TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 20

• Manufacturer Part Number: TEA2029
• Description: APPLICATION NOTE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TEA2028 - TEA2029 APPLICATION NOTE
V.5.1 - Duty of different building blocks
V.5.1.1 - ” 2” Phase comparator
This block generates a current proportional to the
phase difference between the phase reference ” ”
and the middle of the line flyback to be phase-
locked.
V.5.1.2 - Low-pass filter
- Rejects the parasitic component ”sum of phases”
- Smoothens the ”phase difference” component
- Allow ”phase adjustment” by generating an error
V.5.1.3 - Phase modulator
Uses the line saw-tooth voltage to convert the
voltage delivered by the low-pass filter into a phase
corresponding to the line transistor turn-off control
signal.
V.5.1.4 - Flip-flop
Generates the turn-off control signal for a constant
time (fixed by the external capacitor), the phase of
which is set by the modulator.
V.5.1.5 - Output stage
- Delivers the control signal for line transistor driver
- Disables the output during start-up and protection
V.5.1.6 - Line deflection stage
- Generates the saw-tooth current for line yoke
- Generates the high voltage required by picture
V.5.2 - Operation of building blocks
To provide an easier understanding of the subject,
the ” ” loop study will be covered as a function of
various time intervals and not as a function of
phase.
V.5.2.1 - Phase comparator ” 2”
The operation is identical to that of ” ” loop.
The V signal issued by logic block is phased with
respect to the middle of line sync pulse on Pin 27
and delayed by a 2.6 s interval so as to be at the
middle of blanking time on video cathodes.
The output current component ”2f
the low-pass filter.
20/46
within the loop
phases
tube and other supply voltages
The line flyback information is provided by the
EHT transformer.
H
” is rejected by
Figure 37
- The average current is i = 2I
- The conversion gain is therefore :
Figure 38
Where : t = t
A =
At : I = 550 A and T
constant since ”I” is a multiple of ”I
Pin 14.
V
V
V
LF
i
2
t
+I
-I
=
1
2
0
i
T
2I
H
= 17 A/ s
IN
550 A
t
IN
- t
OUT
I
t
0.3 s
t
OUT
H
2.6 s
= 64 s, ”A” will remain
Video on
Cathodes
T
V
Videp on
Pin 27
H
t
CC
i
REF
Filter F(p)
Constant
Voltage
Line
Flyback
(LF)
T
” current on
H