CY7C4421

The CY7C42X1 are high-speed, low-power, first-in first-out (FIFO) memories with clocked read and write interfaces. All are 9 bits wide. The CY7C42X1 are pin-compatible to IDT722X1. Programmable features include Almost Full/Almost Empty flags. The CY7C42X1 provide solutions for a wide variety of data buffering needs, including high-speed data acquisition, multiprocessor interfaces, and communications buffering.

The CY7C42X1 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 two write-enable pins (WEN1, WEN2/LD).

When WEN1 is LOW and WEN2/LD is HIGH, data is written into the FIFO on the rising edge of the WCLK signal. While WEN1, WEN2/LD is held active, data is continually written into the FIFO on each WCLK cycle. The output port is controlled in a similar manner by a free-running read clock (RCLK) and two read-enable pins (REN1, REN2). In addition, the CY7C42X1 has an output enable pin (OE). The read (RCLK) and write (WCLK) 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.

Depth expansion of the CY7C42X1 is possible using one enable input for system control, while the other enable is controlled by expansion logic to direct the flow of data.