The Infineon CY7C1021B-15VXE is a 1Mbit asynchronous SRAM organized as 64K words of 16 bits each, accessed through a parallel interface. The 15 ns write cycle time matches the read access, so back-to-back read-write transitions stay within one clock edge of a typical 66 MHz memory controller without wait states.
Industrial temperature grade — where this SRAM runs
At 125°C the leakage current climbs, but the 15 ns timing is specified across the full temperature range, so the bus margin holds.
This part is now available only through independent distribution — surplus inventory, new-old-stock, or broker-sourced lots. If your BOM still specifies this exact order code, the procurement path is a one-time buy of available stock, not a recurring supply. For a new design or a production line that needs a long-term source, the logical move is to qualify a pin-compatible 5 V asynchronous SRAM in a 44-SOJ package from a current-production family.
44-SOJ package — footprint and layout note
The 44-BSOJ package (0.400-inch body width, 10.16 mm) is a surface-mount SOJ with J-bend leads on 1.27 mm pitch. It is a common footprint for 1Mbit asynchronous SRAMs from the 2000s era. When sourcing a replacement, the 44-SOJ land pattern is the fixed constraint — any alternate must match the JEDEC SOJ-44 footprint exactly.