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SNAU235 – May 2018
Copyright © 2018, Texas Instruments Incorporated
Reference PRO
Appendix B
SNAU235 – May 2018
Reference PRO
The Reference PRO board is used to program the LMX2572LPEVM and provide a clean reference clock
to LMX2572LPEVM at the same time. The board has several control pins dedicated for control of output
format, output frequency, and output enable control. These control pins are configurable through the
jumpers by strapping the center pin to Vdd position or GND position. Connections from the Vdd position to
the device supply or from the GND position to the ground plane are connected by 1.5-k
Ω
resistors. By
default, the board is configured for 100-MHz LVPECL output. Connect the Reference PRO to the PC
through the USB interface to provide the Reference PRO a steady power supply.
B.1
Output Frequency Selection
Jumpers FS1 and FS0 are used to set the output frequency.
Table 8. Reference PRO Output Frequency Selection
FS1
FS0
OUTPUT FREQUENCY (MHz)
GND
GND
100
GND
NC
312.5
GND
Vdd
125
NC
GND
106.25
NC
NC
156.25
NC
Vdd
212.5
Vdd
GND
62.5