el4584 Intersil Corporation, el4584 Datasheet - Page 9

• Manufacturer Part Number: el4584
• Description: Horizontal Genlock, 4fsc
• Manufacturer: Intersil Corporation

For our example, C
fine tuning.) Examples for each frequency using the internal
divider follow.
Typical Application
Horizontal genlock provides clock for an analog to digital
converter, digitizing analog video.
NOTE: Use shielded inductors for optimum performance.
FREQUENCY
LC VCO COMPONENT VALUES (APPROXIMATE) (NOTE)
13.301
17.734
10.738
12.273
14.318
(MHZ)
14.75
13.5
FIGURE 5. TYPICAL XTAL VCO
FIGURE 4. TYPICAL LC VCO
1
(µH)
= 14pF. (A trim cap may be used for
L
15
15
12
12
22
18
15
1
9
(pF)
C
18
17
18
10
20
17
14
1
(pF)
220
220
220
220
220
220
220
C
2
EL4584
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 V1 is the primary control
device. C
maximum modulation capability. The frequency of oscillation
is given by:
F
C
Choosing Loop Filter Components
The PLL, VCO, and loop filter can be described as:
FREQUENCY
T
1
=
is to adjust the center frequency, C
=
------------------------- -
12π LC
13.301
17.734
10.738
12.273
14.318
(MHz)
14.75
XTAL VCO COMPONENT VALUES (APPROXIMATE)
13.5
------------------------------------------------------------------------- -
(
C
1
1
C
2
2
should be much larger than C
)
T
FIGURE 6. COLPITTS OSCILLATOR
+
C
(
C
1
C
1
C
2
C
V
(kΩ)
)
300
300
300
300
300
300
300
V
R
+
1
(
C
2
C
V
)
(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
July 25, 2005
(µF)
C
1
2
has
FN7174.2