MT48LC8M16A2

The Micron 128Mb SDRAM is a high-speed CMOS,dynamic random-access memory containing 134,217,728 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's33,554,432-bit banks is organized as 4,096 rows by 2,048 columns by 4 bits. Each of the x8's 33,554,432-bit banks is organized as 4,096 rows by 1,024 columns by 8 bits. Each of the x16's 33,554,432-bit banks is organized as 4,096 rows by 512 columns by 16 bits.

Read and write accesses to the SDRAM are burst ori-ented; accesses start at a selected location and continue for a programmed number of locations in a programmed sequence. Accesses begin with the registration of an AC-TIVE command, which is then followed by a READ or WRITE command. The address bits registered coinci-dent with the ACTIVE command are used to select the bank and row to be accessed (BA0, BA1 select the bank; A0-A11 select the row). The address bits registered coincident with the READ or WRITE command are used to select the starting column location for the burstaccess.

The SDRAM provides for programmable READ or WRITE burst lengths of 1, 2, 4, or 8 locations, or the full page, with a burst terminate option. An auto precharge function may be enabled to provide a self-timed row precharge that is initiated at the end of the burst sequence.

The 128Mb SDRAM uses an internal pipelined architecture to achieve high-speed operation. This architecture is compatible with the 2n rule of prefetch architectures, but it also allows the column address to be changed on every clock cycle to achieve a high-speed, fully random access. Precharging one bank while access-ing one of the other three banks will hide the precharge cycles and provide seamless high-speed, random-access operation.

The 128Mb SDRAM is designed to operate in 3.3V memory systems. An auto refresh mode is provided, along with a power-saving, power-down mode. All inputs and outputs are LVTTL-compatible.

SDRAMs offer substantial advances in DRAM operat-ing performance, including the ability to synchronously burst data at a high data rate with automatic column-address generation, the ability to interleave between in-ternal banks in order to hide precharge time and the capability to randomly change column addresses on each clock cycle during a burst access.