|Std. Pack Qty
The 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 33,554,432-bit banks is organized as 4,096 rows by 256 columns by 32 bits.
Read and write accesses to the SDRAM are burst oriented; 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 ACTIVE command, which is then
followed by a READ or WRITE command. The address bits registered coincident 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 burst access.
The SDRAM provides for programmable read or write burst lengths (BL) 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
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 accessing 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, low-power 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 operating performance, including the
ability to synchronously burst data at a high data rate with automatic column-address
generation, the ability to interleave between internal banks to hide precharge time and
the capability to randomly change column addresses on each clock cycle during a burst