400 MHz DDR II SRAM — what the 1M x 36 width buys the design
The 36-bit word width is a key differentiator: it matches a 36-bit bus (common with parity or ECC schemes) using a single device, avoiding the layout complexity and added capacitive load of pairing two 18-bit parts. Operating from a 1.7V to 1.9V supply, this part is a native 1.8V device, not a legacy 3.3V or 2.5V SRAM. That means the board needs a dedicated 1.8V rail for the SRAM core and I/O — no dropping in on an existing 2.5V plane.
Obsolete — sourcing reality and the replacement question
Cypress (now Infineon) no longer manufactures this part. Sourcing is limited to surplus and broker channels — independent distribution that holds remaining inventory from last-time-buy lots or overruns. Any stock available today is date-coded from the final production window, so verify date-code freshness and authenticity before committing a BOM line. The closest functional alternatives are other 1M x 36 DDR II SRAMs in a 165-FBGA package from the same generation — but ball-map compatibility is not guaranteed. A cross-reference search against the original Cypress portfolio is the first step; a full PCB layout review is the second.
165-ball FBGA footprint — what to check before ordering
This part is supplied in a 165-ball FBGA (15x17 mm) package, mounted on the board as a surface-mount BGA. The 1.0 mm ball pitch requires careful PCB layout: via-in-pad or microvia fan-out is typical for the inner rows. Decoupling should follow the manufacturer's recommendation for 1.8V DDR-II SRAM — a 0.1 µF capacitor per supply pin pair, placed as close to the balls as the breakout allows. The commercial temperature rating means the part is not specified below 0°C or above 70°C ambient; if the system sees cold starts below freezing, this SRAM is outside its guaranteed operating range.