TDA8218 Datasheet, PDF (6/9 Pages) STMicroelectronics – HORIZONTAL AND VERTICAL DEFLECTION CIRCUIT

TDA8218
Figure 3 : Line Oscillator
Vcc1
R5
Phase
comparator
output
11
R4
The oscillator thresholds are internally fixed by
resistors. The discharge of the capacitor depends
on the internal resistor R4. The control voltage is
applied on resistor R5.
The sync-pulse drives the current in the compara-
tor. The line flyback integrated by the external net
work gives on pin 13 a saw tooth, the DC offset of
this saw tooth is fixed by VC. The comparator
Figure 4 : Phase Comparator
output provides a positive current for the part of the
signal on pin 13 greater than to VC and a negative
current for the other part. When the line flyback and
the video signal are synchronized, the output of the
comparator is an alternatively negativeand positive
current. The frame sync-pulse inhibits the compa-
rator to prevent frequency drift of the line oscillator
on the frame beginning.
Figure 5
Vcc1
Line
Flyback
Integrated
Flyback
Sync pulse
12
Vc
SL2
ST1
13
Vc
Output
Current
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