External Memory Interface Handbook Volume 3: Reference Material

ID 683841
Date 7/24/2019
Public
Document Table of Contents

3.17.1. Ping Pong PHY Feature Description

Conventionally, the address and command buses of a DDR3 or DDR4 half-rate or quarter-rate interface use 2T time—meaning that commands are issued for two full-rate clock cycles, as illustrated below.
Figure 110. 2T Command Timing


With the Ping Pong PHY, address and command signals from two independent controllers are multiplexed onto shared buses by delaying one of the controller outputs by one full-rate clock cycle. The result is 1T timing, with a new command being issued on each full-rate clock cycle. The following figure shows address and command timing for the Ping Pong PHY.

Figure 111. 1T Command Timing Use by Ping Pong PHY


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