Asynchronous FIFO in a 32-PLCC J-Lead — what you are getting
The Cypress CY7C425-20JXCT is a 9K (1K x 9) asynchronous FIFO memory with a 20 ns access time and a 50 MHz data rate, housed in a J-Lead package.
A 20 ns access time means the FIFO can deliver data within 20 ns of the read-enable assertion. At a 50 MHz clock rate (20 ns period), that leaves zero margin for a full-cycle read if the controller expects data back in one clock — you are operating at the ragged edge of a single-cycle handshake. In practice, this part is best matched to a system that uses asynchronous read strobes with a wait-state insertion or a stretched read cycle, not a synchronous pipeline expecting data on the next clock edge. The 20 ns rating also sets the minimum read-pulse width the FIFO will honour; narrower strobes risk data corruption.
1K x 9 depth and retransmit — buffer sizing and debug
With 1K words of storage, this FIFO buffers about one kilobyte of data (or 9 Kbit). That is enough to absorb bursty transfers in a printer, a telecom line card, or a data-acquisition front-end where the host processor cannot service every byte immediately. The retransmit capability lets you re-read the FIFO contents from the beginning without a full reset — useful for retry-on-error protocols or for replaying a data block during debug. Note that there are no programmable flags and no FWFT (First-Word Fall-Through) support, so the empty/full status is the standard asynchronous handshake, not the zero-latency read-ahead mode.
The CY7C425-20JXCT is listed as obsolete. If your BOM calls for this exact part, the only sourcing channel is the independent distribution market — new-old-stock or surplus inventory that has already been manufactured. There is no LTB window to catch, because the discontinuation has already occurred. Any board that depends on this FIFO should be evaluated for a pin-compatible replacement or a redesign to a current-generation FIFO family before the available surplus dries up.
32-PLCC J-Lead — rework and footprint reality
The 32-lead PLCC with J-leads (supplier device package 32-PLCC, 11.43x13.97 mm) is a surface-mount package that is hand-reworkable with a hot-air station — the J-leads are visible and accessible, unlike a QFN or BGA. The footprint is a standard PLCC-32 land pattern; no special via-in-pad or thermal pad is required. The Tape & Reel (TR) packaging option means this part was originally intended for automated pick-and-place, but the PLCC form factor is forgiving enough for bench rework if you are careful with the hot-air profile and do not overheat the plastic body.
Supply voltage and temperature — the guardrails
Maximum supply current is 55 mA, which is modest for a 9K FIFO running at 50 MHz; the 5 V rail should have no trouble supplying that. If your application sees -40°C startup or +85°C ambient, this FIFO is not rated for it, and you would need an industrial-temperature variant from the same family (if one exists) or a different FIFO altogether.