55 ns asynchronous SRAM for 5 V bus designs
The Infineon CY62128BLL-55ZRI is a 1 Mbit asynchronous SRAM from the MoBL® series, organized as 128K x 8 bits. This part is housed in a 32-RTSOP surface-mount package and uses a parallel interface.
55 ns access time — bus timing margin
The 55 ns access time sets the read-cycle window for the bus. For a typical 5 V MCU running at 12 MHz (83 ns cycle), this SRAM leaves about 28 ns of margin after address setup and hold — enough for a clean read without wait states. Faster peers in the same 1 Mbit class (CY7C109D-10ZXIT, CY7C1018DV33-10VXI) offer 10 ns access, but they run from a 3.0 V or 4.5 V rail and cost more per bit. If your bus runs above 16 MHz or you need back-to-back reads at full speed, the 10 ns parts are the right fit; for a 5 V legacy bus at moderate clock rates, the 55 ns part saves BOM cost and avoids a voltage-level translation.
If your design has migrated to 3.3 V, the CY7C1018DV33-10VXI (1 Mbit, 10 ns, 3.0 V) is a pin-compatible alternative worth evaluating.
Package and footprint
The 32-RTSOP package (0.724" body width, 18.40 mm) is a compact footprint for a 1 Mbit SRAM. The fine-pitch leads require careful solder-paste stencil design.