8 Troubleshooting Guide
If the EVM does not work as expected, use
to identify potential root causes. Consider the following:
• Do not make modifications to the EVM or change the default settings until AFTER it is verified to be working.
• Register read back requires the correct software setup. See
for details.
• The POR current of the LMX2820EVM is approximately 220 mA.
• The power-down current of the LMX2820EVM is approximately 10 mA.
Device locked
Congratulation!
Start
Yes
Verify hardware setup:
x
Validate power supply is connected, turned on, and current limit is appropriate for the device.
x
Validate OSCin signal is supplied and turned on, if required.
x
Ensure programming cable is hooked up to the board.
x
Ensure spectrum analyzer center frequency matches target frequency. Choose wide span so that the carrier can
be seen if it is off frequency.
x
Ensure device is not powered down by the CE pin.
x
Load all registers (Ctrl+L).
Device locked
Congratulation!
No
Yes
Verify software setup:
x
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.
x
Validate that no boxes are red. If so, mouse over and read the tool tips.
x
Ensure that all the frequency boxes values are correct. Also understand that the VCO frequency could be
different than the output frequency as there are often dividers after the boxes.
x
Load all registers (Ctrl+L).
x
Try Readback at this point, if necessary.
Device locked
Congratulation!
No
Yes
Verify communications:
x
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,
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, ensure that the USB2ANY button is turned green.
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have the program blink the green LED.
x
Send simple one way communication to the device such as: POWERDOWN, RESET, or change the status of a
pin. Realize that if a RESET is done, do a Ctrl+L to refresh the registers afterwards. For POWERDOWN, you can
validate this looking at the current on the power supply.
Device locked
Congratulation!
No
Yes
No
Contact TI support
www.ti.com/support
Figure 8-1. Troubleshooting Guide
Troubleshooting Guide
16
LMX2820EVM Evaluation Module
SNAU246A – JUNE 2020 – REVISED JANUARY 2021
Copyright © 2021 Texas Instruments Incorporated
