Asynchronous FIFO for 5V data buffering — 15 ns access, 50 MHz throughput
The Cypress CY7C421-15AXCT is a 4.5K (512 x 9) asynchronous FIFO memory designed for 5V data buffering applications. The 9-bit width (8 data bits plus a parity/flag bit) is typical for FIFO buffers used in DSP interfaces, parallel bus bridging, and data acquisition front-ends.
The CY7C421-15AXCT is officially marked as Obsolete by Cypress (now Infineon). No direct replacement has been listed in the official lifecycle documentation. Buyers should verify stock position and lead time for a BOM line.
Retransmit capability and expansion options
This FIFO includes retransmit capability, allowing the read pointer to be reset to the beginning of the stored data without clearing the memory — useful for retry protocols in communication links. Expansion is supported in both depth and width, meaning multiple CY7C421 devices can be cascaded to create larger buffers or wider data paths. Note that programmable flags and FWFT (First-Word Fall-Through) are not supported, so flag logic is limited to the standard empty/full/half-full outputs.