IS61QDB44M18C-250M3

IS61QDB44M18C-250M3 Features

Overview

The 72Mb IS61QDB42M36C and IS61QDB44M18C are syn- chronous, high-performance CMOS static random access memory (SRAM) devices. These SRAMs have separate I/Os, eliminating the need for high-speed bus turnaround. The rising edge of K clock initi- ates the read/write operation, and all internal operations are self-timed. Refer to the Timing Reference Diagram for Truth Table for a description of the basic operations of these QUAD (Burst of 4) SRAMs. Read and write addresses are registered on alternating rising edges of the K clock. Reads and writes are performed in double data rate. Byte writes can change with the corresponding data-in to en- able or disable writes on a per-byte basis. An internal write buffer enables the data-ins to be registered one cycle after the write address. The first data-in burst is clocked one cycle later than the write command signal, and the second burst is timed to the following rising edge of the K# clock. Two full clock cycles are required to complete a write operation. During the burst read operation, the data-outs from the first and third bursts are updated from output registers of the sec- ond and third rising edges of the C# clock (starting 1.5 cycles later after read command). The data-outs from the second and fourth bursts are updated with the third and fourth rising edges of the C clock. The K and K# clocks are used to time the data-outs whenever the C and C# clocks are tied high. Two full clock cycles are required to complete a read operation. The device is operated with a single +1.8V power supply and is compatible with HSTL I/O interfaces.