MAY 2002
DSC-5294/03
1
©2002 Integrated Device Technology, Inc.
Pin Description Summary
Description
The IDT71V2546/48 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 ZBTTM, or Zero Bus
Turnaround.
Features
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◆128K x 36, 256K x 18 memory configurations
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◆Supports high performance system speed - 150 MHz
(3.8 ns Clock-to-Data Access)
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◆ZBTTM Feature - No dead cycles between write and read
cycles
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◆Internally synchronized output buffer enable eliminates the
need to control OE
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◆Single R/WW
WW
W (READ/WRITE) control pin
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◆Positive clock-edge triggered address, data, and control
signal registers for fully pipelined applications
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◆4-word burst capability (interleaved or linear)
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◆Individual byte write (BW1 - BW4) control (May tie active)
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◆Three chip enables for simple depth expansion
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◆3.3V power supply (±5%), 2.5V I/O Supply (VDDQ)
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◆Optional Boundary Scan JTAG Interface (IEEE1149.1
complaint)
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◆Packaged in a JEDEC standard 100-pin plastic thin quad
flatpack (TQFP), 119 ball grid array (BGA) and 165 fine
pitch ball grid array
A0-A17 Ad d re s s Inp uts Inp ut Sy nc hro no us
CE1, CE2, CE2Chip Enab les Input Synchro nous
OE Outp ut Enab le Inp ut As ync hro no us
R/WRead/Write Signal Input Synchro nous
CEN Clo ck Enab le Input Synchro no us
BW1, BW2, BW3, BW4Indi vid ual B yte Write Se le c ts Input Sy nchro no us
CLK Clock Input N/A
ADV/LD A d v ance b urst ad dress / Lo ad ne w ad d res s Input Synchro no us
LBO Line ar / Interle ave d Burst Order Input Static
TMS Test Mode Select Input Synchronous
TDI Test Data Input Input Synchronous
TCK Test Clock Input N/A
TDO Te s t Data Ou tp ut Outp ut S y nc hro n o us
TRST JTAG Reset (Optional) Input Asynchronous
ZZ Sleep Mode Input Synchronous
I/O0-I/O31, I/OP1-I/OP4 Da ta Inp u t / Outp u t I/ O S y nc hro n o us
VDD, VDDQ Core Po wer, I/O Po wer Sup p ly Static
VSS Ground Supply Static
5294 tbl 01
IDT71V2546S
IDT71V2548S
IDT71V2546SA
IDT71V2548SA
128K x 36, 256K x 18
3.3V Synchronous ZBT™ SRAMs
2.5V I/O, Burst Counter
Pipelined Outputs
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 IDT71V2546/48 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 IDT71V2546/48 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 IDT71V2546/48 has an on-chip burst counter. In the burst mode,
the IDT71V2546/48 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 IDT71V2546/48 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 165 fine pitch ball grid array (fBGA).