STV8172A
Application Hints
4.2 AC-Coupled Applications
In AC-coupled applications (See Figure 6), only one supply (VS) 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).
Figure 6: AC-coupled Application
0 470µF 0 0 0 0 0 0 0 0 00.1µF
CF (47 to 100µF)
+Vs Output
Voltage
6
3
2
Flyback
Power
Amplifier
Generator
Output
Current
Ip
7+
00000
5
VM
R3
1-
Thermal
Safety
1.5Ω Rd(*)
Yoke
Ly
Vm
0 040 0 0
00000
0 0 0 0 R5
Cs R4
CL
(*) recommended:
5----0L----µy---s-- < Rd < 2----0L----µy---s--
R2
R1
00000
4.2.1
Application Hints
Gain is defined as in the previous case:
Ip = V-----M------2–-----V----m--- × R-----1---R--×--2---R----3--
Choose R1 then either R2 or R3. For good output centering, V7 must fulfill the following equation:
-R-V----2----S4-------+-–----RV----7-5- = V-----7-----–----V----R------M----3--------+2----------V--------m-------- + R-V----72--
or
V7
×
⎛
⎝
R---1--3--
+ R---1--2-- + -R----4-----+1-----R-----5- ⎠⎞ =
⎛
⎜
⎝
-2---(---R----4-V----+S-----R-----5----)
+
-V---2-M----×--+---R--V--3---m---⎠⎟⎞
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