STMicroelectronics Confidential
7/14
STV8172A
Application Hints
4.2
AC-Coupled Applications
In AC-coupled applications (See
Figure 6
), only one supply (V
S
) is needed. The vertical position of
the scanning cannot be adjusted with input bias (for that purpose, usually some current is injected
or sunk with a resistor in the low side of the yoke).
4.2.1
Application Hints
Gain is defined as in the previous case:
Choose R
1
then either R
2
or R
3
. For good output centering, V
7
must fulfill the following equation:
or
Figure 6: AC-coupled Application
R
3
+Vs
R
2
R
1
Rd(*)
Yoke
Ly
(*)
recommended:
Ly
50
m
s
-------------
Rd
Ly
20
m
s
-------------
<
<
0.1μF
C
F
(47 to 100μF)
Power
Amplifier
Flyback
Generator
Thermal
Safety
470μF
Output
Current
Output
Voltage
I
p
7
3
2
5
6
1
4
V
M
V
m
+
-
C
s
R
4
C
L
R
5
0.22
μ
F
1.5
W
I
p
V
M
V
m
–
2
------------------------
R
2
R
1
R
3
´
----------------------
´
=
V
S
2
--------
V
7
–
R
4
R
5
+
----------------------
V
7
V
M
V
m
+
2
------------------------
–
R
3
--------------------------------------
V
7
R
2
-------
+
=
V
7
1
R
3
-------
è
æ
1
R
2
-------
+
´
1
R
4
R
5
+
----------------------
ø
ö
V
S
2 R
4
R
5
+
(
)
------------------------------
V
M
V
m
+
2
R
3
´
------------------------
+
è
ø
ç
÷
æ
ö
=
+
