FIFO fit and board integration
The CY7C4235V-15ASC is a synchronous FIFO from Infineon's CY7C series, organized as 2K words by 18 bits for a total of 36 Kbit of storage. The 18-bit word width matches a byte-plus-parity or 16-bit data bus with two control/status bits — common in telecom or packet-buffer applications where the extra bits carry sideband flags. Packaged in a 64-LQFP (supplier device package 64-TQFP, 10x10 mm), the 0.5 mm pitch demands a 4-layer PCB for reliable fan-out of all 64 pins.
Timing and flow-control decisions
With a 66.7 MHz data rate and 11 ns access time, the read-cycle window is tight — the downstream logic must latch data within 11 ns of the read clock edge, or the bus margin disappears. The synchronous clocked operation (no strobe handshake) means both read and write clocks must be free-running and phase-managed; a clock jitter above 100 ps may violate setup/hold at the FIFO inputs. Programmable almost-full and almost-empty flags let the system controller set flow-control thresholds at configurable levels, reducing the need for constant polling. Retransmit capability allows rereading a data packet without a full FIFO reset — useful in error-retry data paths where a corrupted word must be re-sent. Note that FWFT (First-Word Fall-Through) is not supported, so the first word written is not available on the output until the first read clock edge after the first read enable — budget one clock cycle of latency. Depth and width expansion is supported, so multiple CY7C4235V-15ASC devices can be cascaded for deeper or wider buffers without external glue logic. The uni-directional bus means data flows one way — not suitable for bidirectional data paths without external transceivers.
RoHS compliance is standard for Infineon's CY7C series, but specific compliance documentation (REACH, UL, IEC) should be requested at quote time as it varies by date code.