Description
The 128Mb DDR SDRAM is a high-speed CMOS, dynamic random-access memory containing 134,217,728 bits. It is internally configured as a quad-bank DRAM.
The 128Mb DDR SDRAM uses a double-data-rate architecture to achieve high-speed operation. The double data rate architecture is essentially a 2n prefetch architecture with an interface designed to transfer two data words per clock cycle at the I/O pins. A single read or write access for the 128Mb DDR SDRAM effectively consists of a single 2n-bit wide, one clock cycle data transfer at the internal DRAM core and two corresponding n-bit wide, one-half-clock-cycle data transfers at the I/O pins.
A bidirectional data strobe (DQS) is transmitted externally, along with data, for use in data capture at the receiver. DQS is a strobe transmitted by the DDR SDRAM during Reads and by the memory controller during Writes. DQS is edge-aligned with data for Reads and center-aligned with data for Writes.

FEATUREs
• Double data rate architecture: two data transfers per clock cycle
• Bidirectional data strobe (DQS) is transmitted and received with data, to be used in capturing data at the receiver
• DQS is edge-aligned with data for reads and is center aligned with data for writes
• Differential clock inputs (CK and CK)
• Four internal banks for concurrent operation
• Data mask (DM) for write data
• DLL aligns DQ and DQS transitions with CK transitions, also aligns QFC transitions with CK during Read cycles • Commands entered on each positive CK edge; data and data mask referenced to both edges of DQS
• Burst lengths: 2, 4, or 8
• CAS Latency: 2, 2.5
• Auto Precharge option for each burst access
• Auto Refresh and Self Refresh Modes
• 15.6ms Maximum Average Periodic Refresh Interval
• Supports tRAS lockout feature
• 2.5V (SSTL_2 compatible) I/O
• VDDQ = 2.5V ± 0.2V
• VDD = 2.5V ± 0.2V
• -7K parts support PC2100 modules.
   -75B parts support PC2100 modules
   -8B parts support PC1600 modules