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I
SB
= 2 mA
Fully asynchronous and simultaneous read and write
operation
Empty, Full, and Programmable Almost Empty and
Almost Full status flags
TTL-compatible
Retransmit function
Output Enable (OE) pin
Independent read and write enable pins
Supports free-running 50% duty cycle clock inputs
Width-Expansion Capability
Depth-Expansion Capability through token-passing
scheme (no external logic required)
64-pin 10 脳 10 STQFP
Functional Description
The CY7C4282/CY7C4292 are high-speed, low-power, FIFO
memories with clocked read and write interfaces. All devices
are nine bits wide. The CY7C4282/CY7C4292 can be
cascaded to increase FIFO depth. Programmable features
include Almost Full/Almost Empty flags. These FIFOs provide
solutions for a wide variety of data buffering needs, including
high-speed data acquisition, multiprocessor interfaces, video
and communications buffering.
These FIFOs have 9-bit input and output ports that are
controlled by separate clock and enable signals. The input port
is controlled by a free-running clock (WCLK) and a
write-enable pin (WEN).
Retransmit and Synchronous Almost Full/Almost Empty flag
features are available on these devices.
Depth expansion is possible using the cascade input (XI),
cascade output (XO), and First Load (FL) pins. The XO pin is
connected to the XI pin of the next device, and the XO pin of
the last device should be connected to the XI pin of the first
device. The FL pin of the first device is tied to VSS and the FL
pin of all the remaining devices should be tied to V
CC
.
When WEN is asserted, data is written into the FIFO on the
rising edge of the WCLK signal. While WEN is held active, data
is continually written into the FIFO on each cycle. The output
port is controlled in a similar manner by a free-running read
clock (RCLK) and a read enable pin (REN). In addition, the
CY7C4282/92 have an output enable pin (OE). The read and
write clocks may be tied together for single-clock operation or
the two clocks may be run independently for asynchronous
read/write applications. Clock frequencies up to 100 MHz are
achievable.
D
0-8
INPUT
REGISTER
Logic Block Diagram
WCLK WEN
FLAG
PROGRAM
REGISTER
WRITE
CONTROL
FF
FLAG
LOGIC
Dual Port
RAM Array
64K x 9
128K x 9
READ
POINTER
EF
PAE
PAF/XO
WRITE
POINTER
RS
RESET
LOGIC
FL/RT
XI/LD
PAF/XO
EXPANSION
LOGIC
THREE-STATE
OUTPUT REGISTER
OE
Q
0
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8
READ
CONTROL
RCLK REN
Cypress Semiconductor Corporation
Document #: 38-06009 Rev. *B
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3901 North First Street
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San Jose
,
CA 95134
鈥?/div>
408-943-2600
Revised August 21, 2003
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