LMX2320 National Semiconductor, LMX2320 Datasheet - Page 12

• Manufacturer Part Number: LMX2320
• Description: Frequency Synthesizer for RF Personal Communications
• Manufacturer: National Semiconductor

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Functional Description
SERIAL DATA INPUT TIMING
Notes Parenthesis data indicates programmable reference divider data
Test Conditions The Serial Data Input Timing is tested using a symmetrical waveform around V
Phase Characteristics
In normal operation the FC pin is used to reverse the polari-
ty of the phase detector Both the internal and any external
charge pump are affected
Depending upon VCO characteristics FC pin should be set
accordingly
When FC is set HIGH or OPEN CIRCUIT the monitor pin of
the phase comparator input f
divider output f
programmable divider output f
PHASE COMPARATOR AND INTERNAL CHARGE PUMP CHARACTERISTICS
Notes Phase difference detection range
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When VCO characteristics are like (1) FC should be set
HIGH or OPEN CIRCUIT
When VCO characteristics are like (2) FC should be set
LOW
Data shifted into register on clock rising edge
Data is shifted in MSB first
The minimum width pump up and pump down current pulses occur at the D
FC
e
HIGH
amplitudes of 2 2V
r
When FC is set LOW f
p
out
V
CC
b
2
is set to the reference
e
2 7V and 2 6V
to
(Continued)
a
2
out
is set to the
V
CC
e
5 5V
12
o
pin when the loop is locked
CC
2 The test waveform has an edge rate of 0 6 V ns with
VCO Characteristics
TL W 12339 – 23
TL W 12339 – 21
TL W 12339 – 22