TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 18

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

TEA2028 - TEA2029 APPLICATION NOTE
Figure 32
Figure 33 : 1 Inhibition Logic Block Diagram
V.4 - Line saw-tooth generator
Before going through a detailedstudy of the second
phase locked loop ” 2”, let’s have an overview of
the linesaw-tooth generator which has been mainly
implemented for 2 phase variations and also the
phase modulation of the switching power supply.
It uses the combination of an external capacitor
connected to Pin 13 and an internally implemented
constant current generatorto generatea saw-tooth
voltage at line frequency.
Its frequency is determined by the reset frequency
Figure 34
18/46
VCR
Line Inhibition
Constant
1.26V
BLK
V
+
CC
I
R
1 4
LINE
INHIBITI ON
LINE SYNC .
1 SIGNAL
I
R14
3.32k
R
FS
x K
&
FRI
1 3
VIDEO
ON PIN 27
Inhibit ion
I
C13
3.3nF
C
Video Recognition
1
0.3 s
T1
Mute
x 1
5.8 s
2 .35 s
Reset
&
S
INH(L)
To 2
and SMPS
&
of the capacitor ”C13”. This reset signal is issued
by the line logic circuitry at a period multiple of VCO
period ( 32).
- I
- V
- V
- In sync mode :
2.35 s
= 3.48V
T
C
H
13PP
CE(SAT)T1
LS
= K I
= 64 s, t
6.5 s
Line Sync.
S
=
INH(S)
I
R
&
&
C
3.5
= K
Reset
T
RESET
V
20mV
H
V
C13
PP
Inhibition
13
0
1.26
R
t
Phase Comparator ( 1)
reset
14
1
500 A
(Long)
= 6.5 s, K = 0.527
64 s
= 200 A
T
V
H
=
6.5 s
13(MAX)
K
1.26
R14 C13
= 3.5V
t
t
T
100 A
(short)
H
t
2%
reset