Advance
Information
IDT71P74204
IDT71P74104
IDT71P74804
IDT71P74604
18Mb Pipelined
QDR™II SRAM
Burst of 4
Description
Features
TM
The IDT QDRII Burst of four SRAMs are high-speed synchronous
memories with independent, double-data-rate (DDR), read and write
data ports. This scheme allows simultaneous read and write access for
the maximum device throughput, with four data items passed with each
read or write. Four data word transfers occur per clock cycle, providing
quad-data-rate(QDR)performance. ComparingthiswithstandardSRAM
common I/O (CIO), single data rate (SDR) devices, a four to one in-
crease in data access is achieved at equivalent clock speeds. Consider-
ing that QDRII allows clock speeds in excess of standard SRAM de-
vices, the throughput can be increased well beyond four to one in most
applications.
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18Mb Density (2Mx8, 2Mx9, 1Mx18, 512kx36)
Separate, Independent Read and Write Data Ports
Supports concurrent transactions
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Dual Echo Clock Output
4-Word Burst on all SRAM accesses
Multiplexed Address Bus One Read or One Write request
per clock cycle
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DDR (Double Data Rate) Data Bus
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Four word burst data per two clock cycles on
each port
Four word transfers per clock cycle
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Using independent ports for read and write data access, simplifies
system design by eliminating the need for bi-directional buses. All buses
associated with the QDRII are unidirectional and can be optimized for
signal integrity at very high bus speeds. The QDRII has scalable output
impedance on its data output bus and echo clocks, allowing the user to
tune the bus for low noise and high performance.
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Depth expansion through Control Logic
HSTL (1.5V) inputs that can be scaled to receive signals
from 1.4V to 1.9V.
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Scalable output drivers
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Can drive HSTL, 1.8V TTL or any voltage level
from 1.4V to 1.9V.
The QDRII has a single SDR address bus with read addresses and
write addresses multiplexed. The read and write addresses interleave
with each occurring a maximum of every other cycle. In the event that no
operation takes place on a cycle, the subsequest cycle may begin with
either a read or write. During write operations, the writing of individual
bytes may be blocked through the use of byte or nibble write control
signals.
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Output Impedance adjustable from 35 ohms to 70
ohms
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1.8V Core Voltage (VDD)
165-ball, 1.0mm pitch, 15mm x 17mm fBGA Package
JTAG Interface
The QDRII has echo clocks, which provide the user with a clock
Functional Block Diagram
(Note1)
DATA
D
REG
WRITE DRIVER
(Note2)
(Note2)
ADD
SA
REG
(Note1)
Q
18M
MEMORY
ARRAY
R
CTRL
LOGIC
W
(Note3)
BWx
K
CLK
CQ
GEN
K
CQ
C
SELECT OUTPUT CONTROL
C
6111 drw16
Notes
1) Represents 8 data signal lines for x8, 9 signal lines for x9, 18 signal lines for x18, and 36 signal lines for x36
2) Represents 19 address signal lines for x8 and x9, 18 address signal lines for x18, and 17 address signal lines for x36.
BW
3) Represents 1 signal line for x9, 2 signal lines for x18, and four signal lines for x36. On x8 parts, the
and there are 2 signal lines.
is a “nibble write”
MARCH 2004
1
©2003 Integrated Device Technology, Inc. “QDR SRAMs and Quad Data Rate RAMs comprise a new family of products developed by Cypress Semiconductor, IDT, and Micron Technology, Inc. “
DSC-6111/00