
IDT71V2558S/XS
2.5V I/O, Burst Counter
IDT71V2556SA/XSA
Pipelined Outputs
IDT71V2558SA/XSA
◆
◆
◆
◆
◆
◆
◆
◆
◆
◆
◆
◆
Features
128K x 36, 256K x 18 memory configurations
Supports high performance system speed - 200 MHz
(3.2 ns Clock-to-Data Access)
ZBT
TM
Feature - No dead cycles between write and read
cycles
Internally synchronized output buffer enable eliminates the
need to control
OE
Single R/W (READ/WRITE) control pin
W
Positive clock-edge triggered address, data, and control
signal registers for fully pipelined applications
4-word burst capability (interleaved or linear)
Individual byte write (BW
1
-
BW
4
) control (May tie active)
Three chip enables for simple depth expansion
3.3V power supply (±5%), 2.5V I/O Supply (V
DDQ)
Optional - Boundary Scan JTAG Interface (IEEE 1149.1
complaint)
Packaged in a JEDEC standard 100-pin plastic thin quad
flatpack (TQFP), 119 ball grid array (BGA) and 165 fine pitch
ball grid array (fBGA)
Description
The IDT71V2556/58 are 3.3V high-speed 4,718,592-bit (4.5 Mega-
bit) synchronous SRAMS. They are designed to eliminate dead bus cycles
when turning the bus around between reads and writes, or writes and
reads. Thus, they have been given the name ZBT
TM
, or Zero Bus
Turnaround.
Address and control signals are applied to the SRAM during one clock
cycle, and two cycles later the associated data cycle occurs, be it read
or write.
The IDT71V2556/58 contain data I/O, address and control signal
registers. Output enable is the only asynchronous signal and can be used
to disable the outputs at any given time.
A Clock Enable (CEN) pin allows operation of the IDT71V2556/58 to
be suspended as long as necessary. All synchronous inputs are ignored
when (CEN) is high and the internal device registers will hold their previous
values.
There are three chip enable pins (CE
1
, CE
2
,
CE
2
) that allow the user
to deselect the device when desired. If any one of these three are not
asserted when ADV/LD is low, no new memory operation can be initiated.
However, any pending data transfers (reads or writes) will be completed.
The data bus will tri-state two cycles after chip is deselected or a write is
initiated.
The IDT71V2556/58 has an on-chip burst counter. In the burst mode,
the IDT71V2556/58 can provide four cycles of data for a single address
presented to the SRAM. The order of the burst sequence is defined by the
LBO
input pin. The
LBO
pin selects between linear and interleaved burst
sequence. The ADV/LD signal is used to load a new external address
(ADV/LD = LOW) or increment the internal burst counter (ADV/LD =
HIGH).
The IDT71V2556/58 SRAMs utilize IDT's latest high-performance
CMOS process and are packaged in a JEDEC standard 14mm x 20mm
100-pin thin plastic quad flatpack (TQFP) as well as a 119 ball grid array
(BGA) and a 165 fine pitch ball grid array (fBGA).
Pin Description Summary
A
0
-A
17
CE
1
, CE
2
,
CE
2
OE
R/W
CEN
BW
1
,
BW
2
,
BW
3
,
BW
4
CLK
ADV/LD
LBO
TMS
TDI
TCK
TDO
TRST
ZZ
I/O
0
-I/O
31
, I/O
P1
-I/O
P4
V
DD
, V
DDQ
V
SS
Address Inputs
Chip Enables
Output Enable
Read/Write Signal
Clock Enable
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
Input
Input
I/O
Supply
Supply
Synchronous
Synchronous
Asynchronous
Synchronous
Synchronous
Synchronous
N/A
Synchronous
Static
Synchronous
Synchronous
N/A
Synchronous
Asynchronous
Synchronous
Synchronous
Static
Static
Individual Byte Write Selects
Clock
Advance burst address / Load new address
Linear / Interleaved Burst Order
Test Mode Select
Test Data Input
Test Clock
Test Data Output
JTAG Reset (Optional)
Sleep Mode
Data Input / Output
Core Power, I/O Power
Ground
1
©2010 Integrated Device Technology, Inc.
MAY 2010
DSC-4875/11
4875 tbl 01
IDT71V2556, IDT71V2558, 128K x 36, 256K x 18, 3.3V Synchronous ZBT™ SRAMs
with 2.5V I/O, Burst Counter, and Pipelined Outputs
Commercial and Industrial Temperature Ranges
Pin Definitions
(1)
Symbol
A
0
-A
17
ADV/LD
Pin Function
Address Inputs
Advance / Load
I/O
I
I
Active
N/A
N/A
Description
Synchronous Address inputs. The address register is triggered by a combination of the rising edge of
CLK, ADV/LD low,
CEN
low, and true chip enables.
ADV/LD is a synchronous input that is used to load the internal reg isters with new address and control
when it is sampled low at the rising edge of clock with the chip selected. When ADV/LD is low with the
chip deselected, any burst in progress is terminated. When ADV/
LD
is sampled high then the internal
burst counter is advanced for any burst that was in progress. The external addresses are ignored
when ADV/LD is sampled high.
R/W signal is a synchronous input that identifies whether the current load cycle initiated is a Read or
Write access to the memory array. The data bus activity for the current cycle takes place two clock
cycles later.
Synchronous Clock Enable Input. When
CEN
is sampled high, all other synchronous inputs, including
clock are ignored and outputs remain unchanged. The effect of
CEN
sampled high on the device
outputs is as if the low to high clock transition did not occur. For normal operation,
CEN
must be
sampled low at rising edge of clock.
Synchronous byte write enables. Each 9-bit byte has its own active low byte write enable. On load
write cycles (When R/W and ADV/LD are sampled low) the appropriate byte write signal (BW
1
-BW
4
)
must be valid. The byte write signal must also be valid on each cycle of a burst write. Byte Write
signals are ignored when R/W is sampled high. The appropriate byte(s) of data are written into the
device two cycles later.
BW
1
-BW
4
can all be tied low if always doing write to the entire 36-bit word.
Sy nchronous active low chip enable.
CE
1
and
CE
2
are used with CE
2
to enable the IDT71V2556/58.
(CE
1
or
CE
2
sampled high or CE
2
sampled low) and ADV/LD low at the rising edge of clock, initiates a
deselect cycle. The ZBT
TM
has a two cycle deselect, i.e., the data bus will tri-state two clock cycles
after deselect is initiated.
Synchronous active high chip enable. CE
2
is used with
CE
1
and
CE
2
to enable the chip. CE
2
has
inverted polarity but otherwise identical to
CE
1
and
CE
2
.
This is the clock input to the IDT71V2556/58. Except for
OE,
all timing referenc es for the device are
made with respect to the rising edge of CLK.
Synchronous data input/output (I/O) pins. Both the data input path and data output path are registered
and triggered by the rising edge of CLK.
Burst order selection input. When
LBO
is high the Interleaved burst sequence is selected. When
LBO
is low the Linear burst sequence is selected.
LBO
is a static input and it must not change during
device operation.
Asynchronous output enable.
OE
must be low to read data from the 71V2556/58. When
OE
is high the
I/O pins are in a high-impedance state.
OE
does not need to be actively controlled for read and write
cycles. In normal operation,
OE
can be tied low.
Gives input command for TAP controller. Sampled on rising edge of TDK. This pin has an internal
pullup.
Serial input of registers placed between TDI and TDO. Sampled on rising edge of TCK. This pin has
an internal pullup.
Clock input of TAP controller. Each TAP event is clocked. Test inputs are captured on rising edge of
TCK, while test outputs are driven from the falling edge of TCK. This pin has an internal pullup.
Serial output of registers placed between TDI and TDO. This output is active depe nding on the state of
the TAP controller.
Optional Asynchronous JTAG reset. Can be used to reset the TAP controller, but not required. JTAG
reset occurs automatically at power up and also resets using TMS and TCK p er IEEE 1149.1. If not
used
TRST
can be left floating. This pin has an internal pullup.
Synchronous sleep mode input. ZZ HIGH will gate the CLK internally and power down the
IDT71V2556/2558 to its lowest power consumption level. Data retention is guaranteed in Sleep Mode.
This pin has an internal pulldown
3.3V core power supply.
2.5V I/O Supply.
Ground.
4875 tbl 02
R/W
Read / Write
I
N/A
CEN
Clock Enable
I
LOW
BW
1
-BW
4
Individual Byte
Write Enables
I
LOW
CE
1
,
CE
2
Chip Enables
I
LOW
CE
2
CLK
I/O
0
-I/O
31
I/O
P1
-I/O
P4
LBO
Chip Enable
Clock
Data Input/Output
Linear Burst Order
I
I
I/O
I
HIGH
N/A
N/A
LOW
OE
Output Enable
I
LOW
TMS
TDI
TCK
TDO
Test Mode Select
Test Data Input
Test Clock
Test Data Output
JTAG Reset
(Optional)
I
I
I
O
N/A
N/A
N/A
N/A
TRST
I
LOW
ZZ
V
DD
V
DDQ
V
SS
Sleep Mode
Power Supply
Power Supply
Ground
I
N/A
N/A
N/A
HIGH
N/A
N/A
N/A
NOTE:
1. All synchronous inputs must meet specified setup and hold times with respect to CLK.
6.42
2
IDT71V2556, IDT71V2558, 128K x 36, 256K x 18, 3.3V Synchronous ZBT™ SRAMs
with 2.5V I/O, Burst Counter, and Pipelined Outputs
Commercial and Industrial Temperature Ranges
Functional Block Diagram
LBO
Address A [0:16]
CE1,
CE2,
CE2
R/W
CEN
ADV/LD
BWx
D
Clk
D
Q
Control
D
Q
128Kx36 BIT
MEMORY ARRAY
Address
Input Register
DI
DO
Q
Control Logic
Mux
Sel
D
Clk
Clock
Output Register
Q
OE
Gate
4875 drw 01a
,
(optional)
TMS
TDI
TCK
TRST
JTAG
(SA Version)
TDO
Data I/O [0:31],
I/O P[1:4]
6.42
3
IDT71V2556, IDT71V2558, 128K x 36, 256K x 18, 3.3V Synchronous ZBT™ SRAMs
with 2.5V I/O, Burst Counter, and Pipelined Outputs
Commercial and Industrial Temperature Ranges
Functional Block Diagram
LBO
Address A [0:17]
CE1,
CE2,
CE2
R/W
CEN
ADV/LD
BWx
D
Clk
Input Register
256x18 BIT
MEMORY ARRAY
D
Q
Address
D
Q
Control
DI
DO
Q
Control Logic
Mux
Sel
D
Clk
Clock
Output Register
Q
OE
Gate
4875 drw 01b
(optional)
TMS
TDI
TCK
TRST
JTAG
(SA Version)
TDO
Data I/O [0:15],
I/O P[1:2]
Recommended DC Operating
Conditions
Symbol
V
DD
V
DDQ
V
SS
V
IH
V
IH
V
IL
Parameter
Core Supply Voltage
I/O Supply Voltage
Supply Voltage
Input High Voltage - Inputs
Input High Voltage - I/O
Input Low Voltage
Min.
3.135
2.375
0
1.7
1.7
-0.3
(1)
Typ.
3.3
2.5
0
____
____
____
Max.
3.465
2.625
0
V
DD
+0.3
V
DDQ
+0.3
(2)
0.7
Unit
V
V
V
V
V
V
4875 tbl 03
NOTES:
1. V
IL
(min.) = –1.0V for pulse width less than t
CYC
/2, once per cycle.
2. V
IH
(max.) = +6.0V for pulse width less than t
CYC
/2, once per cycle.
6.42
4
IDT71V2556, IDT71V2558, 128K x 36, 256K x 18, 3.3V Synchronous ZBT™ SRAMs
with 2.5V I/O, Burst Counter, and Pipelined Outputs
Commercial and Industrial Temperature Ranges
Recommended Operating
Temperature and Supply Voltage
Grade
Commercial
Industrial
Temperature
(1)
0°C to +70°C
-40°C to +85°C
V
SS
0V
0V
V
DD
3.3V±5%
3.3V±5%
V
DDQ
2.5V±5%
2.5V±5%
4875 tbl 05
NOTES:
1. T
A
is the "instant on" case temperature.
Pin Configuration — 128K x 36
CE
2
BW
4
BW
3
BW
2
BW
1
CE
2
V
DD
V
SS
CLK
R/W
CEN
OE
ADV/LD
NC
(2)
NC
(2)
A
8
A
9
A
6
A
7
CE
1
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81
I/O
P3
I/O
16
I/O
17
V
DDQ
V
SS
I/O
18
I/O
19
I/O
20
I/O
21
V
SS
V
DDQ
I/O
22
I/O
23
V
DD
(1)
V
DD
V
DD
(1)
V
SS
I/O
24
I/O
25
V
DDQ
V
SS
I/O
26
I/O
27
I/O
28
I/O
29
V
SS
V
DDQ
I/O
30
I/O
31
I/O
P4
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
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
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
I/O
P2
I/O
15
I/O
14
V
DDQ
V
SS
I/O
13
I/O
12
I/O
11
I/O
10
V
SS
V
DDQ
I/O
9
I/O
8
V
SS
V
DD
(1)
V
DD
V
SS/ZZ
(3)
I/O
7
I/O
6
V
DDQ
V
SS
I/O
5
I/O
4
I/O
3
I/O
2
V
SS
V
DDQ
I/O
1
I/O
0
I/O
P1
4875 drw 02
,
NOTES:
1. Pins 14, 16 and 66 do not have to be connected directly to V
DD
as long as the input voltage is
≥
V
IH
.
2. Pins 83 and 84 are reserved for future 8M and 16M respectively.
3. Pin 64 does not have to be connected directly to V
SS
as long as the input voltage is
≤
V
IL
; on the latest die revision this
pin supports ZZ (sleep mode).
LBO
A
5
A
4
A
3
A
2
A
1
A
0
NC
NC
V
SS
V
DD
NC
NC
A
10
A
11
A
12
A
13
A
14
A
15
A
16
Top View
TQFP
6.42
5
