256Kbit async SRAM, 12 ns — what you need to know
The Infineon CY7C1399BN-12ZXCT is a 256Kbit asynchronous SRAM organized 32K x 8, with a 12 ns access time and a 3V–3.6V supply range. This is a volatile memory — data is lost when power drops below the minimum supply.
12 ns access time — bus timing margin
The 12 ns access time and 12 ns write cycle time mean this SRAM can keep up with a 50–66 MHz bus without wait states, assuming reasonable PCB trace lengths. If your controller's memory interface runs faster than that, you'll need to budget for the access time in your timing closure — or look at a pipelined synchronous SRAM.
3V–3.6V supply — no 5V tolerance
The I/O pins track VDD — applying 5V to any pin will exceed the absolute maximum ratings. If your legacy design runs at 5V, you need a different SRAM or a voltage translation bridge.
Package: 28-TSOP I — rework and footprint
The 28-TSOP I package is a thin small-outline package with a 0.465-inch body width. The TSOP I footprint is shared by many 32K x 8 async SRAMs, which helps if you're looking for a drop-in replacement.
This part is formally obsolete per the manufacturer. That means new-manufacture stock is gone; remaining inventory is limited to what's in the distribution channel or on the surplus market. If you have an active BOM line with this order code, the window for factory-origin parts is closed — procurement now depends on independent-distributor stock, which is finite and quoted to order.