Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
479
UG586 November 30, 2016
Chapter 3:
RLDRAM II and RLDRAM 3 Memory Interface Solutions
°
MIG versions 1.4 and later allow this input clocking setup and properly drive the
CMT backbone.
°
CLOCK_DEDICATED_ROUTE = BACKBONE constraint is used to implement CMT
backbone, following warning message is expected. It can be ignored safely.
WARNING: [Place 30-172] Sub-optimal placement for a clock-capable IO pin and PLL
pair. The flow will continue as the CLOCK_DEDICATED_ROUTE constraint is set to
BACKBONE.
u_mig_7series_0/c0_u_clk_ibuf/diff_input_clk.u_ibufg_sys_clk (IBUFDS.O) is locked
to IOB_X0Y176
u_mig_7series_0/c0_u_infrastructure/plle2_i (PLLE2_ADV.CLKIN1) is locked to
PLLE2_ADV_X0Y1
u_mig_7series_0/c1_u_infrastructure/plle2_i (PLLE2_ADV.CLKIN1) is locked to
PLLE2_ADV_X0Y5
......
• For RLDRAM II interfaces that have the memory system input clock (
sys_clk
) placed
on CCIO pins within one of the memory banks, MIG assigns the DIFF_HSTL_I I/O
standard (VCCO = 1.5V) to the CCIO pins. Because the same differential input receiver is
used for both DIFF_HSTL_I and LVDS inputs, an LVDS clock source can be connected
directly to the DIFF_HSTL_I CCIO pins.
• For RLDRAM 3 interfaces that have the memory system input clock (
sys_clk
) placed
on CCIO pins within one of the memory banks, MIG assigns the DIFF_SSTL12 I/O
standard (VCCO = 1.2V) to the CCIO pins. Because the same differential input receiver is
used for both DIFF_SSTL12 and LVDS inputs, an LVDS clock source can be connected
directly to the DIFF_SSTL12 CCIO pins.
• It is acceptable to have differential inputs such as LVDS and LVDS_25 in I/O banks that
are powered at voltage levels other than the nominal voltages required for the outputs
of those standards (1.8V for LVDS outputs, and 2.5V for LVDS_25 outputs). However,
these criteria must be met:
a. The optional internal differential termination is not used (DIFF_TERM = FALSE, which
is the default value).
Note:
This might require manually changing DIFF_TERM parameter located in the top-level
module or setting this in the UCF or XDC.
b. The differential signals at the input pins meet the VIN requirements in the
Recommended Operating Conditions table of the specific device family data sheet.
c. The differential signals at the input pins meet the VIDIFF (min) requirements in the
corresponding LVDS or LVDS_25 DC specifications tables of the specific device
family data sheet.