Synchronous FIFO for clock-domain crossing and data buffering
The Cypress CY7C4245V-15ASXC is a synchronous FIFO memory from the CY7C series, organized as 4K by 18 bits (72 Kbit total). It operates at a 66.7 MHz data rate with an 11 ns access time, designed for buffering data between clock domains or rate-matching in digital systems.
The CY7C4245V-15ASXC is listed as obsolete. For new designs, a current-production synchronous FIFO from the same family or a pin-compatible alternative should be evaluated.
66.7 MHz data rate and 11 ns access — timing margin for synchronous buses
The 66.7 MHz clock rate gives a 15 ns cycle period. With an 11 ns access time, the part leaves about 4 ns of setup margin before the next clock edge — enough for most 66 MHz bus interfaces but tight if the board has long trace runs or multiple loads. The synchronous architecture eliminates the dead cycles of asynchronous FIFOs, so back-to-back reads and writes run at full clock rate without wait states. The 18-bit word width (16 data + 2 parity/control bits) matches common 16-bit DSP or processor buses with room for a tag bit.
64-TQFP package — rework and layout notes
The 64-TQFP (14x14 mm body) is a fine-pitch (0.8 mm typical) gull-wing package that reflows well with standard lead-free profiles. The exposed pad is not present on this package, so all heat dissipation goes through the leads; the 30 mA max supply current is low enough that thermal issues are unlikely.