External Memory Interfaces Intel® Arria® 10 FPGA IP User Guide

ID 683106
Date 12/19/2023

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Document Table of Contents Command and Address Signals

Command and address signals in SDRAM devices are clocked into the memory device using the CK or CK# signal. These pins operate at single data rate (SDR) using only one clock edge. The number of address pins depends on the SDRAM device capacity. The address pins are multiplexed, so two clock cycles are required to send the row, column, and bank address.

For DDR3, the CS#, RAS#, CAS#, WE#, CKE, and ODT pins are SDRAM command and control pins. For DDR3 SDRAM, certain topologies such as RDIMM and LRDIMM include RESET#, PAR (1.5V LVCMOS I/O standard), and ALERT# (SSTL-15 I/O standard).

Although DDR4 operates in fundamentally the same way as other SDRAM, there are no longer dedicated pins for RAS#, CAS#, and WE#, as those are now shared with higher-order address pins. DDR4 still has CS#, CKE, ODT, and RESET# pins, similar to DDR3. DDR4 introduces some additional pins, including the ACT# (activate) pin and BG (bank group) pins. Depending on the memory format and the functions enabled, the following pins might also exist in DDR4: PAR (address command parity) pin and the ALERT# pin.