8
Configuring the Board
8.1
Default Configuration for Programming and Testing With USB Cable Attached
8.2
Configuration for Programming With USB Cable Attached
8.3
Configuration for Testing From a Saved Configuration With USB Cable Removed
Configuring the Board
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The CDCE72010EVM can be powered from the USB power supply or from an external source. The
CDCE72010EVM only needs a USB cable attached for programming purposes. However, for test
measurements, it is recommended to also use an external 3.3-V power supply. Test measurements also
can be taken with only the USB-supplied power. However, due to USB port power limitations, results may
degrade. It is also possible to program the CDCE72010 and then disconnect the USB cable (may require
minor board configuration changes).
The CDCE72010EVM is configured by default to operate with the USB cable attached and a 3.3-V power
supply added to EXT VDD and GND. In this configuration, the USB microcontroller is powered by the USB
port’s 5-V supply whereas the CDCE72010 is powered by the 3.3-V external supply. This setup is optimal
for programming the CDCE72010 while also taking measurements. This configuration removes the power
variation found in USB power supplies by isolating the CDCE72010 from the USB supply.
The CDCE72010EVM can use power supplied through the USB cable as its sole power source. However,
due to power supply variances in the USB supply, this configuration is not recommended for
measurements. This setup is for saving configuration settings to the CDCE72010 and later powering the
device from its internal memory (useful if a USB port is unavailable in a laboratory or test chamber). In this
configuration, JP_3_3 must be moved from its default position to the new position shown in the following
illustration. Also, the Enable EVM Power box must be checked on the EVM GUI interface software.
After Programming
When operating the CDCE72010 without the USB programming cable (useful in laboratory settings in
which a PC is unavailable at the laboratory station), the CDCE72010 needs to be configured and saved in
the EEPROM in one of the preceding configurations and then reconfigured for external power supply
usage.
Prior to making these board modifications, the CDCE72010 settings must be saved with one of the USB
cable attached configurations. The
Write EEPROM Unlocked
or
Write EEPROM Locked
software button
must be used to save the CDCE72010 to its internal EEPROM. After the settings are saved to EEPROM,
the USB cable can be removed. Once the cable has been disconnected, JP_3_3 must be in the
Using
External 3.3V Supply
position (as seen in the preceding diagram). The EVM now is ready for use without
the USB cable connected. The CDCE72010 always starts from its saved configuration state in this mode.
10
1.5-GHz Low-Phase Noise Clock Evaluation Board
SLAU250 – May 2008