DS737 Datasheet, PDF (2/5 Pages) Xilinx, Inc – Wrapper around the MMCM_ADV primitive

Mixed-Mode Clock Manager (MMCM) Module (v1.00a)
Functional Description
The MMCM Module takes an input clock named CLKIN1, and generates several output clocks, each of
which can be configured to have a different frequency that is dependent on the input clock frequency.
The MMCM Module encapsulates the MMCM_ADV primitive. The MMCM_ADV primitive is
described in the Virtex-6 Libraries Guide that is provided as part of the ISE tools documentation. Detailed
information about the usage of the MMCM_ADV primitive is available in the Virtex-6 User Guide.
The MMCM Module provides optional buffers for the CLKIN1 input, and the CLKOUTn and
CLKFBOUT outputs. CLKOUTn represents the seven clock outputs CLKOUT0 through CLKOUT6.
The second clock input of the MMCM_ADV primitive is not used, and the clock input select input of
the MMCM_ADV primitive is connected to a constant to always select the CLKIN1 signal. The
dynamic reconfiguration inputs and outputs of the MMCM_ADV primitive are hidden/terminated
within the MMCM module. All other inputs and outputs of the MMCM_ADV primitive are inputs and
outputs of the MMCM module, with optional buffering.
In the context of an embedded processor system, the recommended usage of the MMCM module is to
take a single reference clock input, and configure one or more CLKOUTn signals to produce the
different clock frequencies and phases required, with the CLKOUTn and CLKFBOUT signals buffered
as needed, and the CLKFBOUT signal connected back to the CLKFBIN input.
The output clock frequencies are derived from the input clock frequency, and the values of the
C_DIVCLK_DIVIDE, C_CLKFBOUT_MULT and C_CLKOUTn_DIVIDE parameters, as described in
the Virtex-6 Libraries Guide.
MMCM Module Parameters
The MMCM module is configured by selecting appropriate values for its configuration parameters,
described in Table 1.
Table 1: Configuration Parameters for MMCM Module
Parameter Name
Description
Allowed
Values
C_BANDWIDTH
This parameter passes the value to the Same as
equivalent attribute of the MMCM_ADV MMCM_ADV
C_CLKFBOUT_BUF
If C_CLKFBOUT_BUF = true, a BUFG is
inserted between the CLKFBOUT pin of
the MMCM_ADV primitive and
CLKFBOUT output
true, false
C_CLKFBOUT_
USE_FINE_PS
This parameter passes the value to the
equivalent attribute of the MMCM_ADV
true, false
C_CLKFBOUT_MULT_F
This parameter passes the value to the
equivalent attribute of the MMCM_ADV
Same as
MMCM_ADV
C_CLKFBOUT_PHASE
This parameter passes the value to the
equivalent attribute of the MMCM_ADV
Same as
MMCM_ADV
C_CLKIN1_BUF
If C_CLKIN1_BUF = true, a BUFG is
inserted between the CLKIN1 input and
the CLKIN1 pin of the MMCM_ADV
primitive
true, false
Default
Value
Type
OPTIMIZED string
false
Boolean
false
1.000
0.000
Boolean
real
real
false
Boolean
2
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DS737 June 24, 2009
Product Specification