User Manual

1-Aug-2012
6
2 Functional Description
2.1 EPP
The ZedBoard features a Xilinx Zynq XC7Z020-1CSG484 EPP. The initial ZedBoards ship with
Engineering Sample "CES" grade silicon. Later shipments will eventually switch to production "C"
grade silicon once they become available. The EPP part markings indicate the silicon grade.
2.2 Memory
Zynq contains a hardened PS memory interface unit. The memory interface unit includes a
dynamic memory controller and static memory interface modules.
2.2.1 DDR3
The ZedBoard includes two Micron MT41K128M16HA-15E:D DDR3 memory components
creating a 32-bit interface. The DDR3 is connected to the hard memory controller in the
Processor Subsystem (PS) as outlined in the Zynq datasheet.
The multi-protocol DDR memory controller is configured for 32-bit wide accesses to a 512 MB
address space. The PS incorporates both the DDR controller and the associated PHY, including
its own set of dedicated I/Os. DDR3 memory interface speeds up to 533MHz (1066Mbs) are
supported.
The DDR3 uses 1.5V SSTL-compatible inputs. DDR3 Termination is utilized on the ZedBoard.
The EPP and DDR3 have been placed close together keeping traces short and matched.
DDR3 on the PS was routed with 40 ohm trace impedance for single-ended signals, and DCI
resistors (VRP/VRN) as well as differential clocks set to 80 ohms. Each DDR3 chip needs its
own 240-ohm pull-down on ZQ.
DDR-VDDQ is set to 1.5V to support the DDR3 devices selected. DDR-VTT is the termination
voltage which is ½ DDR-VDDQ. DDR-VREF is a separate buffered output that is equal to ½
nominal DDR-VDDQ. The DDR-VREF is isolated to provide a cleaner reference for the DDR
level transitions.