CY7C4255V

The CY7C4255/65/75/85V 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 the CY7C42X5V Synchronous FIFO family. The CY7C4255/65/75/85V 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 is controlled 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 CY7C4255/65/75/85V 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 67 MHz are achievable.

Retransmit and Synchronous Almost Full/Almost Empty flag features are available on these devices.

Depth expansion is possible using the cascade input (WXI, RXI), cascade output (WXO, RXO), and First Load (FL) pins. The WXO and RXO pins are connected to the WXI and RXI pins of the next device, and the WXO andRXO pins of the last device should be connected to the WXI and RXI pins of the first device. The FL pin of the first device is tied to V_SS and theFL pin of all the remaining devices should be tied to V_CC.