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Integrated Device Technology Electronic Components Datasheet

IDT71P73104 Datasheet

18Mb Pipelined DDRII SRAM Burst of 4

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18Mb Pipelined
DDR™II SRAM
Burst of 4
IDT71P73204
IDT71P73104
IDT71P73804
IDT71P73604
Features
18Mb Density (2Mx8, 2Mx9, 1Mx18, 512Kx36)
Common Read and Write Data Port
Dual Echo Clock Output
4-Word Burst on all SRAM accesses
MultiplexedAddress Bus
- One Read or One Write request per two clock
cycles.
DDR (Double Data Rate) Data Bus
- Four word bursts data per two clock cycles
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
from 1.4V to 1.9V.
- Output Impedance adjustable from 35 ohms to 70
ohms
1.8V Core Voltage (VDD)
JTAG Interface
165-ball, 1.0mm pitch, 13mm x 15mm fBGA Package
Description
The IDT DDRIITM Burst of four SRAMs are high-speed synchro-
nous memories with a double-data-rate (DDR), bidirectional data port.
This scheme allows maximization on the bandwidth on the data bus by
passing two data items per clock cycle. The address bus operates at
less than single data rate speeds,allowing the user to fan out addresses
and ease system design while maintaining maximum performance 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 SRAM are HSTL, allowing speeds
beyond SRAM devices that use any form of 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 VDDQ and a separate Vref,
allowing the user to designate the interface operational voltage, inde-
pendent of the device core voltage of 1.8V VDD. The output impedance
control allows the user to adjust the drive strength to adapt to a wide
range of loads and transmission lines.
Functional Block Diagram
DATA
REG
(Note2)
SA
SA0
SA1
ADD
REG
(Note2)
LD
RW
BWx
(Note3)
CTRL
LOGIC
(Note1)
WRITE DRIVER
18M
MEMORY
ARRAY
(Note4)
(Note4)
(Note1) DQ
K CLK
K GEN
C SELECT OUTPUT CONTROL
C
CQ
CQ
Notes
6431 drw 16
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, 20 address signal lines for x18, and 19 address signal lines for x36.
3) Represents 1 signal line for x9, 2 signal lines for x18, and four signal lines for x36. On x8 parts, the BW is a “nibble write” and there are 2
signal lines.
4) Represents 16 data signal lines for x8, 18 signal lines for x9, 36 signal lines for x18, and 72 signal lines for x36.
JULY 2005
1
©2005 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-6431/00
Free Datasheet http://www.datasheet4u.com/


Integrated Device Technology Electronic Components Datasheet

IDT71P73104 Datasheet

18Mb Pipelined DDRII SRAM Burst of 4

No Preview Available !

IDT71P73204 (2M x 8-Bit), 71P73104 (2M x 9-Bit), 71P73804 (1M x 18-Bit) 71P73604 (512K x 36-Bit)
18 Mb DDR II SRAM Burst of 4
Commercial Temperature Range
Clocking
The DDRII SRAM has two sets of input clocks, namely the K, K
clocks and the C, C clocks. In addition, the QDRII has an output “echo”
clock, CQ, CQ.
The K and K clocks are the primary device input clocks. The K
clock is used to clock in the control signals (LD, R/W and BWx or NWx),
the address, and the first and third words of the data burst during a write
operation. The K clock is used to clock in the control signals (BWx or
NWx), and the second and fourth words of the data burst during a write
operation. The K and K clocks are also used internally by the SRAM. In
the event that the user disables the C and C clocks, the K and K clocks
will also be used to clock the data out of the output register and generate
the echo clocks.
The C and C clocks may be used to clock the data out of the
output register during read operations and to generate the echo clocks.
C and C must be presented to the SRAM within the timing tolerances.
The output data from the DDRII will be closely aligned to the C and C
input, through the use of an internal DLL. When C is presented to the
DDRII SRAM, the DLL will have already internally clocked the data to
arrive at the device output simultaneously with the arrival of the C clock.
The C and second data item of the burst will also correspond. The third
and fourth data words will follow on the next clock cycle of the C and C,
respectively.
Single Clock Mode
The DDRII SRAM may be operated with a single clock pair. C
and C may be disabled by tying both signals high, forcing the outputs
and echo clocks to be controlled instead by the K and K clocks.
DLL Operation
The DLL in the output structure of the DDRII SRAM can be used
to closely align the incoming clocks C and C with the output of the data,
generating very tight tolerances between the two. The user may disable
the DLL by holding Doff low. With the DLL off, the C and C (or K and K
if C and C are not used) will directly clock the output register of the
SRAM. With the DLL off, there will be a propagation delay from the time
the clock enters the device until the data appears at the output.
Echo Clock
The echo clocks, CQ and CQ, are generated by the C and C
clocks (or K, K if C, C are disabled). The rising edge of C generates the
rising edge of CQ, and the falling edge of CQ. The rising edge of C
generates the rising edge of CQ and the falling edge of CQ. This
scheme improves the correlation of the rising and falling edges of the
echo clock and will improve the duty cycle of the individual signals.
The echo clock is very closely aligned with the data, guarantee-
ing that the echo clock will remain closely correlated with the data, within
the tolerances designated.
output at the designated time in correspondence with the C and C clocks.
Write operations are initiated by holding the Read/Write control
input (R/W) low, the load control input (LD) low and presenting the write
address to the address port during the rising edge of K, which will latch
the address. On the following rising edge of K, the first word of the four
word burst must be present on the data input bus DQ[x:O], along with the
appropriate byte write or nibble write (BWx or NWx) inputs. On the
following rising edge of K, the second word of the data write burst will be
accepted at the device input with the designated (BWx or NWx) inputs.
The subsequent K and K rising edges will receive the last two words of
the four word burst, with their BWx/NWx enables.
DDRII devices internally store four words of the burst as a single,
wide word and will retain their order in the burst. The x8 and x9 devices
do not have the ability to address to the single word level or change the
burst order; however the byte and nibble write signals can be used to
prevent writing any byte or individual nibbles, or combined to prevent
writing one word of the burst. The x18 and x36 DDRll devices have the
ability to address to the individual word level using the SA0 and SA1
address bits, but the burst will continue in a linear sequence and wraps
around without incrementing the SA bits. When reading or writing x18
and x36 DDRll devices, the burst will begin at the designated address,
but if the burst is started at any other position than the first word of the
burst, the burst will wrap back on itself and read the first locations before
completing. The x18 and x36 DDRII devices can also use the byte write
signals to prevent writing any individual byte or word of the burst.
Output Enables
The DDRII SRAM automatically enables and disables the DQ[X:0]
outputs. When a valid read is in progress, and data is present at the
output, the output will be enabled. If no valid data is present at the output
(read not active), the output will be disabled (high impedance). The
echo clocks will remain valid at all times and cannot be disabled or turned
off. During power-up the DQ outputs will come up in a high impedance
state.
Programmable Impedance
An external resistor, RQ, must be connected between the ZQ pin
on the SRAM and Vss to allow the SRAM to adjust its output drive
impedance. The value of RQ must be 5X the value of the intended drive
impedance of the SRAM. The allowable range of RQ to guarantee
impedance matching with a tolerance of +/- 10% is between 175 ohms
and 350 ohms, with VDDQ = 1.5V. The output impedance is adjusted
every 1024 clock cycles to correct for drifts in supply voltage and tem-
perature. If the user wishes to drive the output impedance of the SRAM
to it’s lowest value, the ZQ pin may be tied to VDDQ.
Read and Write Operations
Read operations are initiated by holding Read/Write control input
(R/W) high, the load control input (LD) low and presenting the read
address to the address port during the rising edge of K, which will latch
the address. The data will then be read and will appear at the device
6.242
Free Datasheet http://www.datasheet4u.com/


Part Number IDT71P73104
Description 18Mb Pipelined DDRII SRAM Burst of 4
Maker IDT
Total Page 25 Pages
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