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Customizing the EVM for Optional Clocking Support
21
SLAU701 – May 2017
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HSDC Pro Settings for Optional ADC Device Configuration
The LMK04828 provides a buffered copy of the onboard crystal oscillator (OSCout) to the LMX2582. By
default, the LMX2582 is configured to generate the ADC device clock using this 100-MHz reference and
the LMK04828 is used in clock distribution mode and provides the SYSREF and device clocks for the
FPGA. The EVM can be configured to use external clocks with the following steps (see
Figure B-2
):
1. Modify the hardware:
(a) Remove C50 and C51, populate C49 and C52.
(b) Remove R67, populate R70.
2. Connect the Signal Generators:
(a) Connect the 10-MHz reference from Sig Gen 1 to Sig Gen 2.
(b) Configure Sig Gen 2 to use the 10-MHz reference input from Sig Gen 1.
(c) Sig Gen 1 connects to DEVCLK (J18). Set to the generator frequency to the desired F
DEVCLK
. Set
output level to +9 dBm.
(d) Sig Gen 2 connects to LMKCLK (J22) with output level +6 dBm to +9 dBm. Set the generator
frequency as follows:
F
LMKCLK
= F
DEVCLK
3. Program the GUI:
(a) In the EVM tab, set the Clock Source to
External
.
(b) Enter the
Sampling Frequency
(F
DEVCLK
) in step 2(b).
Figure B-2. External LMKCLK Configuration
