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3-Feb-2015
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Functional Description
2.1 All Programmable SoC
The PicoZed 7010/7020 includes a Xilinx Zynq XC7Z010-1CLG400 or Zynq XC7Z020-1CLG400
AP SoC. The PicoZed 7010/7020 is available in both commercial and industrial temperature
grade options.
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. PicoZed 7010/7020 takes
advantage of these interfaces to provide system RAM as well as two different non-volatile
memory sources.
2.2.1
DDR3L
PicoZed 7010/7020 includes two Micron MT41K256M16HA-125:E DDR3L memory components
creating a 256M x 32-bit interface, totaling 1 GB of random access memory. The DDR3L
memory is connected to the hard memory controller in the PS of the Zynq AP SoC. The PS
incorporates both the DDR controller and the associated PHY, including its own set of dedicated
I/Os.
Speed of up to 1,066 MT/s for DDR3L is supported.
The DDR3L interface is designed to use 1.35V SSTL-compatible inputs by default. There is an
option to support 1.5V capable DDR3 devices via a resistor change on the PicoZed 7010/7020.
This option is provided as a note on the PicoZed 7010/7020 schematics.
DDR3L Termination is utilized on the PicoZed 7010/7020 and configured for fly-by routing
topology. Additionally the board trace lengths are matched, compensating for the XC7Z010-
CLG400 internal package flight times, to meet the requirements listed in the Zynq-7000 AP SoC
PCB Design and Pin Planning Guide (UG933).
All single-ended signals are routed with 40 ohm trace impedance. DCI resistors (VRP/VRN), as
well as differential clocks, are set to 80 ohms. DDR3-CKE0 is terminated through 40 ohms to
VTT. DDR3-ODT has the same 40 ohm to VTT termination. There was a discrepancy in the
original Xilinx documentation regarding whether DDR3-RESET# should have 40 ohms to VTT or
4.7K ohm to GND, which is why a resistor jumper circuit was designed in to give both options.
Xilinx has since clarified that 4.7K-ohm to GND is the correct configuration for DDR3-RESET#.
The default position of the resistor jumper on production units is 1-2 (GND).
Each DDR3L chip has its own 240-ohm pull-down on ZQ. Note DDR-VREF is not the same as
DDR-VTT.