66.7 MHz synchronous FIFO with 11 ns access — the timing-critical buffer
The Cypress CY7C4215V-15ASC is a synchronous FIFO memory from the CY7C series, organized as 9K (512 x 18) bits. The part supports depth and width expansion, includes programmable flags and retransmit capability, and is housed in a 64-LQFP (64-TQFP 10x10) package for surface-mount assembly.
The CY7C4215V-15ASC is officially obsolete per Cypress's product lifecycle. There is no listed direct replacement or cross-reference from the manufacturer.
In a synchronous system clocked at 66.7 MHz (15 ns period), the 11 ns access leaves about 4 ns of setup margin before the next clock edge — tight but workable if the board's trace delays and clock skew are controlled. If your legacy design used a faster FIFO (e.g., 8 ns access), this part may not meet the read-cycle timing without adding a wait state.
512 x 18 organization and retransmit
The 18-bit word width matches common 16-bit data buses with two parity bits, or 18-bit parallel interfaces on DSPs and network processors. Retransmit capability lets the FIFO reread data from the beginning without a full reset — useful in protocol buffers where a dropped packet needs retransmission. Depth expansion allows cascading multiple devices for larger buffers, while width expansion handles wider data paths.