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
Loop Filter
Loop Bandwidth
14 kHz
K
φ
1440 uA (16X)
Phase Margin
54.1 °
F
PD
10 MHz
Crystal Frequency
10 MHz
Output Frequency
2710 to 2925 MHz (DIV2=0)
1355 to 1462 MHz (DIV2=1)
Supply Voltage
3.0 Volts
VCO Gain
12 to 28 MHz/Volt
VCO
CPout
op
en
100 nF
1K
Ω
100 pF
100 pF
20 K
Ω
20 K
Ω
Vtune
Quick Setup
•
Install the CodeLoader software which is available at
www.national.com/timing/software/
•
Attach the parallel cable or USB <--> uWire cable to the computer and the evaluation board.
•
Connect 3.0 volts to the
Vcc
connector.
•
Connect
the
Fout
connector to a spectrum analyzer or phase noise analyzer.
•
Connect a clean 10 MHz source to the
OSCin
pin. Typically, the 10 MHz output from the back
of the RF test equipment is a good source. Signal generators tend to be very noisy and should
be used with caution. If a signal generator is used, the signal generator phase noise
contribution can be reduced by setting the signal to 80 MHz and dividing this down to a phase
detector frequency of 10 MHz.
•
Set up the CodeLoader software.
o
Select the proper part from the menu as Select Part->PLL+VCO->LMX2531LQ2820E
o
Select the proper mode from the Mode menu.
o
Load the part by pressing Ctrl+L or selecting Keyboard Controls->Load Device from
the menu.
•
It is recommended to ensure proper communication with the device.
o
Click the REG_RST bit on the bits/pins page and observe the current go to 0 mA.
o
Unclick the REG_RST bit AND press Ctrl+L. The current should be approximately
35 mA.
o
If device does not respond to this, consult the troubleshooting section.
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