66.7 MHz synchronous FIFO — the throughput anchor
The CY7C4205-15AXCT is a synchronous FIFO from the CY7C series, organized as 256 words by 18 bits for a total of 4.5 Kbits of storage.
10 ns access time — bus timing margin
At 66.7 MHz the clock period is 15 ns, leaving 5 ns for setup and hold at the receiving device — tight but workable if the board trace lengths are matched and the load capacitance is controlled. The part supports programmable almost-full and almost-empty flags, so the system can set watermarks that match its own latency tolerance and avoid overflow or underflow.
Retransmit and expansion — design flexibility
Retransmit capability lets the FIFO re-read data that has already been output, which is useful for retry protocols or diagnostic loops without external logic. Expansion is supported in both depth and width, so multiple CY7C4205 devices can be cascaded to build larger buffers — depth expansion for longer captures, width expansion for wider datapaths.
It is no longer in production from Cypress (now Infineon), so new-stock availability is limited to existing inventory held by independent distributors.
Housed in a 64-LQFP for surface-mount assembly. Maximum supply current is 45 mA.