18 Mbit DDR II+ SRAM at 400 MHz — what this part is
The Infineon CY7C1148KV18-400BZC is a synchronous DDR II+ SRAM organized 1M x 18, clocked at 400 MHz, in a 165-ball FBGA (13x15 mm) package. This is a high-bandwidth, low-latency memory targeted at networking buffers, telecom line cards, and DSP scratchpad where the 18-bit word width matches the datapath without packing overhead.
The 400 MHz clock rate on a DDR II+ interface means data is transferred on both edges, giving an effective 800 MT/s per pin. For a 1M x 18 configuration, that translates to a peak bandwidth of about 14.4 Gbit/s. The PCB designer needs to treat the clock and data lines as controlled-impedance traces with matched lengths — the 165-ball FBGA fanout is dense, and signal-integrity simulation is advisable before committing the layout.
The supply range of 1.7V to 1.9V is tight, so the 1.8V rail must be regulated within ±5.6%. A standard 1.8V LDO or switching regulator with 1% accuracy will hold the margin, but a 1.8V rail derived from a 3.3V bus through a simple resistor divider will drift out of spec over temperature. Plan for a dedicated regulator with remote sense if the FBGA is more than a few inches from the supply.