lmx2377u National Semiconductor Corporation, lmx2377u Datasheet - Page 28

• Manufacturer Part Number: lmx2377u
• Description: Lmx2377u Pllatinum? Ultra Low Power Dual Frequency Synthesizer For Rf Personal Communications 2.5 Ghz/1.2 Ghz
• Manufacturer: National Semiconductor Corporation

www.national.com
Test Setups
The block diagram above illustrates the setup required to
measure the LMX2377U device’s OSC
level. The same setup is used for the LMX2370TMEB/
LMX2370SLEEB Evaluation Boards. This setup is similar to
the f
now connected to the OSC
V
signal generator. The R counter is typically set to 1000, i.e.
Main R_CNTR Word = 1000 or Aux R_CNTR Word = 1000.
The reference divider output is routed to the F
selecting the Main PLL R Divider Output word (F
Word = 1 or 9) in Code Loader. Similarly, a Universal
= 2 or 10) or the Aux PLL R Divider Output word (F
CC
. The 51 Ω shunt resistor matches the OSC
IN
sensitivity setup except that the signal generator is
(Continued)
in
pin and both f
in
LMX2377U OSC
IN
buffer sensitivity
pins are tied to
in
o
input to the
LD pin by
o
LD Word
o
LD
in
Sensitivity Test Setup
28
Counter is connected to the F
MHz reference output from the signal generator. The output
of the reference divider is monitored and should be equal to
OSC
Again, V
power supply, Vµc, is tied to V
and voltage level are then swept with the signal generator.
The measurements are repeated at different temperatures,
namely T
when the frequency error of the divided input signal is
greater than or equal to 1 Hz.
in
/ Main R_CNTR or OSC
CC
A
= -40˚C, +25˚C, and +85˚C. Sensitivity is reached
is swept from 2.7V to 5.5V. The MICROWIRE
cc
o
in
LD pin and is tied to the 10
. The OSC
/ Aux R_CNTR.
in
input frequency
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