Available options in single channel topology:
- Single Channel 16-bit
- Single Channel 24-bit as 16-bit Data with 8-bit ECC
- Single Channel 32-bit
- Single Channel 40-bit as 32-bit Data with 8-bit ECC
- Single Channel 64-bit
- Single Channel 72-bit as 64-bit Data with 8-bit ECC
PCB Expansion Options:
- Optimum
- CLK Expansion
For Single Channel DDR4 Component interfaces, there are two distinct pinouts. The first is Optimum which efficiently packs the Triplet based on the data width. The other is CLK Expansion which is fundamentally a different pinout than the Optimum with two DDR4 CLK outputs generated for DDP Deep topologies.
For most applications, the Optimum pinout is acceptable and allows for future expansion if adding ECC, 3DS devices, or expanding the data width. The CLK Expansion option is only required when migrating to DDP Deep devices in the future. The current Versal DDR4 solution only supports x8 DDP Deep devices and two DDR4 CLK outputs are only required when five or more components are present as with data widths of 40-bits, 64-bits, or 72-bits.
It is not possible to generate any other Single Channel topology which requires two CLK outputs at this time. The logical ranks found in 3DS devices do not add additional loading like DDP Deep devices, so they do not require CLK expansion. There is no support for DDP Deep 3DS Single Channel or Dual Channel component interfaces. RDIMM/LRDIMM applications support DDP Deep 3DS components.
The Optimum single clock output pinout leaves free Nibbles open on the far Right Bank. Depending on your data width, more Nibbles are available moving Right to Left. The CLK Expansion pinout has two free Nibbles, one in the first Bank and one in the last Bank. The CLK Expansion pinout has more free Nibbles starting in the Right bank and moving Left as your data width decreases.
Both pinouts support 3DS and Rank expansion, but you must use the CLK Expansion pinout for DDP Deep devices with five or more placements. If the DDRMC configuration already has two CLKs enabled, then the only pinout option is Optimum which is the CLK Expansion pinout.