I have 8 DDR3 chips connected to an FPGA (2 controllers) and two DSPs, where 4 DDR3 chips are connected to each of the processors. At this moment I have one VTT regulator TPS5120 on board, will that be enough? Should I include more VTT regulator each near to DDR3's?
I am using a separate VTT LDO per CPU/FPGA<->RAM pair. E.g. if I have a FPGA with two memory chips plus DSP SoC with two memory chips, I use two VTT LDOs. The problem is that if one device does a burst and the current rises, another chip burst could possibly fail if the current is too high. It is expensive, but works good.