12 ns async SRAM — obsolete but still on the BOM
It uses a parallel interface and is organized as 128K words by 8 bits — a standard footprint for legacy 8-bit data buses in telecom line cards, industrial controllers, and test equipment that still run on a 5V rail. Infineon lists the CY7C109B-12ZXC as Obsolete. The only supply path today is through independent distribution, where surplus inventory is still available.
12 ns — what it buys on a 5V bus
The 12 ns access time and write cycle time match, so back-to-back reads and writes at the same speed are possible. The 5V supply (4.5V to 5.5V) is a hard constraint — this SRAM will not operate at 3.3V. If your system has moved to a 3.3V core with a 5V peripheral bus, you need level translators on address, data, and control lines. That adds board area and propagation delay, which may eat into the 12 ns timing margin.
Package and footprint details
The CY7C109B-12ZXC comes in a 32-TFSOP (0.724", 18.40mm width) package, also referred to as 32-TSOP I. The part is surface-mount, shipped in Tube form. The 32-TSOP I footprint is a standard 8 mm x 20 mm body with 0.5 mm pitch leads — common across many 1Mbit async SRAMs from Cypress, ISSI, and Alliance. If your board already has a 32-TSOP I footprint for a 5V async SRAM, this part should drop in without a layout change, assuming the pinout matches (always verify against your existing part's datasheet).