Synchronous FIFO for 5 V bus buffering
The Cypress CY7C4225-15AXC is a synchronous FIFO memory from the CY7C series, organized as 1K x 18 bits (18K total). The part supports depth and width expansion, retransmit capability, and programmable flags — features that simplify flow control in DSP or ASIC interfaces.
At 66.7 MHz the cycle time is 15 ns; the 10 ns access time leaves 5 ns of setup/hold margin for the reading device. That margin shrinks with trace delay and loading, so a board-level timing simulation is advisable when the FIFO feeds a fast ASIC or FPGA. The synchronous interface eliminates the dead cycles of asynchronous FIFOs, enabling back-to-back writes at full clock rate.
18K (1K x 18) — buffer sizing and bus width
The 1K depth holds 1024 18-bit words. For a 16-bit data bus with parity or control bits, the extra two bits per word are useful for sideband signaling. If the application needs deeper buffering, the depth-expansion mode chains multiple devices without external logic. Width expansion handles 32-bit or wider buses by paralleling FIFOs with common control signals.
The CY7C4225-15AXC is officially obsolete per the manufacturer's lifecycle status. Buyers should verify date code and condition (new original, not refurbished) with the supplier.
5 V supply and 45 mA supply current
Maximum supply current is 45 mA — a modest load for a 5 V rail, but the 64-TQFP package's thermal impedance should be checked if the device runs near full clock rate continuously in a still-air enclosure.