el4585 Intersil Corporation, el4585 Datasheet - Page 9

• Manufacturer Part Number: el4585
• Description: Horizontal Genlock, 8fsc
• Manufacturer: Intersil Corporation

For our example, C
tuning.) Examples for each frequency using the internal
divider follow.
NOTE: Use shielded inductors for optimum performance.
FREQUENCY
LC VCO COMPONENT VALUES (APPROXIMATE) (NOTE)
26.602
35.468
21.476
24.546
28.636
(MHz)
27.0
29.5
1
L
=17pF. (A trim cap may be used for fine
1
TYPICAL XTAL VCO
3.3
3.3
2.7
2.2
4.7
3.9
3.3
TYPICAL LC VCO
(µH)
9
C
1
22
21
22
16
26
22
17
(pF)
C
2
220
220
220
220
220
220
220
(pF)
EL4585
Typical Application
Horizontal genlock provides clock for an analog to digital
converter, digitizing analog video.
The above oscillators are arranged as Colpitts oscillators,
and the structure is redrawn here to emphasize the split
capacitance used in a Colpitts oscillator. It should be noted
that this oscillator configuration is just one of literally
hundreds possible, and the configuration shown here does
not necessarily represent the best solution for all
applications. Crystal manufacturers are very informative
sources on the design and use of oscillators in a wide variety
of applications, and the reader is encouraged to become
familiar with them.
C
control from the oscillator, and V
device. C
FREQUENCY
1
is to adjust the center frequency, C
26.602
35.468
21.476
24.546
28.636
(MHz)
XTAL VCO COMPONENT VALUES (APPROXIMATE)
27.0
29.5
2
should be much larger than C
COLPITTS OSCILLATOR
(kΩ)
300
300
300
300
300
300
300
R
1
1
is the primary control
(pF)
C
15
15
15
15
15
15
15
1
2
DC isolates the
V
so that V
0.001
0.001
0.001
0.001
0.001
0.001
0.001
(µF)
C
1
July 1, 2005
2
has
FN7175.3