IDT71V2556S_11 Datasheet, PDF (1/25 Pages) Integrated Device Technology – 3.3V Synchronous ZBT SRAMs

128K x 36
3.3V Synchronous ZBT™ SRAMs
2.5V I/O, Burst Counter
Pipelined Outputs
IDT71V2556S/XS
IDT71V2556SA/XSA
Features
◆ _{128K x 36 memory configurations}
◆ _{Supports high performance system speed - 166 MHz}
(3.5 ns Clock-to-Data Access)
◆ _ZBTTM _{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}
◆ _{Positive clock-edge triggered address, data, and control}
signal registers for fully pipelined applications
◆ _{4-word burst capability (interleaved or linear)}
◆ _{Individual byte write (BW1 - BW4) control (May tie active)}
◆ _{Three chip enables for simple depth expansion}
◆ _{3.3V power supply (±5%), 2.5V I/O Supply (VDDQ)}
◆ _{Optional - Boundary Scan JTAG Interface (IEEE 1149.1}
complaint)
◆ _{Packaged in a JEDEC standard 100-pin plastic thin quad}
flatpack (TQFP) and 119 ball grid array (BGA)
Description
The IDT71V2556 is a 3.3V high-speed 4,718,592-bit (4.5 Megabit)
synchronous SRAM. It is 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 contains 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 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 (CE1, CE2, CE2) 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 has an on-chip burst counter. In the burst mode, the
IDT71V2556 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 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).
Pin Description Summary
A0-A16
CE1, CE2, CE2
OE
R/W
Address Inputs
Chip Enables
Output Enable
Read/Write Signal
Input
Synchronous
Input
Synchronous
Input
Asynchronous
Input
Synchronous
CEN
Clock Enable
Input
Synchronous
BW1, BW2, BW3, BW4
Individual Byte Write Selects
Input
Synchronous
CLK
ADV/LD
LBO
Clock
Advance burst address / Load new address
Linear / Interleaved Burst Order
Input
N/A
Input
Synchronous
Input
Static
TMS
Test Mode Select
Input
Synchronous
TDI
Test Data Input
Input
Synchronous
TCK
Test Clock
Input
N/A
TDO
Test Data Output
Output
Synchronous
TRST
JTAG Reset (Optional)
Input
Asynchronous
ZZ
Sleep Mode
Input
Synchronous
I/O0-I/O31, I/OP1-I/OP4
Data Input / Output
I/O
Synchronous
VDD, VDDQ
Core Power, I/O Power
Supply
Static
VSS
Ground
©2011 Integrated Device Technology, Inc.
Supply
1
Static
4875 tbl 01
APRIL 2011
DSC-4875/12