External Memory Interface Handbook Volume 3: Reference Material

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

3.17.3. Ping Pong PHY Limitations

Ping Pong PHY supports up to two ranks per memory interface. In addition, the maximum data width is x72, which is half the maximum width of x144 for a single interface.

Ping Pong PHY uses all lanes of the address and command I/O bank as address and command. For information on the pin allocations of the DDR3 and DDR4 address and command I/O bank, refer to DDR3 Scheme 1 and DDR4 Scheme 3, in External Memory Interface Pin Information for Arria 10 Devices, on www.altera.com.

An additional limitation is that I/O lanes may be left unused when you instantiate multiple pairs of Ping Pong PHY interfaces. The following diagram shows two pairs of x8 Pin Pong controllers (a total of 4 interfaces). Lanes highlighted in yellow are not driven by any memory interfaces (unused lanes and pins can still serve as general purpose I/Os). Even with some I/O lanes left unused, the Ping Pong PHY approach is still beneficial in terms of resource usage, compared to independent interfaces. Memory widths of 24 bits and 40 bits have a similar situation, while 16 bit, 32 bit, and 64 bit memory widths do not suffer this limitation.

Figure 114. Two Pairs of x8 Pin-Pong PHY Controllers


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