12 ns asynchronous SRAM in a 44-TSOP II footprint
The Infineon CY7C1020BN-12ZXC is a 512Kbit asynchronous SRAM organized as 32K x 16 bits, with a 12 ns access time that gives a 5V bus a clean timing margin for most 16-bit microcontroller and DSP systems from the late-90s through mid-2000s era.
5V-only supply — not a 3.3V part
The supply range of 4.5V to 5.5V means this SRAM is strictly a 5V device. It will not operate from a 3.3V rail. If your system runs on 3.3V logic, you need a different memory — the CY7C1020BN family has no 3.3V variant; look instead at the CY7C1021DV33 or similar 3.3V asynchronous SRAMs in the same 44-TSOP footprint.
Obsolete — sourcing strategy matters
This part carries an official obsolete product status. Infineon (formerly Cypress) has ended production; there is no last-time-buy window still open. Date-code provenance and device authenticity become the buyer's primary concern — verify the parts come from a traceable source, and budget for possible incoming inspection.
If the application sees temperature extremes, a different memory tier is required.