66.7 MHz synchronous FIFO — the throughput ceiling
The CY7C4251-15JXCT is a synchronous FIFO from Infineon's CY7C series, clocked at 66.7 MHz with a 10 ns access time. That clock rate sets the maximum data-transfer rate through the buffer — at full speed, one 9-bit word moves in every cycle, so the sustained throughput is 66.7 million words per second. The 10 ns access time is the window from the clock edge to valid data on the output bus; it governs the setup/hold margin at the receiving end of the bus. Memory depth is 8K words, each 9 bits wide — the extra bit is handy for a parity flag or a control tag alongside an 8-bit data byte. The 9-bit organization matches the classic FIFO architecture used in telecom framers, DSP interconnects, and printer data paths where a sideband signal rides with the data.
32-PLCC J-Lead — hand-solderable legacy package
Housed in a 32-lead PLCC with J-bend leads (supplier package 32-PLCC, 11.43x13.97 mm body). The J-lead footprint is less common in new designs than gull-wing QFP packages, but it is still hand-solderable with a hot-air rework station — the leads are tucked under the body, so a standard iron tip cannot reach them. A PLCC socket is an option for prototyping; the part drops into a 32-pin PLCC socket without soldering. The 35 mA max supply current is modest; the FIFO does not need a heatsink in normal operation.
Infineon lists the CY7C4251-15JXCT as obsolete. For a BOM line that depends on this FIFO, the procurement path is a per-RFQ check of available inventory — no guaranteed continuous supply from the factory.