AS4C128M16D2A-25BIN

The 2Gb DDR2 is a high-speed CMOS Double-DataRate-Two (DDR2), synchronous dynamic random - access memory (SDRAM) containing 2048 Mbits in a 16- bit wide data I/Os. It is internally configured as a 8-bank DRAM, 8 banks x 16Mb addresses x 16 I/Os. The device is designed to comply with DDR2 DRAM key features such as posted CAS# with additive latency, Write latency = Read latency -1, Off-Chip Driver (OCD) impedance adjustment, and On Die Termination(ODT).All of the control and address inputs are synchronized with a pair of externally supplied differential clocks. Inputs are latched at the cross point of differential clocks (CK rising and CK# falling). All I/Os are synchronized with a pair of bidirectional strobes (DQS and DQS#) in a source synchronous fashion. The address bus is used to convey row, column, and bank address information in RAS #, CAS# multiplexing style. Accesses begin with the registration of a Bank Activate command, and then it is followed by a Read or Write command. Read and write accesses to the DDR2 SDRAM are 4 or 8-bit burst oriented; accesses start at a selected location and continue for a programmed number of locations in a programmed sequence. Operating the eight memory banks in an interleaved fashion allows random access operation to occur at a higher rate than is possible with standard DRAMs. An auto precharge function may be enabled to provide a self-timed row precharge that is initiated at the end of the burst sequence. A sequential and gapless data rate is possible depending on burst length, CAS latency, and speed grade of the device.