LMX25311146EVAL National Semiconductor, LMX25311146EVAL Datasheet - Page 4

• Manufacturer Part Number: LMX25311146EVAL
• Description: BOARD EVAL FOR LMX25311146
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMX25311146EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Utilized Ic / Part: LMX2531LQ1146E
• Silicon Manufacturer: National
• Silicon Core Number: LMX2531
• Kit Application Type: Clock & Timing
• Application Sub Type: Frequency Synthesizer
• Kit Contents: Board, Cable, CD
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Problem
All Modes
LPT Mode (Uses Parallel Port Cable)
USB Mode (Uses USB to Parallel Port Converter)
Troubleshooting
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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
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
On the menu, select 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
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
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.
Ensure the OSCin signal and cable provide 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. If the loop bandwidth is decreased,
in-band phase noise can be degraded
Ensure the measurement equipment noise floor is not limiting the measurement.
For spectrum analyzers, the noise floor at a particular setting can be measured
by removing the RF input signal
If the settings are changed from what the board was designed for, ensure the
delta-sigma modulator is not increasing the far-out noise. To know this, tune to
an integer channel and set the ORDER bit to “Reset Modulator”. The far out
phase noise should not decrease.
attenuation or select a lower order delta-sigma modulator.
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Windows often requires Administrative access to write to the parallel
port
Ensure that the parallel port is set to “Enabled” in windows device
manager
A reboot upon installation of CodeLoader is sometimes necessary to get
the parallel port to work.
Standard mode is the most reliable. This can be set in the BIOS mode
of the computer as “Normal”, “Output Only”, or “AT”
L M X 2 5 3 1 L Q 1 1 4 6 E
Corrective Actions
E V A L U A T I O N
If it does, try a loop filter with more
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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