
APRIL 2006
DSC-6112/0A
2006 Integrated Device Technology, Inc. QDR SRAMs and Quad Data Rate RAMs comprise a new famly of products developed by Cypress Semconductor, IDT, and Mcron Technology, Inc.
1
18Mb Pipelined
DDRII SRAM
Burst of 2
IDT71P71804
IDT71P71604
Description
The IDT DDRII
TM
Burst of two SRAMs are high-speed synchro-
nous memories with a double-data-rate (DDR), bidirectional data port.
This scheme allows maximzation of the bandwidth on the data bus by
passing two data items per clock cycle. The address bus operates at
single data rate speeds, allowing the user to fan out addresses and
ease systemdesign while maintaining maximumperformance on data
transfers.
The DDRII 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.
All interfaces of the DDRII SRAMare HSTL, allowing speeds
beyond SRAMdevices that use any formof TTL interface. The inter-
face can be scaled to higher voltages (up to 1.9V) to interface with 1.8V
systems if necessary. The device has a V
DDQ
and
a separate Vref,
allowing the user to designate the interface operational voltage, inde-
pendent of the device core voltage of 1.8V V
DD.
The
output impedance
control allows the user to adjust the drive strength to adapt to a wide
range of loads and transmssion lines.
Clocking
The DDRII SRAMhas two sets of input clocks, namely the K,
K
clocks and the C,
clocks. In addition, the DDRII has an output “echo”
clock, CQ,
CQ
.
Functional Block Diagram
Notes
1) Represents 18 signal lines for x18, and 36 signal lines for x36
2) Represents 20 address signal lines for x18 and 19 address signal lines for x36.
3) Represents 2 signal lines for x18 and 4 signal lines for x36.
4) Represents 36 signal lines for x18 and 72 signal lines for x36.
DATA
REG
ADD
REG
CTRL
LOGIC
CLK
GEN
(Note2)
A
LD
R
/W
(Note3)
BW
x
K
K
C
C
SELECT OUTPUT CONTROL
W
S
O
O
WRITE DRIVER
(Note2)
CQ
DQ
(Note1)
(Note4)
18M
MEMORY
ARRAY
CQ
6112 drw 16
S
SA
0
(Note1)
(Note 1)
Features
◆
18Mb Density (1Mx18, 512kx36)
Common Read and Write Data Port
Dual Echo Clock Output
2-Word Burst on all SRAMaccesses
Multiplexed Address Bus
-
One Read or One Write request per clock cycle
DDR (Double Data Rate) Data Bus
- Two word bursts data per clock
◆
Depth expansion through Control Logic
◆
HSTL (1.5V) inputs that can be scaled to receive signals from
1.4V to 1.9V.
◆
Scalable output drivers
-
Can drive HSTL, 1.8V TTL or any voltage level
from1.4V to 1.9V.
-
Output Impedance adjustable from35 ohms to 70
ohms
◆
1.8V Core Voltage (V
DD
)
◆
165-ball, 1.0mmpitch, 13mmx 15mmfBGA Package
JTAG Interface
◆
◆
◆
◆
◆