36Mbit DDR II+ SRAM at 450 MHz — what it does in the system
The Cypress CY7C12681KV18-450BZXC is a 36Mbit synchronous SRAM using a DDR II+ (Double Data Rate II+) interface, organized as 2M x 18. It operates at a 450 MHz clock frequency, delivering back-to-back read/write throughput without dead cycles — a key requirement for high-bandwidth buffer applications in networking line cards, telecom switches, and test equipment where the memory bus must keep pace with fast packet processors or FPGAs. The part uses a parallel memory interface and requires a 1.7V to 1.9V supply rail, typical for the DDR II+ generation.
450 MHz clock — timing margin and bus design
At 450 MHz the data window is roughly 2.2 ns for a single-edge cycle, and the DDR II+ interface transfers data on both clock edges, so the effective data rate is 900 MT/s per pin. The 165-FBGA package (13x15 mm) keeps signal inductance low, but the board designer must match trace lengths within a few hundred mils and use controlled impedance to maintain setup/hold margins.
Package and mounting — 165-FBGA considerations
Surface-mount assembly requires a BGA reflow profile with proper stencil design for the 1.0 mm ball pitch typical of this package. The package is not compatible with hand-soldering or hot-air rework without a dedicated BGA rework station.