SDRAM ICs

The AS4C4M16D1 DDR SDRAM is a highspeed CMOS double data rate synchronous DRAM containing 64 Mbits. It is internally configured as a quad 1M x 16 DRAM with a synchronous interface (all signals are registered on the positive edge of the clock signal, CK). Data outputs occur at both rising edges of CK and CK . Read and write accesses to the SDRAM 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 a BankActivate command which is then followed by a Read or Write command. The AS4C4M16D1 provides programmable Read or Write burst lengths of 2, 4, 8. An auto precharge function may be enabled to provide a self-timed row precharge that is initiated at the end of the burst sequence. The refresh functions, either Auto or Self Refresh are easy to use. In addition, AS4C4M16D1 features programmable DLL option. By having a programmable mode register and extended mode register, the system can choose the most suitable modes to maximize its performance. These devices are well suited for applications requiring high memory bandwidth and high performance.