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.

• JEDEC Standard Compliant
• JEDEC standard 1.8V I/O (SSTL_18 compatible)
• Power supplies: VDD & VDDQ +1.8V ± 0.1V
• Operating temperature:
  • Commercial (0 ~ 85 °C)
  • Industrial (-40 ~ 95 °C)
• Supports JEDEC clock jitter specification
• Fully synchronous operation
• Fast clock rate: 400MHz
• Differential Clock, CK & CK#
• Bidirectional single/differential data strobe
  • DQS & DQS#
• 8 internal banks for concurrent operation
• 4-bit prefetch architecture
• Internal pipeline architecture
• Precharge & active power down
• Programmable Mode & Extended Mode registers
• Posted CAS# additive latency (AL): 0, 1, 2, 3, 4, 5
• WRITE latency = READ latency - 1 tCK
• Burst lengths: 4 or 8
• Burst type: Sequential / Interleave
• DLL enable/disable
• Off-Chip Driver (OCD) - Impedance Adjustment - Adjustable data-output drive strength