The CY7C42X5 are high-speed, low-power, first-in first-out
(FIFO) memories with clocked read and write interfaces. All
are 18 bits wide and are pin/functionally compatible to
IDT722x5. The CY7C42X5 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, and communications buffering.
These FIFOs have 18-bit input and output ports that are controlled
by separate clock and enable signals. The input port iscontrolled by a free-running clock (WCLK) and a write enable
pin (WEN).
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
CY7C42X5 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.