DRAM Module SDRAM 256Mbyte 144SODIMM

The Micron MT8LSDT864(L)H(I), MT8LSDT1664(L)H(I), and MT8LSDT3264(L)H(I) are high-speed CMOS, dynamic random-access, memory modules organized in a x64 configuration. These modules use SDRAM devices which are internally configured as quad-bank DRAMs with a synchronous interface (all signals are registered on the positive edge of the clock signals CK). Read and write accesses to SDRAM modules 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 device bank and row to be accessed (BA0, BA1 select the device bank; device rows are selected by A0–A11 for 64MB and 128MB; A0–A12 for 256MB). The address bits registered coincident with the READ or WRITE command (A0–A7 for 64MB; A0–A8 for 128MB and 256MB) are used to select the starting device column location for the burst access. SDRAM modules provide 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. These modules use 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 device bank while accessing one of the other three device banks will hide the precharge cycles and provide seamless, high-speed, random access operation. SDRAM modules are 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, outputs, and clocks are LVTTL-compatible. SDRAM modules 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 in order to hide precharge time, and the capability to randomly change column addresses on each clock cycle during a burst access.

• PC100- and PC133-compliant, 144-pin, smalloutline, dual in-line memory module (SODIMM)
• Utilizes 125 MHz and 133 MHz SDRAM components
• Unbuffered
• 64MB (8 Meg x 64), 128MB (16 Meg x 64), and 256MB (32 Meg x 64
• Single +3.3V power supply
• Fully synchronous; all signals registered on positive edge of system clock
• Internal pipelined operation; column address can be changed every clock cycle
• Internal SDRAM banks for hiding row access/ precharge
• Programmable burst lengths: 1, 2, 4, 8, or full page
• Auto Precharge and Auto Refresh Modes
• Self Refresh Mode: Standard and Low Power
• 64MB and 128MB: 64ms, 4,096-cycle (15.625µs) refresh interval; 256MB: 64ms, 8,192-cycle (7.8125µs) refresh interval
• LVTTL-compatible inputs and outputs
• Serial Presence-Detect (SPD)
• Gold edge contacts