General Description

The 256Mb SDRAM is a high-speed CMOS, dynamic random-access memory containing 268,435,456 bits. It is internally configured as a quad-bank DRAM with a synchronous interface (all signals are registered on the positive edge of the clock signal, CLK). Each of the x4’s 67,108,864-bit banks is organized as 8192 rows by 2048 columns by 4 bits. Each of the x8’s 67,108,864-bit banks is organized as 8192 rows by 1024 columns by 8 bits. Each of the x16’s 67,108,864-bit banks is organized as 8192 rows by 512 columns by 16 bits.

Features

• PC100- and PC133-compliant

• Fully synchronous; all signals registered on positive edge of system clock

• Internal, pipelined operation; column address can be changed every clock cycle

• Internal banks for hiding row access/precharge

• Programmable burst lengths: 1, 2, 4, 8, or full page

• Auto precharge, includes concurrent auto precharge and auto refresh modes

• Self refresh mode (not available on AT devices)

• Auto refresh

– 64ms, 8192-cycle refresh (commercial and industrial)

– 16ms, 8192-cycle refresh (automotive)

• LVTTL-compatible inputs and outputs

• Single 3.3V ±0.3V power supply