EL4584CS Ver la hoja de datos (PDF) - Elantec -> Intersil
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EL4584CS Datasheet PDF : 16 Pages
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EL4584C
Horizontal Genlock 4 FSC
Applications Information
Choosing External Components
1 To choose LC VCO components first pick the
desired operating frequency For our example
we will use 14 31818 MHz with an H-sync fre-
quency of 15 734 kHz
2 Choose a reasonable inductor value (10–20mH
works well) We choose 15 mH
3 Calculate CT needed to produce FOSC
1
FOSC e 2q 0LCT
1
1
CT
e
e
4q2F2L
4q2(14
318e6)2(15e
b
e8
6)
2
pF
4 From the varactor data sheet find CV 2 5V
the desired lock voltage CVe23 pF for our
SMV1204-12 for example
5 C2 should be about 10CV so we choose
C2e220 pF for our example
6 Calculate C1 Since
CT
e
(C1C2)
a
C1C2CV
(C1CV) a
(C2CV)
then
C1
e
(C2CV)
C2CTCV
b (C2CT) b
(CTCV)
For our example C1e14 pF (A trim cap may be
used for fine tuning ) Examples for each frequen-
cy using the internal divider follow
Typical Application
Horizontal genlock provides clock for an analog
to digital converter digitizing analog video
Typical LC VCO
Figure 10
4584 – 10
LC VCO Component Values (Approximate)
Frequency
(MHz)
L1
(mH)
C1
(pF)
C2
(pF)
13 301
15
18
220
13 5
15
17
220
14 75
12
18
220
17 734
12
10
220
10 738
22
20
220
12 273
18
17
220
14 318
15
14
220
Note Use shielded inductors for optimum performance
Typical Xtal VCO
Figure 11
4584 – 11
4584 – 18
9
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