36K synchronous FIFO — obsolete but still traceable
The Infineon CY7C4235-15AXCT is a 36K (2K x 18) synchronous FIFO from the CY7C series, designed for buffering data between clock domains in digital systems. It operates at a 66.7 MHz data rate with a 10 ns access time, making it suitable for moderate-speed data path applications where flow control and retransmission are needed.
66.7 MHz synchronous operation with 10 ns access
The 66.7 MHz clock rate sets the maximum write/read cycle frequency — at this speed, the FIFO can sustain a 66.7 million words-per-second throughput, limited by the 10 ns access time which governs how quickly data appears on the output bus after a read request. Organized as 2K words by 18 bits wide, the 36K total memory depth suits applications like PCI bus bridging, DSP data buffering, or network packet queuing where the 18-bit word width matches common bus architectures.
Retransmit and programmable flags — flow control features
Retransmit capability allows the FIFO to re-read data from a previous pointer position without a full reset — useful in protocol retry scenarios where a packet must be resent without flushing the buffer. Programmable flags support means the almost-full and almost-empty thresholds can be set by the user, giving the system designer control over when to throttle the data source or request more data. Expansion is supported in both depth and width — multiple FIFOs can be cascaded to create larger buffers without external logic, though the bus direction is uni-directional so separate FIFOs are needed for bidirectional paths.
64-LQFP package — board-fit considerations
The 14x14 mm footprint is common for mid-density FIFOs and SRAMs, and the tape-and-reel packaging indicates it was originally intended for automated pick-and-place assembly.