Texas Instruments High Performance Frequency Synthesizer System with Integrated VCO LMX25312820EVAL/NOPB LMX25312820EVAL/NOPB 데이터 시트
제품 코드
LMX25312820EVAL/NOPB
L M X 2 5 3 1 L Q 2 8 2 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S
Troubleshooting
Software does not communicate with the evaluation boards
LPT or USB Mode
• Ensure a valid signal is presented to the OSCin connector. If a signal generator is used,
ensure the RF is ON.
• Consult the CodeLoader instructions for more detailed information on communication issues.
LPT Mode (Uses Parallel Port Cable)
• Ensure that CodeLoader is selected to LPT mode on the Port Setup tab
• Ensure the proper port number is selected (LPT1, LPT2, LPT3). CodeLoader does NOT
automatically detect this.
• Ensure the LPT cable is securely connected to the computer and board.
• Exit and Restart CodeLoader.
• Ensure the parallel port is in the correct mode.
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Windows often requires Administrative access to write to the parallel port.
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Ensure that the parallel port is set to “Enabled” in windows device manager.
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A reboot upon installation of CodeLoader is sometimes necessary to get the parallel
port to work.
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Standard mode is the most reliable. This can be set in the BIOS mode of the
computer as “Normal”, “Output Only”, or “AT.”
USB Mode (Uses USB <--> uWire Interface Board, NSID = USB2UWIRE)
• On the menu, select LPT/USB->Version to verify communication with the board.
• Ensure the Green LEDs are lit on the USB board.
• Ensure there are no conflicts with other USB devices and reinstall the board.
Part responds to programming, but does not lock to the correct
frequency
• Ensure that there is a valid signal presented to the OSCin connector. If a signal generator is
used, ensure that the RF is set to ON.
• If using the lower frequency band (DIV2=1), the VCO frequency in CodeLoader should be
twice the frequency at the Fout pin.
• Ensure that the VCO FREQUENCY CAL bits on the Bits/Pins tab are correct.
• Ensure that the loop filter is optimized if the charge pump current, phase detector frequency, or
loop filter values have been changed from their original settings. Ensure that the integrated
loop filter components on CodeLoader are set to their proper settings.
loop filter components on CodeLoader are set to their proper settings.
Close-in phase noise is worse than evaluation board instructions
show
• Ensure the signal presented to OSCin connector is clean. Try another source, or if it is a
signal generator, try using a higher frequency and dividing it down to the phase detector
frequency.
frequency.
• Ensure the OSCin signal after the connecting cable provides sufficient power level.
• If the phase detector frequency or charge pump current are lowered from their original settings,
the in-band phase noise can be degraded, even if the loop filter is re-designed for the same
loop bandwidth.
loop bandwidth.
• If the loop bandwidth is decreased, in-band phase noise can be degraded.
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