A detailed walkthrough of the DDR4 SDRAM startup process covering four phases: power-up initialization, ZQ Calibration (tuning internal 240Ω resistors via an external precision reference), VrefDQ Calibration (setting the internal voltage reference for DDR4's POD signaling), and Read/Write Training. The training phase includes Write Leveling (aligning DQS to CK for each DRAM on a DIMM using fly-by routing), MPR Pattern Write, Read Centering (finding the data eye center for reads), and Write Centering (aligning write data to the write strobe). Periodic calibration for ZQ and read centering is also discussed for devices operating in variable voltage/temperature environments.
Table of contents
Introduction ¶Initialization ¶ZQ Calibration ¶SubscribeVref DQ Calibration ¶Read/Write Training ¶Periodic Calibration ¶In a Nutshell ¶Reference ¶Questions & Comments ¶Sign-up for the NewsletterSort: