12 ns asynchronous SRAM for cache and buffer duty
The 71V256SA12PZI is a 256Kbit asynchronous SRAM from Renesas, organized as 32K x 8 bits with a parallel memory interface. The 12 ns access time and matching 12 ns write cycle time set the bus timing margin — in a system with a 33 MHz bus clock (30 ns period), the 12 ns access leaves 18 ns for address decode, data setup, and board trace delay before the next clock edge. This margin shrinks at higher clock rates; at 50 MHz (20 ns period) the 8 ns window is tight enough that the board layout must minimize stub length and capacitance on the data lines.
28-TSOP footprint and supply rail
Housed in a 28-TSSOP package (0.465" body width, 11.80 mm) with a surface-mount 28-TSOP supplier package designation.